September 2008 Technical Report 

 NREL/TP-550-43827

International Energy Agency Building Energy Simulation Test 

and Diagnostic Method (IEA BESTEST) 

Multi-Zone Non-Airflow In-Depth Diagnostic Cases: 

MZ320 – MZ360 

(Revised Cover) 

By 

J. Neymark 

J. Neymark & Associates, Wheat Ridge, Colorado, U.S. 

R. Judkoff 

National Renewable Energy Laboratory, Golden, Colorado, U.S. 

With 

D. Alexander 

Cardiff University, Cardiff, Wales, U.K. 

C. Felsmann 

Dresden University of Technology, Dresden, Germany 

P. Strachan 

University of Strathclyde, Glasgow, Scotland, U.K. 

A. Wijsman 

VABI Software BV, Delft, The Netherlands 

Link to Accompanying Zipped Data Files (6.5 MB)

National Renewable Energy Laboratory 

1617 Cole Boulevard 

Golden, Colorado 80401-3393
International Energy Agency Building 

Energy Simulation Test and Diagnostic 

Method (IEA BESTEST) 

Multi-Zone Non-Airflow In-Depth 

Diagnostic Cases: MZ320 – MZ360 

J. Neymark

J. Neymark & Associates 

R. Judkoff 

National Renewable Energy Laboratory

Contributors: 

D. Alexander Cardiff University 

C. Felsmann Dresden University of Technology

P. Strachan University of Strathclyde

A. Wijsman VABI Software 

Prepared under Task No. BEC76051 

Technical Report 

NREL/TP-550-43827 

September 2008 

National Renewable Energy Laboratory

1617 Cole Boulevard, Golden, Colorado 80401-3393 

303-275-3000 • www.nrel.gov 

Operated for the U.S. Department of Energy 

Office of Energy Efficiency and Renewable Energy 

by Midwest Research Institute • Battelle 

Contract No. DE-AC36-99-GO10337
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Acknowledgments 

The work described in this report was a cooperative effort involving the members of the International 

Energy Agency (IEA) Testing and Validation of Building Energy Simulation Tools Experts Group. The 

group was composed of experts from the IEA Solar Heating and Cooling (SHC) Programme, Task 34, 

and Energy Conservation in Buildings and Community Systems (ECBCS) Programme Annex 43. 

The project participants that provided the majority of early field-trial work, preliminary sensitivity tests, 

and feedback on the test specification are listed as co-authors. We also gratefully acknowledge the 

contributions from modelers and authors of sections on additional computer programs used in this effort, 

including: 

• Robert Henninger and Michael Witte; GARD Analytics, United States: EnergyPlus 

• Julien L’Hoest, Christophe Adam, Philippe André and Corinne Rogiest; University of Liege, 

Belgium: TRNSYS-16 

• Harry Boyer, Frederic Miranville, and Alain Bastide; University of Reunion Island, France: 

CODYRUN 

• Bruno Peuportier; Paris School of Mines, France: COMFIE 

• Jean Noel; JNLOG, France: KoZiBu. 

The following participants at the beginning of the project provided preliminary simulations and early 

valuable feedback on test cases: Juan Travesi, ACHSL, Spain; Pavel Charvat, Brno University of 

Technology, Czech Republic; Peter Riederer and Zaki El Khoury, Centre Scientifique et Technique du 

Batiment, France. 

We appreciate the support and guidance of Drury Crawley, U.S. Department of Energy (DOE) program 

manager for this IEA research task and DOE representative to the IEA SHC Programme Executive 

Committee; and Richard Karney, DOE representative to the IEA ECBCS Programme Executive 

Committee. 

iii
Preface

This report is a product of a joint effort between the International Energy Agency (IEA) Solar Heating 

and Cooling (SHC) and Energy Conservation in Buildings and Community Systems (ECBCS) 

Programmes. SHC monitors this work as Task 34 and ECBCS monitors this work as Annex 43. Ron 

Judkoff of the National Renewable Energy Laboratory (NREL) was the Operating Agent for IEA SHC 

34/ECBCS 43 on behalf of the United States Department of Energy. 

International Energy Agency 

The International Energy Agency (IEA) was established in 1974 within the framework of the 

Organisation for Economic Co-operation and Development (OECD) to implement an international energy 

programme. A basic aim of the IEA is to foster co-operation among the twenty-four IEA participating 

countries and to increase energy security through energy conservation, development of alternative energy 

sources and energy research, development and demonstration (RD&D). 

Solar Heating and Cooling Programme 

The Solar Heating and Cooling Programme was one of the first IEA Implementing Agreements to be 

established. Since 1977, its members have been collaborating to advance active solar and passive solar 

technologies and their application in buildings and other areas, such as agriculture and industry. Current 

members are: 

Australia Finland Portugal 

Austria France Spain 

Belgium Italy Sweden 

Canada Mexico Switzerland 

Denmark Netherlands United States 

European Commission New Zealand 

Germany Norway 

A total of 39 Tasks have been initiated, 30 of which have been completed. Each Task is managed by an 

Operating Agent from one of the participating countries. Overall control of the program rests with an 

Executive Committee comprised of one representative from each contracting party to the Implementing 

Agreement. In addition to the Task work, a number of special activities—Memorandum of 

Understanding with solar thermal trade organizations, statistics collection and analysis, conferences and 

workshops—have been undertaken. 

The Tasks of the IEA Solar Heating and Cooling Programme, both underway and completed are as 

follows: 

Current Tasks: 

Task 36 Solar Resource Knowledge Management 

Task 37 Advanced Housing Renovation with Solar & Conservation 

Task 38 Solar Assisted Cooling Systems 

Task 39 Polymeric Materials for Solar Thermal Applications 

Completed Tasks: 

Task 1 Investigation of the Performance of Solar Heating and Cooling Systems 

Task 2 Coordination of Solar Heating and Cooling R&D 

iv
Task 3 Performance Testing of Solar Collectors 

Task 4 Development of an Insolation Handbook and Instrument Package 

Task 5 Use of Existing Meteorological Information for Solar Energy Application 

Task 6 Performance of Solar Systems Using Evacuated Collectors 

Task 7 Central Solar Heating Plants with Seasonal Storage 

Task 8 Passive and Hybrid Solar Low Energy Buildings 

Task 9 Solar Radiation and Pyranometry Studies 

Task 10 Solar Materials R&D 

Task 11 Passive and Hybrid Solar Commercial Buildings 

Task 12 Building Energy Analysis and Design Tools for Solar Applications 

Task 13 Advance Solar Low Energy Buildings 

Task 14 Advance Active Solar Energy Systems 

Task 16 Photovoltaics in Buildings 

Task 17 Measuring and Modeling Spectral Radiation 

Task 18 Advanced Glazing and Associated Materials for Solar and Building Applications 

Task 19 Solar Air Systems 

Task 20 Solar Energy in Building Renovation 

Task 21 Daylight in Buildings 

Task 23 Optimization of Solar Energy Use in Large Buildings 

Task 22 Building Energy Analysis Tools 

Task 24 Solar Procurement 

Task 25 Solar Assisted Air Conditioning of Buildings 

Task 26 Solar Combisystems 

Task 28 Solar Sustainable Housing 

Task 27 Performance of Solar Facade Components 

Task 29 Solar Crop Drying 

Task 31 Daylighting Buildings in the 21st Century 

Task 32 Advanced Storage Concepts for Solar and Low Energy Buildings 

Task 33 Solar Heat for Industrial Processes 

Task 34 Testing and Validation of Building Energy Simulation Tools 

Task 35 PV/Thermal Solar Systems 

Completed Working Groups: 

 CSHPSS, ISOLDE, Materials in Solar Thermal Collectors, and the Evaluation of Task 13 Houses 

To find more IEA Solar Heating and Cooling Programme publications or learn about the Programme visit 

our Internet site at www.iea-shc.org or contact the SHC Executive Secretary, Pamela Murphy, e-mail: 

pmurphy@MorseAssociatesInc.com. 

Energy Conservation in Buildings and Community Systems 

The IEA sponsors research and development in a number of areas related to energy. The mission of one 

of those areas, the ECBCS - Energy Conservation for Building and Community Systems Programme, is to 

facilitate and accelerate the introduction of energy conservation, and environmentally sustainable 

technologies into healthy buildings and community systems, through innovation and research in decisionmaking, building assemblies and systems, and commercialisation. The objectives of collaborative work 

within the ECBCS R&D program are directly derived from the on-going energy and environmental 

challenges facing IEA countries in the area of construction, energy market and research. ECBCS 

addresses major challenges and takes advantage of opportunities in the following areas: 

v
• exploitation of innovation and information technology; 

• impact of energy measures on indoor health and usability; 

• integration of building energy measures and tools to changes in lifestyles, work environment 

alternatives, and business environment. 

The Executive Committee 

Overall control of the program is maintained by an Executive Committee, which not only monitors 

existing projects but also identifies new areas where collaborative effort may be beneficial. To date the 

following projects have been initiated by the executive committee on Energy Conservation in Buildings 

and Community Systems (completed projects are identified by (*) ): 

Annex 1: Load Energy Determination of Buildings (*) 

Annex 2: Ekistics and Advanced Community Energy Systems (*) 

Annex 3: Energy Conservation in Residential Buildings (*) 

Annex 4: Glasgow Commercial Building Monitoring (*) 

Annex 5: Air Infiltration and Ventilation Centre 

Annex 6: Energy Systems and Design of Communities (*) 

Annex 7: Local Government Energy Planning (*) 

Annex 8: Inhabitants Behaviour with Regard to Ventilation (*) 

Annex 9: Minimum Ventilation Rates (*) 

Annex 10: Building HVAC System Simulation (*) 

Annex 11: Energy Auditing (*) 

Annex 12: Windows and Fenestration (*) 

Annex 13: Energy Management in Hospitals (*) 

Annex 14: Condensation and Energy (*) 

Annex 15: Energy Efficiency in Schools (*) 

Annex 16: BEMS 1- User Interfaces and System Integration (*) 

Annex 17: BEMS 2- Evaluation and Emulation Techniques (*) 

Annex 18: Demand Controlled Ventilation Systems (*) 

Annex 19: Low Slope Roof Systems (*) 

Annex 20: Air Flow Patterns within Buildings (*) 

Annex 21: Thermal Modelling (*) 

Annex 22: Energy Efficient Communities (*) 

Annex 23: Multi Zone Air Flow Modelling (COMIS) (*) 

Annex 24: Heat, Air and Moisture Transfer in Envelopes (*) 

Annex 25: Real time HEVAC Simulation (*) 

Annex 26: Energy Efficient Ventilation of Large Enclosures (*) 

Annex 27: Evaluation and Demonstration of Domestic Ventilation Systems (*) 

Annex 28: Low Energy Cooling Systems (*) 

Annex 29: Daylight in Buildings (*) 

Annex 30: Bringing Simulation to Application (*) 

Annex 31: Energy-Related Environmental Impact of Buildings (*) 

Annex 32: Integral Building Envelope Performance Assessment (*) 

Annex 33: Advanced Local Energy Planning (*) 

Annex 34: Computer-Aided Evaluation of HVAC System Performance (*) 

Annex 35: Design of Energy Efficient Hybrid Ventilation (HYBVENT) (*) 

Annex 36: Retrofitting of Educational Buildings (*) 

Annex 37: Low Exergy Systems for Heating and Cooling of Buildings (LowEx) (*) 

Annex 38: Solar Sustainable Housing (*) 

Annex 39: High Performance Insulation Systems (*) 

vi
Annex 40: Building Commissioning to Improve Energy Performance (*) 

Annex 41: Whole Building Heat, Air and Moisture Response (MOIST-ENG) 

Annex 42: The Simulation of Building-Integrated Fuel Cell and Other Cogeneration Systems 

(FC+COGEN-SIM) 

Annex 43: Testing and Validation of Building Energy Simulation Tools 

Annex 44: Integrating Environmentally Responsive Elements in Buildings 

Annex 45: Energy Efficient Electric Lighting for Buildings 

Annex 46: Holistic Assessment Tool-kit on Energy Efficient Retrofit Measures for Government 

Buildings (EnERGo) 

Annex 47: Cost-Effective Commissioning for Existing and Low Energy Buildings 

Annex 48: Heat Pumping and Reversible Air Conditioning 

Annex 49: Low Exergy Systems for High Performance Built Environments and Communities 

Annex 50: Prefabricated Systems for Low Energy / High Comfort Building Renewal 

Working Group - Energy Efficiency in Educational Buildings (*) 

Working Group - Indicators of Energy Efficiency in Cold Climate Buildings (*) 

Working Group - Annex 36 Extension: The Energy Concept Adviser (*) 

(*) – Completed 

Participating countries in ECBCS: 

Australia, Belgium, CEC, Canada, Czech Republic, Denmark, Finland, France, Germany, Greece, Israel, 

Italy, Japan, the Netherlands, New Zealand, Norway, Poland, Portugal, Sweden, Switzerland, Turkey, 

United Kingdom and the United States of America. 

SHC Task 34/ECBCS Annex 43: Testing and Validation of Building Energy 

Simulation Tools 

Goal and Objectives 

The goal of this Task/Annex is to undertake pre-normative research to develop a comprehensive and 

integrated suite of building energy analysis tool tests involving analytical, comparative, and empirical 

methods. These methods will provide for quality assurance of software, and some of the methods will be 

enacted by codes and standards bodies to certify software used for showing compliance to building 

energy standards. This goal will be pursued by accomplishing the following objectives: 

• Create and make widely available a comprehensive and integrated suite of IEA Building Energy 

Simulation Test (BESTEST) cases for evaluating, diagnosing, and correcting building energy 

simulation software. Tests will address modeling of the building thermal fabric and building 

mechanical equipment systems in the context of innovative low energy buildings. 

• Maintain and expand as appropriate analytical solutions for building energy analysis tool 

evaluation. 

• Create and make widely available high-quality empirical validation data sets, including detailed 

and unambiguous documentation of the input data required for validating software, for a selected 

number of representative design conditions. 

Scope 

This Task/Annex investigates the availability and accuracy of building energy analysis tools and 

engineering models to evaluate the performance of innovative low-energy buildings. Innovative lowenergy buildings attempt to be highly energy efficient by using advanced energy-efficiency technologies 

or a combination of energy efficiency and solar energy technologies. To be useful in a practical sense, 

such tools must also be capable of modeling conventional buildings. The scope of the Task is limited to 

vii
building energy simulation tools, including emerging modular type tools, and to widely used innovative 

low-energy design concepts. Activities will include development of analytical, comparative and empirical 

methods for evaluating, diagnosing, and correcting errors in building energy simulation software. 

The audience for the results of the Task/Annex is building energy simulation tool developers, and codes 

and standards (normes) organizations that need methods for certifying software. However, tool users such 

as architects, engineers, energy consultants, product manufacturers, and building owners and managers 

are the ultimate beneficiaries of the research, and will be informed through targeted reports and articles. 

Means 

The objectives are to be achieved by the participants in the following projects. 

 Comparative and Analytical Verification Tests: 

Project A: Ground-Coupled Heat Transfer with Respect to Floor Slab and Basement Constructions 

Project B: Multi-Zone Buildings and Air Flow 

 Empirical Validation and Comparative Tests: 

Project C: Shading/Daylighting/Load Interaction 

Project D: Mechanical Equipment and Controls 

Project E: Buildings with Double-Skin Facades 

 Other: 

Project G: Web Site for Consolidation of Tool Evaluation Tests 

Participants 

The participants in the Task are Australia, Belgium, Canada, Czech Republic, Denmark, France, 

Germany, Japan, The Netherlands, Spain, Sweden, Switzerland, the United Kingdom, and the United 

States. The United States served as the Operating Agent for this Task; Ron Judkoff of the National 

Renewable Energy Laboratory provided Operating Agent services on behalf of the U.S. Department of 

Energy. 

This report documents work carried out under Project B: Multi-Zone Buildings and Air Flow. 

viii
 ix

Table of Contents

Page

Acknowledgments ............................................................................................................................... iii 

Preface ............................................................................................................................................... iv 

Electronic Media Contents .................................................................................................................. xi 

Executive Summary ............................................................................................................................ xii 

 References for Executive Summary ............................................................................................. xx 

Introduction ........................................................................................................................................ xxiii 

 References for Introduction ......................................................................................................... xxiv 

1.0 Part I: User's Manual: Procedure and Specification ...................................................................... 1 

 1.1 General Description of the Test Cases ....................................................................................... 1 

 1.1.1 Accompanying Electronic Files ........................................................................................ 1 

 1.2 Performing the Tests ................................................................................................................ 3 

 1.2.1 Modeling Rules ................................................................................................................ 3 

1.2.2 Comparing Your Output to the Analytical Solution and Example Simulation Results .... 5 

 1.3 Test Case Specifications ............................................................................................................ 6 

 1.3.1 Case MZ320: 3-Zone Steady-State Conduction Analytical Verification Test .................. 6 

 1.3.1.1 Objective ............................................................................................................... 6 

 1.3.1.2 Method ................................................................................................................ 6 

 1.3.1.3 Input Specification ................................................................................................ 6 

 1.3.1.4 Output Requirements ............................................................................................ 10

 1.3.1.5 Analytical Solution ............................................................................................... 10 

 1.3.2 In-Depth Multi-Zone Shading Test Cases ........................................................................ 12 

 1.3.2.1 Case MZ340: Unshaded Calorimeter – In-Depth Shading Test Base Case .......... 12 

 1.3.2.1.1 Objective ................................................................................................... 12

 1.3.2.1.2 Method ...................................................................................................... 12

 1.3.2.1.3 Input Specification .................................................................................... 12 

 1.3.2.1.4 Output Requirements ................................................................................ 16 

 1.3.2.2 Case MZ350: In-Depth Multi-Zone Fin Shading ................................................. 17 

 1.3.2.2.1 Objective ................................................................................................... 17

 1.3.2.2.2 Method ...................................................................................................... 17

 1.3.2.2.3 Input Specification .................................................................................... 18 

 1.3.2.2.4 Output Requirements ................................................................................ 19 

 1.3.2.3 Case MZ355 In-Depth Multi-Zone Automated Building Self-Shading ............... 20 

 1.3.2.3.1 Objective ................................................................................................... 20

 1.3.2.3.2 Method ...................................................................................................... 20

 1.3.2.3.3 Input Specification .................................................................................... 20 

 1.3.2.3.4 Output Requirements ................................................................................ 22 

 1.3.3 Case MZ360: In-Depth Internal Window Calorimeter ..................................................... 22 

 1.3.3.1 Objective ................................................................................................................ 22 

 1.3.3.2 Method .................................................................................................................. 23 

 1.3.3.3 Input Specification ................................................................................................ 23 

 1.3.3.4 Output Requirements ............................................................................................ 26

Appendix A – TMY2 File Format ...................................................................................................... 28 

Appendix B: Output Spreadsheet Instructions .................................................................................... 33 

Appendix C: Abbreviations and Acronyms ........................................................................................ 35 

Appendix D: Glossary ........................................................................................................................ 37 
Appendix E: Remarks About The Test Cases .................................................................................... 39 

Appendix F: Using the Flow Diagrams to Diagnose the Results......................................................... 41 

References for Part I ........................................................................................................................ 44 

2.0 Part II: Production of Simulation Results ................................................................................... 45 

 2.1 Introduction ......................................................................................................................... 45 

 2.2 Selection of Simulation Programs and Modeling Rules for Simulations ............................... 45 

 2.3 Improvements to the Test Specification as a Result of the Field Trials.................................. 47 

 2.4 Examples of Error Trapping with BESTEST Diagnostics...................................................... 53 

 2.4.1 EnergyPlus .................................................................................................................... 53 

 2.4.2 ESP-r ......................................................................................................................... 56 

 2.4.3 HTB2 ......................................................................................................................... 61 

 2.4.4 VA114 ......................................................................................................................... 67 

 2.4.5 TRNSYS-TUD ............................................................................................................. 75 

 2.4.6 TRNSYS-16 ................................................................................................................. 84 

 2.4.7 CODYRUN .................................................................................................................. 86 

 2.4.8 COMFIE ...................................................................................................................... 88 

 2.5 Interpretation of Results ......................................................................................................... 89 

 2.5.1 Use of Calorimetry and An Analytical Solution to Isolate Effects of Specific Models 89 

 2.5.2 Improvements to Simulations during the Field Trials................................................... 90 

 2.5.3 Test Cases for Future Work .......................................................................................... 98

 2.6 Conclusions and Recommendations ...................................................................................... 99 

 2.6.1 Conclusions ................................................................................................................ 99 

 2.6.2 Recommendations......................................................................................................... 103 

 2.7 Abbreviations and Acronyms for Parts II and III ................................................................... 105 

 2.8 References for Part II ............................................................................................................. 107 

 2.9 Appendix II: Simulation Modeler Reports.............................................................................. 110 

 Appendix II-A: EnergyPlus Version 2.1.0.012, GARD Analytics, United States............. 111 

 Appendix II-B: ESP-r Version 11.5, University of Strathclyde, United Kingdom ........... 119 

 Appendix II-C: HTB2 Version 2.20AD, Cardiff University, United Kingdom ............... 122 

 Appendix II-D: TRNSYS-TUD, Dresden University of Technology, Germany .............. 127 

 Appendix II-E: TRNSYS-16, University of Liège, Belgium ............................................ 132 

 Appendix II-F: VA114 Version 2.25, VABI Software, The Netherlands ........................ 140 

 Appendix II-G: CODYRUN, University of Reunion Island, France ................................ 169 

 Appendix II-H: COMFIE, Paris School of Mines, France ............................................... 172 

 Appendix II-I: KoZiBu, JNLOG, France .......................................................................... 181 

3.0 Part III: Simulation Field Trial Results ......................................................................................... 183 

 3.1 Introduction ......................................................................................................................... 183 

 3.2 Zone Cooling Load Versus Transmitted Solar Radiation Results for Cases MZ340 – MZ360 183 

 3.3 Further Comments on Results for Multi-Zone Shading Cases MZ340, MZ350, and MZ355 184 

 3.4 Results Graphs and Tables ..................................................................................................... 185 

 Graphs ......................................................................................................................................... 186 

 Tables .......................................................................................................................................... 214 

x
Electronic Media Contents 

Files apply as they are called out in the test procedure. 

README-MZ.DOC: Electronic media contents 

MZ320.TM2: TMY2 weather data for 20°C constant ODB, 4.3 m/s wind speed, solar off 

MZ340.TM2: TMY2 weather data for 20°C constant ODB, 4.3 m/s wind speed, solar on (Miami.TM2) 

MZ-Output.XLS: Raw output data spreadsheet 

MZ-RESULTS-Annuals.XLS: Results spreadsheet to assist users with plotting their results versus the 

example simulation annual summary results 

MZ-RESULTS-Hourlies.XLS: Results spreadsheet to assist users with plotting their results versus the 

example simulation hourly results 

MZ-Results.DOC: Documentation for navigating MZ-RESULTS-Annuals.XLS and MZ-RESULTSHourlies.XLS

\InpFiles-MZ subfolder: (IEA SHC Task 34/ECBCS Annex 43 participant simulation input files) 

 \EnergyPlus 

 \ESP-r 

 \HTB2 

 \TRNSYS-TUD 

 \VA114 

 \COMFIE 

xi
Executive Summary 

This report documents a set of in-depth diagnostic test cases for multi-zone heat transfer models that do 

not include the heat and mass transfer effects of airflow between zones. Another set of test cases dealing 

with airflow modeling is under development by the Japanese team participating in this IEA Task and will 

be published in a separate report. The multi-zone non-airflow test cases represent an extension to IEA 

BESTEST.1

 This new work was conducted by the National Renewable Energy Laboratory (NREL), 

United States in collaboration with a working group of international experts under International Energy 

Agency (IEA) Solar Heating and Cooling (SHC) Programme Task 34 and IEA Energy Conservation in 

Buildings and Community Systems (ECBCS) Programme Annex 43 (IEA 34/43). 

Background 

The development of practical procedures and data for tool evaluation and improvement is part of an overall 

IEA validation methodology that NREL2,3,4 and the IEA5,6 have been developing for many years. The 

methodology combines empirical validation, analytical verification, and comparative analysis techniques; 

details are discussed in the Background Section of HVAC BESTEST Volume 1,7

 with updates published in 

the 2005 ASHRAE Handbook of Fundamentals8

 and elsewhere.4 NREL originally developed the BESTEST 

method in IEA SHC Task 12 to test building thermal fabric (envelope) models, and to diagnose sources of 

predictive disagreements.1

 This method of test was adopted with some refinements by the American Society 

of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) in accordance with procedures of the 

American National Standards Institute (ANSI), and now forms the basis for ANSI/ASHRAE Standard 140, 

Method of Test for the Evaluation of Building Energy Analysis Computer Programs.9,10,11 Since Standard 

140 was first published, three HVAC BESTEST test suites developed within IEA SHC Task 22 have been 

added: two that address unitary space cooling equipment,7,12 and one that addresses fuel-fired furnaces.13

The new in-depth multi-zone non-airflow test cases described in this report are also planned for inclusion in 

Standard 140. 

Importance of the Multi-Zone Modeling Problem

Many buildings have multiple mechanical equipment control zones, and are therefore better modeled with 

multiple zones. Additionally, architectural features related to shading or that use internal windows are 

often applied in a multi-zone context. For example, a shading device associated with one zone of a model 

may cast a shadow on a window associated with another zone of that model. 

Current IEA BESTEST building thermal fabric test cases originally published by NREL in 19951,11 test 

the ability to model the thermal physics related to many typical building features such as thermal mass, 

windows, shading devices, orientation, internal gains, mechanical ventilation, and thermostat set point 

variation. These test cases are applied in a single-zone modeling context, except for one test case for 

modeling a sunspace that interacts with a conditioned zone via a common wall. HERS BESTEST,14 also 

published by NREL in 1995, is designed to similarly test simplified tools commonly used with residential 

modeling. These test cases provide a more realistic, but less diagnostic context than IEA BESTEST.15

HERS BESTEST includes the possibility for (but does not require) multi-zone modeling in all of its cases 

for an unconditioned attic, and in two of its cases that include a basement. However, the HERS BESTEST 

output requirements do not disaggregate results for separate zones, which inhibits multi-zone modeling 

diagnostics. 

If a model has good agreement for the current set of building thermal fabric test cases that emphasize 

single-zone modeling, phenomena specific to multi-zone configurations are not necessarily being 

correctly modeled. Additional work published during IEA SHC Task 12 by Tampere University of 

xii
Technology16 developed six test cases in a realistic commercial building/multi-zone context using two 

conditioned zones separated by a conditioned or unconditioned corridor zone, where only walls with 

windows are exposed to ambient conditions. NREL reviewed this work and observed the following:17 

• Although the cases use a multi-zone configuration, multi-zone modeling effects are not well 

isolated. 

o The only discernible multi-zone modeling observation was that an unconditioned corridor 

caused disagreement among simulation results to expand versus a conditioned corridor. 

o Other than that, because of many simultaneously acting phenomena, it was difficult to 

make specific conclusions regarding multi-zone interactions. 

• No found bugs were documented for the simulation programs that ran the field trials of the multizone test cases, whereas several found bugs were documented and fixed during field trials of the 

IEA BESTEST single-zone test cases that were also developed during IEA SHC Task 12. 

As none of the test suites described above adequately isolates phenomena specific to multi-zone 

modeling, test cases must be developed to address such phenomena. 

The Current IEA 34/43 Multi-Zone Non-Airflow Diagnostic Test Cases

This report documents a set of five diagnostic test cases for multi-zone non-airflow heat transfer models. 

The test cases cover modeling of: 

• Interzonal conduction heat transfer, assuming one-dimensional conduction 

• Multi-zone shading, including building self shading 

• Internal windows between zones. 

We began the test cases by developing a relatively simple steady-state analytical solution (analytical 

verification test) for multi-zone conduction. Good agreement for the multi-zone conduction analytical 

verification tests was obtained early in the project. This provided a good starting point for developing 

diagnostic comparative test cases that test multi-zone shading models and internal window models. 

We specified the multi-zone shading and internal window test cases by using building zones designed to 

be modeled as precise calorimeters, where the only thermal mass is for the zone air. The basic principle is 

that all solar radiation incident on an exterior window is captured within a zone, such that the zone 

cooling load is equivalent to the solar radiation incident on that window. Causes of disagreements are 

therefore limited to either an issue with the specific model being tested (the shading or internal window 

model), modeling of incident solar radiation, inability to precisely model the idealizations defining the 

zone as a calorimeter, or an input error. Additionally, sensitivity “delta” cases allow intermodel 

comparison of the difference between zone cooling loads with a shading device and without shading. This 

allows better isolation of shading model effects, as differences among models not related specifically to 

shading models should cancel out. 

The effects of thermal mass were not tested in these new cases because the original IEA BESTEST1

comparative cases explored building envelope thermal mass effects in detail in a single-zone context (and 

in a two-zone case with a sunspace). By excluding thermal inertia and minimizing other simultaneous 

effects, the current specialized multi-zone cases maximize diagnostic power, and also minimize the 

number of cases required to address the tested phenomena. In the absence of multi-zone mass interaction 

test cases for the current configurations, if a simulation model demonstrates agreement for the original 

IEA BESTEST cases with thermal mass and demonstrates agreement for the new multi-zone test cases, 

that would suggest that such tested simulations may provide agreement where aspects of both types of test 

cases are combined. As thermal mass interactions (and other interactions) are important to test explicitly, 

xiii
our recommendations for future activities (see Section 2.5.3) include developing multi-zone cases with 

thermal mass. 

Results and Conclusions 

Field trials of the new IEA BESTEST cases were conducted with a number of detailed state-of-the-art 

whole-building energy simulation programs from around the world (see Table ES-1). The field-trial 

process was iterative in that executing the simulations led to refinement of the BESTEST cases, and the 

results of the tests led to improving and debugging the models. Improvements to simulation programs or 

simulation inputs made by participants must have a mathematical and a physical basis, and must be 

applied consistently across tests. Arbitrary modification of a simulation program’s input or internal code 

just for the purpose of more closely matching a given set of results is not allowed. All improvements were 

required to be documented and justified in the modeler reports. 

Initial results for the multi-zone conduction cases with adiabatic exterior walls and conducting internal walls 

are shown in Figure ES-1. Disagreement for the initial two- and three-zone cases with a simple analytical 

solution ranged from 6% to 8%, where only two programs are shown as disagreeing. Here, disagreement is 

the difference between the maximum and minimum results for each case, divided by the mean of the 

results for each case ((max-min)/mean). Two other software developers reported fixing issues before 

submitting their results; based on anecdotal discussion from modeler reports these “pre-initial” results would 

have had disagreements with order of magnitude similar to those shown for the other programs. 

Additionally, three of the four reported initial disagreements arose because the boundary conditions 

specified by the test cases could not be modeled exactly; the other was an input error. Subsequent fixes to 

the programs yielded very good agreement with the analytical solutions. 

This initial good agreement led us to design a more challenging three-zone test case with more conduction 

interactions, which was still analytically solvable. This case is a system of three zones in series with a 

conditioned zone on one end adjacent to two adjacent unconditioned (floating temperature) zones, where 

both the interior and exterior walls are conductive (see Part I, Section 1.3.1 for details). All models tested 

agreed with the analytical solution within ≤ 0.3% except for one program (see Figure ES-2). (For results 

shown in Figures ES-1 and ES-2, some participants for the earliest cases were not able to submit results 

for later cases, and vice versa.) 

For the multi-zone shading and internal window test cases, improvements to the simulation programs are 

evident when initial results are compared to final results, as shown in Figures ES-3 and ES-4, 

respectively, for the multi-zone shading cases, and Figures ES-5 and ES-6, respectively, for the internal 

window cases. These results indicate that there was initially 20%–90% and 40%–155% disagreement 

among annual cooling loads for various zones for the multi-zone shading and internal window cases, 

respectively, with substantial scatter among the programs. After correcting software and modeling errors 

using BESTEST diagnostics – there have been 31 fixes so far – the remaining disagreements among 

results for various zones for multi-zone shading are 5%–13%, and for a single internal-window 

configuration are 7%–34%. For the most challenging configuration with a second internal window in 

series, disagreement for annual cooling load for the zone interior to the second internal window is 112% 

(see bars for Zone C in Figure ES-6), thus indicating further refinement of models for this configuration 

may be warranted. Scatter among results was reduced for all the cases. 

xiv
Table ES-1. Participating Organizations and Models 

Simulation 

Program Authoring Organization Implemented by Abbreviation 

EnergyPlus 

2.1.0.012 

LBNL/UIUC/DOE-BT,a,b,c United 

States 

GARD Analytics, Inc., United 

States 

EnergyPlus/GARD 

ESP-r ESRU,d

 United Kingdom ESRU,d United Kingdom ESP-r/ESRU 

HTB2 WSA,e

 United Kingdom WSA, e United Kingdom HTB2/WSA 

TRNSYS-TUD University of Wisconsin/Dresden 

University of Technology, United 

States/Germany 

Dresden University of 

Technology, Germany 

TRNSYS-TUD/TUD 

TRNSYS-16 University of Wisconsin, United 

States 

University of Liège, Belgium TRNSYS-16/ULg 

VA114 2.25 VABI Software BV, The 

Netherlands 

VABI Software BV, The 

Netherlands 

VA114-CirBm/VABI 

VA114-CirDf/VABI 

Simulation 

Program 

(MZ320 Only)

Authoring Organization Implemented by 

 

Abbreviation 

CODYRUN University of Reunion Island, 

France 

University of Reunion Island, 

France 

UR 

COMFIE EdMP/IZUBA,f,g France EdMP,f

 France EdMP 

KoZiBu INSA-Lyon/JNLOG,h,i JNLOG,i

 France JNLOG 

a

LBNL: Lawrence Berkeley National Laboratory, United States 

b

UIUC: University of Illinois Urbana/Champaign, United States c

DOE-BT: U.S. Department of Energy, Office of Building Technologies, Energy Efficiency and Renewable Energy, United States 

d

ESRU: Energy Systems Research Unit, University of Strathclyde, United Kingdom 

e

Welsh School of Architecture, Cardiff University, United Kingdom 

f

Ecole des Mines de Paris, France 

g

IZUBA Energies, France 

h

INSA-Lyon Thermal Center, France 

i

Jean Noel, France 

xv
IEA BESTEST Multi-Zone: MZ200, MZ300 

Steady-State Sensible Cooling Load, Zone A

0

200

400

600

800

1000

1200

1400

MZ200, 2-Zone MZ300, 3-Zone

Sensible Cooling Load (W or Wh/h)

HTB2/WSA TRNSYS/TUD TRNSYS/Brno COMFIE/EdMP

ESP/ESRU CODYRUN/UR DOE-2/ACHSL SIMBAD-mrt/CSTB

SIMBAD-mrss/CSTB Analytical

Figure ES-1. BESTEST multi-zone conduction – preliminary case results before BESTESTing 

IEA BESTEST Multi-Zone: MZ320 

Steady-State Zone C Sensible Cooling Load

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

MZ320, 3-Zone

Sensible Cooling Load (W or Wh/h)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg COMFIE/EdMP

ESP-r/ESRU CODYRUN/UR VA114/VABI EnergyPlus/GARD

KoZiBu/JNLOG Analytical

Figure ES-2. BESTEST multi-zone conduction – final case results after BESTESTing 

xvi
IEA BESTEST Multi-Zone: MZ340, MZ350, MZ355 

Annual Sensible Cooling Load, All Zones

0

3000

6000

9000

12000

15000

MZ340 MZ350, MZ355

Zone B

MZ350, MZ355

Zone E

MZ350, MZ355

Zone A

MZ350, MZ355

Zone D

 MZ350 

Zone C

 MZ350 

Zone F

Sensible Cooling Load (kWh)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg

ESP-r/ESRU VA114-CirBm/VABI VA114-CirDf/VABI

EnergyPlus/GARD VA114-CirBm-MZ355/VABI VA114-CirDf-MZ355/VABI

EnergyPlus-MZ355/GARD

Figure ES-3. BESTEST multi-zone shading cases – sensible cooling load, before BESTESTing 

(Abbreviations along the x-axis are shorthand for the case descriptions; see Part I for full case 

descriptions; building self-shading results are three rightmost bars for zones B, E, A, and D.) 

IEA BESTEST Multi-Zone: MZ340, MZ350, MZ355 

Annual Sensible Cooling Load, All Zones

0

3000

6000

9000

12000

15000

MZ340 MZ350, MZ355

Zone B

MZ350, MZ355

Zone E

MZ350, MZ355

Zone A

MZ350, MZ355

Zone D

 MZ350 

Zone C

 MZ350 

Zone F

Sensible Cooling Load (kWh)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg

ESP-r/ESRU VA114-CirBm/VABI VA114-CirDf/VABI

EnergyPlus/GARD VA114-CirBm-MZ355/VABI VA114-CirDf-MZ355/VABI

EnergyPlus-MZ355/GARD

Figure ES-4. BESTEST multi-zone shading cases – sensible cooling load, after BESTESTing

(Abbreviations along the x-axis are shorthand for the case descriptions; see Part I for full case 

descriptions; building self-shading results are three rightmost bars for zones B, E, A, and D.)

xvii
IEA BESTEST Multi-Zone: MZ360 

Annual Sensible Cooling Loads

0

20000

40000

60000

80000

100000

120000

140000

Building, Qbldg Zone A, QA Zone B, QB Zone C, QC QB + QC

Sensible Cooling Load (kWh)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg ESP-r/ESRU

VA114-CirBm/VABI VA114-CirDf/VABI EnergyPlus/GARD

Figure ES-5. BESTEST internal windows – sensible cooling load, before BESTESTing

(Abbreviations along the x-axis are shorthand for the output descriptions; see Part I for full 

case descriptions.) 

IEA BESTEST Multi-Zone: MZ360 

Annual Sensible Cooling Loads

0

20000

40000

60000

80000

100000

120000

140000

Building, Qbldg Zone A, QA Zone B, QB Zone C, QC QB + QC

Sensible Cooling Load (kWh)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg ESP-r/ESRU

VA114-CirBm/VABI VA114-CirDf/VABI EnergyPlus/GARD

Figure ES-6. BESTEST internal windows – sensible cooling load, after BESTESTing 

(Abbreviations along the x-axis are shorthand for the output descriptions; see Part I for full 

case descriptions.) 

xviii
xix

Findings 

A number of important technology advances occurred as a result of running the test cases: 

• The improved final agreement for shading cases using idealized/modeled calorimetry enabled us 

to identify disagreements and diagnose errors that may have been missed using the original IEA 

BESTEST shading cases,1

 where for the original IEA BESTEST cases disagreements related to 

modeling realistic optical properties of glazing and interior opaque surfaces along with realistic 

wall conduction employing thermal mass may have obscured disagreements caused by shading 

models. 

• Of 49 found disagreements, 31 were diagnosed and fixed, 11 are planned for investigation by the 

software authors, 3 were judged as acceptable by the software authors, and 4 are awaiting 

notification of the software developer by the modeler. Several of the found errors affected some 

individual results by > 20%. A list of the problems found among the tested models appears in 

Table 2-12 (see Part II, Section 2.6.1); supporting details are included in Part II, Section 2.4. 

• Based on this work, there are a number of recommended areas for further investigation with 

respect to developing additional validation test cases for multi-zone modeling. These are 

described in detail in Part II, Section 2.5.3. 

Based on results after several iterations of BESTESTing, and resulting model improvements, all the 

tested programs now appear to have reliable models for phenomena isolated by the test cases including 

interzonal conduction, multi-zone shading, and internal windows where there are no multiple internal 

windows in series. These test cases did not address thermal inertia interactions for the modeled 

phenomena because thermal mass effects were tested in IEA BESTEST.1

 Some remaining disagreements 

(discussed in Part II, Section 2.4) should be addressed, especially with respect to deficiencies identified 

for three of the models related to modeling a second internal window in series. The simulation results 

(with the noted exceptions) may therefore be used as a reference or benchmark against which other 

software can be tested. 

With respect to the value of the test cases to software developers, a software-developer/vendor 

participants made the following comment about this IEA project: 

“Bestest and IEA-34/43 tests brought a number of new errors to the surface. This shows the 

importance of these test [cycles]!! And still there will be errors in the software!! Development of 

new, specific test cases is of big importance!!”18

Closing Remarks 

The work presented in this report, other work of IEA 34/43, and the work that preceded it in IEA SHC 

Tasks 8, 12, and 22 are important for two reasons: 

• The methods have been extremely successful at correcting software errors in advanced building 

energy simulation programs throughout the world. 

• The methods are finding their way into industry by being adopted as the theoretical basis for 

formalized standard methods of test and software certification procedures; in this sense the work 

may be thought of as pre-normative research. 

ANSI/ASHRAE Standard 14011 and the BESTEST reports that comprise the test suites contained therein 

are being referenced and used by a growing number of code promulgation authorities throughout the 

world. ASHRAE Standard 90.1,19 which is ASHRAE’s consensus energy code for commercial buildings 

and for non-low-rise residential buildings, requires that software used for demonstrating performance 
compliance with Standard 90.1 be tested using ASHRAE Standard 140-2004.10 Software used for 

calculating energy savings for purposes of the energy-efficient commercial building tax deductions

United States must be tested with Standard 140-2007. As part of building energy performance 

assessments under the European Community’s Energy Performance Directive, several countries

using software tools that have been checked with BESTEST. Further details of international use of 

BESTEST, along with growing evidence that the BESTEST procedures are becoming part of softwa

developers’ normal in-house quality control efforts, are included elsewhere. 

 in the 

 are 

re 

omputer scientists universally accept the merits of software testing. A well-known rule of thumb is that 

e 

f 

,

4,8

• Analytical verification 

 diagnostics 

Future work should therefore: 

• Continue to produce a standard set of analytical tests. 

hasize the important modeling issues in large 

• ation. 

inally, the authors wish to acknowledge that the expertise available through the IEA and the dedication 

e 

erts. 

eferences for Executive Summary 

Judkoff, R.; Neymark, J. (1995). International Energy Agency Building Energy Simulation Test (IEA 

Judkoff, R.; Wortman, D.; O’Doherty, B.; Burch, J. (2008). A Methodology for Validating Building 

gy 

20

21

4,22

C

in a typical programming project more than 50% of the total cost is expended in testing the program or 

system being developed.23 Of this about 20% of development time goes toward system testing.24 Becaus

new energy-related technologies are continually being introduced into the buildings market, there will 

always be a need for further development of simulation models, combined with a substantial program o

testing and validation. Such an effort should contain all the elements of an overall validation methodology

including: 

• Comparative testing and

• Empirical validation. 

• Develop a set of diagnostic comparative tests that emp

commercial buildings, including more tests for heating, ventilating, and air-conditioning systems, 

and other mechanical equipment including on-site power generation equipment. 

Develop a sequentially ordered series of high-quality data sets for empirical valid

F

of the participants were essential to the success of this project. Over the four-year field trial effort, there 

were several revisions to the BESTEST specifications and subsequent re-executions of the computer 

simulations. This iterative process led to the refining of the new BESTEST cases, and the results of th

tests helped us improve and debug the simulation models. The process underscores the leveraging of 

resources for the IEA countries participating in this project. Such extensive field trials, and resulting 

enhancements to the tests, were much more cost effective with the participation of the IEA-34/43 exp

R

1

BESTEST) and Diagnostic Method. NREL/TP-472-6231. Golden, Colorado, US: National Renewable 

Energy Laboratory. Available from http://www.nrel.gov/docs/legosti/old/6231.pdf (PDF 13.8 MB). 

2 

Energy Analysis Simulations. NREL/TP-550-42059. Golden, Colorado, US: National Renewable Ener

Laboratory. This is a formal publication of work that was brought to final draft in 1983 and referenced in 

a number of documents as SERI/TR-254-1508. The two reports are identical except for a few minor edits 

to complete the previous draft.

xx
3

Judkoff, R. (1988). “Validation of Building Energy Analysis Simulation Programs at the Solar Energy 

Research Institute.” Energy and Buildings, Vol. 10, No. 3, p. 235. Lausanne, Switzerland: Elsevier 

Sequoia. 

 

4

Judkoff, R.; Neymark, J. (2006). “Model Validation and Testing: The Methodological Foundation of 

ASHRAE Standard 140.” ASHRAE Transactions, 112 (2) 367–376. Atlanta, Georgia, US: American 

Society of Heating, Refrigerating and Air-Conditioning Engineers. 

5

Bloomfield, D., ed. (November 1989). Design Tool Evaluation: Benchmark Cases. IEA T8B4. Solar 

Heating and Cooling Programme, Task VIII: Passive and Hybrid Solar Low-Energy Buildings. Building 

Research Establishment. Garston, Watford, UK: Building Research Establishment. 

6

Lomas, K. (1991). “Dynamic Thermal Simulation Models of Buildings: New Method of Empirical 

Validation.” BSER&T 12(1):25–37. 

7

Neymark J.; Judkoff, R. (2002). International Energy Agency Building Energy Simulation Test and 

Diagnostic Method for Heating Ventilating and Air-Conditioning Equipment Models (HVAC BESTEST), 

Volume 1: Cases E100–E200. NREL/TP-550-30152. Golden, Colorado, US: National Renewable Energy 

Laboratory. Available from http://www.nrel.gov/docs/fy02osti/30152.pdf. 

8

ASHRAE. (2005). 2005 Handbook of Fundamentals, Atlanta, Georgia, US: American Society of 

Heating, Refrigerating and Air-Conditioning Engineers. 

9

ANSI/ASHRAE Standard 140-2001. (2001). Standard Method of Test for the Evaluation of Building 

Energy Analysis Computer Programs. Atlanta, Georgia, US: American Society of Heating, Refrigerating 

and Air-Conditioning Engineers.

10ANSI/ASHRAE Standard 140-2004. (2004). Standard Method of Test for the Evaluation of Building 

Energy Analysis Computer Programs. Atlanta, Georgia, US: American Society of Heating, Refrigerating 

and Air-Conditioning Engineers. 

11ANSI/ASHRAE Standard 140-2007. (2007). Standard Method of Test for the Evaluation of Building 

Energy Analysis Computer Programs. Atlanta, Georgia, US: American Society of Heating, Refrigerating 

and Air-Conditioning Engineers. 

12Neymark, J.; Judkoff, R. (2004). International Energy Agency Building Energy Simulation Test and 

Diagnostic Method for Heating, Ventilating, and Air-Conditioning Equipment Models (HVAC BESTEST), 

Volume 2: Cases E300-E545. NREL/TP-550-36754. Golden, Colorado, US: National Renewable Energy 

Laboratory. www.nrel.gov/docs/fy05osti/36754.pdf. 

13Purdy, J.; Beausoleil-Morrison, I. (2003). Building Energy Simulation Test and Diagnostic Method for 

Heating, Ventilation, and Air-Conditioning Equipment Models (HVAC BESTEST): Fuel-Fired Furnace Test 

Cases. Ottawa, Ontario, Canada: CANMET Energy Technology Centre, Natural Resources Canada. 

Available from www.iea-shc.org/task22/deliverables.htm. 

14Judkoff, R.; Neymark, J. (1995). Home Energy Rating System Building Energy Simulation Test (HERS 

BESTEST). NREL/TP-472-7332. Golden, Colorado, US: National Renewable Energy Laboratory. 

Volume 1: Tier 1 and Tier 2 Tests User's Manual, NREL/TP-472-7332a, available from 

http://www.nrel.gov/docs/legosti/fy96/7332a.pdf (PDF 5.6 MB); 

Volume 2: Tier 1 and Tier 2 Tests Reference Results, NREL/TP-472-7332b, available from 

http://www.nrel.gov/docs/legosti/fy96/7332b.pdf (PDF 1.9 MB). 

xxi
15Neymark, J.; Judkoff, R. (1997). “A Comparative Validation Based Certification Test for Home Energy 

Rating System Software.” Proc. Building Simulation ’97. September 8–10, Prague, Czech Republic. 

International Building Performance Simulation Association. 

16Haapala, T.; Kalema, T.; Kataja, S. (1995). Energy Analysis Tests for Commercial Buildings (Commercial 

Benchmarks). Report 101. Tampere, Finland: Tampere University of Technology. 

17Neymark, J; Judkoff, R. (2003). IEA BESTEST Multi-Zone Review. Golden, Colorado, US: J. Neymark 

& Associates and National Renewable Energy Laboratory. Presented at 1st Experts Meeting of IEA SHC 

Task 34/ECBCS Annex 43, Duebendorf, Switzerland, 30 Sep 2003. See files “MZ-Breakout092703.ppt” 

and “MZ-Prelim092203.doc”, available upon request. 

18Wijsman, A. (2008). Modeler Report for BESTEST Cases MZ320-MZ360, VA114 Version 2.25. Delft, 

Netherlands: VABI Software BV. March 2008. Included with Section 2.9, Appendix II-F, of this final 

report. 

19ANSI/ASHRAE/IESNA. (2007). ANSI/ASHRAE/IESNA Standard 90.1-2007, Energy Standard for 

Buildings Except Low-Rise Residential Buildings. Atlanta, Georgia, US: American Society of Heating, 

Refrigerating and Air-Conditioning Engineers. 

20Internal Revenue Service (IRS). (2008). Amplification of Notice 2006-52, Deduction for Energy 

Efficient Commercial Buildings. IRS Notice 2008-40. Appears in Internal Revenue Bulletin (IRB) No. 

2008-14, April 7, 2008. Washington, DC, US: United States Department of Treasury, Internal Revenue 

Service. 

21European Union. (2002). On the Energy Performance of Buildings. Directive 2002/91/EC of the 

European Parliament and of the Council, Official Journal of the European Communites, December. 

22 Neymark, J.; Judkoff, R.; with Beausoleil-Morrison, I; Ben-Nakhi, A.; Crowley, M.; Deru, M.; 

Henninger, R.; Ribberink, H.; Thornton, J.; Wijsman, A.; Witte, M. (2008). International Energy Agency 

Building Energy Simulation Test and Diagnostic Method (IEA BESTEST) In-Depth Diagnostic Cases for 

Ground Coupled Heat Transfer Related to Slab-On-Grade Construction. NREL/TP-550-43388. Golden, 

Colorado, US: National Renewable Energy Laboratory. 

23Myers, G. (2004). The Art of Software Testing. Hoboken NJ: John Wiley & Sons. See p. xiii. 

24McConnell, S. (2004). Code Complete: A Practical Handbook of Software Construction. Microsoft 

Press, p. 502. 

xxii
Introduction 

A method of test for evaluating building energy simulation computer programs – International Energy 

Agency Building Energy Simulation Test and Diagnostic Method (IEA BESTEST) – was developed by the 

National Renewable Energy Laboratory (NREL), United States, in collaboration with IEA SHC Task 12 

and ECBCS Annex 21 (Judkoff and Neymark 1995a). New work presented herein, which follows up Task 

12, was conducted by NREL in collaboration with the participants of IEA SHC Task 34/ECBCS Annex 

43, Project B (“Multi-Zone Buildings and Air Flow”). The objective of this sub-project is to extend the 

original IEA BESTEST to include additional test cases for multi-zone conduction, multi-zone shading, 

and modeling of internal windows. 

Background 

A discussion of the importance of the multi-zone modeling problem is included in the Executive 

Summary of this report. 

Advantages of BESTEST Methodology

An advantage of the BESTEST methodology is that a program is examined over a broad range of 

parametric interactions based on a variety of output types, minimizing the possibility that compensating 

errors will conceal problems. Performance of the tests resulted in quality improvements to all but one of 

the building energy simulation models used in the field trials, and all of the models used in the multi-zone 

shading and internal window test cases. Some of the bugs that were found may well have been present for 

several years. The fact that they have just now been uncovered shows the power of BESTEST and 

suggests the importance of continuing to develop formalized validation and diagnostic methods. Only 

after coding bugs have been eliminated can the assumptions and approximations in the algorithms be 

evaluated. 

Checking a building energy simulation program for the first time with the BESTEST in-depth multi-zone 

non-airflow test cases requires a few days for an experienced user, not including any necessary 

improvements to the software. Subsequent program checks are faster because input files may be reused. 

Because the simulation programs have taken many years to produce, the new BESTEST cases provide a 

cost-effective way of testing them. As we continue to develop new test cases, we will adhere to the principle 

of parsimony so that the entire suite of BESTEST cases may be implemented by users with a reasonable 

time commitment. 

Software developers, architects, engineers, and researchers can use these new BESTEST cases in a 

number of ways, to: 

 

• Compare output from building energy simulation programs to a set of analytical solutions that 

constitute a reliable set of theoretical results given the underlying physical assumptions in the case 

definitions. 

• Compare several building energy simulation programs to determine their degree of disagreement. 

• Diagnose the algorithmic sources of prediction differences among several building energy 

simulation programs. 

• Compare predictions from other building energy simulation programs to the analytical solution 

and simulation results in this report. 

• Check a program against a previous version of itself after internal code modifications to ensure 

that only the intended changes actually resulted. 

xxiii
• Check a program against itself after a single algorithmic change to understand the sensitivity 

among algorithms. 

Other BESTEST Procedures 

As a BESTEST user, if you have not already tested your software with previously developed BESTEST 

procedures, we strongly recommend that you run all the building thermal fabric and mechanical 

equipment cases currently included in ANSI/ASHRAE Standard 140-2007. (ANSI/ASHRAE 2007. Also 

see: Judkoff and Neymark 1995a; Neymark and Judkoff 2002, 2004; Purdy and Beausoleil-Morrison 

2003.) Another set of building thermal fabric test cases, which were designed to test simplified tools such 

as those currently used for home energy rating systems (HERS), is included in HERS BESTEST (Judkoff 

and Neymark 1995b; Judkoff and Neymark 1997). HERS BESTEST, which is being adapted for Standard 

140, has a more realistic base building than the IEA BESTEST building thermal fabric test cases currently 

included with Standard 140; however, its ability to diagnose sources of differences among results is not as 

robust (Neymark and Judkoff 1997). 

Final Report Structure 

This report is divided into three parts. Part I is a user’s manual that furnishes instructions on how to apply 

this BESTEST procedure. Part II describes the development, field-testing, and production of results data 

for the procedure. Part III presents the simulation program example results in tables and graphs along 

with disagreement statistics that compare the simulation programs to each other; these data can be used to 

compare results from other programs to Part III results. 

References for Introduction 

ANSI/ASHRAE Standard 140-2007. Standard Method of Test for the Evaluation of Building Energy 

Analysis Computer Programs. (2007). Atlanta, GA: American Society of Heating, Refrigerating and AirConditioning Engineers. 

Judkoff, R.; Neymark, J. (1995a). International Energy Agency Building Energy Simulation Test 

(BESTEST) and Diagnostic Method. Golden, Colorado, US: National Renewable Energy Laboratory, 

NREL/TP-472-6231, www.nrel.gov/docs/legosti/old/6231.pdf. 

 

Judkoff, R.; Neymark, J. (1995b). Home Energy Rating System Building Energy Simulation Test (HERS 

BESTEST). Golden, Colorado, US: National Renewable Energy Laboratory, NREL/TP-472-7332. 

Volume 1: Tier 1 and Tier 2 Tests User’s Manual, NREL/TP-472-7332a, 

www.nrel.gov/docs/legosti/fy96/7332a.pdf; 

Volume 2: Tier 1 and Tier 2 Tests Reference Results, NREL/TP-472-7332b, 

www.nrel.gov/docs/legosti/fy96/7332b.pdf. 

Judkoff, R.; Neymark, J. (1997). Home Energy Rating System Building Energy Simulation Test for 

Florida (Florida-HERS BESTEST). Golden, Colorado, US: National Renewable Energy Laboratory, 

NREL/TP-550-23124, www.nrel.gov/docs/legosti/fy97/23124a.pdf. 

Neymark, J.; Judkoff, R. (1997). “A Comparative Validation Based Certification Test for Home Energy 

Rating System Software.” Proc. Building Simulation ’97. September 8–10, Prague, Czech Republic. 

International Building Performance Simulation Association. 

xxiv
Neymark J.; Judkoff, R. (2002). International Energy Agency Building Energy Simulation Test and 

Diagnostic Method for Heating Ventilating and Air-Conditioning Equipment Models (HVAC BESTEST), 

Volume 1: Cases E100–E200. NREL/TP-550-30152. Golden, Colorado, US: National Renewable Energy 

Laboratory. Available from www.nrel.gov/docs/fy02osti/30152.pdf. 

Neymark, J.; Judkoff, R. (2004). International Energy Agency Building Energy Simulation Test and 

Diagnostic Method for Heating, Ventilating, and Air-Conditioning Equipment Models (HVAC BESTEST), 

Vol. 2: Cases E300-E545. Golden, Colorado, US: National Renewable Energy Laboratory, NREL/TP550-36754, www.nrel.gov/docs/fy05osti/36754.pdf. 

Purdy, J.; Beausoleil-Morrison, I. (2003). Building Energy Simulation Test and Diagnostic Method for 

Heating, Ventilating, and Air-Conditioning Equipment Models (HVAC BESTEST): Fuel-Fired Furnace 

Test Cases. Ottawa, Canada: Natural Resources Canada, CANMET Energy Technology Centre. www.ieashc.org/task22/deliverables.htm. 

xxv
1

1.0 Part I: BESTEST User’s Manual: Procedure and Specification 

Cases MZ320 – MZ360 

1.1 General Description of the Test Cases 

Five test cases are summarized in Table 1-1. The test cases are designed to test the ability of building 

energy analysis tools to model multi-zone conduction (one case), multi-zone shading including automated 

building self-shading (three cases), and modeling of internal windows (one case). The multi-zone 

conduction case is an analytical verification test, where simulation results are compared to an analytical 

solution (mathematical truth standard). The remaining cases are comparative tests, where simulation 

results are compared to each other. 

1.1.1 Accompanying Electronic Files 

1.1.1.1 Weather Data Files 

The following TMY2-format weather data files are included with the accompanying electronic media: 

MZ320.TM2 

MZ340.TM2.

A summary of site and weather parameters is given in Table 1-2. The weather data files are applied to the 

test cases as follows: 

Case Weather Data 

MZ320 MZ320.TM2 

MZ340 MZ340.TM2 

MZ350 MZ340.TM2

MZ355 MZ340.TM2

MZ360 MZ340.TM2

1.1.1.2 Other Accompanying Electronic Files 

For reporting output use the following file provided with the accompanying electronic media: 

MZ-Output.XLS. 
2

Table 1-1. Multi-Zone Steady-State Conduction Test Case Summary

Description Comments

Zone A B C A B C Weather

MZ320 Base Case (Steady State) OFF OFF 15 2500 1000 0 To = 20°C TA, TB, qC have 1st L

External Conduction Solar OFFConstant interior and exterior combined surface coefficients

MZ340 Unshaded "Calorimeter" To = 20°C Zone cooling loads = 

 Shading test base case, 2 story Real solar Establishes solar dis Adiabatic walls, ideal windows

MZ350 Fin Shading To = 20°C MZ350-MZ340 tests 

 Fin height > Building height Real solar

MZ355 Building Shading To = 20°C MZ355 = MZ350 inte

 Add zone to match fin shading Real solar

MZ360 2 Internal Windows in Series To = 20°C Zone cooling loads = 

Internal window base case Real solar Tracks ideally transmCalorimetry using adiabatic walls and 

ideal windows

 solar radiation with 

In-Depth Internal Window All All

20 020 020 0

In-Depth MZ Window/Shading All All

20 0

Case Set Point (°C) Internal Gains (W)In-Depth Conduction
Table 1-2. Site and Weather Summary for Multi-Zone Non-Airflow Tests—TMY2 Data 

Weather Type Artificial Conditions 

Weather Format TMY2 

Latitude 25.8° North 

Longitude (local site) 80.3° West 

Altitude 2 m (6.56 ft) 

Time Zone (Standard Meridian Longitude) 5 (75° West) 

Site Flat, unobstructed, located exactly at 

weather station 

Mean Ambient Dry-Bulb Temperature (constant) 20°C (68°F) 

Dew Point Temperature (constant) -56.6°C (-69.9°F) 

Humidity Ratio (constant) 0.000007 kg moisture/kg dry air 

(0.000007 lb moisture/lb dry air) 

Relative Humidity (constant) 0.05% 

Mean Annual Wind Speed 4.3 m/s (9.62 miles/h) 

Maximum Annual Wind Speed 4.3 m/s (9.62 miles/h) 

Quantities That Vary between Data Sets MZ320.TM2 MZ340.TM2 

Global Horizontal Solar Radiation Annual Total 0 kWh/m2 (0 kBtu/ft2) 1793 kWh/m2 (568 kBtu/ft2) 

Direct Normal Solar Radiation Annual Total 0 kWh/m2 (0 kBtu/ft2) 1505 kWh/m2 (477 kBtu/ft2) 

Diffuse Horizontal Solar Radiation Annual Total 0 kWh/m2 (0 kBtu/ft2) 810 kWh/m2 (257 kBtu/ft2) 

1.2 Performing the Tests 

1.2.1 Modeling Rules 

1.2.1.1 Consistent Modeling Methods 

If a simulation program has options for modeling a specific thermal behavior, consistent modeling methods 

shall be used for all cases. For example, if the program being tested gives a choice of methods for modeling 

interior walls, the same interior-wall modeling method shall be used for all cases. Similarly, if the program 

being tested allows different shading algorithms (e.g., shading for a window determined by one central point 

of the window versus disaggregated shading for multiple sub-areas of the window), the same shading 

algorithm shall be used for all cases and for all zones/windows for a given case. 

To generate the example results, the IEA SHC Task 34/ECBCS Annex 43 (IEA 34/43) participants used the 

most detailed level of modeling that was allowed by their simulation programs and that was consistent with 

the level of detail provided in this test specification; more discussion about this is included in Part II, Section 

2.2. When a program has options for modeling this specification, these were discussed in the IEA-34/43 

participant modeler reports included in Part II (Section 2.9). 

1.2.1.2 Equivalent Modeling Methods 

If a program or specific model within a program does not allow direct input of specified values, or if input 

of specified values causes instabilities in a program’s calculations, modelers should develop equivalent 

inputs that match the intent of the test specification as nearly as the software being tested allows. Such 

equivalent inputs are to be developed based on the data provided in the test specification, and such 

equivalent inputs shall have a mathematical, physical, or logical basis, and shall be applied consistently 

throughout the test cases. Document the equivalent modeling method in the modeler report for the tested 

program. 

3
1.2.1.3 Non-applicable Inputs 

In some instances the specification will include input values that do not apply to the input structure of the 

program being tested. When this occurs, disregard the non-applicable inputs and continue. Such inputs are 

in the specification for programs that may need them. 

1.2.1.4 Time Convention 

References to time in this specification are to local standard time. Assume that hour 1 = 0:00–1:00 (the 

interval from midnight to 1:00 a.m.). Do not use daylight savings time or holidays for scheduling. The 

required TMY2 data are in hourly bins corresponding to standard time, consistent with all other schedules. 

1.2.1.5 Geometry Convention 

For these multi-zone cases, geometry convention varies depending on the objective of the test case. 

Instructions regarding the geometry convention for each test case are included with specific test cases 

descriptions where appropriate. 

1.2.1.6 Simulation Initialization and Preconditioning 

If the program being tested allows, begin the simulation initialization process with zone air conditions that 

equal the outdoor air conditions. If the program being tested allows for preconditioning (iterative 

simulation of an initial time period until temperatures or fluxes, or both, stabilize at initial values), use 

that capability. 

 

1.2.1.7 Simulation Duration 

Use the weather data provided to run the full annual simulation. Give outputs as required per the test case 

descriptions below. 

1.2.1.8 Simulation Input Files 

All supporting data required for generating results with the tested software shall be saved, including: 

• Input files 

• Processed weather data 

• Intermediate files containing calculations used for developing inputs 

• A “Readme-softwarename-yymmdd.pdf” file that briefly describes the contents of the above files 

according to their file type (i.e., their “.xyz” file extension). 

1.2.1.9 Omitted Test Cases 

If a program being tested omits a test case, provide an explanation in the modeler report.

1.2.1.10 Modeler Reports 

The IEA-34/43 participants submitted modeler reports along with their simulation results (see Part II, 

Section 2.9). Users developing modeler reports may consider using the structure of any of those modeler 

reports as a template. 

4
1.2.2 Comparing Your Output to the Analytical Solution and Example Simulation 

Results 

 

For Case MZ320, compare output with the Case MZ320 analytical solution; output may also be compared 

with other example simulation results provided in Part III, or with other results that were generated using 

this test procedure. For the other test cases (MZ340 through MZ 360), output may be compared with 

example simulation results provided in Part III, or with other results that were generated using this test 

procedure. For the convenience to users who wish to plot or tabulate their results along with the example 

results of Part III, electronic versions of the example results have been included with the accompanying files 

MZ-RESULTS-Annuals.XLS and MZ-RESULTS-Hourlies.XLS. 

1.2.2.1 Criteria for Determining Agreement between Results 

There are no formal criteria for when results agree or disagree. Determination of when results agree or 

disagree is left to the user. In making this determination the user should consider: 

 

• Magnitude of results for individual cases 

• Magnitude of difference in results between certain cases (e.g., Case MZ350–MZ340)

• Same direction of sensitivity (positive or negative) for difference in results between certain cases 

(e.g., MZ350–MZ340) 

• If results are logically counterintuitive with respect to known or expected physical behavior 

• Availability of a mathematical truth standard (analytical solution) 

• Where a mathematical truth standard is provided, the degree of disagreement that occurred for 

other simulation results versus the mathematical truth standard 

• Example simulation results do not represent a truth standard. 

For any given case, a tested program may fall outside the range of example results without necessarily 

being incorrect. However, it is worthwhile to investigate the source of significant differences, as the 

collective experience of the authors is that such differences often indicate problems with the software or 

its use, including, but not limited to: 

• User input error, where the user misinterpreted or incorrectly entered one or more program inputs 

• A problem with a particular algorithm in the program 

• One or more program algorithms used outside their intended range. 

Also, for any given case, a program that yields values in the middle of the range established by the 

example results should not be perceived as better or worse than a program that yields values at the borders 

of the range. 

1.2.2.2 Diagnostic Logic for Determining Causes of Differences among Results 

To help you identify which algorithm in the tested program is causing specific differences between 

programs, we have included diagnostic flow charts in Appendix F. 

1.2.2.3 Rules for Modifying Simulation Programs or Simulation Inputs 

Modifications to simulation programs or simulation inputs shall have a mathematical, physical, or logical 

basis, and shall be applied consistently across tests. Such improvements must be documented in modeler 

reports. Arbitrary modification of a simulation program’s input or internal code just for the purpose of 

more closely matching a given set of results shall not be allowed. 

5
6

1.3 Test Case Specifications 

1.3.1 Case MZ320: 3-Zone Steady-State Conduction Analytical Verification Test 

1.3.1.1 Objective 

Test the ability of whole-building energy simulation software to model steady-state interzonal conduction 

for three zones.

1.3.1.2 Method

This case tests steady-state multi-zone conduction in a three-zone building with temperature controlled in 

one zone, temperature floating in two other zones, and conduction to the exterior environment. Cooling 

loads are generated with internal gains. Interzonal heat transfer is driven by different temperatures in each 

zone. Constant combined surface coefficients are used to eliminate disagreements among the tested 

programs that may be caused by different convective or radiative surface heat transfer models. This helps 

to better isolate disagreements related specifically to multi-zone modeling, and allows for calculation of 

an analytical solution assuming one-dimensional conduction. Surface heat transfer models are tested in 

the single-zone context in IEA BESTEST (Judkoff and Neymark 1995). Constant temperature weather 

data (TMY2-format) are provided. Compare whole-building simulation results to the analytical solution. 

1.3.1.3 Input Specification 

Case MZ320 is summarized in Figure 1-1. Input parameters are described below. 

Figure 1-1. Case MZ320 – plan view 

Internal Walls

Zone A Zone C

Set Point 15°C 

Cooling Only

Conductive Exterior Walls

Set Point OFF (floating) 

Internal Gains = OFF

6 m 6 m

8 m

0.15 m

N

0.15 m

Zone B

Set Point OFF (floating)

6 m

Internal Gains = 2500 W Internal Gains = 1000 W

hint,combined = 8.29 W/m2K hint,combined = 8.29 W/m2K hint,combined = 8.29 W/m2K

To = 20°C, Solar OFF (αext = 0)

hext,combined = 30.49 W/m2K
1.3.1.3.1 Geometry Convention. If the program being tested automatically includes the thickness of walls 

in a three-dimensional definition of the building geometry, define the wall, roof, and floor dimensions such 

that the interior air volume of each zone remains as specified (e.g., 6 m × 8 m × 2.7 m = 129.6 m3

). 

1.3.1.3.2 Building Construction 

• Zone plan dimensions: each zone = 6 m (19.685 ft) by 8 m (26.247 ft), see Figure 1-1. 

• Zone height = 2.7 m (8.858 ft). 

• Air volume of each zone = 129.6 m3

 (4577 ft3) 

o Site altitude = 2 m (6.56 ft) 

o If the program being tested does not automatically calculate zone air properties or 

provide default values, for density (ρ) and specific heat (cp) of air use: 

 ρ = 1.204 kg/m3

 (0.075 lb/ft3) 

 cp = 1.004 kJ/(kg⋅K) (0.24 Btu/(lb⋅°F)), for dry air. 

• The internal walls common to and separating Zone A from Zone B, and Zone B from Zone C 

have material properties as described in Tables 1-3a and 1-3b using SI and IP units, respectively; 

IP units were developed using conversions of ASHRAE (2005). 

• Internal wall dimensions: length = 8 m (26.247 ft), height = 2.7 m (8.858 ft), thickness = 0.15 m 

(0.4921 ft). 

• All external surfaces of the zones including exterior walls, floor, and roof have material 

properties as described in Tables 1-4a and 1-4b using SI and IP units, respectively; IP units were 

developed using conversions of ASHRAE (2005). 

• Exterior solar absorptance = 0; if the software being tested does not allow a value of 0, use the 

lowest value the software allows (e.g., 0.000001). 

• Interior solar absorptance = 0; if the software being tested does not allow a value of 0, use the 

lowest value the software allows (e.g., 0.000001). 

• Ground reflectance = 0; if the software being tested does not allow a value of 0, use the lowest 

value the software allows (e.g., 0.000001). 

• The floor is suspended above the ground such that its exterior surface interacts with outside air at 

ambient conditions (similar to other exterior surfaces). 

• No windows. 

• No infiltration or ventilation. 

1.3.1.3.3 Internal Gains 

• Zone A: 2500 W (8530 Btu/h) 

• Zone B: 1000 W (3412 Btu/h) 

• Zone C: 0 W (0 Btu/h) 

• Internal gains are 100% convective, 0% radiative 

• Internal gains are 100% sensible, 0% latent. 

These are internally generated sources of heat (from equipment, lighting, occupants, etc.) that are not 

related to operation of mechanical space cooling equipment. 

7
Table 1-3a. Common Wall Material Properties – SI Units 

2

⋅°F)), per ASHRAE (2005). This value is applied to: 

•

b. 

If the program being tested allows direct user input of combined interior surface coefficients, ignore the 

rem ce coefficients, but allows 

only t to 

.29 W/(m2

⋅K) (1.46 Btu/(h⋅ft2⋅°F)) and set the surface infrared emittance to 0 (or as low as the program 

allows). If the program does not allow direct user input of convective surface coefficients, input infrared 

Conductivity Thickness Conductance Resistance Density Specific Heat

Element (W/(m·K)) (m) (W/(m2

·K)) (m2·K/W) (kg/m3) (J/(kg·K))

Int Combined Surf Coef 8.2900 0.1206

Common Wall Material 1.20 0.15 8.0000 0.1250 1400 1000

Int Combined Surf Coef 8.2900 0.1206

Total air-air 2.7303 0.3663

Table 1-3b. Common Wall Material Properties – IP Units 

Conductivity Thickness Conductance Resistance Density Specific Heat

Element (Btu/(h·ft°·F)) (ft) (Btu/(h·ft2

·°F)) (h·ft2·°F/Btu) (lb/ft3) (Btu/(lb·°F))

Int Combined Surf Coef 1.4600 0.6849

Common Wall Material 0.6932 0.4921 1.4089 0.7098 87.5 0.2390

Int Combined Surf Coef 1.4600 0.6849

Total air-air 0.4809 2.0796

Table 1-4a. Exterior Wall Material Properties – SI Units 

Conductivity Thickness Conductance Resistance Density Specific Heat

Element (W/(m·K)) (m) (W/(m2

·K)) (m2·K/W) (kg/m3) (J/(kg·K))

Int Combined Surf Coef 8.2900 0.1206

Exterior Wall Material 0.24 0.15 1.6000 0.6250 1400 1000

Ext Combined Surf Coef 30.4872 0.0328

Total air-air 1.2846 0.7784

Table 1-4b. Exterior Wall Material Properties – IP Units 

Conductivity Thickness Conductance Resistance Density Specific Heat

Element (Btu/(h·ft°·F)) (ft) (Btu/(h·ft2

·°F)) (h·ft2·°F/Btu) (lb/ft3) (Btu/(lb·°F))

Int Combined Surf Coef 1.4600 0.6849

Exterior Wall Material 0.1386 0.4921 0.2818 3.5488 87.5 0.2390

Ext Combined Surf Coef 5.3694 0.1862

Total air-air 0.2262 4.4199

MZ-Results-Annuals.xls!Analytical-MZ320

1.3.1.3.4 Interior Combined Surface Coefficients. Interior combined surface coefficients = 8.29 

W/(m2

⋅K) (1.46 Btu/(h⋅ft

Both sides of the common internal walls, see Tables 1-3a and 1-3b. 

• The interior side of the exterior surfaces (walls, floor, and ceiling), see Tables 1-4a and 1-4

ainder of this paragraph. If it allows direct user input of convective surfa

 automatically calculated surface infrared radiative exchange, set the convective surface coefficien

8

8
9

emittance = 0.9 and use the convective surface coefficient that the program being tested automatically 

calculates. Discuss in your modeler report any resulting deviation from the combined surface coefficients 

specified above.

1.3.1.3.5 Exterior Combined Surface Coefficients. Exterior combined surface coefficients = 30.4872 

W/(m2

⋅K) (5.3694 Btu/(h⋅ft2⋅°F)), see Tables 1-4a and 1-4b. This value applies to all exterior surfaces, 

including the floor. This value corresponds with 4.3 m/s wind speed in the weather data for a rough (brick 

or rough plaster) surface (Judkoff and Neymark 1995, p. C-1; Walton 1983, p. 71). 

If the program being tested allows direct user input of combined exterior surface coefficients, ignore the 

remainder of this paragraph. If the program allows direct user input of convective surface coefficients, but 

allows only automatically calculated surface infrared radiative exchange, set the convective surface 

coefficient to 30.4872 W/(m2

⋅K) (5.3694 Btu/(h⋅ft2⋅°F)) and set the surface infrared emittance to 0 (or as 

low as the program allows). If the program does not allow direct user input of convective surface 

coefficients, input infrared emittance = 0.9 and use the convective surface coefficient that the program 

automatically calculates. Discuss in your modeler report any resulting deviation from the combined 

surface coefficients specified above.

1.3.1.3.6 Mechanical System. Zone A and Zone B have no heating or cooling; those zone temperatures 

are allowed to float to equilibrium. 

The Zone C mechanical system provides sensible cooling only (no heating), and is ideal. The purpose of 

the cooling system is to give results for energy consumption that are equal to the sensible cooling load. 

Model the cooling system as closely as the program being tested allows, as follows: 

• Set points 

o Zone A: Cool = always OFF; Heat = always OFF 

o Zone B: Cool = always OFF; Heat = always OFF 

o Zone C: Cool = ON if temperature > 15°C (59°F); otherwise Cool = OFF. Heat = always 

OFF 

• Sufficient (or greater) capacity to maintain the zone air temperature set point; for example, 1000 

kW (3412 kBtu/h) 

• Uniform zone air temperature (well-mixed air) 

• 100% efficiency (coefficient of performance [COP] = 1) 

• 100% convective air system 

• Ideal controls (zone always at set point); for example, assume the heat extraction rate equals the 

equipment capacity (non-proportional control) and there is continuous ON/OFF cycling within 

the hour as needed 

• Thermostat sensing the zone air temperature only 

• There is no moisture (latent heat) removal. 

1.3.1.3.7 Weather Data. Use the TMY2-format weather data provided with the file 

“MZ320.TM2.” 

TMY2 weather data format is described in Appendix A. A summary of site and weather data parameters 

was provided in Table 1-2. This weather data file is based on Miami.TM2, but has ambient dry-bulb 

temperature set to a constant value of 20°C (68°F), constant wind speed of 4.3 m/s, and solar radiation 

off. The weather data also include many data elements set to 0 or approximate lower limits, and other data 

elements set to neutral (non-extreme) constant values, as follows: 
10

• Global horizontal, direct normal, and diffuse horizontal radiation and illuminance are all set to 0 

(extraterrestrial horizontal and direct normal radiation were left unchanged from the original 

weather data file). 

• Total and opaque sky cover = 10 tenths, implying the entire sky dome is covered by clouds; this 

setting intended to reduce exterior infrared radiation exchange. 

• Dew-point temperature = –56.6°C (–69.9°F) (corresponds with humidity ratio of 0.000007 kg/kg 

and standard atmospheric pressure); calculation of dew point temperature applies common 

psychrometric formulae (ASHRAE 2005; Brandemuehl 1993). TMY2 documentation indicates 

that –60°C (–76°F) is the lower limit for TMY2 data. 

• Relative humidity = 0.05% (corresponds with humidity ratio of 0.000007 kg/kg, standard 

atmospheric pressure, and given dry-bulb temperature); calculations apply common 

psychrometric formulae (ASHRAE, 2005; Brandemuehl 1993). This value rounds to 0% in the 

weather data. 

o If the program being tested does not allow a very low value for relative humidity, adjust 

the input weather data (or other software input) to use the lowest allowable relative 

humidity. 

• Atmospheric pressure = 1013 millibars (= standard atmosphere of 14.696 psia). 

• Wind speed = 4.3 m/s (9.73 miles/h) (Miami.TM2 annual average wind speed = 4.34 m/s, but 

TM2 weather data allow input only to the nearest 0.1 m/s). 

• Visibility = 20 km (rough annual average for Miami and Denver). 

• Ceiling height = 2000 m (rough annual average for Miami and Denver). 

• Present weather: no rain, hail, etc. 

• Precipitable water = 0 mm. 

• Aerosol optical depth = 0.1 broadband turbidity (rough annual average of Miami and Denver). 

• Snow depth = 0 cm, with ≥ 88 days since last snowfall. 

1.3.1.4 Output requirements 

To obtain equivalent steady-state results, run the simulation for one year and submit the following values 

for the last hour of the year:

• Sensible cooling load in Zone C (qC) in W or Wh/h 

• Air temperature in Zone A (TA) (°C) 

• Air temperature in Zone B (TB) (°C) 

• Air temperature in Zone C (TC) (°C). 

1.3.1.5 Analytical solution 

Steady-State First Law Energy Balances: 

Zone A: qA = 0 = qintA – UAcom(TA – TB) – UAextAC(TA – TO) [Eqn. 1] 

Zone B: qB = 0 = qintB + UAcom(TA – TB) – UAcom(TB – TC) – UAextB(TB – TO) [Eqn. 2] 

Zone C: qC = qintC + UAcom(TB – TC) + UAextAC(TO – TC) [Eqn. 3] 

Unknowns: TA, TB, qC
11

The three equations solve the three unknowns. Heat flow conventions used in the equations are for flow 

arrows indicated in Figure 1-2. Nomenclature is defined below: 

qA Sensible cooling load, Zone A (= 0 W, zone temperature allowed to float) 

qB Sensible cooling load, Zone B (= 0 W, zone temperature allowed to float) 

qC Sensible cooling load, Zone C (W, to be solved, cooling load indicated by solution value > 0) 

qintA Internal gains, Zone A (= 2500 W) 

qintB Internal gains, Zone B (= 1000 W) 

qintC Internal gains, Zone C (= 0 W) 

TA Air temperature, Zone A (°C, to be solved) 

TB Air temperature, Zone B (°C, to be solved) 

TC Air temperature, Zone C (= 15°C) 

TO Ambient air temperature (= 20°C) 

UAcom Wall conductance, common wall (W/°C, calculated from the test specification) 

UAextAC Combined exterior surface conductance, Zones A, C (W/°C, calculated from the test 

specification) 

UAextB Combined exterior surface conductance, Zone B (W/°C, calculated from the test specification). 

This is a simple system of equations to solve, as Eqn. 1 and Eqn 2 are a system of two equations with two 

unknowns that can be used to solve for TA and TB. Solved TB can then be entered into Eqn. 3 to obtain 

qC. Solution follows. 

Using Eqn. 1 to isolate TB as f(TA) gives: 

TB = (– qintA + (UAcom + UAextAC)TA – UAextAC TO) / UAcom [Eqn. 1a] 

Replacing TB where it appears in Eqn. 2 with the right side of Eqn. 1a, and solving Eqn. 2 for TA gives: 

[Eqn. 4] 

(qintB+(2+UAextB/UAcom)qintA+UAcomTC+(2UAextAC+UAextBUAextAC/UAcom+UAextB)TO ) 

(UAcom+2UAextAC+UAextB+UAextBUAextAC /UAcom)

Entering appropriate known values from the test specification into the above system of equations results 

in the solution values shown in Figure 1-2. 

Additional symbols used in Figure 1-2 are: 

qAO Heat flow between ambient and Zone A (W, negative value is outward flow from zone) 

qBO Heat flow between ambient and Zone B (W, negative value is outward flow from zone) 

qCO Heat flow between ambient and Zone C (W, positive value is inward flow to zone) 

qAB Heat flow between Zone A and Zone B (W, negative value is outward flow from Zone A) 

qBC Heat flow between Zone B and Zone C (W, negative value is outward flow from Zone B). 

TA = 
12

Figure 1-2. Analytical solution for Case MZ320 

1.3.2 In-Depth Multi-Zone Shading Test Cases 

1.3.2.1 Case MZ340: Unshaded Calorimeter – In-Depth Shading Test Base Case 

1.3.2.1.1 Objective. Define a multi-zone building calorimeter for measuring sensible cooling loads 

caused by transmitted solar radiation. These results will be compared to cases MZ350 and MZ355 that 

test shading of windows by a large fin and by other zones of the building, respectively. 

1.3.2.1.2 Method. Apply a six-zone building as a calorimeter with idealized windows such that results 

disagreements are attributable either to modeling of incident solar radiation, or to inability to model the 

idealizations. Six zones allow comparison of shading effects among different zones (and window 

locations) in later cases. The calorimeter is achieved by specifying ideal windows with solar transmittance 

= 1 and thermal conductance = 0, and non-conductive exterior and interior walls. Interior walls have solar 

absorptance = 1 (to eliminate reflections). Constant combined interior surface coefficients are applied. 

Weather data are provided with typical hourly varying solar radiation. Compare whole-building 

simulation results to each other. 

1.3.2.1.3 Input Specification. The bulk of the work for implementing cases MZ340 through MZ355 is 

assembling an accurate base building model. Thoroughly check base building inputs and results before 

going on to the other cases. 

UAcom 58.975 W/K

UAextAC 192.70 W/K

UAextB 164.95 W/K

To 20 °C

qAO -2130.81 W qBO -791.371 W qCO 963.4804 W

qintA 2500 W qintB 1000 W qintC 0 W

qAB -369.195 W qBC -577.823 W

Tc 15 °C

TA 31.05786 °C TB 24.79771 °C qC 1541.304 W

check 1541.304

Zone A Zone B Zone C
13

1.3.2.1.3.1 Geometry Convention. If the program being tested automatically includes the thickness of walls 

in a three-dimensional definition of the building geometry, define the wall, roof, and floor dimensions such 

that the exterior dimensions of each zone are as specified (e.g., 6 m × 8 m × 5 m). 

1.3.2.1.3.2 Building Construction. The overall six-zone building configuration for Case MZ340 is 

summarized in Figure 1-3. The building comprises six geometrically identical zones with windows on 

only the side facing due west. Geometry of a typical zone is described in Figure 1-4. Input parameters are 

described below. 

• Zone plan dimensions each zone = 6 m × 8 m (19.685 ft × 26.247 ft), with zone height = 5 m 

(16.404 ft); see Figure 1-4. 

• Air volume of each zone = 240 m3

 (8476 ft3) 

o Site altitude and air properties are the same as for MZ320. 

• All opaque external boundaries and common walls of the zones (including all walls, floors, and 

roofs) are adiabatic (thermal conductance = 0 W/(m2

⋅K)); if the program being tested does not 

allow adiabatic surfaces, use the lowest allowable thermal conductance or thermal conductivity 

(e.g. 0.000001 W/(m2

⋅K) or 1·10-8 W/(m⋅K)). 

• Wall thickness = 0.01 m (0.0328 ft), for all walls (including floors and roofs) 

o This thickness minimizes disagreements that could arise if there is difficulty with adherence 

to the geometry convention. 

• All external boundaries and common walls are massless; if the program does not allow massless 

surfaces, use the lowest allowable density and/or thermal capacitance (e.g. 0.000001 kg/m3

 and/or 

J/(kg⋅K)). 

• Exterior solar absorptance = 0; if the software does not allow a value of 0, use the lowest 

allowable value (e.g., 0.000001). 

• Interior solar absorptance = 1 (no internal reflections); if the program does not allow a value of 1, 

use the highest allowable value (e.g., 0.99999...). 

• Ground reflectance = 0; if the program does not allow a value of 0, use the lowest allowable value 

(e.g., 0.000001). 

• No internal gains (set to 0 W for all zones). 

• No infiltration or ventilation. 

1.3.2.1.3.3 Interior Combined Surface Coefficients for Opaque Surfaces. Interior combined surface 

coefficients = 30.4872 W/(m2

⋅K) (5.3694 Btu/(h⋅ft2⋅°F)); this is the same as the exterior surface 

coefficients, and is applied to keep the calorimeter inside surface temperatures to reasonable values. This 

value is applied to: 

• Both sides of the common internal walls 

• The interior side of the exterior surfaces (walls, floor, and ceiling). 

If the program being tested allows direct user input of combined interior surface coefficients, ignore the 

remainder of this paragraph. If the program allows direct user input of convective surface coefficients, but 

allows only automatically calculated surface infrared radiative exchange, set the convective surface 

coefficient to 30.4872 W/(m2

⋅K) (5.3694 Btu/(h⋅ft2⋅°F)) and set the surface infrared emittance to 0 (or as 

low as the program allows). If the program does not allow direct user input of convective surface 

coefficients, input infrared emittance = 0.9 and use the convective surface coefficient that the program 

automatically calculates. Discuss in your modeler report any resulting deviation from the combined 

surface coefficients specified above. 

See Section 1.3.2.1.3.6 regarding surface coefficients for windows. 
14

Figure 1-3. Case MZ340 – unshaded calorimeter isometric 

Figure 1-4. Case MZ340 – single zone detail 

Not to Scale

6 m

6 m

6 m

8 m

5 m

5 m

• Windows face West

• Building geometry is rectangular 

(all angles are 90°) 

Zone A

Zone D

Zone E

Zone C

Zone B

Zone F

N

Not to Scale

5 m

• Window Faces West

• Rectangular geometry 

(all angles are 90°) 

6 m

8 m 4 m

1.0 m

0.5 m

N

Window

4 m
15

1.3.2.1.3.4 Exterior Combined Surface Coefficients for Opaque Surfaces 

• Exterior combined surface coefficients for opaque surfaces are the same as for Case MZ320. 

• See Section 1.3.2.1.3.6 regarding surface coefficients for windows. 

1.3.2.1.3.5 Windows. Each zone has one west-facing window located as shown in Figures 1-3 and 1-4. 

Window physical properties are ideal. To achieve the ideal window properties listed below as nearly as 

possible, use whatever means the program being tested allows. Describe in your modeler report how 

windows were modeled. The window properties are: 

• Window area = 16 m2

 (172.22 ft2) 

o Window height = 4 m (13.123 ft) 

o Window length = 4 m (13.123 ft). 

• Solar transmittance = 1 (independent of incidence angle) 

o Window index of refraction = 1 (same as air) 

o Window extinction coefficient = 0/mm 

o Equations relating index of refraction and extinction coefficient to window transmittance 

are included in Judkoff and Neymark (1995), p. E-1. 

• Thermal conductance = 0 W/(m2

⋅K) (0 Btu/(h⋅ft2⋅°F)) 

o Window conductivity = 0 W/(m⋅K) (0 Btu/(h⋅ft⋅°F)). 

• Thermal mass = 0 

o Window density = 0 

o Window specific heat = 0. 

• Exterior face of the window is flush with the exterior face of the wall (no setback). 

If the program being tested can achieve an ideal window with single-pane construction, use the following 

window thickness: 

• Total window thickness = 3.175 mm (0.125 in.) 

o Number of panes = 1 

o Pane thickness = 3.175 mm (0.125 in.). 

If the program requires multiple pane construction to achieve or approximate a zero-conductance window, 

use the lowest allowable conductance air gap (between panes). For example: 

• Total window thickness = 19.35 mm (0.762 in.) 

o Number of panes = 2 

o Pane thickness = 3.175 mm (0.125 in.) 

o Air gap combined radiative and convective coefficient = 0 W/(m2

⋅K) (0 Btu/(h⋅ft2⋅°F)) 

o Air gap thickness = 13 mm (0.512 in.) 

 If necessary, use a thicker air gap, and adjust overall thickness accordingly. 

• The exterior face of the window must remain flush with the exterior face of the wall (no setback). 

1.3.2.1.3.6 Window Combined Surface Coefficients 

Interior and exterior combined surface coefficients for the windows are the same as those for opaque 

surfaces. 
16

If the zero-conductance windows can be modeled without using very low combined surface coefficients, 

ignore the remainder of this paragraph. For the ideal windows, the window surface coefficients are not of 

primary importance; IF the program being tested requires very low values of combined surface 

coefficients to achieve very low window thermal conductance, use very low combined surface coefficient 

values instead. (IF reduced surface coefficients are applied to windows AND only the convective portion 

of surface coefficients can be reduced, also set window interior and exterior surface emittances = 0 [or as 

low as the program allows].) Discuss in your modeler report any resulting deviation from the combined 

surface coefficients specified above. 

1.3.2.1.3.7 Mechanical System. All zones apply the same mechanical system and set points. The 

mechanical system is the same as in Case MZ320, except for the following changes to cooling set points. 

• All zones: Cool = ON if temperature > 20°C (68°F); otherwise Cool = OFF. Heat = always OFF. 

1.3.2.1.3.8 Weather Data. Use the TMY2-format weather data provided with the file 

“MZ340.TM2.” 

TMY2 weather data format is described in Appendix A. A summary of site and weather data parameters 

was provided in Table 1-2. This weather data file is based on Miami.TM2, but has ambient dry-bulb 

temperature set to a constant value of 20°C (68°F) and constant wind speed of 4.3 m/s. The weather data 

also include some data elements set to 0 or approximate lower limits, and other data elements set to 

neutral (non-extreme) constant values, as follows: 

• Dew-point temperature = –56.6°C (–69.9°F) (corresponds with humidity ratio of 0.000007 kg/kg 

and standard atmospheric pressure); calculation of dew point temperature applies common 

psychrometric formulae (ASHRAE 2005; Brandemuehl 1993). TMY2 documentation indicates 

that –60°C (–76°F) is the lower limit for TMY2 data. 

• Relative humidity = 0.05% (corresponds with humidity ratio of 0.000007 kg/kg, standard 

atmospheric pressure, and given dry-bulb temperature); calculations apply common 

psychrometric formulae (ASHRAE 2005; Brandemuehl 1993). This value rounds to 0% in the 

weather data. 

o If the program being tested does not allow a very low value for relative humidity, adjust 

the input weather data (or other software input) to use the lowest allowable relative 

humidity. 

• Atmospheric pressure = 1013 millibars (= standard atmosphere of 14.696 psia). 

• Wind speed = 4.3 m/s (Miami.TM2 annual average wind speed = 4.34 m/s, but TM2 weather data 

allows input only to the nearest 0.1 m/s.). 

1.3.2.1.4 Output requirements. Nomenclature and units described here are for use with the output 

spreadsheet, “MZ-Output.xls.” Instructions for inputting time of occurrence (for maximum values) are 

included in the upper left portion of the output spreadsheet. If a maximum value occurs for more than one 

hour, give the time of first occurrence. 

Include the following outputs for Case MZ340: 

• Annual sensible cooling load for entire building (QBldg [kWh]) 

• Annual hourly integrated maximum sensible cooling load for entire building, with the time of 

first occurrence (qmax,Bldg [Wh/h]) 

• Annual sensible cooling load for each zone (QA, QB, QC, QD, QE, QF [kWh]) 
17

• Annual hourly integrated maximum sensible cooling loads for each zone, with the time of first 

occurrence (qmax,A, qmax,B, qmax,C, qmax,D, qmax,E, qmax,F [Wh/h]) 

• Annual average air temperature for each zone (TA, TB, TC, TD, TE, TF [°C]) 

• Annual hourly integrated maximum air temperature for each zone, with the time of first 

occurrence (Tmax,A, Tmax,B, Tmax,C, Tmax,D, Tmax,E, Tmax,F [°C]) 

• Annual incident unshaded total solar radiation (sum of diffuse and direct) on west facing surface 

of Zone A (IA [kWh/m2

]) 

• Disaggregated annual incident direct beam (IbA) and diffuse (IdA) solar radiation on the westfacing surface of Zone A (kWh/m2

) 

o These results directly categorize solar processor disagreements, and may be useful if a 

program does not disaggregate transmitted beam and diffuse solar in its output. 

• Annual transmitted total solar radiation (sum of diffuse and direct) through each window (Itr,A, 

Itr,B, Itr,C, Itr,D, Itr,E, Itr,F [kWh]) 

o This quantity may be taken as the optically transmitted solar radiation through a window 

that is backed by a perfectly absorbing black cavity. 

• Disaggregated annual transmitted direct beam (Itrb,A, Itrb,B, Itrb,C, Itrb,D, Itrb,E, Itrb,F) and diffuse (Itrd,A, 

Itrd,B, Itrd,C, Itrd,D, Itrd,E, Itrd,F) solar radiation through each window (kWh) 

o These results are for scaling the importance of direct beam versus diffuse shading in a 

multi-zone context. 

• Daily hourly transmitted total solar radiation for Zone A only for March 15 (high direct normal 

radiation during the afternoon), August 4 (high direct normal radiation after 18:00), and October 

14 (low direct normal radiation during the afternoon) (Itrh,A [Wh/h]) 

• Daily hourly disaggregated transmitted direct beam (Itrbh,A) and diffuse (Itrdh,A) solar radiation for 

Zone A only, for August 4 (Wh/h) 

o This allows identification of results disagreements caused by differences in solar data 

processing; within MZ340.TM2, August 4 provides a robust mix of direct-normal and 

diffuse-horizontal solar radiation. 

• Daily hourly sensible cooling load for Zone A only, for March 15 (high direct normal radiation 

during the afternoon) (qA [Wh/h]) 

o This is to check sensible cooling load versus transmitted solar radiation for an unshaded 

zone. 

• To produce daily hourly output, run the program for a normal annual run. Do not just run the 

required days because the results could contain temperature history errors. 

1.3.2.2 Case MZ350: In-Depth Multi-Zone Fin Shading 

1.3.2.2.1 Objective. Test shading effect on neighboring zones, by a shading fin not directly attached to 

those zones. Compare results to Case MZ340 (unshaded calorimeter). 

1.3.2.2.2 Method. Use multiple methods for implementing shading, applying all shading-object models 

that the program being tested is capable of. For example, a shading device may be modeled as associated 

with: 

• Zone C window (MZ350a) 

• Zone C exterior wall (MZ350b) 

• Separate shading object; e.g., as the software would account for a tree or neighboring building 

(MZ350c) 

• Other (MZ350d). 
18

Submit separate results for each shading method tested, and document the methods in your modeler 

report. Note that Case MZ355 addresses automated building self-shading, i.e., equivalent shading of 

Zones A, B, D, and E by another zone of the building.

Compare sensible cooling loads and transmitted solar radiation for the entire building and for each zone to 

results of Case MZ340. Compare whole-building simulation results to each other. 

1.3.2.2.3 Input Specification. These cases are exactly as Case MZ340 except for changes described 

below. 

1.3.2.2.3.1 Building Construction. A 24 m × 24 m (78.74 ft × 78.74 ft) external shading fin is applied as 

shown in Figure 1-5 (such that it primarily shades Zones A, B, D, and E during the afternoon). 

Figure 1-5. Case MZ350 – fin shading isometric 

6 m

6 m

6 m

8 m

5 m

5 m

Not to Scale

Zone D

Zone E

Zone A

Zone B

Zone C

• Windows face West

• Building geometry is rectangular 

(all angles are 90°) 

N

Zone F

Shading Fin

5.0 m

24 m

24 m

1.0 m
19

To model this case, apply all shading-object models that the program being tested is capable of; associate 

the following possible modeling techniques with the following results designations: 

MZ350a: shading device associated with Zone C window 

MZ350b: shading device associated with Zone C exterior wall 

MZ350c: shading device defined as separate shading object (e.g., a tree) 

MZ350d: other (describe in your modeler report). 

Do not provide results for these modeling techniques that the program does not use. 

If the program includes more than four ways to describe a shading object, use an additional results 

spreadsheet and discuss additional modeling methods in your modeler report. 

1.3.2.2.3.2 Fin Construction 

Fin optical properties: 

• Solar absorptance = 1 (reflectance = 0, transmittance = 0) independent of incidence angle 

• Infrared emittance = 0 

• Apply these values as nearly as the program being tested allows 

• All heat from solar radiation absorbed by the fin is dissipated to the ambient environment via 

convection 

• Both sides of the fin actively shade the building 

o The properties listed above apply to both sides of the fin. 

Thickness: If the program requires an input for thickness of shading devices, use the smallest allowable 

value (e.g., 0.001 m). 

1.3.2.2.4 Output requirements. To model this case, apply all shading-object models that the program 

being tested is capable of; associate the following possible modeling techniques with the following results 

designations: 

MZ350a: shading device associated with Zone C window 

MZ350b: shading device associated with Zone C exterior wall 

MZ350c: shading device defined as separate shading object (e.g., a tree) 

MZ350d: other 

Do not provide results for these modeling techniques that the program does not use. 

If the program includes more than four ways to describe a shading object, use an additional results 

spreadsheet and discuss additional modeling methods in your modeler report. 

In addition to the outputs for MZ340, include: 

• Daily hourly transmitted total solar radiation for Zones A, B, D, and E for March 15 (high direct 

normal radiation during the afternoon) and October 14 (low direct normal radiation during the 

afternoon) (Itrh,A Itrh,B Itrh,D Itrh,E [Wh/h]) 

• Daily hourly transmitted total solar radiation for Zones C and F for August 4 (high direct normal 

radiation after 18:00) and October 14 (low direct normal radiation during the afternoon) (Itrh,C Itrh,F

[Wh/h]) 

o This is to check the back side of fin shading of direct normal and diffuse solar radiation. 
20

• Daily hourly sensible cooling load for Zone B only, for March 15 (high direct normal radiation 

during the afternoon) and October 14 (low direct normal radiation during the afternoon) (qB, 

[Wh/h]) 

o This is to check cooling load versus transmitted solar radiation for a shaded zone

• To produce this output, run the program for a normal annual run. Do not just run the required 

days because the results could contain temperature history errors. 

Do not include: 

• Annual incident unshaded total solar radiation (diffuse and direct) on the west-facing surface of 

Zone A (IA [kWh/m2

]) 

o For the ideal glass, transmitted solar radiation results are sufficient for determining 

shading effects after checking transmitted versus incident solar radiation in unshaded 

Case MZ340. 

• Daily hourly cooling loads for Zone A 

o Hourly cooling loads for Zone A of Case MZ340 and Zone B of MZ350 are sufficient for 

checking hourly cooling loads versus transmitted solar gains in unshaded and shaded 

cases. 

1.3.2.3 Case MZ355: In-Depth Multi-Zone Automated Building Self-Shading 

1.3.2.3.1 Objective. Test automated building self-shading. This is the automated shading effect for a zone 

of a building by a neighboring zone of the same building. Compare results to Case MZ340 (unshaded 

calorimeter), and MZ350 (shading by an external fin). 

1.3.2.3.2 Method. Attach an additional adiabatic zone (Zone G) to the west side of the southern most 

zones of the six-zone calorimeter of MZ340. This zone is applied such that it shades Zones A, B, D, and E 

exactly as the fin of Case MZ350. Sensible cooling loads and transmitted solar radiation for Zones A, B, 

D, and E should be the same as for Case MZ350. Also, compare results with Case MZ340. Compare 

whole-building simulation results to each other. 

If the program being tested can automatically model shading of zones by neighboring zones of the 

building, ignore the remainder of this paragraph. If the program being tested cannot automatically 

shade zones by neighboring zones of the building, do not run this test case. If the program can do 

Case MZ350 but not Case MZ355, its ability to model multi-zone shading can be judged based on its 

Case MZ350 output. 

1.3.2.3.3 Input Specification. This case is exactly as Case MZ340 except for changes described below. 

An additional zone is affixed to the west side exterior surfaces of Zones C and F (such that it primarily 

shades Zones A, B, D, and E during the afternoon), as shown by Zone G in Figure 1-6. 
21

 

Figure 1-6. Case MZ355 – building self-shading isometric 

1.3.2.3.3.1 Zone G Material Properties 

• Zone G is 24 m (78.74 ft) long × 5 m (16.404 ft) deep × 24 m (78.74 ft) high; see Figure 1-6. 

• Air volume of Zone G = 2880 m3

 (101706 ft3) 

o Site altitude and air properties are the same as for MZ320. 

• All opaque external boundaries and common walls of the zones (including all walls, floors, and 

roofs) have thermal conductance = 0 W/(m2

⋅K); if the program being tested does not allow zeroconductance surfaces, use the lowest allowable thermal conductance or thermal conductivity 

(e.g., 0.000001 W/(m2

⋅K) or 1·10-8 W/(m⋅K)). 

• Wall thickness = 0.01 m, for all walls (including floor and roof) 

o This thickness minimizes disagreements that could arise related to adherence to the 

geometry convention. If the program being tested automatically includes the thickness of 

walls in a three-dimensional definition of the building geometry, adjust the dimensions of 

Zone G such that it shades the building equivalently as the fin of Case MZ350. 

6 m

6 m

6 m

8 m

5 m

5 m

Not to Scale

Zone D

Zone E

Zone A

Zone B

Zone C

• Windows Face West

• Rectangular building geometry 

(all angles are 90°)

N

Zone F

5.0 m

24 m

24 m

1.0 m

Zone G
22

• All Zone G external boundaries and common walls (with Zones C and F) are massless; if the 

program being tested does not allow massless surfaces, use the lowest allowable density or 

thermal capacitance or both (e.g., 0.000001 kg/m3

 or J/(kg⋅K) or both). 

• Exterior solar absorptance = 1 (no external reflections); if the program being tested does not 

allow a value of 1, use the highest allowable value (e.g., 0.99999...). 

• Exterior surface infrared emittance = 0 (or as low as the program being tested allows). 

• Exterior combined surface coefficients = 25.4 W/(m2

⋅K) (4.47 Btu/(h⋅ft2⋅°F)). This value applies 

to all exterior surfaces, including the floor. 

o This value corresponds with the 4.3 m/s wind speed in the weather data for a rough (brick 

or rough plaster) surface (Walton 1983, p. 71; Judkoff and Neymark 1995, p. C-1), with 

the infrared radiation exchange portion of 5.13 W/(m2

⋅K) subtracted because exterior 

surface infrared emittance = 0 (Judkoff and Neymark 1995, p. D-1). 

o If the program being tested does not allow direct user input of combined or convective 

surface coefficients, use the convective surface coefficient the program automatically 

calculates. 

• Interior solar absorptance = 0; if the program being tested does not allow a value of 0, use the 

lowest allowable value (e.g., 0.000001). 

• Interior surface coefficients are the same as for the other zones (see Case MZ340). 

• No internal gains (set to 0 W for all zones). 

• No infiltration or ventilation. 

• No windows. 

1.3.2.3.3.2 Zone G Mechanical System. Zone G applies the same mechanical system and set point as the 

other zones, as described for Case MZ340 in Section 1.3.2.1.3.7. 

1.3.2.3.3.3 Adjustments to Zones C and F. Replace the previous west wall and window of both Zones C 

and F with: 

• Common walls adjoining Zone G with dimensions of 5 m (16.404 ft) length × 5m (16.404 ft)

height, as shown in Figure 1-6 

o These common walls do not include a window. 

• Exterior walls with dimensions of 1 m (3.281 ft) length × 5 m (16.404 ft) height as shown in 

Figure 1-6. 

These walls have the same properties as noted above under “Zone G Material Properties.” 

 

1.3.2.3.4 Output requirements. Give same outputs as for MZ350, with changes noted below: 

• Do not give any outputs for Zones C, F, or G. 

1.3.3 Case MZ360: In-Depth Internal Window Calorimeter 

1.3.3.1 Objective 

This case defines a multi-zone building calorimeter for measuring sensible cooling loads caused by solar 

radiation transmitted through internal windows. This case tests the ability to track transmitted beam and 

diffuse solar radiation through multiple zones. 
23

1.3.3.2 Method 

Apply a three-zone building as a calorimeter with idealized exterior and internal windows such that 

results disagreements are attributable either to modeling of internal windows, or to inability to model the 

idealizations. Two internal windows are modeled in series; an alternative two-zone modeling 

specification is provided for simulation tools that allow only one internal window (not two internal 

windows in series). The calorimeter is achieved similarly as in Case MZ340. Compare whole-building 

simulations to each other. 

1.3.3.3 Input Specification 

1.3.3.3.1 Geometry Convention. If the program being tested automatically includes the thickness of walls 

in a three-dimensional definition of the building geometry, define the wall, roof, and floor dimensions such 

that the given dimensions for the spacing of southwest-facing surfaces correspond to the southwest-facing 

side of those surfaces (e.g., in Figure 1-7, the distance between the southwest-facing sides of Walls AB and 

BC is exactly 3 m.) 

1.3.3.3.2 Building Construction. The overall three-zone building configuration with two internal 

windows is summarized in Figure 1-7. The building is oriented such that windows face to the southwest 

(45° west of south). In Figure 1-7, gray dashed lines indicate window outer edge boundaries. The detailed 

locations of windows within each wall are included in Figures 1-8, 1-9, and 1-10, respectively for Walls 

AO, AB, and BC identified in Figure 1-7. Input parameters are described below. 

• Zone plan dimensions: 

o Zone A = 12 m (39.370 ft) by 1 m (3.281 ft). 

o Zone B = 12 m (39.370 ft) by 3 m (9.843 ft). 

o Zone C = 12 m (39.370 ft) by 6 m (19.685 ft) 

o Height, all zones = 12 m (39.370 ft). 

• Air volumes: 

o Zone A = 144 m3

 (5085 ft3) 

o Zone B = 432 m3

 (15256 ft3) 

o Zone C = 864 m3

 (30512 ft3) 

o Site altitude and air properties are the same as for MZ340. 

• All opaque external boundary and common wall thermal properties, except for zone dimensions 

and air volume noted above, are as in Case MZ340 (see Section 1.3.2.1.3.2). 

• Ground reflectance = 0; if the program being tested does not allow a value of 0, use the lowest 

allowable value (e.g., 0.000001). 

• Wall thickness = 0.01 m (0.0328 ft), for all walls (including floors and roofs). 

o This thickness minimizes disagreements that could arise if there is difficulty with adherence 

to the geometry convention. 

• No internal gains (set to 0 W for all zones). 

• No infiltration or ventilation.

1.3.3.3.3 Interior Combined Surface Coefficients for Opaque Surfaces. Interior combined surface 

coefficients for opaque surfaces are the same as for Case MZ340 (see Section 1.3.2.1.3.3). 

1.3.3.3.4 Exterior Combined Surface Coefficients for Opaque Surfaces. Exterior combined surface 

coefficients for opaque surfaces are the same as for Case MZ340 (see Section 1.3.2.1.3.4). 
24

Figure 1-7. Case MZ360 – internal window isometric 

Figure 1-8. Wall AO with Window AO, elevation facing southwest 

12 m

12 m

Opaque Wall

Not to Scale

11.8 m

11.8 m

0.1 m 0.1 m

Window AO

1 m 6 m 3 m

12 m

• Windows face Southwest 

(45° west of South)

• Rectangular building geometry 

(all angles are 90°) 

Wall AO

Not to Scale

12 m

Wall BC Wall AB

Zone C

Zone B

Zone A

N

45°
25

Figure 1-9. Wall AB with Window AB, elevation facing southwest 

Figure 1-10. Wall BC with Window BC, elevation facing southwest 

12 m

12 m

Opaque Wall

10 m

10 m

Window AB

1 m

1 m

2.5 m

12 m

2.5 m

12 m

Opaque Wall

7 m

7 m

Window BC
26

1.3.3.3.5 Windows 

• Each zone has one southwest-facing window located as shown in Figures 1-8, 1-9, and 1-10. 

• Window thermal and optical properties are as in Case MZ340 (see Section 1.3.2.1.3.5). 

• Interior and exterior combined surface coefficients for the windows are the same as for Case 

MZ340 (see Section 1.3.2.1.3.6). 

• The southwest-facing side of each window is flush with the southwest-facing side of its 

corresponding wall (no setback). 

1.3.3.3.6 Mechanical System. All zones apply the same mechanical system and set points. The 

mechanical system is the same as in Case MZ340 (see Section 1.3.2.1.3.7). 

1.3.3.3.7 Weather Data. Weather data are the same as for Case MZ340 (MZ340.TM2). 

1.3.3.3.8 Alternative Two-Zone Modeling Specification. If the program being tested allows modeling 

of two internal windows in series, ignore the remainder of this paragraph. If it does not allow modeling of 

two internal windows in series, model Case MZ360 exactly as described above except for the following 

instructions. 

• Change Window BC to a black opaque surface with the same properties as Wall BC. 

• Provide the same outputs as listed in Section 1.3.3.4; enter “n/a” as outputs for Zone C. 

• Include a note in the modeler report for the tested software that the two-zone alternative modeling 

specification was applied for Case MZ360. 

• Analysis notes 

o For the annual results, compare QB for two-zone models to (QB + QC) for three-zone 

models. 

o Transmitted solar radiation through windows AO and AB remains directly comparable 

for two-zone and three-zone models. 

1.3.3.4 Output requirements. 

Nomenclature and units described here are for use with the output spreadsheet, “MZ-Output.xls.” 

Instructions for inputting time of occurrence (for maximum values) are included in the upper left portion 

of the output spreadsheet. If a maximum value occurs for more than one hour, give the time of first 

occurrence. 

Include the following outputs for Case MZ360: 

• Annual sensible cooling load for entire building (QBldg [kWh]) 

• Annual hourly integrated maximum sensible cooling load for entire building, with the time of 

first occurrence (qmax,Bldg [Wh/h]) 

• Annual sensible cooling load for each zone (QA, QB, QC [kWh]) 

• Annual hourly integrated maximum sensible cooling loads for each zone, with the time of first 

occurrence (qmax,A, qmax,B, qmax,C [Wh/h]) 

• Annual average air temperature for each zone (TA, TB, TC [°C]) 

• Annual hourly integrated maximum air temperature for each zone, with the time of first 

occurrence (Tmax,A, Tmax,B, Tmax,C [°C]) 

• Annual incident unshaded total solar radiation (sum of diffuse and direct) on the southwest-facing 

surface of Zone A (IA [kWh/m2

]) 
27

• Disaggregated annual incident direct beam (IbA) and diffuse (IdA) solar radiation on the southwestfacing surface of Zone A (kWh/m2

) 

o These results directly categorize solar processor disagreements, and may be useful if a 

program does not disaggregate transmitted beam and diffuse solar. 

• Annual transmitted total solar radiation (sum of diffuse and direct) through each window (Itr,A 

[through Window AO], Itr,B [through Window AB], Itr,C [through Window BC] [kWh]). 

o This quantity may be taken as the optically transmitted solar radiation through a window 

that is backed by a perfectly absorbing black cavity. 

o This quantity is NOT the net solar transmission for the zone (e.g., is not initially 

transmitted radiation less the radiation transmitted to a neighboring zone). 

• Disaggregated annual transmitted direct beam (Itrb,A, Itrb,B, Itrb,C) and diffuse (Itrd,A, Itrd,B, Itrd,C) solar 

radiation through each window (kWh) 

o These results are for scaling the importance of direct beam versus diffuse transmission in 

an internal-window context. 

• Daily hourly sensible cooling load for Zone B only, and daily hourly transmitted total solar 

radiation for Zones A, B, and C for March 15 (high direct normal radiation during the afternoon) 

and October 14 (low direct normal radiation during the afternoon) (qB, Itrh,A, Itrh,B, Itrh,C [Wh/h]). 

o To produce this output, run the program for a normal annual run. Do not just run the 

required days because the results could contain temperature history errors. 
Appendix A. TMY2 File Format 

This format information was taken from the TMY2 User’s Manual (Marion and Urban 1995), and can be 

fou a nd t www.nrel.gov. 

Da a

For c

data h ated to 

rm th ch station. 

l 

indicate whether 

tainty of the 

er, city, state, time zone, latitude, longitude, and elevation. The field positions and 

efinitions of these header elements are given in Table A-1, along with sample FORTRAN and C formats 

for d

Definition 

ta nd Format 

ea TMY2 file contains 1 year of hourly solar radiation, illuminance, and meteorological h station, a

. T e files consist of data for the typical calendar months during 1961-1990 that are concaten

fo e typical meteorological year for ea

Each hourly record in the file contains values for solar radiation, illuminance, and meteorologica

elements. A two-character source and uncertainty flag is attached to each data value to 

the data value was measured, modeled, or missing, and to provide an estimate of the uncer

data value. 

File Header 

The first record of each file is the file header that describes the station. The file header contains the 

WBAN numb

d

rea ing the header. 

Table A-1. TMY2 Weather File Header Format (for First Record of Each File) 

Field Position Element 

 002 0 - 06 WBAN Number number (see Table 2-1 of Marion and Urban 

Station's Weather Bureau Army Navy 

[1995]) 

 008 - 0 here the station is located (maximum of 22 

characters) 29 City City w

State where the station is located (abbreviated to 

two letters) 031 - 032 State 

 034 - 036 Time Zone 

Time zone is the number of hours by which the 

local standard time is ahead of or behind 

Universal Time. For example, Mountain Standard 

Time is designated -7 because it is 7 hours 

behind Universal Time. 

 038 - 044

 038 Latitude Latitude of the station N = North of 

 040 - 041 

equator 

 043 - 044 

Degrees 

Minutes 

 046 - 053

 046 Longitude Longitude of the station 

 048 - 050 Degrees 

 052 - 053 Minutes 

W = West, E = East 

 056 - 059 Elevation Elevation of station in meters above sea level 

FORTRAN Sample Format: 

 ( 1X,A5,1X,A22,1X,A2,1X,I3,1X,Al,lX,I2,1X,I2,1X,Al,lX,I3,1X,I2,2X,I4 )

C Sample Format: 

 ( %s %s %s %d %s %d %d %s %d %d %d )

28
Ho y

Followi

meteorolog d

elem t

Each ho

followed by

time (previo

For a u g 

minutes 

or meas

observation

data alu

valu a

Sourc

With the ex t field 

ositions immediately following the data value provide source and uncertainty flags both to indicate 

whether the data were measured, modeled, or missing, and to provide an estimate of the uncertainty of the 

data. Source and uncertainty flags for extraterrestrial horizontal and extraterrestrial direct radiation are not 

provided because these elements were calculated using equations considered to give exact values. 

For the most part, the source and uncertainty flags in the TMY2 data files are the same as the ones in 

NSRDB, from which the TMY2 files were derived. However, differences do exist for data that were 

missing in the NSRDB, but then filled while developing the TMY2 data sets. Uncertainty values apply to 

the data with respect to when the data were measured, and not as to how "typical" a particular hour is for 

a future month and day. More information on data filling and the assignment of source and uncertainty 

flags is found in the TMY2 User’s Manual (Marion and Urban 1995). 

url Records 

ng the file header, 8760 hourly data records provide 1 year of solar radiation, illuminance, and 

ical ata, along with their source and uncertainty flags. Table A-2 provides field positions, 

en definitions, and sample FORTRAN and C formats for reading the hourly records. 

urly record begins with the year (field positions 2-3) from which the typical month was chosen, 

 the month, day, and hour information in field positions 4-9. The times are in local standard 

us TMYs based on SOLMET/ERSATZ data are in solar time). 

 sol r radiation and illuminance elements, the data values repres the energy rec ed rin the 60 ent eiv d

preceding the hour indicated. For meteorological elements (with a few exceptions), observations 

urements were made at the hour indicated. A few of the meteorological elements had 

s, measurements, or estimates made at daily, instead of hourly, intervals. Consequently, the 

 v es for broadband aerosol optical depth, snow depth, and days since last snowfall represent the 

es vailable for the day indicated. 

e and Uncertainty Flags 

cep ion of extraterrestrial horizontal and extraterrestrial direct radiation, the two

p

29
Table A-2. TMY2 Data Records 

Field 

Position Element Values Definition 

 002 - 009 Local Stand

 002 - 003 

 004 - 005 

 Year 

 Month 

 006 - 007 

 008 - 009 

 Day 

 Hour 

 1 - 31 

 1 - 24 

 Day of month 

 Hour of day in local standard time 

ard Time 

 61 - 90 

 1 - 12 

 Year, 1961-1990 

 Month 

 010 - 013 Extraterrestrial Horizontal 0 - 141

2

 top of the atmosphere during the 6

 minutes preceding the hour indicated 

 Radiation 

5 Amount of solar radiation in Wh/m 

 received on a horizontal surface at the 

0 

 014 - 017 Extraterrestrial Direct 0 - 1415 Amount of solar radiation in Wh/m

 Normal Radiation sun at the top of the atmosphere 

 during the 60 minutes preceding the 

 hour indicated 

2

 

 received on a surface normal to the 

 

 018 - 023 

 018 - 021 

 022 

 023 

 Global Horizontal 

Radiation 

 Data Value 

 Flag for Data Source 

 Flag for Dat

 0 - 1200 

 A - H, ? 

 Total amount of direct and diffuse 

 solar radiation in Wh/m

a Uncertainty 0 - 9 minutes preceding the hour indicated 

2

 received on 

 a horizontal surface during the 60 

 024 - 029 

 024 - 027 

 028 

 029 

ata So

ata Un

 A - H, ? 

 0 - 9 

2

 

ew 

 cen sun during the 60 

 min ur indicated 

 Direct Normal Radiation 

 Data Value 0 - 1100 

 Amount of solar radiation in Wh/m

 received within a 5.7° field of vi

 Flag for D

 Flag for D

urce 

certainty 

tered on the 

utes preceding the ho

 030 - 

 030 - 033 

 034 

 035 

e Horiz

on 

 Data Value 

r Da e 

r Da tainty 

 

 

 

2

 

ng the 

 solar disk) on a horizontal surface 

e 

cated 

035 Diffus

Radiati

ontal 

 Flag fo

 Flag fo

ta Sourc

ta Uncer

0 - 700 

 Amount of solar radiation in Wh/m

 received from the sky (excludi

A - H, ? 

0 - 9 during the 60 minutes preceding th

 hour indi

 036 - 

 036 - 039 

 040 

 041 

l Horiz. Illuminance 

 Data Value 

 for Da 

 

 

 

 

 diffuse illuminance in hundreds of lux 

eding the 

0 - 1300 

 Average total amount of direct and 041 Globa

 Flag for Dat

 Flag

a Source 

ta Uncertainty

I, ? 

0 - 9 

 received on a horizontal surface 

 during the 60 minutes prec

 hour indicated 

 0 to 1300 = 0 to 130,000 lux 

 042 - 047

 042 - 

 046 

 047 

Normal Illuminance 

 Value

 for Da Source 

r Da Uncertainty 

 

 

 

mount of direct normal 

nce in hundreds of lux 

d within a 5.7° field of view 

 centered on the sun during the 60 

 minutes preceding the hour indicated. 

 = 0 to 110,000 lux 

 

045 

 Direct 

 Data

 Flag

 Flag fo

 

ta

ta

0 - 1100 

I, ? 

0 - 9 

 illumina

 receive

 Average a

 0 to 1100

 048 - 

 048 - 

 052 

 053 

e Horiz. Illuminance 

 Value

 for Da Source 

r Da 

 

 

 

ge amount of illuminance in 

 hundreds of lux received from the sky 

 (excluding the solar disk) on a 

 0 to 800 = 0 to 80,000 lux 

0 - 800 

I, ? 

 Avera 053 

051 

 Diffus

 Data

 Flag

 

ta

 Flag fo ta Uncertainty 0 - 9 horizontal surface during the 60 

 minutes preceding the hour indicated. 

30
Field 

Position Element Values Definition 

 054 - 059 

 054 - 057 

 Zenith Luminance 

 Data Value 0 - 7000 

 Average amount of luminance at the 

 sky's zenith in tens of Cd/m

 058 

 059 Flag for Data Uncertainty 

 

 0 - 9 

 

 indicated. 

 0 to 7000 = 0 to 70,000 Cd/m

 Flag for Data Source I, ? 

 during 

 the 60 minutes preceding the hour 

2

2

 060 - 063 

060 - 061 

 Total Sky Cover 

 Data Value 0 - 10 Amount of s 

 062 

 063 

 Flag for Data Source 

 Flag for Data Uncertainty 

 A - F 

 0 - 9 phenomena at the hour indicated 

ky dome in tenths 

 covered by clouds or obscuring 

 064 - 067 

 064 - 065 

 066 

 067 

 Opaque Sky Cover 

 Data Value 

 Flag for Data Source 

 Flag for Data Uncertainty

 0 - 10 

 A - F 

 Amount of sky dome in tenths 

 covered by clouds or obscuring 

 phenomena that prevent observing the 

 sky or higher cloud layers at the hour 0 - 9 indicated 

 068 - 073 

 068 - 071 

 Dry Bulb Temperature 

 Data Value 

 072 

 073 

 Flag for Data Source 

 Flag for Data Uncertainty 

 A - F 

 0 - 9 

 at the hour indicated 

 -500 to 500 = -50.0 to 50.0°C 

 -500 to 500 Dry bulb temperature in tenths of °C 

 074 - 079 

 074 - 077 

 078 

 079 

 Dew Point Temperature 

 Data Value 

 Flag for Data Source 

 Flag for Data Uncertainty 

 -600 to 300 

 A - F 

 0 - 9 

 Dew point temperature in tenths of 

 °C at the hour indicated 

 -600 to 300 = -60.0 to 30.0°C 

 080 - 084 

 080 - 082 

 083 

 084 

 Relative Humidity 

 Data Value 

 Flag for Data Source 

 Flag for Data Uncertainty 

 0 - 100 

 A - F 

 0 - 9 

 Relative humidity in percent at the 

 hour indicated 

 085 - 090 

 085 - 088 

 089 

 Atmospheric Pressure 

 Data Value 

 Flag for Data Source 

 700 - 1100 

 A - F 

 Atmospheric pressure at station in 

 millibars at the hour indicated 

 090 Flag for Data Uncertainty 0 - 9 

 091 - 095 

 091 - 093 

 094 

 095 

 Wind Direction 

 Data Value 

 Flag for Data Source 

 Flag for Data Uncertainty 

 0 - 360 

 A - F 

 0 - 9 

 Wind direction in degrees at the hour 

 indicated. ( N = 0 or 360, E = 90, 

 S = 180,W = 270 ). For calm winds, 

 wind direction equals zero. 

 096 - 100 

 096 - 098 

 099 

 100 

 Wind Speed 

 Data Value 

 Flag for Data Source 

 Flag for Data Uncertainty 

 0 - 400 

 A - F 

 0 - 9 

 Wind speed in tenths of meters per 

 second at the hour indicated. 

 0 to 400 = 0 to 40.0 m/s 

 101 - 106 

 101 - 104 

 105 

 106 

 Visibility 

 Data Value 

 Flag for Data Source 

 Flag for Data Uncertainty 

 0 - 1609 

 A - F, ? 

 0 - 9 

 Horizontal visibility in tenths of 

 kilometers at the hour indicated. 

 7777 = unlimited visibility 

 0 to 1609 = 0.0 to 160.9 km 

 9999 = missing data 

 107 - 113 

 107 - 111 

 112 

 113 

 Ceiling Height 

 Data Value 

 Flag for Data Source 

 Flag for Data Uncertainty 

 0 - 30450 

 A - F, ? 

 0 - 9 

Ceiling height in meters at the hour 

indicated. 

 77777 = unlimited ceiling height 

 88888 = cirroform 

 99999 = missing data 

31
Field 

Position Element Values Defin tion i

 Se

ppendix B of 

5) 

Present weath denoted by 

 10-digit number. See Appendix B in 

5) for key to 

ments. 

e 

A

Marion and

Urban (199

er conditions

 114 - 123 Present Weather a

the Marion and Urban (199

present weather ele

 124 - 128 

 124 - 126 

 127 

 128 

 Precip

 Data V

itable Water 

alue 

 Flag for Data Source 

 Flag for Data Uncertainty 

 0 - 100 

 A - F 

 0 - 9 

 Precipitable water in millimeters at 

 the hour indicated 

 

 

129 - 133 

129 - 131 

tical Depth 

Data Value 0 - 240 

 132 

 133 

 Aerosol Op

 

 Flag for Data Source 

 Flag for Data Uncertainty 

 

 A - F 

 0 - 9 

 Broadband aerosol optical depth 

 (broad-band turbidity) in thousandths 

 on the day indicated. 

 0 to 240 = 0.0 to 0.240 

 

 

 

134 - 138 

134 - 136 

137 

Data Value 

Flag for Data Source 

rtainty 

 0- 150 

 A - F, ? ata 138 

 Snow Depth 

 

 

 Flag for Data Unce

 

 

 0 - 9 

 Snow depth in centimeters on the day

 indicated. 

 999 = missing d

 139 - 142 

 139 - 140 

 141 

 142 

 Days Sinc

 Data Value 

 Flag for Data Source 

 Flag for Data Uncertainty 

e Last Snowfall 

 0 - 88 

 A - F, ? 

 0 - 9 

 Number of days since last snowfall. 

 88 = 88 or greater days 

 99 = missing data 

FORTRAN S

 (lX,4I2,

 l(

 l(I

a

,I1),2(I2,Al Al,

I4,Al (I4,A ,Al

2,Al

d%4d%1s%1d%4 d%1s

d %1s%1 %4d

s%1d %51d% 1d%1

d%3d 1

e b ept d

mple Format: 

2I4,7(I4,Al

,Il),2(I3,Al,I1),l

,Il)) 

,Il),2(I4,

l,Il),l(I5

Il),l(I3,Al,Il), 

,Il),l0Il,3(I3,Al,Il), 

 C Sample F

 (%2d%2d

 %1d%4

 %1

 %1

ormat: 

%2d%2d%4d%4

%1s%1d%2d%1s%1d%2d

%3d%1s%1d%4d%1s%ld

%1s%1d%3d%1s%1d%2d%1s%

d%1s%1d%4

d%4d%1s%1d

1s%1d%1d%

d) 

%1d%4d%1s%1d%4d%1s%1d%4d%1s 

%1s%1d%3d%1s%1d%4d%1s%1d%3d 

d%1d%1d%1d%1d%1d%1d%1d%3d%1s 

 Note: For c iling height data, integer varia le should acc ata values as large as 99999. 

32
Appendix B. Output Spreadsheet Instructions

MZ-Output. 

a ne Non-A pth

 

UCT 

 

i 

 

 entry ng 

 

tware Nam on, a 

20 Ste Outpu

Z orimetr

E93..Y99; H102..Y108: MZ340-MZ360 Calorimetr tegrated Maxima Ouputs 

0 Ho

50a th d 

E o uts 

E Hourly Outputs 

 

320 St or he r of the 

 

e annual 

t for th ual s 

 

r he output section of the sp

at da o te follo ed by a three-letter month code and 

clock) as shown . 

 

TH C

 

N CODE 

 

JANU

R Feb 

R Mar 

APR 

MAY

E un 

Y Jul 

G

SEPT

 OCTOBER Oct 

 NOVEMBER Nov 

 DECEMBER Dec 

XLS 

dsheet for Multi-Zo

 

IONS 

 

 Cases: MZ320-MZ360 

 

 

 

Output spre

 

INSTR

irflow InDe

1. Use spec

 

2. Data

fied units 

 

 is restricted to the followi ranges: 

 

 

 

 

nd Date of Results 

ts 

y Annual Summary Outputs 

y Hourly In

E60..E62: Sof

E70..H70: MZ3

E79..AL85: MZ340-M

e, Versi

ady-State 

360 Cal

 E1

E116..J139: MZ34

46..BN169: MZ3

176..L199: MZ355 H

urly Outputs 

rough MZ350

urly Outp

 

Hourly Outputs 

 

 

3. MZ

206..L229: MZ360 

 

eady-state results are f t

 

 

 

 one-year simulation 

 

 final hou

4. Annual to

minima are 

tals are for the entir

hose values that occur

 

simulation. Sim

e entire ann

ilarly, annual means, maxima, and 

imulation. 

5. Output te

applicable 

6. Form

minology is defined in t

 

 

tes using the appropriate tw

ecification for each case, where 

 

-digit da w

two-digit ho

 

 MON

ur code (24-hour 

 

ODES: 

below 

 

 

 

 MO

 

TH 

 

ARY Jan 

 

 

 

 FEB

 MA

UARY 

CH 

IL Apr 

 May 

 

 

 

 

 

 JUN

 JUL

 AU

 J

 

UST Aug 

EMBER Sep 

 

 

 

 

33
 

F e a maxim ccuring on A during the 15th l (2:00–3:00 

p.m.), should be input as: 

Date Hour 

 16-Aug 15 

or exampl um value o ugust 16 hour interva

 

 

 

 

 

 

 

34
Appendix C. Abbreviations and Acronyms 

Abs: absorptance 

ASHRAE: American Society of Heating, Refrigerating and Air-Conditioning Engineers 

mmunity Systems Programme of IEA 

d: 

e 

: ent of Zone A for cases 

one A for cases 

e A or Cas

rip ne 

through window 

ith 

/h) 

one (W or 

one (W or 

BESTEST: Building Energy Simulation Test and Diagnostic Method 

Coef: coefficient 

Const: constant 

COP: coefficient of performance 

ECBCS: Energy Conservation in Buildings and Co

Ext: exterior 

hint,combined: combined convective and radiative interior surface coefficient 

hent,combine combined convective and radiative exterior surface coefficient 

IA: annual incident total solar radiation (sum of diffuse and direct) on west-facing surface of 

Zone A for cases MZ340, MZ350, and MZ355, and on southwest-facing surface of Zon

A for Case MZ360 

IbA annual incid direct beam solar radiation on west-facing surface 

MZ340, MZ350, and MZ355, and on southwest-facing surface of Zone A for Case 

MZ360 

IdA: annual incident diffuse solar radiation on west-facing surface of Z

MZ340, MZ350, and MZ355, and on southwest-facing surface of Zon f e 

MZ360 

Itr,x: annual transmitted total solar radiation (sum of diffuse and direct) through window 

corresponding with subscripted zone 

I rresponding with trb,x: annual transmitted direct beam solar radiation through window co

subscripted zone 

Itrd,x: annual transmitted diffuse solar radiation through window corresponding with 

subsc ted zo

Itrh,x: hourly transmitted total solar radiation (sum of diffuse and direct) 

corresponding with subscripted zone 

Itrbh,x: hourly transmitted direct beam solar radiation through window corresponding with 

subscripted zone 

Itrdh,x: hourly transmitted diffuse solar radiation through window corresponding w

subscripted zone 

IEA: International Energy Agency 

IEA 34/43: IEA SHC Task 34/ECBCS Annex 43 

Int: interior 

I-P: inch-pound 

MZ: multi-zone 

NSRDB: National Solar Radiation Data Base 

qx: hourly or steady-state sensible cooling load of subscripted zone (W or Wh

qmax,bldg: annual hourly integrated maximum sensible cooling load for subscripted z

Wh/h) 

qmax,x: annual hourly integrated maximum sensible cooling load for subscripted z

Wh/h) 

QBldg: annual sensible cooling load for entire building (kWh/y) 

Qx: annual sensible cooling load for subscripted zone (kWh/y) 

35
SHC: Solar Heating and Cooling Programme of IEA 

SI: Système Internationale 

Surf: surface 

Tx: air temperature of subscripted zone (°C) 

Tmax,x: annual hourly integrated maximum air temperature of subscripted zone (°C) 

TMY2: Typical Meteorological Year 2 

Total air-air: total air-to-air conductance, including materials and interior and exterior combined 

surface coefficients 

trans: transmittance 

U: unit thermal conductance (W/(m2

⋅K)) 

WBAN: Weather Bureau Army Navy 

αext: exterior solar absorptance 

TO: ambient air temperature (°C) 

TMY: Typical Meteorological Year 

36
Appendix D. Glossary 

[Note: This glossary highlights terms that are either already defined in ANSI/ASHRAE Standard 140-

/ASH Italicized 

ry.] 

s wi ain of heat; an adiabatic boundary does not allow heat to flow through it. 

i l solu tion of a model that has an exact result for a given set of 

d 

rly aximum sensible cooling load is the hourly load that represents the 

um for th

st t; 

e.g., for hourly oneear simulation

Annual sensibl e.g., 

r ourly simu

lation perio

al transm

a asses throu s not 

de radiation be taken 

black 

.

urf

e. 

r ra ived from the sun after its direction has been changed 

 by ground. 

ra ar radiation received from the sun without having been scattered by the 

r o e ground; this is also called beam or direct-beam radiation. 

eter would measure. 

ere I is the 

medium. 

Hourly sensible cooling load is the sensible cooling load for a given hour. 

n and diffuse solar radiation 

that passes through a given window for a given hour. 

2007 (ANSI RAE 2007), or may be included or revised in a later version of Standard 140.

terms used within the glossary are also defined elsewhere within the glossa

Adiabatic i thout loss or g

Analyt ca tion is the mathematical solu

parameters an simplifying assumptions. 

Annual hou integrated m

maximum for the one-year simulation period. 

Annual hourly integrated maximum air temperature is the hourly temperature that represents the 

maxim e one-year simulation period. 

Annual incident unshaded total solar radiation is the sum of direct solar radiation and diffuse solar 

radiation that rikes a given surface for the entire one-year simulation period when no shading is presen

simulation programs this is the sum of the hourly total incident solar radiation for the

y period.

e cooling load is the sensible cooling load for the entire one-year simulation period; 

fo h lation programs this is the sum of the hourly sensible cooling loads for the one-year 

simu d.

Annu itted total solar radiation is the sum of direct solar radiation and diffuse solar radiation 

th t p gh a given window for the entire one-year simulation period. This quantity doe

inclu that is absorbed in the glass and conducted inward as heat. This quantity may 

as the optically transmitted solar radiation through a window that is backed by a perfectly absorbing 

cavity

Combined s ace coefficient is a constant of proportionality relating the rate of convective and 

radiative heat transfer at a surface to the temperature difference across the air film on that surfac

Diffuse sola diation is the solar radiation rece

by scattering osphere or other objects on the the atm

Direct solar iation d is the sol

atmosphere o ther objects on th

Dry-bulb temperature is the temperature a thermom

Extinction coefficient is the proportionality constant K in Bouguer’s Law ((dI) = (I K dx), wh

local intensity of solar radiation within a medium and x is the distance the radiation travels through the

Hourly transmitted total solar radiation is the sum of direct solar radiatio

37
Incidence angle is the angle defined by the intersection of a line normal to a surface and a ray that strikes 

refrac face 

ices of 

tta d by 

t t

nside the space or zone. 

 of accuracy for predicting system behavior based on an 

 soluti

ensible heat is the change in enthalpy associated with a change in dry-bulb temperature caused by the 

addition or removal of heat. 

Solar absorptance is the ratio of the solar spectrum radiant flux absorbed by a body to that incident on it. 

Zone air temperature is the temperature of just the zone air, not including infrared radiation from the 

interior surfaces; such a temperature would be measured by a sensor housed in a well-aspirated 

containment shielded by a material with a solar and infrared reflectance of one; well-mixed air is 

assumed. 

that surface.

In x of ion de t relates the angle of refraction (x2) to the angle of incidence (x1) at the sur

interface of two media according to Snell’s law (n1sin(x1) = n2sin(x2)), where n1 and n2 are ind

refraction for each medium. 

Infrared emi nce is the ratio of the infrared spectrum radiant flux emitted by a body to that emitte

a blackbody a he same temperature under the same conditions. 

Internal gains are heat gains generated i

Mathematical truth standard is the standard

analytical on. 

S

38
Appendix E. Remarks About the Test Cases

ontext (MZ340–MZ350) for each zone should be sufficient. Especially per MZ340.TM2 for March 15, 

 of diffuse horizontal radiation (diffuse is heavily dominant). 

herefore, adding more hourly outputs (e.g., hourly disaggregated shaded direct beam and diffuse for 

rsus 

he current test specification allows testing multiple shading methods, if they are provided by the tested 

ng possible modeling techniques with the following results designations: 

device defined as separate shading object (e.g. a tree) 

MZ350d: other (describe in your modeler report). 

t 

e software being tested includes more than four ways to describe a shading object, use an 

additional results spreadsheet and discuss additional modeling methods in your modeler report.” 

ifficult to adapt for automating tabulation and plotting new results. When this work is adapted for 

ding method. 

= (Itrh,B - 

 qA and qC. 

isaggregated incident beam and diffuse solar are useful if a program doesn’t disaggregate 

The following remarks relate to development of the test cases. 

MZ340 

To analyze the effects of shading on direct and diffuse solar, analysis of given hourly data in the delta 

c

diffuse horizontal radiation is 5%–9% of direct beam radiation (beam is heavily dominant), and for 

October 14 direct normal radiation is <1%

T

each zone of MZ350x) would not produce a much clearer diagnostic regarding analysis of direct ve

diffuse shading. 

MZ350 

T

software, as follows: 

“For modeling this case apply all shading-object models that the program being tested is capable of; 

associate the followi

MZ350a: shading device associated with Zone C window 

MZ350b: shading device associated with Zone C exterior wall 

MZ350c: shading 

Do not provide results for above listed modeling techniques that the software being tested does no

use. 

If th

The analysis spreadsheet that resulted for this may be difficult to adapt for Standard 140, or may be 

d

Standard 140, it may be worthwhile to revise the test specification and accompanying spreadsheets so a 

complete individual spreadsheet is submitted for each tested sha

Output Requirements 

For Case MZ360 hourly results, we are looking at qB only because it is the center zone. If qB 

Itrh,C) and if Itr,A, Itr,B, and Itr,C are checked, it is not necessary to check

For cases MZ340 through MZ360, disaggregated annual incident and transmitted beam and diffuse solar 

radiation for each zone allows scaling of importance of beam versus diffuse shading in multi-zone 

context. D

transmitted beam and diffuse. 

39
It is necessary to compare only incident versus transmitted solar radiation (ideal window check) for Case 

 problem implies a shading/significance problem. 

 ideal 

MZ340. For MZ350 and MZ355, comparing transmitted solar through ideal windows is enough: a 

transmittance

For cases MZ340 through MZ360, maximum zone temperatures are a basic controller check; for an

controller the programs should have 20°C (68°F) for hour 1. 

40
Appendix F. Using the Flow Diagrams to Diagnose the Results 

.1 General Description 

Figure F-1 is a flow diagram that serves as a guide for diagnosing the cause of disagreeing results that 

l 

. 

d 

lation Results 

l solution (Case MZ320 only) and example simulation results are presented in Part III. At a 

inimum, compare output with the analytical solution results. For cases without analytical solution 

re. Information about how the analytical solution was produced is included in 

ection 1.3.1.5. Information about how example simulation results were produced is included in the 

mod

wit ple 

results has been included with the accompanying electronic files MZ-RESULTS-Annuals.XLS and MZRE

The of the agreement or 

disa determination, the user should consider that an 

analytical solution represents a mathematical truth standard based on acceptance of the underlying 

phy

phy ssumptions of the case definitions are a simplification of reality and may not fully represent real 

empirical behavior. As discussed in Section 1.2.2.1, in making a determination about the agreement of 

resu

ases 

l truth standard is provided, the degree of disagreement that occurred for 

e mathematical truth standard 

heck the program being tested for agreement with the absolute outputs and the sensitivity (or “delta”) 

ompare all available output types specified for each case that can be produced by the program being 

tested. This includes appropriate zone cooling loads, transmitted solar radiation, peak-hour results, and 

supporting results presented in Part III, for all of that listed output the software being tested can produce. 

A disagreement with any one of the output types may be cause for concern. 

F

may arise from using this test. The flow diagram lists the features being tested, thus indicating potentia

sources of algorithmic differences, and may be used in two ways. The most powerful but time-consuming

way is to perform all the cases, and then use the diagnostic logic in the flow diagrams to analyze the

results. The least time-consuming way is to perform the tests in sequence according to the flow diagrams

F.2 Comparing Tested Software Results to Verified Numerical-Model Results an

Example Simu

Analytica

m

results, compare output with the example simulation results, or with other results that were generated 

using this test procedu

S

eler reports of Section 2.9. For convenience to users who wish to plot or tabulate their results along 

h the analytical solution or example simulation results, or both, an electronic version of the exam

SULTS-Hourlies.XLS. 

re are no formal criteria for when results agree or disagree; determination

greement of results is left to the user. In making this

sical assumptions represented by the case specifications. The authors recognize that the underlying 

sical a

lts, the user should also consider: 

• Magnitude of results for individual cases 

• Magnitude of difference in results between certain cases (e.g., “MZ350–MZ340”) 

• Same direction of sensitivity (positive or negative) for difference in results between certain c

(e.g., “MZ350–MZ340”) 

• If results are logically counterintuitive with respect to known or expected physical behavior 

• Availability of a mathematical truth standard (analytical solution) 

• Where a mathematica

other simulation results versus th

• Example simulation results do not represent a mathematical truth standard. 

C

outputs. For example, when comparing to the example simulation results for Case “MZ350–MZ340” in 

Figure F-1, the program results are compared with both the Case MZ350 results and the Case MZ350–

MZ340 sensitivity results. 

C

41
It is recommend to perform/analyze results of the tests in logical blocks as shown in the flow diagra

all at once for each series of cases. For cases MZ320 and MZ340

ms, or 

, it is very important to have confidence 

 results of both before proceeding to the other cases. If output from the tested program agrees 

gram disagrees with results for cases 

Z320 and MZ340, check for input errors. If no input error is found, run all other test cases and follow 

the diagnostic logic accordingly, as this may help to olate the source of the difference (especially with 

respect to Case MZ340) to one of the specifically tested parameters. 

For other BESTEST suites, there are some cases where it is reasonable to proceed, even if disagreements 

were uncovered in the previous case. However, for these cases we recommend to obtain a satisfactory 

result for each case the software being tested can perform, as listed sequentially in Figure F-1, before 

proceeding to the next case. 

F.2.1 If Tested Software Results Disagree with Example Results 

For all test cases, if the tested program shows disagreement (as defined above) with an analytical solution 

or other example simulation results, recheck the inputs against the specified values. Use the diagnostic 

logic flow diagram to help isolate the source of the difference. If no input error can be found, look for an 

error in the software. If an error is found, fix it and rerun the tests. If in the engineering judgment of the 

user the disagreement is caused by a reasonable difference in algorithms between the tested software and 

the example results, continue with the next test case. 

F.2.2 Example 

A program shows disagreement with MZ360. Figure F-1 suggests the potential source of algorithmic 

differences includes modeling of internal windows, incident solar radiation, idealizations, or internal 

shading. If no input error can be found, recheck diagnostics A, B1, and B2. If the disagreement persists 

for A, it may be related to shading of an internal window. If there is no disagreement for B1 or B2, the 

difference may be related specifically to internal window modeling. 

Section 2.4 gives examples of how the tests were used to trace and correct specific algorithmic and input 

errors in the programs used in the field trials. 

F.2.3 Note for Future Integration of Diagnostic Logic with Other Test Suites 

Because of idealizations in the test cases (see Section 2.5.1), these new multi-zone test cases have more 

diagnostic power for testing the modeling of some specific phenomena than the tests for some of these 

phenomena currently included in the building thermal fabric test cases of ANSI/ASHRAE Standard 140-

2007, Section 5.2 (ANSI/ASHRAE 2007). For future integration of these test cases with Standard 140, 

the Standard 140 diagnostic logic flow diagrams should be revised to indicate the new multi-zone tests as 

in-depth diagnostics, especially with respect to modeling thermal conduction (Case MZ320) and shading 

(cases MZ350 and MZ355). 

in

satisfactorily with the results for those cases, continue to check output for the remaining cases according 

to the flow diagram (Figure F-1). If output from the tested pro

M

is

42
START PROBABLE C SE OF DISAGREEMENT DIAGNOSE (GOTO)

D

AU

Steady State Multi-Zone Conduction

MZ320 Analytical Verification

Iterative closure, solid conduction and/or

A internal gains

(Multi-Zone Shading Cases)

Shading Test Base Case, Unshaded

A MZ340 D Incident solar, idealizations (windows: 

trans. = 1, U = 0; walls: abs,int. = 1, U = 0) 

A

B1 MZ350 & (MZ350-MZ340) D Shading device, incident solar, idealizations

A

MZ355 & (MZ355-MZ340) D Automated building self shading

& (MZ355-MZ350) D

A

(Internal Windows Case)

Internal windows

MZ360 D Incident solar, idealizations A

Internal shading B1, B2

A

END

ABBREVIATIONS

 A = Agree; D = Disagree. For Case MZ32

B2

0 agreement/disagreement is determined relative to analytical solution results.

 For th termined relative to example simulation results or other user- 

 p id

e remaining cases agreement/disagreement is de

rov ed results for the case itself and for the listed sensitivity case(s).

Figure F-1. Multi-zone non-airflow in-depth diagnostic logic flow diagram 

43
References for Part I 

igerating 

ients, see Chapter 25. 

5). International Energy Agency Building Energy Simulation Test 

ESTEST) and Diagnostic Method, NREL/TP-472-6231. Golden, Colorado, US: National Renewable 

ANSI/ASHRAE Standard 140-2007. Standard Method of Test for the Evaluation of Building Energy 

Analysis Computer Programs. (2007). Atlanta, Georgia, US: American Society of Heating, Refr

and Air-Conditioning Engineers. 

ASHRAE, 2005 Handbook of Fundamentals, American Society of Heating, Refrigerating and AirConditioning Engineers, Atlanta, GA. Regarding conversion factors, see Chapter 38; regarding 

psychrometrics, see Chapter 6; regarding surface heat transfer coeffic

Brandemuehl, M. (1993). HVAC 2 Toolkit. Atlanta, Georgia, US: American Society of Heating, 

Refrigerating, and Air-Conditioning Engineers. See pp. 7-15. 

Judkoff, R.; Neymark, J. (199

(B

Energy Laboratory. www.nrel.gov/docs/legosti/old/6231.pdf (PDF 13.8 MB) 

Marion, W.; Urban, K. (1995). User’s Manual for TMY2s. Golden, Colorado, US: National Renewable 

Energy Laboratory. 

Walton, G. (1983). Thermal Analysis Research Program Reference Manual (TARP). NBSIR 83-2655. 

Washington, D.C., US: National Bureau of Standards. 

44
Part II: Production of Simulation Results 

2.1 Introduction 

In this section we describe how the working group members produced example results for several stateof-the-art whole-building energy simulation programs from Europe and North America. The objectives of 

developing the simulation results were to: 

• Demonstrate the applicability and usefulness of the Building Energy Simulation Test Multi-Zone 

Non-Airflow In-Depth Diagnostic Cases: MZ320–MZ360. 

• Improve the test procedure through field trials. 

• Identify the range of disagreement that may be expected for simulation programs relative to each 

other (see Part III). 

The field trial effort took about three years and involved revisions to the test specifications and 

subsequent re-execution of the computer simulations. The process was iterative in that executing the 

simulations led to the refinement of the test suite, and the results of the tests led to improving and 

debugging various models in the programs related to modeling multi-zone shading and internal windows. 

This process underscores the importance of IEA participation in this project; such extensive field trials, 

and resulting enhancements to the tests, were much more cost effective with the participation of the IEA34/43 experts. 

Table 2-1 describes the models used to generate the simulation results. Appendix II (Section 2.9) presents 

reports written by the modelers for each simulation program. For three of the programs, final results were 

generated for Case MZ320 only, as noted in Table 2-1. For cases MZ340 through MZ360, the VA114 

modelers provided results for two modeling approaches for shading and solar radiation transmission 

through windows: modeling circumsolar diffuse radiation as diffuse radiation, and modeling circumsolar 

diffuse radiation as beam radiation. 

The tables and graphs in Part III present the final results from all the models used in this study. 

Abbreviations and acronyms used in Sections 2.2 through 2.6 and in Part III are given in Section 2.7. 

ces cited in Section 2.2 through 2.7 are given in Section 2.8. 

2.2 Selecti s 

The countries participating in this IEA task made the initial selections of the simulation programs used in 

this study. The selection criteria required that: 

• The program be a true simulation based on hourly weather data and calculative time increments of 

one hour or less. 

• The program be representative of the state of the art in whole-building energy simulation as defined 

by the country making the selection. 

The modeling rules were somewhat more stringent for the simulation programs used for Part III example 

results than for a given program to be normally tested with this BESTEST suite (see Section 1.2.1, 

Modeling Rules). For the Part III simulation results, we allowed a variety of modeling approaches. 

However, we required that these cases be modeled in the most detailed way possible for each simulation 

program. 

Referen

on of Simulation Programs and Modeling Rules for Simulation

45
Table 2-1. Participating Organizations and Models 

Simulation 

Program Authoring Organization Implemented by Abbreviation 

EnergyPlus LBNL/UIUC/DOE-BT,

2.1.0.012 States States 

a,b,c United GARD Analytics, Inc., United EnergyPlus/GARD 

ESP-r ESRU,d

 United Kingdom ESRU,d United Kingdom ESP-r/ESRU 

HTB2 WSA, United Kingdom WSA, United Kingdom HTB2/WSA e e

TRNSYS-TUD University of Wisconsin/Dresden 

University of Technology, United 

Dresden University of 

Technology

TRNSYS-TUD/T

States/Germany 

, Germany 

UD 

TRNSYS-16 University of Wisconsin, United 

States 

University of Liège, Belgium TRNSYS-16/ULg 

VA114 2.25 VABI Software BV, The 

Netherlands 

VABI Software BV, The 

Netherlands 

VA114-CirBm/VABI 

VA114-CirDf/VABI 

Simulation 

lemented by Abbreviation 

Program 

(MZ320 Only) Authoring Organization Imp

 

CODYRUN University of Reunion Island, 

France 

University of Reunion Island, 

France 

UR 

COMFIE EdMP/IZUBA,f,g France EdMP,f

 France EdMP 

KoZiBu INSA-Lyon/JNLOG,h,i JNLOG,i

 France JNLOG 

a

LBNL: Lawrence Berkeley National Laboratory, United States 

b

UIUC: University of Illinois Urbana/Champaign, United States c

DOE-BT: U.S. Department of Energy, Office of Building Technologies, Energy Efficiency and Renewable Energy, United States 

d

ESRU: Energy Systems Research Unit, University of Strathclyde, United Kingdom 

e

Welsh School of Architecture, Cardiff University, United Kingdom 

f

Ecole des Mines de Paris, France 

g

IZUBA Energies, France 

h

INSA-Lyon Thermal Center, France 

i

Jean Noel, France 

To minimize the potential for user error, we encouraged more than one modeler to develop input files for 

each program. Where only a single modeler was involved, we strongly recommended that another 

modeler familiar with the program check the inputs carefully. 

Where improvements to simulation programs or simulation inputs were made as a result of running the 

tests, such improvements must have a mathematical and physical basis, and must be applied consistently 

across tests. In addition, all improvements were required to be documented in modeler reports. Arbitrary 

modification of a simulation program’s input or internal code just for the purpose of more closely 

matching a given set of results is not allowed. The diagnostic process of trapping bugs discussed in Section 

2.4 also isolated input errors that were corrected, as noted there and in the modeler reports (Section 2.9). 

46
2.3 Improvements Trials 

y the IEA-34/43 participants during the field trials, we made a number of 

mments and 

s particularly valuable because the project 

xp 

seve l 

itera e f the tests led to the improvement and 

debuggi

part p ot 

hav oc articipation of the IEA-34/43 experts. 

 basis for the airflow test cases being developed by Utsumi and Mitamura (2008). 

with many data elements set to 0 or approximate lower 

e test 

 be interested in returning to cases that enable radiative 

er and 

 to the Test Specification as a Result of the Field

Based on comments b

improvements and revisions to the test specification. Although researching the co

communicating specification revisions to the field trial participants was very time-consuming, the 

importance of the accuracy and clarity of the test specification for this type of work cannot be overstated. 

The contribution of the IEA-34/43 participating countries wa

e erts supplied continuous feedback throughout the four-year field trial effort. Their feedback resulted in

ra revisions to the test specifications and subsequent re-execution of the computer simulations. This 

tiv process led to refinement of the test cases, and the results o

ng of the programs. The process underscores the leveraging of resources for the IEA countries 

ici ating in this project. Such extensive field trials, and resulting enhancements to the tests, would n

e curred without the p

2.3.1 Revisions to Initial Draft Test Specification (March 2004 – May 2004) 

The initial draft of these in-depth diagnostic test cases was issued in March 2004 for comments; 

simulation by the participants was optional at this stage. The test specification included an initial set of 

four multi-zone conduction test cases, which included two 2-zone and two 3-zone cases where infrared 

radiation exchange was disabled (ideal version) or enabled. The ideal versions of these test cases also 

provided a configuration

One participant ran the conduction test cases and several participants provided comments. A revised 

version of the test specification was then distributed in May 2004 that included the following changes 

based on participants’ comments: 

• Added surface temperature outputs for cases with interior infrared radiation exchange enabled (all

interior surfaces) 

• Revised artificial/dummy weather data 

limits, and other data elements set to neutral (non-extreme) constant values as noted in th

specification 

• Dual units employed (I-P units calculated from original SI units) 

• Editorial revisions. 

2.3.2 Second Round of Revisions (May 2004–February 2005) 

Observations about the initial results based on simulations of the May 2004 version of the test 

specification indicated the following issues: 

• For all cases, require use of constant combined surface heat transfer coefficients as if infrared 

radiation exchange were on, using typical values of ASHRAE, CIBSE, CEN, etc. 

• Do not continue to pursue cases that test infrared radiation because they distract from the 

objective to address modeling issues that are specific to multi-zone cases (accounting, 

convergence, etc.); participants may

exchange calculations. 

• Continue to develop additional test cases beginning with a three-zone configuration with separate

analytically solvable cases for the center zone floating, and for two neighboring zones (cent

an outer zone) floating. 

47
• Incrementally inc e building clearly 

defined) varying internal gains and weather, transmitted solar radiation, internal window, and 

 of ng zone by external fin and by the building. 

 test c ) may be one building dynamic 

We es to addres estion: If single-zone results are satisfactory, 

can we extrapolate will be sa is ques r 

developing cases that compare disagreement among simulation results for single-zone cases versus 

com e multi-z

Base u , f by the lead authors, and planned 

test cases, the follow the February the test specification: 

32 ous ; this se 

Case MZ320 represents an analytically solvable multi-zone conduction case that is potentially 

more diffic olve iterat MZ200. 

otab Z320 are:

o Exterior walls are non-adiabatic. 

The floor is suspended above the ground such that its exterior surface interacts with 

outside air at ambient conditions (similar to other exterior surfaces

o tive and coefficients re t 

convective-only disabled); this enables 

cal lution con tion, which 

fac solation of disagreement y to multi-zone modeling while 

usi stant surfa ssumption. (Surface heat transfer 

models are tested in the single-zone context in IEA BESTEST [Judkoff and Neymark 

199

at of zone air were included in the test specification. 

ta were updated to have constant wind speed consistent 

 to keep first round blind. 

Z310 (radiation exchange enabled) were deleted. 

0 and MZ355 were added for testing multi-zone shading models. 

Z360 was added for testing internal window models. 

• MZ340.TM2 artificial weather data were added for cases MZ340 through MZ360. 

• The output results spreadsheet was revised to include outputs for cases MZ340 through MZ360; 

ndard 140-2004. 

• The shading models cause increased range of results disagreements versus unshaded solar results, 

and disagreement for “back side” of fin shading was unexpectedly large; diagnostics may be 

improved by specifying a larger fin, requiring outputs of disaggregated beam and diffuse solar 

radiation, and additional hourly results comparisons. 

lude (from initial steady state with conditions around th

shading

• Final

neighbori

ase (for later work cycle to develop a 27-z that includes 

loading, shading, etc. 

may also develop additional test cas s the qu

that multi-zone results tisfactory? To answer th tion, conside

parabl one cases. 

d on these iss es, other participant comments

ing revisions were made for 

urther consideration 

 2005 version of 

• Case MZ 0 was added, replacing previ cases MZ200 and MZ300 was done becau

ult for simulations to s

le changes for Case M

ively than MZ300 and

• Other n

o

o C

). 

nstant combined convec radiative surface place constan

 coefficients (radiation excha

culation of an analytical so

ilitates i

nge was previously

 assuming one-dimensional

s related specificall

duc

ng a more realistic con ce coefficient a

5].) 

o Values for density and specific he

o MZ320.TM2 artificial weather da

with the constant exterior surface coefficient. 

• The MZ320 analytical solution was left out,

• Cases MZ210 and M

• Cases MZ340, MZ35

• Case M

this spreadsheet file was named “MZ-Output022205.xls.” 

• Sections on “Modeling Rules” and “Comparing Your Output to the Analytical Solution and

Example Results” were added, for consistency with Sta

2.3.3 Third Round of Revisions (February 2005–August 2005) 

Observations about the second iteration of results, based on simulations of the February 2005 version of 

the test specification were: 

• Shading models for both direct beam and diffuse radiation are working in multi-zone context. 

48
o Include stronger language to require participants to test all shading methods their 

programs are capable of. 

 (four of 

uts—but 

m 

• For the internal window cases, trend agreement between results for ESP-r and TRNSYS-TUD is 

r 

into the test specification. 

mmendations from field trials of the February 2005 version of the test 

pecification, the following revisions were made for the test specification version dated August 2005: 

 

• Case MZ340 to 4 m for greater variation of shading effects among the 

•

• cation that both sides of the fin of Case MZ350 are actively shading the building 

their model allows—for 

 a note was also added to delete this statement for the final version of 

the test specification (as others may want to test simplified models as well as detailed models) 

rograms can apply 

automated building self-shading 

and that 

 a window 

• For Case MZ360, clarified that for required outputs transmitted solar radiation through each 

ed 

0: 

t-facing 

60 

nnual transmitted direct beam and diffuse solar radiation through each 

00) for Case MZ340 

o Consider directly providing disaggregated incident beam and diffuse as an input

the programs that participated in the field trials can use such data for direct inp

this won’t work for a general test if other programs must use solar data directly fro

weather data files). 

encouraging, but additional diagnostic outputs are needed (similar for shading cases); also, some

output specification clarifications are needed. 

o Zone C would have more signal (transmitted solar radiation) if Zone B were less deep. 

• Some minor non-substantive clarifications for Case MZ320 were recommended. 

• Add note that if software does not allow very low relative humidity, adjust weather data or othe

input to use lowest value allowed. 

• Incorporate various errata from February and March 2005 

Additional test cases were suggested, including: 

• Develop a two-zone (one internal-window) version of the internal window case. 

o Incrementally include realistic windows and realistic walls in the 2-zone context. 

o Keep the three-zone context as ideal only. 

• Considering enabling and testing infrared radiation exchange in the pure-conduction test (Case

MZ320) context by comparing relative disagreement for a set of multi-zone case results versus a 

similarly excited single zone case. 

Based on the observations and reco

s

Increased zone height in 

windows in cases MZ350 and MZ355 

Increased shading object height to 18 m for cases MZ350 and MZ355, for more robust shading 

Included clarifi

• Included reminder for participants to use the most detailed shading method 

developing example results;

• Clarified for Case MZ355 that modelers are to run the case only if their p

• Clarified Case MZ355 Zone G mechanical system and set points (same as for other zones), 

Zone G common walls do not include

window is NOT the net solar transmission for the zone (does not include solar radiation transmitt

to a neighboring zone) 

• Included the following additional diagnostic outputs for MZ340, MZ350, MZ355, and MZ36

o Disaggregated annual incident direct beam and diffuse solar radiation on the wes

surface of Zone A for Case MZ340, and on the southwest-facing surface for Case MZ3

o Disaggregated a

window for cases MZ340 through MZ360 

o Added daily hourly transmitted total, direct beam, and diffuse solar radiation for August 4 

(high dn after 18:

49
o Added daily hourly transmitted total solar radiation for Case MZ350 zones C and F fo

August 4 and October 14, to check back side of fin shading of direct and diffuse solar 

radiation 

r 

nsmitted total solar for one day only 

o Updates included to output spreadsheet in “MZ-Output082205.xls.” 

ses 

ntent 

nt that “if the program being tested does not allow a very low value for 

relative humidity, adjust the input weather data (or other software input) to use the lowest 

comments received at the Spring 2005 experts meeting, in the modeler reports, and elsewhere 

We dec put (with 

disa re are already demonstrated by differences between 

shaded (MZ urations for both annual summary results and selected 

hourly resul o

programs ma n

2.3.4 Fourth 

Field trials of the

• Shading ne 

cases ha ranges of disagreement: 

• To refin g fin dimensions may be increased to 24 m 

g an ESP-r shading 

project leader. 

jections 

rent set of internal window cases 

 run the test case. This can be 

 (of the two-zone 

model) to the combined cooling load of Zone B + Zone C in the three-zone model. 

 to Zone C. 

• For internal window cases include the effect of realistic walls (reflectance about 0.5 [realistic] or 

ealistic windows would be a lower priority because the amount of effort to 

specify realistic windows is large relative to what may be learned with respect to 

r, 

o Revised daily hourly cooling load for Zone A for only March 15 for Case MZ340; need to 

check versus tra

• For all cases: 

o Geometry convention revised to vary, based on the varying objectives of the test ca

o Clarified ground reflectance = 0 for all test cases; this was the original (but unstated) i

o Added stateme

relative humidity allowed by the software.” 

• Incorporated other changes from February and March 2005 errata communications, and from 

• Editorial revisions. 

ided to set aside the idea of directly providing incident radiation data as an in

gg gation of beam and diffuse). Shading effects 

35x) versus unshaded (MZ340) config

ts f r high beam (March 15) and high diffuse (October 14) days. Also, some computer 

y ot be able to easily use these data as input. 

Round of Revisions (August 2005–August 2006) 

 August 2005 test specification engendered further comments as noted: 

 disagreements are difficult to diagnose with BESTEST 1995, because those single-zo

ve large 

o 610–600 [south overhang] (Max-Min)/Mean = 1/1.8; see Figure 2-1 

o 630–620 [east/west fin and overhang] (Max-Min)/Mean = 0.9/1.5; see Figure 2-2. 

e hourly shading diagnostics, the MZ350 shadin

height and 15 m width, based on analysis by one of the participants, usin

visualization tool; this change to be checked with further analysis by the 

• Participants suggested developing a case to test the proper modeling of multiple shading pro

on a shaded area; however, they agreed that completing the cur

should be a higher priority. 

• Include an option in the three-zone (two internal windows) internal-window case so simulation 

tools that cannot model two internal windows in series can

accomplished by specifying an option to change window BC into an optically black, zeroconductance ideal surface and then comparing the cooling load in Zone B

• Reduce the Zone B depth so that more solar radiation can be transmitted

0.9 [ideal]) in a separate case; ideal reflectance may provide a more robust test. 

o A case for r

diagnosing internal reflections versus easier-to-specify realistic internal walls; howeve

because some windows have substantial reflectance, such a case should be included if 

possible. 

50
Figure 2-2. East/west overhang and fin shading disagreements from IEA BESTEST 

(Judkoff and Neymark 1995) 

Large range of disagreement relative to mean sensitivity

Figure 2-1. South overhang shading disagreements from IEA BESTEST 

(Judkoff and Neymark 1995) 

Large range of disagreement relative to mean sensitivity

51
Revisions in p are 

listed below: 

• Geo t

follo in s run by NREL, resulted in more 

beam sh

sed zone height to 5 m and increased window size to 4 m × 4 m for Case MZ340 

• For s

• Included

04a) 

odeling methods (ANSI/ASHRAE 2007, Section 5.1.5) 

o To include input files with final results (ANSI/ASHRAE 2007, Section 4.3.2) 

 was not possible to develop additional test cases because of temporary funding cuts during this project 

st 2006) 

Add on

• Typical rial participants 

app 

ns of 

rts will 

•

t Spreadsheet Instructions” 

) 

ks 

Z-Outputr the 

o

cor orated in the August 2006 (substantively final) version, resulting from these comments, 

me ry revisions for cases MZ340, MZ350, and MZ355 for improved shading diagnostics; the 

w g revisions, based on sensitivity tests using EnergyPlu

aded hours for Zone A on March 15: 

o Increa

o Increased shading object size to 24 m × 24 m for cases MZ350 and MZ355 

Ca e MZ360 

o Depth of Zone B reduced 

o Alternative two-zone modeling specification provided 

 analytical solution for Case MZ320 

• Added clauses from ANSI/ASHRAE Standard 140-2004, Addendum b (ANSI/ASHRAE 20

regarding 

o Equivalent m

o Explaining test case results omissions (ANSI/ASHRAE 2007, Section 4.3.1) 

o Changes to software must have a logical basis (revisions to previous language) 

(ANSI/ASHRAE 2007, Section 4.4.3) 

• Editorial revisions. 

It

cycle. 

2.3.5 Fifth Round of Revisions (non-substantive changes after Augu

iti al minor clarifications were made for the final published version of the user’s manual, including: 

users are to apply consistent modeling methods; the IEA-34/43 field t

lied the most detailed modeling methods their program allowed. 

• Deleted references to the modeler report template that was used by the IEA-34/43 participants only 

(which is consistent with the HVAC BESTEST final reports) and replaced that with instructio

Section 1.2.1.10. To adapt this test suite for Standard 140, the Standard-140 modeler repo

apply. 

For convenience to future users we added the following appendices: 

o Appendix B, “Outpu

o Appendix C, “Abbreviations and Acronyms” (includes editing of symbols for consistency

o Appendix D, “Glossary” 

o Appendix E, “Remarks about the Test Cases”; this consolidates informational remar

previously included with each case into one section 

o Appendix F, Using the Flow Diagrams to Diagnose the Results. 

• Editorial revisions 

o Section, table, and figure numbering 

o Remove extraneous notes from MZ-Output082205.xls and renamed it as M

0308.xls 

o Further minor revisions to MZ-Output-0308.xls and renamed it as MZ-Output.xls fo

final revision 

Etc. 

52
2.4 Examples of Error Trapping with BESTEST Diagnostics 

This section summarizes examples that demonstrate how the IEA BESTEST in-depth diagnostic cases for 

multi-zone non-airflow modeling were used to isolate and correct bugs in the simulation programs used for 

the field trials of the test specification. Further description may be found in the individual modeler reports 

presented in Appendix II (see Section 2.9). 

Simulations were performed for each test case with the participating computer programs. At each stage of 

the exercise, output data from the simulations were compared to each other, and to the Case MZ320 

analytical solution, according to the diagnostic logic of the test cases. The test diagnostics revealed (and 

led to the correction of) bugs, faulty algorithms, input errors, or some combination of those in all models, 

except for one of the models that was applied for Case MZ320 only. In the following examples 

improvements to the models that were used for field trials of all the test cases (i.e. EnergyPlus, ESP-r, 

HTB2, TRNSYS-TUD, TRNSYS-16, and VA114) are presented first in sections 2.4.1 to 2.4.6. 

Improvements identified for models for Case MZ320 that did not run the other cases in their final form 

(i.e., CODYRUN and COMFIE) follow in sections 2.4.7 and 2.4.8. KoZiBu ran only Case MZ320 and 

did not report any changes to their model as a result of running the test case. 

2.4.1 EnergyPlus 

EnergyPlus (2008) is developed and maintained by the U. S. Department of Energy (DOE), and is the 

eneration building energy simulation program. Table 2-2 describes field trial iterations 

y GARD Analytics (GARD) for this project. Input file and software modifications for each iteration are 

also shown. A s of the table. 

Table 2-2 Summary of EnergyPlus Changes that Were Implemented 

Version Code Changes Input File Changes 

department’s next-g

b

ingle results set was submitted corresponding to changes described in each row

1.2.2.023 

(March 2005) 

Initially tested version for IEA-34/43 in-depth cases Initial IEA-34/43 input files 

1.2.2.039 

(September 2005) 

Updated version, no changes related to this 

testing 

Incorporate August 2005 

test specification updates 

1.4.0.016 

(September 2006) 

Updated version, no changes related to this testing Incorporate August 2006 

test specification updates 

2.1.0.012 

(October 2007) 

Modeling of diffuse solar transmitted through 

exterior and interior windows improved to better 

account for initial absorption, transmittance and 

reflection of short-wave radiation 

2.4.1.1 Unintended lost diffuse solar radiation; 33% increase in cooling load for Case 

MZ360 and 4% increase in cooling load for cases MZ340 through MZ355 

Before EnergyPlus 2.1.0.012, the diffuse radiation transmitted through an exterior window (e.g. Window 

AO in Case MZ360) was evenly distributed to all surfaces within the zone, including the inside of the 

exterior window. For version 2.1.0.012 the method for modeling transmitted diffuse solar radiation was 

reworked to first be incident all interior surfaces except the inside surface of the exterior window. Figure 

2-3 shows the effect on results before and after the fix, indicating a 33% increase in Case MZ360 total 

building annual cooling load after the fix. This fix also increased cooling loads for cases MZ340, MZ350, 

and MZ355 by 4%.

53
2.4.1.2 No beam radiation to Zone C of Case MZ360; likely increase for Zone C cooling 

load of 240% and overall building cooling load of 6% 

Res s 

low. Th

transmis radiation) through a second-in-series internal 

window (W

radiation th g irect beam 

radiation would increase the Zone C cooling load by a factor of 2 to almost 3 (factor of 2.4 average 

estimate). This could cause about 6% underestimation of total building cooling load, assuming half the 

beam radiat he TRNSYS-TUD and TRNSYS16 m n, and have Zone C results similar to the EnergyPlus 

resu . 

in Part III. As double-skin facades become more popular in buildings (e.g., see Poirazis 2007), more 

accurate mo i tance. The 

EnergyPlus lar 

modeling al i

Figure 2- E

ult for Zone C in Figure 2-3 also indicate that after the described fix, Zone C cooling load may be 

e EnergyPlus modeler report (see Section 2.9, Appendix II-A) indicates that EnergyPlus allows

sion of diffuse radiation only (no direct beam

indow BC). Comparison with results for programs that allow transmission of direct beam 

rou h Window BC (ESP-r and VA114) indicate that including transmission of d

ion modeled as diffuse is lost back through Window AO. T

odels also exclude transmission of beam radiatio

lts Disaggregated transmitted direct and diffuse solar radiation results for Case MZ360 are included 

del ng of solar radiation through a series of internal windows gains impor

developers have been notified of this issue, and they are looking at their diffuse so

gor thms. 

IEA BESTEST Multi-Zone: MZ360 

Annual Sensible Cooling Loads

0

20000

4

140000

120000

3. nergyPlus annual cooling loads before and after fix of unintended solar lost error

0

000

000

60

80

QB + QC

Sensible Cooling Load (

100000

kWh)

000

Building, Qbldg Zone A, QA Zone B, QB Zone C, QC

HTB2/WSA TRNSYS/TUD TRNSYS/Liège

ESP/ESRU VA114-cb/VABI VA114/VABI

EPlus/GARD Before Fix EPlus/GARD After Fix

54
2.4.1.3 Documentation unclear to modeler regarding if MZ360 Zone B transmitted solar 

 gross or net (after some diffuse transmitted through to Zone C); no effect on cooling 

ecified by the test cases.

 this 

is

load, limits diagnosis of results

The EnergyPlus team is developing outputs for interior window transmitted diffuse solar radiation, which

tracks such transmitted solar radiation as sp

2.4.1.4 Check October 17 hourly shaded solar; minor difference worth noting

Hourly results for shaded solar radiation (MZ340–MZ350 difference) shown in Figures 2-4 and 2-5 

indicate possible disagreement for Zone B (front side of fin shading) for hours 17 and 18, and for Zone C 

(back side of fin shading) for hours 15 and 17. The EnergyPlus developers have been notified of

issue, and they are looking at their diffuse solar modeling and shading algorithms. 

BESTEST Multi-Zone: MZ340-MZ350, Delta High-Diffuse-Da

Figure 2-4. Hourly shaded total solar radiation for high diffuse day, Zone B 

y Shading

October 14 (low dn) Hourly Shaded Solar, Zone B (Most Shaded)

1000

1 2 8 1 20 21 22 23 24

Shaded Solar Radiation (Wh/h) 2000

1500

0

500

3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 1 9

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS16/Liege VA114-CirDf/VABI VA114-CirBm/VABI

55
BESTEST Multi-Zone: MZ340-MZ350, Delta High-Diffuse-Day Shading

October 14 (low dn) Hourly Shaded Solar, Zone C (Back Side Shade)

500

1000

1500

2000

Shaded Solar Radiation (Wh/h)

0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

EnergyPlus/GARD

Figure 2-5. Hourly shaded total solar radiation for high diffuse Day, Zone C 

2.4.2 ESP-r 

ESP-r (ESRU 2008) is developed by the Energy Systems Research Unit, University of Strathclyde, 

Scotland, UK. Modeling details are described in ESRU’s modeler report; see Section 2.9, Appendix II-B. 

2.4.2.1 Interprets half-hour hour centered solar data as hour-centered; 12% cooling load 

effect for MZ340

Figure 2-6 indicates a timing offset for solar radiation submitted in December 2005, for 

initial simulations of the final fin and window design fo 0 and MZ350. The source of the 

disagreement was diagnosed to be that ESP-r assumes s are hour-centered, whereas TMY2 data are 

preceding-hour (e.g. 00:00–01:00) half-hour centered da was made to allow halfhour centered solar data. Comparison in Figure 2-7 for ESP-r results mitted December 2005 

(“ESP/ESRU-Dec2005”) and September 2006 -Sep2006”)—se indicates a 12% 

decrease in Case M shaded) cooling lo the improvem

for ESP-r results

r cases MZ34

olar data 

ta. A software modification 

sub

(“ESP/ESRU e red arrow—

Z340 (un ad results from ent.

ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS16/Liege VA114-CirDf/VABI VA114-CirBm/VABI

56
IEA BESTEST Multi-Zone: MZ340 (UNSHADED) 

March 15 (high dn) Hourly Transmitted Solar, Zone A 

14000

12000

0

2000

10000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Transm

4000

6000

8000

itted Solar Radiation (Wh/h)

ESP-r 

TRNSYS/TUD

Figure 2-6. ESP-r hourly solar offset disagreement from December 2005 

2.4.2.2 No diffuse shading; 19%–35% effect on cooling load

Figure 2-7 also indicates that after the above fix, which results in good agreement for Case MZ340, ESP-r

ostly increased disagreements (error described in Section 2.4.2.1 was somewhat compen

shaded solar radiation for all zones in sensitivity Case MZ340–MZ350 (see “ESP/ESRU-Sep2006” 

marked with black arrows). Furthermore, hourly results shown in Figure 2-8 indicate no shadin

occurs on a day dominated by diffuse solar radiation. Based on these results, a major enhancement w

to ESP-r to add diffuse shading based on the daylight coefficient method documented in Section 4

SP-r modeler report (see Appendix II-B). 

for after implementation of the new shading method are shown in Figure 2-7 (see results labe

has m sating) for 

results g 

as 

made of 

the E

Results led 

,” patterned bar just to right of arrows). These results indicate a small decrease 

round 2%) in annual solar load for Case MZ340 (unshaded), for sensitivity Case MZ340–MZ350 an 82% 

 87% increase in the amount of shaded solar radiation for zones where the front (south) side of the fin 

dominates sh (north) 

side of the fin (diffuse shading) dominates shading. This translates to a 19%–35% reduction in Case MZ350 

cooling load, depending on the position of the shading fin with respect to a given zone. 

“ESP/ESRU-Mar2007

(a

to

ading and about a 230% increase to shaded solar radiation for zones where the back

ESP/ESRU VA114/VABI EnergyPlus/JNA

57
IEA BESTEST Multi-Zone: MZ340 - MZ350x Delta Shaded Solar 

Shaded Solar Radiation (kWh)

Annual Shaded TOTAL Solar Radiation, All Zones

0

2000

4000

6000

8000

10000

12000

14000

16000

Unshaded

(MZ340)

Zone B Zone E Zone A Zone D Zone C Zone F

HTB2/WSA-d TRNSYS/TUD-a ESP/ESRU-Dec2005 ESP/ESRU-Sep2006

ESP/ESRU-Mar2007 VA114a-CircBeam VA114/VABI-a EPlus/GARD-b,c,d

Unshaded 

Shaded Solar (“MZ340-MZ350”) 

Figure 2-7. ESP-r total solar radiation, from Dec. 2005, Sep. 2006, and March 2007 

Figure 2-8. Hourly results indicating no shaded solar radiation by ESP-r for a diffuse solardominated day, from September 2006

BESTEST Multi-Zone: MZ340-MZ350, Delta High-Diffuse-Day Shading 

October 14 (low dn) Hourly Shaded Solar, Zone B (Most Shaded) 

0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

2000

500

1000

Shaded Solar Radiation (Wh/h) 1500

ESP-r 

HTB2/WSA-d TRNSYS/TUD-a ESP/ESRU-c

VA114-CircBeam VA114/VABI-a EnergyPlus/GARD-b,c,d

58
2.4.2.3 Custom weather processor

Also for results submitted in September 2006, a disagreement was found (see Figure 2-9). This led to 

discovery in the climate file for March 15, hours 13:00 and 14:00, the values in the weather file for direct 

normal radiation were 1006 and 1000 W/m2

 respectively, but were incorrectly set as 6 and 0 W/m2. These 

were the only two hours in the year where the direct normal reached 1000W/m2. At some stage in the 

conversion from the original TMY2 climate format, an error was made in the formatting. The ESP-r 

modeler considers this to be more of a modeler error than an error in ESP-r, as a TMY2 processor was 

custom written for this project. (For typical TMY2 files ESP-r normally uses EPW [EnergyPlus processed] 

data files.) The modeler did not provide separate results for this fix. The overall impact of the fix is masked 

by changes in solar modeling for diffuse shading (see Section 2.4.2.2), but this error would not be present 

for weather data typically used by ESP-r. However, identification of this relatively minor problem further 

underscores the power of the diagnostics.

For results submitted in March 2007, ESP-r did not disaggregate direct and diffuse solar radiation from total 

solar radiation in its output. The ESP-r developers agreed that disaggregating solar radiation in the output is 

a useful diagnostic feature, and included that capability in their software for generating results submitted in 

July 2007. 

BESTEST Multi-Zone: MZ360, Internal Windows

March 15 (high dn) Hourly Transmitted Solar, Window "AO" (Zone A) 

0

20000

40000

1 2 3 4 5 6 7 8 91

60000

Shaded Solar Radiation (Wh/h)

80000

100000

120000

0 11 12 13 14 15 16 17 18 19 20 21 22 23 24

ESP-r 

HTB2/WSA TRNSYS/TUD TRNSYS/Liège

ESP/ESRU VA114/VABI EnergyPlus/GARD

Figure 2-9. Results from March 2007 including ESP-r with new solar shading algorithm 

2.4.2.4 No disaggregation of direct and diffuse solar in output

59
2.4.2.5 Solar/shading algorithm refinement; 10%–11% peak cooling load effect for Case 

MZ350, zones B and E; < 2% annual cooling load effect cases MZ340, MZ350, all 

zones

For results submitted in March 2007, ESP-r also exhibited some disagreement for MZ350 peak cooling 

load, as shown in Figure 2-10 (solid red bars). The results submitted in July 2007 improve the resolution of 

modeling the direct sky component with increased numbers of daylight coefficients for direct radiation 

(going from 145 preset positions to 2035 preset positions). This caused an increase in Case MZ350 peak 

cooling load (see Figure 2-10, solid black bars) for zones B and E (most shaded zones) of 11% and 10%, 

respectively; peak load variation for the other shaded zones and for unshaded zones (Case MZ340) was < 

1%. Annual load variation (not shown here) was < 2% for all zones in both the shaded and unshaded cases. 

Figure 2-10. MZ340–MZ350 peak cooling load sensitivity, from March 2007 and Sep. 2007 Results

2.4.2.6 Back side of fin shading disagree ase MZ350, zones C and F

Figure 2-10 indicates some remaining peak cooling disagreement for results submitted July 2007, for zones 

C and F (back side of fin shading), see black arrows in the figure. The ESP-r developers have been informed 

of this issue and indicate they are further revising their shading algorithm (Strachan 2008). Updated results 

were not ready in time for inclusion in this report.

ment, C

IEA BESTEST Multi-Zone: MZ340, MZ350x 

Annual Hourly Integrated Peak Cooling Load, All Zones

0

2000

4000

6000

10000

12000

14000

16000

Unshade (MZ340) Zone B Zone E Zone A Zone D Zone C Zone F

Cooling Load (Wh/h)

8000

HTB2/WSA-d TRNSYS/TUD-a TRNSYS/Liège-c ESP/ESRU-Mar2007

EPlus/GARD-b,c,d

"Back side" of Fin Shading

ESP/ESRU-Jul2007 VA114a-CircBeam VA114/VABI-a

60
 2.4.3 HTB2 

HTB2 is a research-based thermal modeling program developed and maintained by the Welsh Schoo

Architecture at Cardiff University. Other modeling details are described in the HTB2 modeler report; se

Section 2.9, Appendix II-C. 

2.4.3.1 User-input constant exterior combined surface coefficients ignored; 1.3% e

Initial specification of fixed external combined coefficients for Case MZ320 led to disagreement with the 

analytical solution. The difference was traced to the default exterior surface coefficient calculation algorithm

still being used; the user-input values specified were being ignored. HTB2’s initialization code was altered

to allow the proper detection and use of exterior surface coefficient override values. This fault applied only

to exterior surface coefficients; user-specifi

l of 

e 

ffect 

ed interior surface coefficients were detected and used properly 

 the original code. This fault has been fixed in the latest version. Table 2-3 indicates a 1.3% effect for the 

change, going from version 2.20R to 2.20T. 

Table 2-3. HTB2 Results before and after Fix to Detect User-Input Exterior Surface Coefficients 

HTB2 2.20R HTB2 2.20T 

in

QC (W) 1521.06 1541.3 

TA (°C) 31.283 31.058 

TB (°C) 24.910 24.798 

2.4.3.2 Infrared emittance = 0 not allowed; program crashed

Case MZ340 required the use of zero emissivity for all surfaces in a zone; the original code failed when the 

total emissivity of a zone was zero. The failure was traced to a prev ide-by-zero fault. 

The code was revised to allow the use of zero emissivity surfaces. ue was not detected in Case 

MZ320, as radiant calculations for that case were disabled to use the required combined surface heat transfer 

coefficients, and as solar calculations were not needed for that case.) 

2.4.3.3 Shadow/window overlap; 1%–2% effect on MZ340–MZ350 load sensitivity

During the modeler’s inspection of the shading preprocessor output before revisions were run, anomalous 

behavior was noticed in the shading factor data for high altitude angles (there were discontinuous “jumps” 

in the data). This was traced to faulty logic in determining the shadow overlap cases in HTB2’s Hshade 

reprocessor, which wrongly excluded a valid case triggered at acute vertical angles. This was corrected 

 prod uary 

005 version 

ade the problem more noticeable. Differences in results documented in the HTB2 modeler report (see 

ing [MZ340–MZ350 

s the results comparison. 

iously undetected div

 (This iss

p

to uce more smoothly varying factors. Although this error was present for results using the Febr

2 of the test specification, the larger fin size for the August 2005 test specification revision 

m

Section 2.9, Appendix II-C) were generally small (2% or less for solar shad

sensitivity]) but notable in some of the hourly solar data. Table 2-4 include

61
Table 2-4. HTB2 Results before and after Shadow/Window Overlap Fix 

 Annual Cooling Loads 

 QBldg QA QB QC QD QE QF

Case (kWh) (kWh) (kWh) (kWh) (kWh) (kWh) (kWh) 

MZ340 27780.97 4630.163 4630.162 4630.163 4630.162 4630.162 4630.162

MZ350 after 19780.07 3662.931 2598.483 3522.517 3778.519 2689.97 3529.65

MZ350 before 19671.46 3654.766 2574.947 3511.967 3770.976 2650.103 3508.705

MZ350 del% –0.5% –0.2% –0.9% –0.3% –0.2% –1.5% –0.6% 

MZ340–350 after 8000.9 967.232 2031.679 1107.646 851.643 1940.192 1100.512

MZ340–350 before 8109.51 975.397 2055.215 1118.196 859.186 1980.059 1121.457

MZ340–MZ350 del% 1.4% 0.8% 1.2% 1.0% 0.9% 2.1% 1.9% 

2.4.3.4 Shading interpolation

Investigation into the afternoon “hump” (see Figure 2-11) observed in the HTB2 shaded results for Zone 

A of Case MZ350 (August 2005 version of test specification) suggested that the time and spatial 

interpolation used for shading factors in HTB2 were too coarse; as a result a transient shadow could be 

considered to be in place for a full recalculation interval. This effect was magnified by the large fin 

dimensions set by the test. For runs using the August 2006 version of the test specification, HTB2 was 

modified to increase the shading recalculation interval and a new interpolation algorithm was used to 

estimate shading factors at arbitrary angles. A small reduction in disagreement was noted as a result. It 

was not possible to establish what the effect of this change was on overall cooling loads, because of 

changes to the test specification for the shading cases, modifications to other program models based on 

diagnosis of previous results (no consistent point of comparison), and insufficient time for the HTB2 

participant to go back and run the unrepaired version of HTB2 using the new test specification. 

Figure 2-11. HTB2 shaded solar radiation disagreement from September 2005 

BESTEST Multi-Zone: MZ340-MZ350, Delta High-Beam-Day Shading 

March 15 (high dn) Hourly Shaded Solar, Zone A (Less Shaded) 

0

1000

1500

3000

3500

4000

ded Sola tion ( h/h)

0 implies no shading

W

2500

HTB2 2000

r Radia

500

Sha

-500

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

HTB2/WSA-d TRNSYS/TUD-a TRNSYS/Liège-c COMFIE/EdMP-b ESP/ESRU-c CODYRUN/UR-12m

VA114/VABI-a VA114/VABI-c EnergyPlus/GARD-b,c,d HTB2bad/WSA-d

62
2.4.3.5 Synchronization of solar data with surface insolation model; up to 0.4% increase

in zone peak cooling load, up to 23% effect on specific-hour cooling load, negligible 

effect on annual cooling load

w match hourly total transmitted solar (hourly transmitted 

olar did not change), and the solar gains and cooling loads in a zone are now essentially identical. As 

h

i

Table 2-5. HTB2 Cooling L versus Tran r Gains s from September 2006, 

ersion 2.20AA) and after (Version ) Fix 

n)

Initial results for the August 2006 test specification shown in Table 2-5 indicate a difference of up to 23% 

in hourly output of solar gain versus cooling load for cases MZ340 and MZ360. Inspection of the dataflow

in the model led to the conclusion that the solar data, as generated by HTB2’s meteorological and solar 

transmission modules, and the surface insolation data, as used by HTB2’s fabric module, were one time step 

(on the order of 100 seconds) out of phase when the fabric calculations were made. This would be 

significant at reporting and solar calculation boundaries for hourly outputs, and could lead to differences in 

highly transient conditions (e.g., at sunset). As of version 2.20AB, the ordering of the calculation modules 

has been revised, but otherwise no changes were made to algorithms, parameters, or data. This appears to 

have solved the problem: hourly cooling loads no

s

s own in Table 2-6, the change has negligible effect on annual cooling load (minor variation in seventh 

s gnificant digit), and caused up to a 0.4% increase to zone peak cooling load. 

oad smitted Sola

before (V

 Discrepancie

 2.20AB

 HTB2 MZ340 Hourly Results MZ360 Hourly Results

2.20AA March 15 (high dn) Mar. 15 (high d

qA Itrh,A q I B trh,B

1895 -0.5%

13 1131 1177 -3.9% 18226 18560 -1.8%

Hour (Wh/h) (Wh/h) Delta % (Wh/h) (Wh/h) Delta %

600 #DIV/0! 0 0 #DIV/0!

7 153 155 -1.5% 569 577 -1.5%

8 251 255 -1.6% 933 948 -1.6%

9 395 398 -0.9% 1467 1481 -0.9%

10 507 510 -0.5% 1885

11 596 598 -0.4% 2202 2208 -0.3%

12 644 646 -0.2% 6684 6911 -3.3%

14 4652 4753 -2.1% 32508 32879 -1.1%

15 8278 8362 -1.0% 45983 46296 -0.7%

16 11032 11092 -0.5% 55273 55450 -0.3%

17 12180 12197 -0.1% 55804 55743 0.1%

18 10488 10433 0.5% 43047 42665 0.9%

19 1461 1200 21.8% 5389 4379 23.1%

20 6 0 #DIV/0! 22 0 #DIV/0!

21 0 0 #DIV/0! 0 0 #DIV/0!

63
Table 2-6. HTB2 Results before (version 2.20AA) and After (version 2.20AB) Fix 

 

 Annual Cooling 

Loads Peak Cooling Loads 

 Qbldg Qzones qbldg qzones

Case (kWh) (kWh) (Wh/h) (Wh/h) 

MZ340 “9/13/06”(before) 74116.84 12352.80 73081.4 12180.2 

MZ340 “9/24/06” (after) 74116.93 12352.82 73182.2 12197.0 

MZ340 del% negligible negligible 0.14% 0.14% 

MZ360 “9/13/06”(before) 121815.50 52654.00* 110796 70722* 

MZ360 “9/24/06” (after) 121815.48 52654.05* 111067 70999* 

MZ360 del% negligible negligible 0.24% 0.36% 

 * for Zone B of two-zone implementation of Case MZ360 

2.4.3.6 Internal window reflection Case MZ360; QA decreased by 16%, QB increased by 

18%, negligible change to Qbldg

Figures 2-12 and 2-13 indicate disagreements for HTB2 (bars with red background and red arrows) versus 

results with no known fundamental anomalies as of field trials completed October 2006 (bars with blue 

background). Investigation of these differences led to discovery that cosine of incidence angle was 

effectively accounted for twice in the calculation of transmission through the internal glazing (Window 

AB); the end effect was that energy so “lost” in transmission to Zone B appeared as a diffuse reflection 

back into Zone A. This problem was corrected in version 2.20AD, and the case rerun with no changes to 

parameters. This caused a 16% decrease in QA and an 18% increase in QB, with negligible change to 

bldg; the results now appear more consistent with other models, as shown in Part III.

 HTB2 MZ3 Hour Results

2.20AB March gh dn Mar. 15 (high dn

q

40 Hourly Results MZ360 ly 

15 (hi ) )

Itrh,A qB I A trh,B

Hour (W

6

7

8

9

1177 117 0.0% 1856

14 4753 4753 0.0% 32879 32879 0.0%

8362 0.0% 46296 46296 0.0%

11092 0.0% 55450 55450 0.0%

h/h) (W

0

h/h) De

0 #D

lta % (Wh/h)

IV/0!

(

0

Wh/h)

0

Delta %

#DIV/0!

155 155 0.0% 577 577 0.0%

255 255 0.0% 948 948 0.0%

398 398 0.0% 1481 1481 0.0%

10 510 510 0.0% 1895 1895 0.0%

11 598 598 0.0% 2208 2208 0.0%

12

13

646 646

7

0.0% 6911

0

6911

18560

0.0%

0.0%

15 8362

16 11092

17 12197 12197 0.0% 55743 55743 0.0%

18 10433 10433 0.0% 42665 42665 0.0%

19 1200 1200 0.0% 4379 4379 0.0%

20 0 0 #DIV/0! 0 0 #DIV/0!

21 0 0 #DIV/0! 0 0 #DIV/0!

input 

Q

64
IEA BESTEST Multi-Zone: MZ360 

Annual Sensible Cooling Loads

140000

QB + QC

120000

0

20000

40000

60000

80000

100000

Building, Qbldg Zone A, QA Zone QB Zone C, QC

Sensible Cooling Load (kWh)

B,

HTB2/WSA TRNSYS/TUD TRNSYS/Liège ESP/ESRU VA114/VABI EPlus/GARD

Figure 2-13. HTB2 transmitted solar radiation disagreements from September 2006

Figure 2-12. HTB2 cooling load disagreements from September 2006

IEA BESTEST Multi-Zone: MZ360 

Annual Incident & Transmitted Solar Radiation

0

20000

40000

60000

80000

100000

120000

140000

SW Inc. x

11.8^2, I

Zone A,

ItrA

Zone B,

ItrB

Zone C,

ItrC

SW Inc. x

11.8^2, Ib

Zone A,

ItrbA

Zone B,

ItrbB

Zone C,

ItrbC

SW Inc. x

11.8^2, Id

Zone A,

ItrdA

Zone B,

ItrdB

Zone C,

ItrdC

Solar Radiation (kWh)

HTB2/WSA TRNSYS/TUD TRNSYS/Liège ESP/ESRU VA114/VABI EPlus/GARD

65
66

2.4.3.7 March 15, hour 17 disagreement for sensitivity Case MZ340–MZ350

For the final results for the MZ340–MZ350 hourly shading sensitivity for March 15 (dominated by direct 

normal solar), a disagreement occurs for hour 17 (see Figure 2-14). According to the HTB2 modeler 

report, this is similar to an issue reported in Section 2.4.3.4: “The suspected source of the difference may 

be a limitation of the sky mask model. The problem is likely that the sectoring is too coarse for this 

sensitive problem. Currently the descriptions are given in steps of 10 degrees; the solar position is 

updated every 15 minutes. Some interpolation is done using neighboring sectors, and that if the shadow is 

sharp edged then the result would be fuzzy. At hour 17, the sun may be just passing the shade, so the 

coarseness of the mask may introduce an error. It is possible to increase the mask resolution (to 5 and 2 

degrees), to see if that improves the result, and this issue has been flagged to check for a future update.” 

The modifications to the software required to check this were not completed for inclusion in this report.

reement for Case MZ360

BESTEST Multi-Zone: MZ340-MZ350, Delta High-Beam-Day Shading

March 15 (high dn) Hourly Shaded Solar, Zone B (Most Shaded)

4000

6000

8

10000

12000

14000

7 8 6 17 21

Shaded Solar Radiation (Wh/h)

Figure 2-14. HTB2 shaded solar radiation disagreements for Hour 17 of a day with high direct 

normal solar radiation

2.4.3.8 October 14, hourly disag

For the final results for MZ360, the hourly results of Figure 2-15 for October 14 (dominated by diffuse 

solar) indicate that the cooling load for Zone B using the alternative two-zone specification for HTB2 

(comparable to zones B + C for the other programs) is less than the Zone-B-only results for the other 

programs. According to the HTB2 modeler report, this difference is attributable to the relatively 

simplified method of modeling internal windows using assigned user input transfer ratios based on the 

geometry of the case; e.g., relative areas of window and wall surfaces. Additionally, this disagreement is 

seen only for diffuse solar; the direct-solar dominated day has better agreement. The code author 

considers that there is no coding error involved, but that this result indicates the limitation of the 

0

2000

000

1 2 3 4 5 6 9 10 11 12 13 14 15 1 18 19 20 22 23 24

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSY D S-TUD/TU

TRNSYS16/Liege VA114-CirDf/VABI VA114-CirBm/VABI
underlying method used to estimate interzone diffuse solar radiation transfer. To improve the result it 

would have been possible to “tune” the input parameters. However, the code author prefers to provide 

unbiased results, so no further changes will be made. 

This 

for a se changes 

some of the old features were not called correctly anymore. 

BESTEST Multi-Zone: MZ360 Internal Windows

October 14 (low dn) Hourly Transmitted Solar, Window "AB" (Zone B)

0

5000

10000

15000

20000

25000

30000

35000

23 24

Transmitted Solar Radiation (Wh/h)

Figure 2-15. HTB2 shaded solar radiation disagreements for Hour 17 of a day with high direct 

normal solar radiation

2.4.4 VA114 

VA114, initial development by TNO, current development and distribution, maintenance, and support by

VABI Software BV, The Netherlands, is widely used in The Netherlands (VABI Software 2008). 

Before participating in this project beginning in April 2005, VABI made some major changes to VA114 

(beginning in 2004): 

• Calculated solar distribution using ray tracing 

• Implemented internal window modeling 

• Improved of solar shading and solar distribution modeling 

• Added features to reduce solar calculation computation time. 

IEA research task gave VABI an opportunity to test these new features, which replaced old, less 

general, models. Both the old and the new models were part of the tests; the old models were checked only

comparison with the new models, and are no longer av ilable to u rs of VA114. After these

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS16/Liege VA114-CirDf/VABI VA114-CirBm/VABI

EnergyPlus currently does not provide this 

output exactly as specified by the test cases.

HTB2 

67
A number of errors were reported by VABI in the June 30, 2005 draft of its modeler report, which 

accompa ing the 

ion of these 

rrors is included with the VA114 modeler report in Section 2.9, Appendix II-F. 

d 

are 

2.4.4.2 VA114 “comfort cube” in wrong coordinate system; submitted with June 30, 

2005 modeler report, effect not given (Case MZ320) 

VA114’s comfort module calculates the radiative temperature on the six surfaces of a comfort cube. It was 

found that after running Case MZ320 that the position of the comfort cube was in a wrong coordinate system. 

VABI fixed this error, but did not submit prior results showing the effect of this revision. 

2.4.4.3 Thermal conductance of a construction layer cannot = 0; submitted with June 

30, 2005 modeler report, effect not given (Case MZ340) 

For Case MZ340, thermal conductance of a construction layer cannot = 0 in VA114; however, very low 

values are allowed. VA114 was modified to provide a warning if thermal conductance < 0.00001. VABI did 

not submit prior results showing the effect of this revision. 

2.4.4.4 Shading of direct solar radiation excluded for model using shading device affixed 

to building (Case MZ350a) 

For a shading device modeled as affixed to a building, VABI tested numerous related modeling options 

available for VA114. The initial run of Case MZ350a indicated a large difference among results when the 

modeling option for rectangular zones was applied (“Ishape” = 0) and for where only surface areas are known 

(“Ishape” = –1), versus for any shape zone (“Ishape” = 1). It was found that when either Ishape = 0 or Ishape 

= –1 (which are no longer available to VA114 users) were designated that the modeling of shading of direct 

solar radiation was bypassed (old feature not called correctly). VABI did not submit prior results showing the 

fect of this error. 

.4

no

ilding or trees) VA114 intentionally 

d modeling options available for 

or 

 of 

nied initial results of the same date. For these errors VABI did not submit prior results show

effect of those errors (old features that did not work correctly anymore). More detailed discuss

e

2.4.4.1 For emittances or absorptances < 0.2, sum of exchange factors > 1; submitte

with June 30, 2005 modeler report, effect not given (Case MZ320) 

For Case MZ320, for internal infrared emittances < 0.2, the sum of exchange factors was > 1.0. A softw

correction was made so that VA114 properly calculates exchange factors for emittances > 0.01. A similar 

error occurred for developing distribution factors for diffuse solar radiation using inside-surface solar 

absorptance; VA114 was also repaired to properly calculate such exchange factors for absorptances > 0.01. 

VABI did not submit prior results showing the effect of these revisions. 

ef

2 .4.5 Shading of direct solar radiation excluded for model using shading by objects 

t affixed to building, diffuse shading intentionally excluded (Case MZ350c) 

For a shading device modeled as not affixed to a building (e.g., other bu

excludes shading of diffuse solar radiation. VABI tested numerous relate

VA114 using this shading method. Initial run of Case MZ350c indicated a large difference among results 

when modeling option for rectangular zones was applied (“Ishape” = 0) and for where only surface areas are 

known (“Ishape” = –1) versus for any shape zone (“Ishape” = 1). It was found that when either Ishape = 0 

Ishape = –1 (which are no longer available to VA114 users) were designated that the modeling of shading

direct solar radiation was bypassed (old feature not called correctly). VABI did not submit prior results 

showing the effect of this error. 

68
2.4.4.6 Shading of all solar radiation excluded for model using automated building

shading, two errors (Case MZ355) 

For automated building self-shading, the initial VA114 run of Case MZ355 indicated no shading. VABI’s 

June 30, 2005 modeler report indicates two related errors

 self-

: a direct shading routine was not called (old feature 

not called correctly), and a problem with the ray-tracing algorithms. VABI did not submit prior results 

showing the effect of these errors. 

2.4.4.7 Minor differences for beam shading of solar radiation by fin affixed to building 

versus automated building self-shading; < 0.3% transmitted beam radiation, < 0.1% 

zone cooling load (Case MZ355) 

For VABI’s final results for cases MZ355 and MZ350, for comparable zones (zones A, B, D, and E) there are 

minor differences between results for automated building self-shading versus results for shading with a fin 

affixed to a building. These differences amount to < 0.3% for transmitted beam radiation to < 0.1% for zone 

cooling load. Table 2-7 (circled data) and Figure 2-16 indicate where a r rence in hourly results for 

March 15, hour 16 occurs for circumsolar radiation modeled as diffuse r “VA114-CirDf/VABI”) and 

circumsolar radiation modeled as beam radiation (“VA114-CirBm/VABI”). VABI’s modeler report indicates 

that this difference occurs for March 12 through March 17, and that VABI is searching for the cause of the 

difference, but has not yet been able to find it. [Primary author’s note: This difference could be caused by 

minor differences in a program’s geometry convention for locating a shading device as affixed to a building 

versus for building self-shading by a zone (the fin of Case MZ350 and Zone G of Case MZ355 are specified 

in the BESTEST user’s manual to have matching shading characteristics with respect to zones A, B, D, and 

E).] 

Table 2-7 VA114 MZ355 v. MZ350 Disagreements for Hour 16 of a Day with High Direct Normal 

Solar Radiation

4 #DIV/0! #DIV/0!

5 #DIV/0! #DIV/0! #DIV/0!

6 #DIV/0! #DIV/0! #DIV/0!

7 0.00000 0.00000 0.00000

8 0.00000 0.00000 0.00000

9 0.00000 0.00000 0.00000

13 0.00000 0.00000 0.00000

16 0.00000 -1.30595

17 0.00000 0.00000

00 0.00000

00 0.00000

#DIV/0!

#DIV/0!

V/0!

V/0!

24 #DIV/0! #DIV/0! #DIV/0!

elated diffe

adiation (

March 15 (high dn) Zone A Hourly Transmitted Solar (MZ355 - MZ350x) / MZ355 [fraction]

Hour EnergyPlus/GARD VA114-CirDf/VABI VA114-CirBm/VABI

1 #DIV/0! #DIV/0! #DIV/0!

2 #DIV/0! #DIV/0! #DIV/0!

3 #DIV/0! #DIV/0! #DIV/0!

#DIV/0!

10 0.00000 0.00000 0.00000

11 0.00000 0.00000 0.00000

12 0.00000 0.00000 0.00000

14 0.00000 0.00000 0.00000

15 0.00000 0.00000 0.00000

-2.74037

0.00000

18 0.00000 0.000

19 0.00000 0.000

20 #DIV/0! #DIV/0!

21 #DIV/0! #DIV/0!

22 #DIV/0! #DIV/0! #DI

23 #DIV/0! #DIV/0! #DI

69
Figure 2-16. VA114 March 15 hourly transmitted total solar: MZ355 v. MZ350 

2.4.4.8 Hard-coded internal window reflectance = 0.1; 7% effect for Case MZ360 total

building annual cooling load, 22% effect for Zone C coolin

ooling loads 

found, for the routine that 

alculates the distribution of the diffuse solar radiation, the reflectance w was fixed (hard-coded) 

ow in zo del the test, the solar 

flection was reprogrammed as 1.0 – transmittance (for user-input transmittance). ulation results 

or 

Building Zone A Zone B Zone C 

g load, similar effects for peak 

c

VABI’s modeler report indicates that for Case MZ360 the total cooling load was “a few %” lower than the 

total incident solar radiation on Window AO (area * total solar in kWh/m2

). It was 

c of the windo

at 0.10. So, 10% of the solar (direct and diffuse) incident on an internal window is reflected, and therefore 

partly reflected through the external wind ne A to ambient. To properly mo

re Sim

provided by VABI for Case MZ360 with interior window reflectance = 0.1, compared with final results f

idealized reflectance = 0, are shown in Table 2-8. (Wijsman 2008a) 

Table 2-8 Case MZ360 Results for VA114 with Internal Window Reflectance = 0.1 versus Final 

Results with Internal Window Reflectance = 0 (Transmittance = 1) 

Case MZ360

Annual Cooling (kWh/y): Refl = 0.1 121101 44579 53285 23237 

Annual Cooling (kWh/y): Refl = 0.0 129653 43480 57751 28421 

Delta % 7.1% –2.5% 8.4% 22.3% 

 

Peak Cooling (W): Refl = 0.1 109753 40009 50969 33498 

Peak Cooling (W): Refl = 0.0 118713 39057 55176 41037 

Delta % 8.2% –2.4% 8.3% 22.5% 

VA114 

Sec. (2.4.4.9) VA114 

Sec. (2.4.4.10)

BESTEST Multi-Zone: MZ350 ABSOLUTE High-Beam-Day

March 15 (high dn) Hourly Transmitted Solar, Zone A (Less Shaded)

14000

0

8000

2000

4000

6000

Shaded Solar Radiation (Wh/h) 10000

12000

VA114, MZ350 

VA114, MZ355

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA

TRNSYS-TUD/TUD TRNSYS-16/ULg VA114-CirDf/VABI

VA114-CirBm/VABI VA114-CirDf-MZ355/VABI VA114-CirBm-MZ355/VABI

70
2.4.4.9 Input error: incorrect time zone 

Figure 2-17 indicates a phase shift for hourly unshaded transmitted solar radiation for March 15 (day 

dominated by direct normal solar radiation). The problem was traced to proper time zone not input, which 

aused misinterpretation of longitude. New results were completed after changes to cases MZ340 through 

se MZ340 (west-facing surface) changed from 886 kWh/m to 

04 kWh/m (9% reduction), and for Case MZ360 (southwest-facing surface) changed from 995 kWh/m2

 to 

Figure 2-17. VA114 hourly high DN day unshaded transmitted solar from August 2005 

2.4.4.10 Input error: fin input twice for modeling fin as neighboring building 

VA114 results from August 2005 indicated greater back side of fin shading (for zones C and F) of incident 

beam radiation for sensitivity Case MZ340–MZ350 by VA114 with fin modeled as not affixed to the 

building (MZ350c) than the other programs (including VA114 with fin modeled as affixed to the building 

[MZ350a]). VABI notes in its modeler report (see Section 2.9, Appendix II-F) that this was caused by an 

input error. 

c

MZ360 in the test specification. So, direct comparison with later-submitted results is not available except for 

annual incident solar radiation, which for Ca 2

2 8

931 kWh/m2

 (6% reduction). For the idealized zones used in these cases, the change in incident solar 

radiation translates directly to 9% and 6% reductions in cooling load for cases MZ340 and MZ360, 

respectively. 

IEA BESTEST Multi-Zone: MZ340 (UNSHADED) 

March 15 (high dn) Hourly Transmitted Solar, Zone A 

0

1000

6000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

2000

3000

4000

5000

Transmitted Solar Radiation (Wh/h)

VA114 

HTB2/WSA TRNSYS/TUD TRNSYS/Liège

COMFIE/EdMP ESP/ESRU CODYRUN/UR

VA114/VABI EnergyPlus/GARD KoZiBu/Noel

71
2.4.4.11 Case MZ360 Total cooling load slightly greater than solar transmitted through 

Window AO; 0.04% difference

For Case MZ360, the annual total building cooling (Zone A + Zone B + Zone C = 129653 kWh) is not 

exactly the same as the transmitted solar radiation through Window AO = 129595 kWh. According to 

VABI’s modeler report, the hourly results show a constant cooling load of –4 W (Zone A), –2 W (Zone 

B), and –1 W (Zone C) during the hours when there is no solar input. A run without solar radiation 

incident on the window gives the same flows for all hours. This annual cooling load is 58 kWh; this is 

equal to the found imbalance between solar radiation and cooling load (0.04%). So the imbalance is not 

caused by the solar calculation method, but by some other reason (probably the infrared radiative 

exchange model, which may become slightly inaccurate at emissivities of 0.01). 

2.4.4.12 Note regarding testing of VA114 option for modeling a shading device as not 

affixed to a building (e.g., a surrounding building or tree); omitting diffuse intentionally 

may be reasonable in this context, but it is important to test all options

VA114 includes two methods for modeling shading: shading device affixed to the building, and shading 

device not affixed to the building. The primary difference in the models is that for a shading device not 

affixed to the building, shading of diffuse solar radiation is intentionally not calculated. Such shading 

devices are assumed to be remote enough from building windows that only the obstruction of beam 

diation would be considered important. The final shaded solar radiation (sensitivity Case MZ340–

bea

m

reco

ra

MZ350) results for this modeling method are shown in Figure 2-18, and indicate a substantial difference 

in results versus other programs, as expected. However, as noted in Section 2.4.4.5 it was important to 

test this model. Additionally, including diagnostic output requiring disaggregating transmitted direct 

m radiation allowed analysis of this specific model. VABI remarked in its modeler report that to 

odel diffuse shading by surrounding buildings, the surrounding buildings should be modeled as “affixed

to the building” (as shading devices don’t have to be “affixed” to the building in VA114). We might 

mmend including an option in VA114 to allow the user to switch diffuse shading on or off (allow 

user discretion, with default as diffuse shading = off) to model shading by surrounding buildings. 

72
IEA BESTEST Multi-Zone: MZ340 - MZ350x Delta Shaded Solar 

Annual Shaded TOTAL Solar Radiation, All Zones

16000

6000

0

2

4000

Unshaded Zone B Zone E Zone A Zone D Z e F

000

8000

10000

12000

14000

Shaded Solar Radiation (kWh)

(MZ340)

Zone C on

HTB2/WSA-d TRNSYS/TUD-a ESP/ESRU-c VA114a-CircBeam

VA114/VABI-a VA114/VABI-c EPlus/G d

Figure 2-18. VA114 total shaded solar for shade not affixed to building from September 2007 

bout 4% 

cident solar radiation. This may the milar differences versus other results 

own in Part III. VABI indicates this difference was not apparent in the Subtask E (Double-Skin Façade 

sts) results. VABI plans to check modeling of diffuse radiation in the VA114 solar processor (Wijsman 

2008a, 2008b). 

2.4.4.14 Note regarding testing isolation of VA114 window discretization

VABI also found evidence of the strength of the tests in that Case MZ360 isolated the discretization 

method used in VA114 to model solar radiation (beam) through an internal window, as shown in Figure 

2-20; also see VABI’s modeler report (Section 2.9, Appendix II-F). This difference does not seem to 

appear for Case MZ360 annual hourly integrated peak zone loads shown in Part III, which occur on 

different dates (not March 15). 

ARD-b,c,

2.4.4.13 Annual unshaded transmitted diffuse solar disagreement; 8% difference for 

transmitted diffuse solar, 4% difference for cooling load

In reviewing the final results, VABI noticed that VA114’s diffuse radiation is about 8% higher than the 

other programs (see arrow in Figure 2-19). Figure 2-19 also indicates beam radiation is the same; 

propagation of the diffuse radiation difference to total solar radiation (beam + diffuse) results in a

higher total in be cause of si

sh

te

73
Figure 2-19. VA114 annual incident diffuse solar radiation disagreement 

Figure 2-20. Hourly Transmitted Solar Radiation for Case MZ 360, Window AB, 

Submitted October 2007 

IEA BESTEST Multi-Zone: MZ340 

Annual Incident Total Solar Radiation, Facing West

0

100

200

300

400

500

600

700

800

900

Total (IA) Beam (IbA) Diffuse (IdA)

Incident Solar Radiation (kWh/m2

)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg ESP-r/ESRU

VA114-CirBm/VABI VA114-CirDf/VABI EnergyPlus/GARD

BESTEST Multi-Zone: MZ360 Internal Windows

March 15 (high dn) Hourly Transmitted Solar, Window "AB" (Zone B)

120000

Transmitted Solar Radiation (Wh/h)

VA114 

60000

80000

100000

EnergyPlus currently does not provide this 

output exactly as specified by the test cases.

40000

0

20000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS16/Liege VA114-CirDf/VABI VA114-CirBm/VABI

74
2.4.5 TRNSYS-TUD 

TRNSYS is considered to be the most advanced program that DOE has sponsored for simulating active 

olar systems. The program was originally written at the University of Wisconsin. Technische Universitat 

s 

he TUD participant discussed in the modeler report that, although it was assumed that interior walls do not 

flect any solar radiation (solar absorptance = 1) and ideal windows neither reflect nor absorb any solar 

radiation (solar transmittance = 1), the zone cooling load was not equal to the net transmitted solar radiation. 

The reason for this error was that within a zone, i.e., just after passing through the window, solar radiation 

was treated to be diffuse before contact with interior walls. This caused some transmitted solar radiation to 

be lost back out the window before contacting (potential reflection by) any interior surfaces (no such 

reflection occurs in these idealized test cases). To avoid this problem, the calculation procedure for solar 

distribution was revised. In the current program version only solar radiation that was reflected at interior 

surfaces (walls and windows) is diffusely reflected. For cases MZ340, MZ350, and MZ360 with idealized 

windows and interior walls, the cooling load now equals the transmitted solar radiation, as shown in the 

final results of Part III. The TUD participant did not provide results before fixing this error, but recollects 

that for the initial run of Case MZ340, cooling load was 3%–4% lower than total solar radiation transmitted 

into the zone. This matches the effect of a similarly described error documented for EnergyPlus (see Section 

2.4.1.1), where the effect of fixing this error was a 4% increase in cooling load for cases MZ340 and 

MZ350, and a 33% increase in cooling load for Case MZ360. 

2.4.5.2 Ray tracing algorithm error; discussed in September 9, 2005 modeler report; 

effect of error not given 

TRNSYS-TUD offers the option to use ray tracing for direct solar radiation that enters the room through an 

external window. Only multi-zone test Case MZ360 was calculated with this program feature. Use of ray 

tracing has no effect in cases MZ340 and MZ350, because the solar absorptance of interior surfaces is 1 and 

there is no heat conduction between zones; so it does not matter on which surface solar radiation has been 

absorbed. Ray tracing has a substantial effect for Case MZ360 because transmittance of solar radiation 

through an internal window depend radia led (Felsm test results 

revealed a loop error in the calculation ro y occurr here are at l in a building. 

TUD did not results s fect of th

s

Dresden (TUD) acquired a license for the source code and has since developed new source code for TUD’s 

own calculation routines. This new version is designated TRNSYS-TUD, and was originally based on 

TRNSYS 14.2 distributed by TRANSSOLAR, Germany. New algorithms developed at TUD related to 

multi-zone modeling were tested for this project. 

Two errors were reported by TUD in the September 9, 2005 draft of its modeler report. For these errors 

TUD did not submit prior results showing their effects. However, for one error it was possible to estimate it

effect based on the occurrence of a similar error in another program. More detailed discussion is included 

with the TRNSYS-TUD modeler report in Section 2.9, Appendix II-D; also see Felsmann (2008). 

2.4.5.1 Zone cooling load not equal to transmitted solar radiation; discussed in 

September 9, 2005 modeler report, 3%–4% increase in cooling load for Case MZ340 

T

re

s on how beam tion is mode ann 2008). The 

utine that onl ed if t east two zones 

submit prior howing the ef is revision. 

75
76

2.4.5.3 Comparison of detailed ray tracing algorithm to simplified assumption of Window 

AB transmitted radiation as 100% diffuse for Case MZ360; 15%–23% effect on specific 

zone load 

To check the importance of detailed modeling of interior solar distribution for zones with internal windows, 

TUD used the test cases to compare results of models included in TRNSYS-TUD. For Case MZ360, the 

comparison between a simplified solar distribution model that assumes any solar radiation entering a room 

to be diffuse versus a more detailed ray tracing model (developed between 2001 and 2004) for the direct 

part of solar radiation shows substantial differences in solar transmission through internal windows and 

annual cooling load. In Figure 2-21 the annual transmitted solar radiation of each zone as calculated from 

the models with and without ray tracing are compared. Transmittance into Zone A must be the same in both 

approaches, but transmittance through Window AB into Zone B is much higher if the ray tracing model is 

used. This consequently has an impact on annual cooling load, where Figure 2-22 shows that for the ray 

tracing method annual cooling load is lower in zone A and higher in Zone B than for the simplified method. 

The total annual cooling load of the building is the same for both models, as expected for the non-reflective 

interior surfaces. The TRNSYS-TUD modeler report (see Section 2.9, Appendix II-D) includes further 

discussion of this comparison, including figures showing effects of the different modeling techniques on 

dynamic (hourly) load profiles. 

Figure 2-21. MZ360, comparison of annual transmitted solar radiation 
77

2.4.5.4 No disaggregation of direct and diffuse solar in output

For results submitted in September 2005, TRNSYS-TUD did not disaggregate transmitted direct and diffuse 

solar radiation from total solar radiation in its output. The TRNSYS-TUD developers agreed that 

disaggregating solar radiation in the output is a useful diagnostic feature, and included that capability in their 

software for generating results submitted in September 2006. 

2.4.5.5 Shading model input error; 30%–40% effect on cooling load for zones B, E, C, 

and F, and 5%–8% on cooling loads for zones A and D 

For results submitted in September 2005, TRNSYS-TUD indicated a disagreement for Case MZ350 

(shaded) hourly transmitted solar radiation, as shown in Figure 2-23. Additionally, results for sensitivity 

Case MZ340–MZ350 annual shaded solar radiation indicated low shaded solar radiation for zones B and E, 

and high shaded solar radiation for zones C and F, as shown in Figure 2-24. 

The reason diagnosed for that disagreement was incorrect input of the shading device. In TRNSYS, shading 

devices are modeled by assigning a separate wing-wall to each window. During this process the left- and 

right-hand sides of the window were juxtaposed such that they were seen as viewed from the room to the 

outside rather than from outside into the room. So the initial calculations were for a shading device moved 

to the south for zones C and F (higher shading effect) and assumed to be moved to the north for zones A, B, 

D, and E (lower shading effect), which is why Figure 2-23 shows additional unshaded solar (Felsmann 

2008). 

Based on the disagreement shown in Figure 2-25 versus the mean of the other results shown, and current 

agreement for results shown in Part III, the effect of this input error is 30%–40% on cooling loads for zones 

B, E, C, and F, and 5%–8% on cooling loads for zones A and D. 

Figure 2-22. MZ360, comparison of annual cooling loads 
BESTEST Multi-Zone: MZ350, ABSOLUTE High-Beam-Day 

March 15 (high dn) Hourly Transmitted Solar, Zone B (Most Shaded) 

Figure 2-23. TRNSYS-TUD disagreement for Case MZ350 hourly transmitted solar for diffu

dominated day, from results submitted September 2005 

seFigure 2-24. TRNSYS-TUD disagreement for Case MZ350 annual total shaded solar radiation, from 

results submitted September 2005 

 

0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

1000

2000

3000

Shaded Solar Radiat

4000

5000

6000

ion (Wh/h)

TRNSYS-TUD 

HTB2/WSA-d TRNSYS/TUD-a TRNSYS/Liège-c COMFIE/EdMP-b ESP/ESRU-c CODYRUN/UR-12m

VA114/VABI-a VA114/VABI-c EnergyPlus/GARD-b,c,d

HTB2bad/WSA-d

IEA BESTEST Multi-Zone: MZ340 - MZ350x Delta Shaded Solar 

Annual Shaded TOTAL Solar Radiation, All Zones

5000

6000

Wh)

0

1000

2000

Unshaded

(MZ340)

Zone B Zone E Zone A Zone D Zone C Zone F

Shaded Sola

3000

4000

r Radiation (k

HTB2/WSA-d TRNSYS/TUD-a COMFIE/EdMP-b VA114/VABI-a EPlus/GARD-b,c,d

"Back side" of Fin Shading

78
Norm

20...90 

was revis

itical value 

MZ34 sed 

1%, from increase was 

April 2008 sensitivity tests by TUD using the Reindl solar radiation model. 

Figure 2-25. TRNSYS-TUD disagreement for Case MZ350 annual sensible cooling load, from 

results submitted September 2005 

2.4.5.6 Calculation of solar transmittance as function of incidence angle; 1% effect on 

cooling load for Case MZ340 

ally TRNSYS-TUD internally calculates window optical properties as a function of incidence angle 

using a quartic approximation based on optical properties given at discrete incidence angles (0, 10, 

degrees). Figure 2-26 shows both transmittance as defined in the specification and as used in the 

TRNSYS-TUD model based on the approximation formula. Because of this difference TRNSYS-TUD 

ed to check for the root mean square of the difference between optical properties given for 

certain incident angles and those normally calculated internally. If the RMS is greater than a cr

TRNSYS-TUD now linearly interpolates between values (Felsmann 2008). 

Based on results submitted in December 2005 and September 2006 applying the software revision, Case 

0 (unshaded) total transmitted solar radiation using TRNSYS’ isotropic diffuse model i

Wh/y to 12454 kWh/y as a result of this modeling improvement. A similar 

ncrea

 12327 k

observed for 

IEA BESTEST Multi-Zone: MZ340,MZ350x 

Annual Sensible Cooling Load, All Zones

6000

0

1000

2000

3000

4000

5000

Space Cooling Load (kWh)

Unshade (MZ340) Zone B Zone E Zone A Zone D Zone C Zone F

EPlus/GARD-b,c,d

"Back side" of Fin Shading

HTB2/WSA-d TRNSYS/TUD-a VA114/VABI-a

79
Figure 2-26. TRNSYS-TUD approximation of solar transmittance depending on incident angle for a 

rease for Zone C cooling 

ad of 220% and overall building cooling load of 5% 

low. The 

on) through a second-in-series internal 

indow (Window BC). Comparison with results for programs that allow transmission of direct-beam 

to 2.6 (factor of 2.2 average estimate). 

his could cause about 5% underestimation of total building cooling load, assuming half the beam 

odels 

oirazis 2007), more accurate 

odeling of solar radiation through a series of internal windows gains importance. The TRNSYS-TUD 

window with 100% transmittance (Felsmann 2008) 

2.4.5.7 No beam radiation to Zone C of Case MZ360; likely inc

lo

Current results for Zone C in Figure 2-27 (see arrow) indicate that Zone C cooling load may be 

TRNSYS-TUD modeler report (see Section 2.9, Appendix II-D) indicates that TRNSYS-TUD allows 

transmission of diffuse radiation only (no direct beam radiati

w

radiation through Window BC (ESP-r and VA114) indicate that including transmission of direct-beam 

radiation would increase the Zone C cooling load by a factor of 1.8 

T

radiation modeled as diffuse is lost back through Window AO. The EnergyPlus and TRNSYS-16 m

also exclude transmission of beam radiation, and have Zone C results similar to the TRNSYS-TUD 

results. Disaggregated transmitted direct and diffuse solar radiation results for Case MZ360 are included 

in Part III. As double-skin facades become more popular in buildings (see P

m

developers have been notified of this issue. 

80
IEA BESTEST Multi-Zone: MZ360 

Annual Sensible Cooling Loads

0

20000

40000

60000

80000

100000

120000

140000

Building, Qbldg Zone A, QA Zone B, QB Zone C, QC QB + QC

Sensible Cooling Load (kWh)

HTB2/WSA TRNSYS/TUD TRNSYS/Liège

 

al cooling loads for Case MZ360 indicating low Zone C cooling load attributable 

to no beam r diation tr smitted to Zone C (through Window BC) 

2.4.5.8 Inconsistency with implementation of Reindl diffuse solar radiation model for 

unshaded and shaded cases; for Case MZ340–MZ350 sensitivity: potential 18%–32% 

effect on annual diffuse shaded solar radiation (MZ340–MZ350), potential 9%–14% 

effect on annual cooling load sensitivity for shading (total shaded solar radiation) 

The TRNSYS-TUD modeler report indicates a modeling difficulty that occurred is an inconsistency 

related to TRNSYS’ implementation of the Reindl anisotropic sky model for shading calculations. 

Although windows without a shading device apply the Reindl model, for a shaded window both skydiffuse and ground reflected radiation apply diffuse solar radiation based on an isotropic sky model. Thus, 

when the Reindl model is applied the comparison of results for shading sensitivity Case MZ340–MZ350 

apply different diffuse radiation models. Estimation of the disagreement for shaded diffuse solar radiation 

that results from use of inconsistent models among the cases MZ340 and MZ350 is shown in Figure 2-28. 

This indicates that the potential effect of the modeling inconsistency is an 18%–32% effect on annual 

diffuse shaded solar radiation for sensitivity Case MZ340–MZ350 (compare results for “TRNSYS/TUD-

‘Reindl’” to “TRNSYS/TUD-a” in Figure 2-28). This represents a potential 9%–14% effect on annual 

cooling load sensitivity (total shaded solar radiation) for sensitivity Case MZ340–MZ350. 

This problem has been reported t obtain consistent results for their 

plementation of the test specification, they have applied the isotropic sky model option. 

Figure 2-27. Annu

a an

o the TRNSYS-TUD author. Currently, to

im

VA114-cb/VABI VA114/VABI EPlus/GARD

ESP/ESRU

81
Figure 2-28. Reindl y in TRNSYS-TUD

t on annual peak load 

 model implementation inconsistenc

2.4.5.9 Further observations about Reindl versus isotropic diffuse solar model; 4% 

effect on annual load, 8% effec

Figure 2-29 indicates the difference between the Reindl and isotropic models for hourly results. For these 

test cases, this difference for hourly behavior of the sky models seems consistent with the relatively lower

annual hourly integrated peak cooling loads for the final results as indicated by the arrow for Case MZ340

in Figure 2-30. (Compare TRNSYS-TUD, TRNSYS-16 and HTB2 results that use isotropic diffuse sky 

models versus other results.) Annual and peak load effects of Reindl versus isotropic sky models are 

summarized in Table 2-9. 

Table 2-9. Peak Load Differences for Reindl versus Isotropic Sky Models in TRNSYS-TUD 

TRNSYS-TUD Case MZ340 

Results 

Isotropic Model Reindl Model % Difference 

QA (annual load) 12454 kWh 12995 kWh + 4.3% 

qA (peak load) 12164 W 13091 W + 7.6% 

IEA BESTEST Multi-Zone: MZ340 - MZ350x Delta Shaded Solar 

Annual Shaded DIFFUSE Solar Radiation, All Zones

0

1000

2000

3000

4000

5000

6000

7000

8000

Unshaded

(MZ340)

Zone B Zone E Zone A Zone D Zone C Zone F

Shaded Solar Radiation (kWh)

HTB2/WSA-d TRNSYS/TUD-a TRNSYS/TUD-"Reindl" TRNSYS/Liège-c

ESP/ESRU-c VA114a-CircBeam VA114/VABI-a EPlus/GARD-b,c,d

82
BESTEST Multi-Zone: MZ340 Unshaded

August 4 TOTAL Hourly Transmitted Solar, Zone A

2000

4000

6000

8000

10000

12000

1 2 3 20 21 22 23 24

Transmitted Solar Radiation (Wh/h)

Isotropic 

Reindl 

0

4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA

Figure 2-29. Reindl model versus isotropic sky model in TRNSYS-TUD 

Figure 2-30. Integrated hourly peak cooling loads, Cases MZ340 through MZ355 

TRNSYS-TUD/TUD TRNSYS-16/ULg VA114-CirDf/VABI

VA114-CirBm/VABI TRNSYS-TUD-Reindl/TUD

IEA BESTEST Multi-Zone: MZ340, MZ350, MZ355 

Annual Hourly Integrated Peak Cooling Load, All Zones

6000

8000

10000

12000

14000

16000

Cooling Load (Wh/h)

0

2000

4000

MZ340 MZ350, MZ355

Zone B

MZ350, MZ355

Zone E

MZ350, MZ355

Zone A

MZ350, MZ355

Zone D

 MZ350 

Zone C

 MZ350 

Zone F

HTB2/WSA TRNSYS/TUD TRNSYS/ULg

ESP-r/ESRU VA114-CirBm/VABI VA114-CirDf/VABI

EnergyPlus/GARD VA114-CirBm-MZ355/VABI VA114-CirDf-MZ355/VABI

EnergyPlus-MZ355/GARD

83
2.4.6 TRNSYS-16 

NSYS is considered to be the most advanced program that DOE has sponsored for simulating active 

systems. The TRNSYS version is TRNSYS 16.01.0002, developed by Solar Energy Laboratory, 

ersity of Wisconsin-Madison, United States (University of Wisconsin 2005). The building model us

TR

solar 

Univ ed 

with 

the 

The 

diffu ation 

ng 

the 

Z340 an he ULg have been asked 

to inform the TRNSYS-16 developers of this issue. 

4.6.2 Solar processor; 1.6% and 2.3% annual cooling load effect for MZ340 and 

igure 2-31 indicates a disagreement for Case MZ340 unshaded hourly transmitted solar radiation for hour 

9. This occurred for the Type 109 solar processor provided with TRNSYS. For subsequent simulation runs, 

he 

• Case MZ340 peak load decrease 

e 

r and 23% 

wer, respectively, for TRNSYS-16 versus TRNSYS-TUD. The difference is likely attributable to more 

YS-16. This 

roduces results differences similar to those observed for model sensitivity testing by the TUD participant 

documented in Section 2.4.5.3. The ULg modelers have been asked to inform the TRNSYS-16 developers 

of this issue. 

in this work is TYPE 56, developed by TRANSSOLAR Energietechnik GmbH, Stuttgart, Germany. The 

ideal window was modeled using WINDOW 5.2. More detailed discussion of the modeling is included 

TRNSYS-16 modeler report by University of Liège in Section 2.9, Appendix II-E. 

2.4.6.1 Zone cooling load not equal to transmitted solar radiation; initially discussed in 

February 13, 2007 modeler report, effect of fixing similar error in another program was 

33% increase in cooling load for Case MZ360 and 4% increase in cooling load for cases 

MZ340 and MZ350 

University of Liège (ULg) participants discussed in their modeler report that to have better control over 

se radiation, it was added to direct radiation; otherwise, part of the initially transmitted diffuse radi

would be lost back out Window AO. This is a work-around for a problem that was fixed in TRNSYS-TUD 

(see Section 2.4.5.1), but not in TRNSYS-16. The ULg participants did not provide results before applyi

work-around, so its effect is not known. However, for a similarly described error documented for 

EnergyPlus (see Section 2.4.1.1), the effect of fixing this error was 33% increase in cooling load for Case 

MZ360 and 4% increase in cooling load for cases M d MZ350. T modelers

2.

MZ360 respectively, 8.6% peak cooling load effect (MZ340) 

F

1

ULg changed to the Type 16g solar processor, which provided better agreement with the other results. T

ULg modelers have been asked to inform the TRNSYS-16 developers of this issue. The change of solar 

processor had the following effects: 

• Case MZ340 annual unshaded solar/load decrease = 1.6% 

= 8.6% 

• Case MZ350 (shaded) annual transmitted solar decrease = 1.6% 

• Case MZ350 (shaded) annual transmitted peak load decrease = 0.2% 

• Case MZ360 (internal windows) annual load decrease = 2.3%. 

2.4.6.3 Less detailed modeling method for TRNSYS-16 versus TRNSYS-TUD; for Cas

MZ360 annual cooling load effect of 27% and 15% for zones A and B, respectively, 

peak cooling load effect of 81% and 23% for zones A and B, respectively 

For Case MZ360, Figure 2-32 (see red arrows) indicates that annual cooling loads for zones A and B are 

27% higher and 15% lower, respectively, for TRNSYS-16 versus TRNSYS-TUD. Similarly, additional

results included in Part III indicate that peak cooling loads for zones A and B are 81% highe

lo

detailed modeling of direct-beam radiation through Window AB using ray tracing for TRNSYS-TUD, 

versus less detailed modeling of transmitted solar radiation through Window AB for TRNS

p

84
BESTEST Multi-Zone: MZ340 Unshaded

March 15 (high dn) Hourly Transmitted Solar, Zone A

0

2000

4000

6000

8000

10000

12000

14000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Transmitted Solar Radiation (Wh/h)

TRNSYS-16 

EnergyPlus/GARD

Figure 2 Z340 M ded smitted n, including 

TRNSYS-16 results submitted March 2007

Figure 2-32. Annual cooling loads for Case MZ360 indicating differences between TRNSYS-16 and 

TRNSYS-TUD for Zones A and B, and low Zone C cooling load for both TRNSYS models

-31. Case M arch 15 unsha hourly tran solar radiatio

ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS16/Liege VA114-CirDf/VABI VA114-CirBm/VABI

IEA BESTEST Multi-Zone: MZ360 

Annual Sensible Cooling Loads

bldg Zone A, QA QB

120000

140000

40000

60000

80000

100000

Sensible Cooling Load (kWh)

0

Building, Q

20000

Zone B, QB Zone C, QC + QC

HTB2/WSA TRNSYS/TUD TRNSYS/Liège ESP/ESRU

VA114-cb/VABI VA114/VABI EPlus/GARD

85
may

se radiation only (no direct beam radiation) through a secondin-series internal window (Window BC). It appears that similar behavior is exhibited by TRNSYS-16, 

although ULg indicates that for Zone C the allocation of direct and diffuse is recalculated as a function of 

user-defined average annual ratio (Andre 20 ison with results for programs that allow 

transmission of direct beam radiation through Window BC (ESP-r and VA114) indicates that including 

transmission of direct beam radiation would increase the Zone C cooling load by a factor of 2.4 to 3.3 

(factor of 2.9 average estimate). This could cause about 6% underestimation of total building cooling 

load, assuming half the beam radiation modeled as diffuse is lost back through Window AO. The 

EnergyPlus and TRNSYS-TUD models also exclude transmission of beam radiation, and have Zone C 

results similar to the TRNSYS-16 results. Disaggregated transmitted direct and diffuse solar radiation 

results for Case MZ360 are included in Part III. As double-skin facades become more popular in 

buildings (see Poirazis 2007), more accurate modeling of solar radiation through a series of internal 

windows gains importance. The ULg modelers have been asked to inform the TRNSYS-16 developers of 

this issue.

 de Génie 

Industriel (Industrial Engineering Laboratory) of University of Reunion Island (UR), France. Information 

about the software is provided in the modeler report in Section 2.9, Appendix II-G.

2.4.7.1 Constant surface coefficients not allowed; submitted with March 2005 modeler 

report, 2%–8% effect on zone cooling load for prelim

based on results for a similar correction for another program 

The UR modeler report indicates that CODYRUN was m

convective surface coefficients. No results were submitted before changes were made; however, based on 

results for a similar modification described for COMFIE (see Section 2.4.8.1), there is potentially a 2%–

8% effect on cooling load. 

2.4.7.2 Minor modifications to allow modeling of the test cases; submitted with March 

2005 modeler report, effect of changes not given 

The UR modeler report discusses the owing modifications that were made to CODYRUN to be able to 

run Case MZ320 as specified: 

• Allow more significant digits for long wave emissivities; previous limit was 0.01 

• Allow input of specific values for density and specific heat of air composing each thermal zone. 

No results were efore changes w ects of not known. 

However, effects of these revisions should be minor. 

2.4.6.4 No beam radiation to Zone C of Case MZ360; likely increase for Zone C cooling 

load of 290% and overall building cooling load of 6% 

Current results for Zone C, also shown in Figure 2-32 (see black arrow), indicate that Zone C cooling load 

 be low. The TRNSYS-TUD modeler report (see Section 2.9, Appendix II-D) indicates that 

TRNSYS-TUD allows transmission of diffu

08). Compar

2.4.7 CODYRUN 

CODYRUN is a whole-building energy simulation program under development at Laboratoire

inary cases MZ200 and MZ300 

odified to allow specification of individual wall 

foll

submitted b ere made, so the eff the changes are 

86
2.4.7.3 C

notified 

As shown in Figure 2-33, Case MZ320 Zone C load for CODYRUN is 2% lower than the analytical 

solution; Zone A air temperature is 0.9°C above the analytical solution. Results for all other programs show 

much closer agreement with the analytical solution. The code authors have been notified of this 

disagreement. 

Figure 2-33. Results for Case MZ320 indicating CODYRUN disagreements 

ase MZ320 Zone C cooling load is 2% below analytical solution; authors

IEA BESTEST Multi-Zone: MZ320 

Steady State Zone-A, -B Air Temperatures and Zone-C Cooling Loads 

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

Zone A Zone B Zone C

Temperature (°C)

0

200

400

600

800

1000

1200

1400

1600

1800

Sensible Cooling Load (W or Wh/h)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/Liège COMFIE/EdMP ESP/ESRU

CODYRUN/UR VA114/VABI EnergyPlus/GARD KoZiBu/Noel Analytical

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/Liège COMFIE/EdMP ESP/ESRU

CODYRUN/UR VA114/VABI EnergyPlus/GARD KoZiBu/Noel Analytical

 Zone Air Temperatures Loads 

87
2.4.8 COMFIE 

COMFIE is a whole-building energy simulation program developed by Ecole des Mines de Paris and Izu

Energies (for the PLEIADES interface), France. Information about the software is provided in the mode

report in Section 2.9, Appendix II-H.

2.4.8.1 Constant surface coefficients not allowed; 2%–8% effect on zone cooling load 

for preliminary cases MZ200 and MZ300 

ba 

ler 

rt that 

ey do not plan to MFIE to allow the user to choose ace heat tr coefficients, because 

As described in the COMFIE modeler report, COMFIE applies automatically calculated surface 

coefficients. For this work the COMFIE developers modified the source code so the constant combined 

surface heat transfer coefficients indicated in the test specification are used. This was hardwired for a 

custom version of COMFIE specifically for these test cases. The developers note in their modeler repo

th modify CO surf ansfer

that would add unnecessary complexity to the user interface. Table 2-10 shows the effects of changing from 

automated to constant surface coefficients on zone cooling loads for preliminary cases MZ200 and MZ300 

(for the May 2004 preliminary version of the test specification—see Section 2.3.1). 

Table 2-10. Effect of Constant versus Automated Surface Coefficients for COMFIE 

Case qA (W) qB (W) B

MZ200 – automated surface coefs 704 1294 

MZ200 – constant surface coefs 653 1345 

Del % MZ200, (auto – const)/const + 7.8% – 3.8% 

MZ300 – automated surface coefs 1282 1578 

MZ300 – constant surface coefs 1257 1603 

Del % MZ300, (auto – const)/const + 2.0% – 1.6% 

88
2.5 Interpretation of Results 

2.5.1 Use of Calorimetry and an Analytical Solution to Isolate Effects of Specific 

Models 

The diagnostic power of test cases is enhanced when modeling errors are easy entification 

of errors is facilitated when the potential range of disagreement for a given set of test results is 

minimized, which can occur when a specific modeling effect is isolated as well as possible by a given test 

case. This requires minimizing noise from other models used to perform a whole-building simulation that 

are not intended to be tested by a given test case. Specification of precise boundary conditions required 

for analytical verification tests inherently isolates the effects of specific models and inhibits extraneous 

noise, thereby minimizing potential legitimate disagreement among simulation program results (Neymark 

and Judkoff et al. 2008; Neymark and Judkoff 2002) Where meaningful analytical verification cases 

cannot be achieved, diagnostic comparative tests can be designed with a strong signal-to-noise ratio for 

the phenomena of interest. 

A major accomplishment of this work was to enhance the diagnostic power of the multi-zone shading and 

internal window test cases by using building zones designed to be precise calorimeters, where the only 

thermal mass is for the zone air. The basic principle is that all solar radiation incident on an exterior 

window is captured within a zone, such that the zone cooling load is equivalent to the solar radiation 

incident on that window. This is achieved by specifying ideal windows with solar transmittance = 1 and 

therm

abso

applied, and are sufficiently hi sed by high interior surface 

temperatures. Causes of disagreements are therefore limited to an issue with the specific model being 

tested (the shading or internal window model), modeling of incident solar radiation, inability to precisely 

model the idealizations defining the zone as a calorimeter, or an input error. Additionally, sensitivity 

“delta” cases (MZ350–MZ340, MZ355–MZ340) allow intermodel comparison of the difference between 

zone cooling loads with a shading device and without shading. This allows better isolation of shading 

model effects, as differences among models not related specifically to shading models should cancel out. 

The effects of thermal mass were not tested in these new cases because the original IEA BESTEST1

comparative cases explored building envelope thermal mass effects in detail in a single-zone context (and 

in a two-zone case with a sunspace). By excluding thermal inertia and minimizing other simultaneous 

effects, the current specialized multi-zone cases maximize diagnostic power, and also minimize the 

number of cases required to address the tested phenomena. In the absence of multi-zone mass interaction 

test cases for the current configurations, if a simulation model demonstrates agreement for the original 

IEA BESTEST cases with thermal mass and demonstrates agreement for the new multi-zone test cases, 

that would suggest that such tested simulations may provide agreement where aspects of both types of test 

cases are combined. As thermal mass interactions (and other interactions) are important to test explicitly, 

our recommendations for future activities (see Section 2.5.3) include developing multi-zone cases with 

thermal mass. 

It was possible in these test cases to specify limits of parametric extremes required to define zones as 

precise calorimeters, because all but one project participant were also authors of the programs being 

tested. Having program authors do the m portant because they understand 

which parametric extremes can be exact for a gi m versus which extremes must be 

approximated for their program to run in a stable manner. Absolute limits of parametric extremes could 

ot be used for the IEA BESTEST single-zone cases Judkoff and Neymark 1995), because an objective 

un them, so that selected parametric extremes were 

 to identify. Id

al conductance = 0, and non-conductive exterior and interior walls, where interior walls have solar 

rptance = 1 (to eliminate reflections). Constant combined interior surface coefficients are also 

gh to avoid a simulation crash that may be cau

odeling for this project was im

ly modeled ven progra

n

for those cases was to allow non-code authors to r

(

89
chosen to excite modeling sensitivities as robustly as possible while avoiding stability issues (e.g., divide 

by zero). 

for the original single-zone IEA 

ESTEST shading cases versus the final range of disagreement for the new in-depth diagnostic multiixes to 

andard. 

st 

dary 

ts. 

ow substantial disagreement with analytical solution results, we often find a coding error, a 

able algorithm, a documentation problem, or an input error. Similarly, for the comparative test 

tion program has results that fall substantially outside of the range of disagreement of 

vesting the source of the difference is recommended. Criteria for determining 

greement among results is provided in Section 1.2.2.1. 

opriateness of the 

olution; that is, we accept the given underlying physical assumptions while recognizing that these 

omparison of simulation 

sults with a perfectly performed empirical experiment, with all simulation inputs perfectly defined. In 

.5.2 Improvements to Simulations during the Field Trials 

 and clarification of the test specifications, the 

greement among simulation results improved with each iteration of the field trials. Improvements to 

sistently across tests. Arbitrary modification of a simulation program’s 

put or internal code just for the purpose of more closely matching a given set of results is not allowed. 

Also ll

itial results for the preliminary version of the multi-zone conduction cases, with adiabatic exterior walls 

or the 

cal solution ranged from 6% to 8%, where only two 

programs are shown as disagreeing. Here, disagreement is the difference between the maximum and 

Improvement in the ability to diagnose shading models using this calorimetry method for in-depth 

diagnostics is evident from comparing final disagreement ranges 

B

zone shading cases, as discussed in Section 2.5.2. The improved diagnostics also allowed identification of 

44 disagreements related to modeling multi-zone shading and internal windows, resulting in 28 f

the models so far, as documented in Section 2.6.1.2. 

Another accomplishment of this work is the development of a relatively simple steady-state analytical 

solution for testing the modeling of multi-zone conduction, which provides a mathematical truth st

Here the term analytical solution is the mathematical solution of a model that has an exact result for a 

given set of parameters and simplifying assumptions. In general, it is difficult to develop worthwhile te

cases that can be solved analytically, but such solutions are extremely useful. 

Where simulation programs have results that disagree substantially with analytical solution results, 

investigating the sources of the differences is recommended. In this case a difference does not necessarily

mean that such a program or model is faulty, because differences among modeling techniques, boun

condition approximations, and other input assumptions may cause unavoidable differences among resul

However, our collective experience in this task and previous BESTEST work has indicated that when such 

programs sh

question

cases, where a simula

the example results, in

a

It is important to understand the difference between a mathematical truth standard and an absolute truth 

standard. In the former, we test only the solution process for a model, not the appr

s

assumptions represent a simplification of physical reality. An approximate truth standard from an 

experiment tests both the solution process and appropriateness of the model within experimental 

uncertainty. The ultimate or absolute validation truth standard would be a c

re

reality, an experiment is performed and the experimental object is specified within some acceptable range 

of uncertainty. Such experiments are possible, but expensive. We recommend developing a set of 

empirical validation experiments in the future. 

2

Because of iterative correction of input errors, software bugs,

a

simulation programs or simulation inputs made by participants must have a mathematical and a physical 

basis, and must be applied con

in

, a improvements were required to be documented in modeler reports. 

In

and conducting internal walls (cases MZ200 and MZ300) are shown in Figure 2-34. Disagreement f

initial two- and three-zone cases with a simple analyti

90
minimum results for each case, divided by the mean of the results for each case ((max-min)/mean). Two 

ther software developers reported fixing issues before submitting their results; based on anecdotal 

 similar to the disagreements shown for the other programs. Additionally, three of the four 

ts were caused by inability to exactly model the boundary conditions specified 

put of 

initial good agreement led us to design a more challenging three-zone test case with more conduction 

interactions (Case MZ320), which was still analytically solvable. This case is a system of three zones in 

series with a conditioned zone on one end adjacent to two adjacent unconditioned (floating temperature) 

zones, where the interior and exterior walls are conductive (see Section 1.3.1 for details). All models tested 

agreed with the analytical s one progr wn in Figure 2-35. (Note 

for results shown in Figures 2-34 and 2-35, some participants for the earliest cases were not able to 

submit results for later cases, and vice versa.) 

For the multi-zone shading and internal window test cases, improvements to the simulation programs are 

evident when initial results are compared to final results, as shown in Figures 2-36 and 2-37, respectively, 

for the multi-zone shading cases, and Figures 2-38 and 2-39, respectively, for the internal window cases. 

(In these figures abbreviations along the x-axis are shorthand for the case descriptions given in Part I.) 

Because a number of parameters for the final set of multi-zone shading and internal window test cases 

varied substantially from the first round of test cases distributed in February 2005—see Section 2.3—it 

was difficult to develop a direct comparison between cases for initial results that were submitted before 

the current test cases were developed in August 2006. Therefore, Figures 2-36 and 2-38 include some 

results that were determined based on estimates of what they would have been, had corrections not been 

made during earlier test cases. Estimates are based on examples of error trapping documented in Section 

2.4. For Figures 2-36 and 2-38, initial results are included for each model: 

• Energ th 200 of the test 

specif arc or ca Z MZ355, results submitted September 

13, 2006 are shown as submitted, as there were no changes to EnergyPlus related to field trials of 

the te used. For 

those results, original values of Qbldg, QA, and QB+C are used; however, to normalize for increased 

depth of Zone B in the final version of Case MZ360, QB and QC are modified to sum to QB+C and 

to have the same ratio QB/QC as for results submitted for the August 2006 test specification. For 

EnergyPlus Case MZ360, values of Qbldg for the March 2005 results (before fixes documented in 

Section 2.4.1) were 3% lower than for the September 2006 results, which were also submitted 

before fixes documented in Section 2.4.1. 

• ESP-r: Results were initially submitted for the February 2005 version of the test specification in 

March 2005. For cases MZ340 and MZ350, results submitted December 17, 2005 are used, as 

there were no changes to ESP-r related to field trials of the test cases before this submittal; these 

are for preliminary simulations of the substantively final (August 2006) test specification. For 

Case MZ360, results submitted March 2005 are used. For those results, original values of Qbldg, 

QA, and QB+C are used; however, to normalize for increased depth of Zone B in the final version 

of Case MZ360, QB and QC are modified to sum to QB+C and to have the same ratio QB/QC as for 

results submitted for the August 2006 test specification. This allows results to be estimated for QB

and QC prior to the change documented in Section 2.4.2.1 (which was made between December 

2005 and September 2006). 

o

discussion from modeler reports these “pre-initial” results would have had disagreements with order of 

magnitude

reported initial disagreemen

by the test cases; the other was an input error. Subsequent fixes to the programs allowed direct user in

(or hardwired in a special version) previously automatically determined parameters to enable precise 

matching of the surface heat transfer coefficient boundary conditions, and yielded very good agreement with 

the analytical solutions. 

This 

olution within ≤ 0.3% except for am, as sho

yPlus: Results were initially submitted for e February 5 version

ication in M h 2005. F ses MZ340, M 350, and

st cases before this submittal. For Case MZ360 results submitted March 2005 are

91
IEA BESTEST Multi-Zone: MZ200, MZ300 

0

Z200, 2-Zone 

Steady-State Sensible Cooling Load, Zone A

1400

200

400

600

800

Sensible Cooling Load (W or Wh/h) 1000

1200

M MZ300, 3-Zone

HTB2/WSA TRNSYS/TUD TRNSYS/Brno COMFIE/EdMP

ESP/ESRU CODYRUN/UR DOE-2/ACHSL SIMBAD-mrt/CSTB

SIMBAD-mrss/CSTB Analytical

•

Figure 2-34. BEST res fore BESTESTing 

Figure 2-35. BESTEST multi-zone conduction—final case results after BESTESTing 

EST multi-zone conduction—preliminary case ults be

IEA BESTEST Multi-Zone: MZ320 

Steady-State Zone C Sensible Cooling Load

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

MZ320, 3-Zone

Sensible Cooling Load (W or Wh/h)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg COMFIE/EdMP

ESP-r/ESRU CODYRUN/UR VA114/VABI EnergyPlus/GARD

KoZiBu/JNLOG Analytical

92
IEA BESTEST Multi-Zone: MZ340, MZ350, MZ355 

Annual Sensible Cooling Load, All Zones

15000

3000

6000

9000

12000

Sensible Cooling Load (kWh)

0

MZ340 MZ350, MZ355

Zone B

MZ350, MZ355

Zone E

MZ350, MZ355

Zone A

MZ350, MZ355

Zone D

 MZ350 

Zone C

 MZ350 

Zone F

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg

ESP-r/ESRU VA114-CirBm/VABI VA114-CirDf/VABI

EnergyPlus/GARD VA114-CirBm-MZ355/VABI VA114-CirDf-MZ355/VABI

EnergyPlus-MZ355/GARD

Figure 2-36. BESTEST multi-zone shading cases—sensible cooling load, before BESTESTing 

(Case MZ355 results are three rightmost bars for zones B, E, A, and D.)

IEA BESTEST Multi-Zone: MZ340, MZ350, MZ355 

Annual Sensible Cooling Load, All Zones

15000

3000

6000

9000

12000

Sensible Cooling Load (kWh)

0

MZ340 MZ350, MZ355

Zone B

MZ350, MZ355

Zone E

MZ350, MZ355

Zone A

MZ350, MZ355

Zone D

 MZ350 

Zone C

 MZ350 

Zone F

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg

ESP-r/ESRU VA114-CirBm/VABI VA114-CirDf/VABI

EnergyPlus/GARD VA114-CirBm-MZ355/VABI VA114-CirDf-MZ355/VABI

EnergyPlus-MZ355/GARD

Figure 2-37. BESTEST multi-zone shading cases—sensible cooling load, after BESTESTing 

(Case MZ355 results are three rightmost bars for zones B, E, A, and D.)

93
IEA BESTEST Multi-Zone: MZ360 

Sensible Cooling Load (kWh)

Annual Sensible Cooling Loads

140000

80000

100000

120000

20000

40000

60000

0

Building, Qbldg Zone A, QA Zone B, QB Zone C, QC QB + QC

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg ESP-r/ESRU

VA114-CirBm/VABI VA114-CirDf/VABI EnergyPlus/GARD

Figure 2-38. BESTEST internal windows, MZ360—sensible cooling load, before BESTESTing

IEA BESTEST Multi-Zone: MZ360 

Annual Sensible Cooling Loads

Figure 2-39. BESTEST internal windows, MZ360—sensible cooling load, after BESTESTing 

40000

60000

80000

100000

120000

140000

Sensible Cooling Load (kWh)

0

20000

Building, Qbldg Zone A, QA Zone B, QB Zone C, QC QB + QC

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg ESP-r/ESRU

VA114-CirBm/VABI VA114-CirDf/VABI EnergyPlus/GARD

94
• HTB2: Results for cases MZ340 and MZ350 were initially submitted for the February 2005 

version of the test specification in March 2005. For cases MZ340 and MZ350, results sub

September 24, 2006 provide the basis for estimates of initial results. These results were reduc

based on Section 2.4.3.3. The effect of another change to HTB2 before September 2006 (se

Section 2.4.3.4) was not documented and could not be included in the initial results chart. For 

Case MZ360, results shown are those initially submitted September 24, 2006. 

• TRNSYS-TUD: Results for all cases were initially submitted for the February 2005 version

the test specification in March 2005. For cases MZ340 and MZ350, results shown are those 

submitted Decem

mitted 

ed 

e 

 of 

ber 17, 2005 for preliminary simulations of the substantively final (August 

2006) test specification, and revised based on model corrections before this submittal (see 

Sections 2.4.5.1 and 2.4.5.5). For Case MZ360, results submitted March 2005 are used. For those

results, original values of Qbldg, QA, and QB+C are used; however, to normalize for increased depth 

of Zone B in the final version of Case MZ360, QB and Q B

C are modified to sum to QB+C and to 

have the same ratio QBB

oes not indicate any changes to the TRNSYS-16 model 

related to field trials of cases MZ340 and MZ350 before this submittal. For Case MZ360, results 

/QC as for results submitted for the August 2006 test specification. 

• TRNSYS-16: Results for all cases were initially submitted for the February 2005 version of the 

test specification in March 2005. For cases MZ340 and MZ350, results submitted February 20, 

2007 are shown. The modeler report d

submitted March 2005 are used. For those results, original values of Qbldg, QA, and QB+C are used; 

however, to normalize for increased depth of Zone B in the final version of Case MZ360, QB and 

Q

B

C are modified to sum to QB+C and to have the same ratio QBB

• VA114 (Circumsolar as Beam): Although a number of fixes were discussed in Section 2.4.4 and 

s 

on 

The resu e that there was initially a 20%–90% and 40%–155% 

disa e

window hat 

after co

for vario re 

7%–34%

for annu

in Figur

Scatter 

diagnos

/QC as for results submitted for the 

August 2006 test specification. 

in VABI’s modeler report, VABI did not submit results that show direct effects of the changes.

Showing the effects of these changes and input errors is found not applicable according to VABI

Software BV (Wijsman 2008a). Therefore, for the VA114 results for cases MZ340, MZ350, 

MZ355, and MZ360, the initial results for VA114 (see Figure 2-36) are equal to the VA114 final 

results. 

• VA114 (Circumsolar as Diffuse): VABI ran VA114 with circumsolar radiation modeled as 

diffuse radiation to make a better comparison with the other simulation programs, which model 

circumsolar diffuse radiation as diffuse radiation rather than as direct-beam radiation. For case

MZ340, MZ350, and MZ355, results shown are those initially submitted for this model 

December 15, 2005; these are for preliminary simulations of the substantively final (August 

2006) test specification. Results for these cases were generated after corrections to VA114 

shading and internal window models were made using VA114’s usual method of modeling 

circumsolar diffuse radiation as beam radiation (see Sections 2.4.4.3, 2.4.4.9 and 2.4.4.10). For 

Case MZ360, results shown are those documented in Section 2.4.4.8 for internal window 

reflectance = 0.1 (what these results would have been before VA114 was changed to allow other 

internal window transmittances). 

lts shown in Figures 2-36 and 2-38 indicat

gre ment among annual cooling loads for various zones for the multi-zone shading and internal 

 cases, respectively, with substantial scatter among the programs. Figures 2-37 and 2-39 show t

rrecting software errors with BESTEST diagnostics, the remaining disagreements among results 

us zones for multi-zone shading are 5%–13%, and for a single internal window configuration a

. For the most challenging configuration with a second internal window in series, disagreement 

al cooling load for the zone interior to the second internal window is 112% (see bars for Zone C 

e 2-39), thus indicating further refinement of the models for this configuration may be warranted. 

among results was reduced for all the cases. This shows how the BESTEST method is used to 

e and correct faulty algorithms in complex simulation programs. 

95
Table 2-11 summarizes final ranges of disagreement for predictions of cooling loads, disaggregated by 

m

nt noise hms that 

calculate incident solar radiation, and i –21% ranges of disagreement when shading model 

effects are isolated. The greatest differences for shading results occurred for zones C and F, where beam 

shading b

if

ses indicate large percentage differences. However, as peak cooling loads occur at times when solar 

radiation is not obscured by the shading device, peak cooling load sensitivity to shading is slight, and the 

large percentages there indicate reasonable differences relative to a slight sensitivity. 

Improvement in the ability to diagnose shading models is evident from comparing final disagreement 

ranges for the original single-zone IEA BESTEST shading cases for more realistic constructions, versus 

the final range of disagreement for the new in-depth diagnostic multi-zone shading cases. For the more 

realistic original single-zone cases with shading devices, the range of annual cooling load disagreement is 

38%–73% for the absolute results (cases considered alone), and 46%–63% for the delta results (sensitivity 

results to isolate shading model effects, e.g., Case 630–620) (ANSI/ASHRAE 2007; Judkoff and 

Neymark 1995). A graphic example of original single-zone shading case disagreement in the delta 

context, excerpted from IEA BESTEST, is provided in Figure 2-40. Disagreement ranges for final delta 

results of the current multi-zone cases are smaller relative to mean sensitivities, (see Figure 2-41). 

Table 2-11 also indicates that for the internal window case (MZ360), results for whole-building annual 

cooling load have good agreement (within 7%), consistent with differences among algorithms for 

calculating incident solar gains. However, disagreement increases for cooling load (allocation of 

transmitted solar gains) disaggregated for each zone to: 34% for Zone A, 16% for Zone B, and 112% for 

Zone C. The large disagreement for Zone C is caused by three of the models not allowing direct-beam 

radiation transmission through a second internal window. As double-skin facades become more popular in 

buildings (see Poirazis 2007), more a ing es of internal 

windows gains imp

test case and zone. The results indicate excellent agreement compared with the Case MZ320 interzonal 

conduction analytical solution within 2% for Zone C steady-state space cooling load, where all but one 

odel are within 0.3% of the analytical solution for this result. 

Table 2-11. Final ranges of disagreement among simulation results

The results for the shading cases (MZ340, MZ350, and MZ355) indicate good agreement, within 13% for 

zone annual cooling loads in all cases. The delta annual cooling-load sensitivity comparisons for the 

shading cases (MZ350–MZ340, MZ355–MZ340) reduce disagreeme from algorit

ndicate 5%

ccurate model of solar radiation through a seri

ortance. 

y the north-facing side of the fin and diffuse shading are more predominant. Peak cooling load 

d ferences are consistent with annual cooling load differences. Delta peak cooling loads for the shading

ca

Unshaded

Output Building Zone A Zone B Zone C Zone D Zone E Zone F (MZ340)

MZ320, steady-state cooling -- -- -- 0.3%-1.9% -- -- -- --

MZ340, MZ350, MZ355 Shading 

 Annual cooling (MZ35x) 8.8% 8.6% 12.8% 10.2% 8.1% 12.3% 9.8% 4.5%

 Delta ann. cooling (MZ35x-MZ340) 5.1% 6.3% 5.1% 19.9% 6.3% 5.0% 20.6% --

 Peak annual cooling (MZ35x) 11.9% 8.4% 13.0% 11.8% 8.4% 13.0% 11.8% 5.4%

 Delta peak cooling (MZ35x-MZ340)* 142.9% 124.8% 123.6% 281.9% 127.3% 126.8% 283.1% --

MZ360 Internal Windows Zones B+C

 Annual cooling 7.3% 34.3% 16.0% 112.4% 32.5% -- -- --

 Peak cooling 11.6% 66.4% 27.3% 155.6% -- -- -- --

* Reasonable variation relative to small sensitivity

96
Figure 2-40. IEA BESTEST single-zone east- and west-shaded window delta sensitivity, annual 

Fi s

heating and sensible cooling loads (Judkoff and Neymark 1995)

IEA BESTEST Multi-Zone: MZ350-MZ340, MZ355-MZ340 

Delta Annual Cooling Load, All Zones

-7000

-6000

-5000

-4000

-3000

-2000

-1000

0

Zone B Zone E D Z Zone F

Shaded Solar Radiation (kWh)

Zone A Zone one C

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg

ESP-r/ESRU VA114-CirBm/VABI VA114-CirDf/VABI

EnergyPlus/GARD VA114-CirBm-MZ355/VABI VA114-CirDf-MZ355/VABI

EnergyPlus-MZ355/GARD

gure 2-41. In-depth diagnostic multi-zone delta sensible cooling load

97
Based on results after several iterations of BESTESTing, and resulting model improvements, all the 

ecause of 

funding flow constraints. These test cases would include: 

o Shading fin surface reflectance > 0 

er 

rsus 

 dyn hading, interzonal 

air exchan s, e

o This case could provide a starting point for future certification tests for software intended 

o

simultaneously active physical phenomena. 

tested programs now appear to have reliable models for phenomena isolated by the test cases including 

interzonal conduction, multi-zone shading, and internal windows where there are no multiple internal 

windows in series. These test cases did not address thermal inertia interactions for modeled phenomena 

because thermal mass effects were tested in IEA BESTEST (Judkoff and Neymark 1995). Some 

remaining disagreements (discussed in Section 2.4) should be addressed, and especially with respect to 

Case MZ360 for deficiencies identified for three of the models related to modeling a second internal 

window in series. The simulation results (with the noted specific exceptions for Case MZ360) may 

therefore be used as a reference or benchmark against which other software can be tested. 

2.5.3 Test Cases for Future Work 

We suggest that additional work related to model testing and validation, outlined in the sections that 

follow, be considered. 

2.5.3.1 Additional Shading and Internal Window Cases 

This project developed a set of idealized in-depth diagnostic test cases for multi-zone conduction, multizone shading, and internal window models. During this project, participants discussed a number of 

important test case configurations that could not be included with the current test cases b

at includes full amic interactions of loading, s

ge, thermal mas tc. 

• Shading case parametric variations, including: 

o Modeling of multiple shading projections on a shaded area 

• Internal window parametric variations in a two-zone context, including: 

o Two-zone version of MZ360 (idealized calorimeter) 

o Zero-conductance walls with realistic interior solar reflectance, with ideal windows 

o Realistic windows, with ideal walls (zero-conductance; interior solar absorptance = 1) 

o Realistic windows, and zero-conductance walls with realistic interior solar absorptance 

o Realistic windows with realistic thermally conducting walls 

• Shading/Internal window interaction. 

Other cases to consider include: 

• Enable/test infrared radiation exchange in the conduction context of Case MZ320 by comparing 

relative disagreement for a set of multi-zone case results versus a similarly excited single-zone 

case. 

• Whether an analytically solvable dynamic version of Case MZ320 can be developed using eith

stepped internal gains or thermostat set points 

• Addressing the question, “If single-zone results are satisfactory, can we extrapolate that multizone results will be satisfactory?” Answering this question may require developing cases that 

compare disagreement among a set of results from multiple programs for a multi-zone case ve

a similar set of results for a comparable single-zone case. 

• Multi-zone shading and internal windows with thermal mass interactions 

• Develop a 27-zone building th

for modeling large buildings, and for future BESTEST diagnostic logic. 

This case would not provide diagnostic capability by itself because of many 

98
 Additional Building Thermal Fabric and Mechanical Equipment Test Cases 

nal building thermal fabric and mechanical equipment model test cases, for consideration to be 

ed in the future, are summarized in HVAC BESTEST Volume 2 (Neymark and Judkoff 2004, Sect

nd in IEA BESTEST In-Depth Diagnostic Cases for Ground Coupled Heat Transfer Related to

2.5.3.2

Additio

develop ion 

2.5.2), a SlabOn- a

2.6 Co

2.6.1 C

2.6.1.1

The ma

•

•

 avoids noise from potentially larger results disagreements 

ous 

• ent of a steady-state analytical solution for the interzonal conduction test case, 

•

, 

e 

, 

, initial disagreement of 20%–90% improved to 5%–13% 

 For the internal windows case: 

–

Gr de Construction (Neymark and Judkoff et al. 2008, Section 2.5.4.1). 

nclusions and Recommendations 

onclusions 

 Major Accomplishments 

jor accomplishments of this project were: 

Extension of the IEA BESTEST building thermal fabric envelope tests to include an in-depth 

diagnostic analytical verification test case for interzonal conduction, and in-depth diagnostic 

comparative test cases for multi-zone shading and internal windows 

Use of idealized calorimetry to enhance the diagnostic power of the multi-zone shading and 

internal window test cases, which

related to modeling realistic windows and opaque internal surfaces 

o Range of annual cooling load disagreement for cases with shading devices decreased 

from 38%–73% for the original single-zone IEA BESTEST cases (ANSI/ASHRAE 2007;

Judkoff and Neymark 1995) to 8%–13% for these new test cases, allowing the numer

disagreements listed in Section 2.6.1.2 to be identified and diagnosed. 

Developm

assuming one-dimensional conduction 

Accuracy improvements to all but one of the models that participated in the field trials of the test

cases, and to all the models that participated in the multi-zone shading and internal-window test 

cases 

o 31 errors were diagnosed and fixed 

o By applying the diagnostic logic of the test cases to expose problems with the models

disagreement ranges for steady-state or annual cooling loads were improved during th

field trials of the test cases, as follows: 

 For interzonal conduction, initial disagreement of 4%–8% improved to ≤ 0.3%

except for one model that has 2% disagreement 

 For multi-zone shading

• Overall building load initial disagreement of 40% improved to 7% 

• Individual zone loads initial disagreement of 65%–155% improved to 16%

112% (or from 65%–95% to 16%–34%, excluding disagreements for the zone 

with a second internal window in series). 

With respect to the value of the test cases to software developers, one software-developer/vendor 

participant made the following comment about this IEA project: 

99
“Bestest and IEA-34/43 tests brought a number of new errors to the surface. This shows the 

importance of these test [cycles]!! And still there will be errors in the software!! Development of 

new, specific test cases is of big importance!!” (Wijsman 2008b) 

2.6.1.2 Summary of Findings 

Test cases for in- nd internal 

windows have been added to the IEA's method for systematically comparing whole-building energy 

simulation software and determining the algorithms responsible for prediction differences. This work 

applied an analytical solution result (Case MZ320) as a mathematical truth standard for modeling interzonal 

conduction, and applied idealized calorimetry as described in Section 2.5.1 to enhance identification of and 

diagnostics for multi-zone shading and internal window model disagreements. 

The procedure has been field tested using a number of building energy simulation programs from around the 

world. The method has proven effective at isolating the sources of predictive differences. The diagnostic 

procedures revealed bugs, faulty algorithms, limitations, and input errors in all but one of the simulation 

models tested in this study, and in all of the simulation models that ran the shading and internal window 

cases. This includes the following models that ran all the cases—EnergyPlus, ESP-r, HTB2, TRNSYSUD, TRNSYS-16, and VA114—along with two of the three programs that did not run all of the cases in 

eir final form—CODYRUN and COMFIE; the developer of KoZiBu did not report finding any issues for 

ing 

vestigation by the 

software authors, 3 were judged as acceptable by the software authors, and 4 are awaiting 

f 

ot 

depth diagnosis of models for interzonal heat transfer, multi-zone shading, a

T

th

the Case MZ320 results. Some important technology advances occurred by running the test cases: 

• The improved final agreement for shading cases using idealized/modeled calorimetry (cool

loads equal to solar radiation incident on external glazing) allowed disagreements to be identified 

and errors to be diagnosed that may have been missed using the original IEA BESTEST singlezone shading cases (Judkoff and Neymark 1995), where for the original IEA BESTEST cases 

disagreements related to modeling realistic optical properties of glazing and interior opaque 

surfaces along with realistic wall conduction employing thermal mass may have obscured 

disagreements caused by shading models. 

• Of 49 found disagreements, 31 were diagnosed and fixed, 11 are planned for in

notification of the software developer by the modeler; Table 2-12 summarizes notable examples o

error trapping; supporting details are given in Section 2.4. 

Many of the errors listed in Table 2-12 were significant with greater than 20% effect on sensible cooling 

load. For individual programs applying the current in-depth cases, some errors had relatively minor (< 2%) 

effect on cooling load. Where a program had multiple errors of smaller magnitude, such errors did n

necessarily compensate each other, and may have been cumulative. Therefore, correcting the minor as well 

as the major errors was important. 

After correcting software errors using BESTEST diagnostics, the remaining disagreements for cooling 

load results are: 

• ≤ 0.3% for the interzonal conduction analytical verification test case, except for one program with 

2% disagreement 

• 5%–13% for the multi-zone shading cases 

• 7%–112% for the internal window case (7%–34% if the zone with second internal window in 

series is excluded). 

100
Table 2-12. Summary of Software Problems Found Using IEA BESTEST Multi-Zone Cases 

Modela,b Error Descriptiona % Cooling Load Effect or 

Disagreementa,c Outcomea,b

CODYRUN User input surface coefficients not allowed ≤ 8%? (MZ2/300 see COMFIE) Fixed 

CODYRUN (2) IR emit < 0.01, custom zone air properties Minor (MZ320) Fixed (2) 

CODYRUN Case MZ320 Zone C cooling load 2% (MZ320) A.N.d

COMFIE User input surface coefficients not allowed 2%–8% (prelim MZ200, MZ300) A.N.d,e

EnergyPlus Unintended lost diffuse solar radiation 33% (MZ360); 4% (MZ340) Fixed 

EnergyPlus No beam radiation to Zone C (MZ360) MZ360: 6%? bldg, 240% Zone C A.N.d 

EnergyPlus Internal windows output documentation 0% (MZ360), limits diagnosis A.N.d 

EnergyPlus October 14 hour-17,18 disagreements Minor issue? (MZ340–MZ350) A.N.d 

ESP-r Only allows hour-centered solar time 12% (MZ340) Fixed 

ESP-r No diffuse shading 19%–35% (MZ350) Fixed 

ESP-r Custom solar data processing by modeler Minor issue (MZ340 – MZ360) Fixed 

ESP-r Beam and diffuse output not disaggregated 0%; limited diagnosis Fixed 

ESP-r Solar/shading algorithm improvement Up to 11% peak clg. (MZ350) Fixed 

ESP-r High back side of fin shading ?% (MZ350, MZ340–MZ350) A.N.d 

HTB2 User input ext surface coefficients ignored 1% (MZ320) Fixed 

HTB2 Infrared emittance = 0 not allowed Crashed (MZ340) Fixed 

HTB2 Shadow/window overlap 1%–2% (MZ340–MZ350) Fixed 

HTB2 Shading interpolation algorithm ?% (MZ340, MZ350) Fixed 

HTB2 Synch solar data with surf. insolation model ≤ 23% hr, 0.4% pk (MZ340,360) Fixed 

HTB2 Internal window reflection (MZ360) –16% QA, +18% QB, 0% Q B

bldg Fixed 

HTB2 March 15, hour 17 disagreement ?% (MZ340–MZ350) A.N. 

d

HTB2 October 14, hourly disagreement ?% (MZ360) A.N.d,e 

TRNSYS-TUD Unintended lost diffuse solar radiation 3%–4% (MZ340) Fixed 

TRNSYS-TUD Ray tracing algorithm error ?% (MZ360) Fixed 

TRNSYS-TUD Ray tracing versus 100%-diffuse transmitted 15%, 23% zones A,B (MZ360) Fixed 

TRNSYS-TUD Beam and diffuse output not disaggregated 0%; limited diagnosis Fixed 

TRNSYS-TUD Shading device input error 30%-40% MZ350 zones B,E,C,F Fixed 

TRNSYS-TUD Optical properties as f(incidence angle) 1% (MZ340) Fixed 

TRNSYS-TUD No beam radiation to Zone C (MZ360) MZ360: 5%? bldg, 220%? Zone C A.N.d 

TRNSYS-TUD Reindl model shading inconsistency 7%–14% (MZ340–350) A.N.d 

TRNSYS-TUD Isotropic sky model versus Reindl model 4% annual, 8% peak (MZ340) A.N.d 

TRNSYS-16 Unintended lost diffuse solar radiation 33%? (MZ360); 4%? (MZ340) M.N.f,g 

TRNSYS-16 Modeler used less detailed solar processor 2% annual, 9% peak (MZ340) M.N.f,g

TRNSYS-16 Less detailed beam model v.TRNSYS-TUD 15%, 27% zones A,B (MZ360) M.N.f,h

TRNSYS-16 No beam radiation to Zone C (MZ360) MZ360: 6%? bldg, 290% ?Zone C M.N.f,h

VA114 If emit or abs < 0.2, Σ(exchange factors) > 1 ?% (MZ320) Fixed 

VA114 Comfort modeling uses wrong coordinates ?% (MZ320) Fixed 

VA114 U = 0 not allowed ?% (MZ340) Fixed 

VA114 Beam shading excluded, fin affixed to bldg. (MZ350a) Fixed 

VA114 Beam shading excluded, not affixed to bldg. (MZ350c) Fixed 

VA114 (2) All shading excluded, auto-self shading (MZ355) Fixed (2) 

VA114 MZ355 not = MZ350 for hr 16, Mar 12–17 < 0.1% (MZ355 v. MZ350) A.N.d

VA114 Internal window hard-coded refl. = 0.1 MZ360: 7% bldg, 22% Zone C Fixed 

VA114 Input error: incorrect time zone (MZ340, MZ360) Fixed 

VA114 Input error: fin input twice (MZ350c) Fixed 

VA114 not = Window AO transmitted 0.04% (MZ360) A.N.d,e Total cooling 

VA114 Annual diffuse solar 4%? (MZ340) A.N.d

a Acronyms and abbreviations used in this column are defined in Section 2.7. 

101
b Numbers in parenthesis are number of changes associated with the listing, if > 1 

Effects are for are included in 

versus 

model 

 appear to have reliable models for phenomena isolated by 

, multi-zone shading, and internal windows where there are 

r the 

discussed in Section 2.4) should be addressed, especially with 

odels related to modeling a second 

ecific exceptions for Case MZ360) 

to 

st cases that emphasize special modeling issues 

sso t C systems (see Section 2.5.3.2). 

2.6.1.3 Ad t

Sim r y of uses, including: 

• Com r

constitut

defi

egree of disagreement 

ic sources of prediction differences among several building energy 

• ing a program against a previous version of itself after the internal code has been modified, to 

• lgorithmic change to understand the sensitivity 

An adva

paramet ossibility of concealing 

problem rovements to all but one 

of th b

shading ome of the bugs that were found may well have been present for 

several year

suggests the imp thods. Only 

c annual cooling load unless otherwise noted; specific cases relevant to the described effects

parentheses. For disagreements listed as fixed, listed percentage values are the effect of the change for new results 

previous results for a given model. d A.N. = Authors notified. e Software developer indicates this disagreement is acceptable for their model; no software revision planned. f M.N. = Modelers notified. Modelers have been asked to inform the software developers of the issue. g Modelers developed an input work-around. h No work-around available. i

 Errors were related to calling older models no longer available to users; these errors were fixed to allow comparison of new

models versus the previous models.

This shows how the BESTEST method is used to diagnose and correct faulty algorithms in complex 

simulation programs. Based on results after several iterations of BESTESTing, and resulting 

improvements, all of the tested programs now

the test cases including interzonal conduction

no multiple internal windows in series. These test cases did not address thermal inertia interactions fo

modeled phenomena because thermal mass effects were tested in IEA BESTEST (Judkoff and Neymark 

1995). Some remaining disagreements (

respect to Case MZ360 for deficiencies identified for three of the m

internal window in series. The simulation results (with the noted sp

may therefore be used as a reference or benchmark against which other software can be tested. 

Based on this work, there are a number of recommended areas for further investigation with respect 

developing additional validation test cases for multi-zone modeling. These are described in detail in

Section 2.5.3.1. For the longer term we hope to develop te

a cia ed with more complex building types and HVA

van ages of BESTEST Methodology 

ila to pr io ev us test suites that applied BESTEST, these new cases have a variet

pa ing output from building energy simulation programs to a set of analytical solutions that 

e a reliable set of theoretical results given the underlying physical assumptions in the case 

nitions 

• Comparing several building energy simulation programs to determine the d

among them 

• Diagnosing the algorithm

simulation programs 

• Comparing predictions from other building energy simulation programs to the analytical solution, 

and simulation results in this report 

Check

ensure that only the intended changes actually resulted 

Checking a program against itself after a single a

between algorithms. 

ntage of the BESTEST methodology is that a program is examined over a broad range of 

ric interactions based on a variety of output types, minimizing the p

s by compensating errors. Performance of the tests resulted in quality imp

e uilding energy simulation models used in the field trials, and all the models used in the multi-zone 

 and internal window test cases. S

s. The fact that they have just now been uncovered shows the power of BESTEST and 

ortance of continuing to develop formalized validation and diagnostic me

102
after coding g hms be 

evaluated wh re

ne 

on-airflow test cases requires a few days for an experienced user, not including improvements to the 

e the 

rs with a reasonable time 

mmitment. 

est Procedures for ANSI/ASHRAE Standard 140 

work of IEA 34/43, and the work that has preceded it in IEA SHC 

asks 8, 12, and 22 is important for two reasons: 

•

•

Along w

2008), whic

following test su

approved as a st

Evaluation 

•

• ent comparative tests (Neymark and Judkoff 

2004) 

• H C

Beaus

Within the BES S

developed in areas r rchitectural fabric of the building. 

BESTEST work la

and configuratio o

The new in-depth multi-zo

Standard 140. Additional t

planned for future inclusio eymark and Judkoff et al. 2008) 

 bu s have been eliminated can the assumptions and approximations in the algorit

e necessary. 

Checking a building energy simulation program for the first time with the BESTEST in-depth multi-zo

n

software, if necessary. Subsequent program checks are faster because input files may be reused. Becaus

simulation programs have taken many years to produce, the new BESTEST cases provide a very costeffective way of testing them. As we continue to develop new test cases, we will adhere to the principle of 

parsimony so the entire suite of BESTEST cases may be implemented by use

co

2.6.2 Recommendations 

2.6.2.1 Adaptation of T

The work presented in this report, other 

T

The methods have been extremely successful at correcting software errors in advanced building 

energy simulation programs throughout the world. 

The methods are finding their way into industry by being adopted as the theoretical basis for 

formalized standard methods of test and software certification procedures; in this sense the work

may be thought of as pre-normative research. 

ith the overall validation methodology (Judkoff 1988; Judkoff and Neymark 2006; Judkoff et al. 

h has recently been added to the ASHRAE Handbook of Fundamentals (ASHRAE 2005), the 

ites, developed in conjunction with IEA, have been code-language adapted and formally 

andard method of test, ANSI/ASHRAE Standard 140-2007, Standard Method of Test for the

of Building Energy Analysis Computer Programs (ANSI/ASHRAE 2007): 

IEA BESTEST, building thermal fabric comparative tests (Judkoff and Neymark 1995) 

• HVAC BESTEST Volume 1, unitary cooling equipment analytical verification tests (Neymark 

and Judkoff 2002) 

HVAC BESTEST Volume 2, unitary cooling equipm

VA BESTEST Fuel-Fired Furnace analytical verification and comparative tests (Purdy and

oleil-Morrison 2003). 

TE T/Standard 140 structure, there is room to add new test cases. BESTEST is better

elated to energy flows and energy storage in the a

 re ted to mechanical equipment is still in its early phases in that there are many kinds

ns f mechanical systems to test. 

ne non-airflow test cases described in this report are planned for inclusion in 

est cases either currently being adapted for inclusion in Standard 140, or 

n in Standard 140, are listed elsewhere. (N

103
2.6

Stan tained therein, are being referenced 

nd used worldwide by a growing number of code promulagation authorities. ASHRAE Standard 90.1 

hich is ASHRAE’s consensus energy code for commercial buildings and 

r non-low-rise residential buildings, requires that software used for demonstrating performance 

 tax 

ilding 

that the BESTEST 

rocedures are becoming part of software developers’ normal in-house quality control efforts, are included 

at 

 an 

verall validation methodology (ASHRAE 2005, Chp. 32; Judkoff and Neymark 2006), including: 

•

•

•

Future w

•

neration equipment. 

 IEA Executive Committees for Solar Heating and Cooling and for 

ina y,

the t

were e and subsequent re-executions of the computer 

sim ti

test d of 

esource es participating in this project. Such extensive field trials, and resulting 

nhancements to the tests, were much more cost effective with the participation of the IEA-34/43 experts. 

.2.2 Closing Remarks 

dard 140 and the BESTEST reports that comprise the test suites con

a

(ANSI/ASHRAE/IESNA 2007), w

fo

compliance with Standard 90.1 be tested using ASHRAE Standard 140-2004 (ANSI/ASHRAE 2004b). 

Software used for calculating energy savings for purposes of the energy-efficient commercial building

deductions in the United States must be tested with Standard 140-2007 (IRS 2008). As part of their bu

energy performance assessments under the European Community’s Energy Performance Directive 

(European Union 2002), several countries are using software tools that have been checked with BESTEST.

Further details of international use of BESTEST, along with growing evidence 

p

elsewhere (Judkoff and Neymark 2006; Neymark and Judkoff et al. 2008, Section 2.6.2).

Computer scientists universally accept the merits of software testing. A well-known rule of thumb is th

in a typical programming project more than 50% of the total cost is expended in testing the program or

system being developed (Myers 2004). Of this, about 20% of development time goes toward system 

testing (McConnell 2004). Because new energy-related technologies are continually being introduced into

the buildings market, there will always be a need for further development of simulation models, combined 

with a substantial program of testing and validation. Such an effort should contain all the elements of

o

Analytical verification 

Comparative testing and diagnostics 

Empirical validation. 

ork should therefore: 

• Continue to produce a standard set of analytical tests. 

Develop a set of diagnostic comparative tests that emphasize the modeling issues important in large 

commercial buildings, including more tests for heating, ventilating, and air-conditioning systems, 

and other mechanical equipment, including on-site power ge

• Develop a sequentially ordered series of high-quality data sets for empirical validation. 

The work described here represents continuing progress in the effort to develop carefully validated building 

energy simulation tools. Continued development and validation of whole-building energy simulation 

programs are two of the most important activities meriting the support of national energy research programs.

The U.S. Department of Energy and

Energy Conservation in Buildings and Community Systems should diligently consider what sort of future 

collaborations would best support this essential research area.

F ll the authors wish to acknowledge that the expertise available through IEA and the dedication of 

par icipants were essential to the success of this project. Over the four-year field trial effort, there 

 s veral revisions to the BESTEST specifications 

ula ons. This iterative process led to the refining of the new BESTEST cases, and the results of the

s le to improving and debugging of the simulation models. The process underscores the leveraging

r s for the IEA countri

e

104
2.7 

These abbreviations and acrony e used in Sections 2.1 through 2.6 and in Part III. 

a sor

A ACH

A Ame

A April

A Ame and A

BESTEST Build agnostic

b build

BLAST-US/IT BL o ( 1995) 

B Brno 

C Europ

C Chart ices Engine

CSTB Centr Batiment 

D Dece

d disag

D eM

d rec

D .S. 

D OE

E erg muni ogramme (of the IE

E ole

e itt

E ESPE ESP N

E Energ tr

F Febru

G GAR

H high 

h hour 

H heatin

I solar dia cript 

I Intern

d Cooling Programme Task 34 and 

 Systems Programme Annex 43 

Abbreviations and Acronyms for Parts II and III

ms ar

bs ab ptance 

CHSL SL Consultoria 

NSI rican National Standards Institute 

pr 

SHRAE rican Society of Heating, Refrigerating ir-Conditioning Engineers 

ing Energy Simulation Test and Di Method 

ldg ing 

AST run by NREL and Politecnico Torin Judkoff and Neymark

rno University of Technology 

EN ean Committee for Standardization 

IBSE ered Institution of Building Serv ers 

e Scientifique et Technique du

ec mber 

isag gregated 

MU D ontfort University 

n di t normal solar radiation 

OE U Department of Energy 

OE2 D -2.1D, see Judkoff and Neymark (1995) 

CBCS En y Conservation in Buildings and Com ty Systems pr A) 

dMP Ec des Mines de Paris 

mit em ance 

SP r 

SP-LP run by Leicester Polytechnic (Judkoff and eymark 1995) 

SRU y Systems Research Unit, University of S athclyde 

eb ary 

ARD D Analytics 

IMASS mass 

r 

VAC g, ventilating, and air-conditioning 

radiation, see subscripts; incident solar ra

cy 

tion for no subs

EA ational Energy Agen

IEA 34/43 International Energy Agency joint Solar Heating an

Energy Conservation in Buildings and Community

105
IESNA Illuminating Engineering Society of North America 

IN

e 

A J. Neymark & Associates 

 

refl 

SHC

SI 

SRE B

SRE S

surf. 

Syn

S3PAS 

 ature 

SA-Lyon INSA-Lyon Thermal Center 

I-P inch-pound 

IR infrared 

IRS Internal Revenue Servic

Jan January 

JN

JNLOG Jean Noel, consulting engineer 

k slab/soil thermal conductivity 

LBNL Lawrence Berkeley National Laboratory 

LOMASS low mass 

Mar March 

Max maximum 

Mid-PM mid-afternoon 

Min minimum 

MZ35x MZ350 and MZ355 

NREL National Renewable Energy Laboratory 

pk peak 

q peak hour or hourly cooling load (W or Wh/h) 

Q Annual cooling load (kWh) 

reflectance 

 Solar Heating and Cooling Programme (of the IEA) 

Système Internationale 

S- RE SERIRES run by Building Research Establishment (Judkoff and Neymark 1995) 

S/ UN SUNCODE 5.7, see Judkoff and Neymark (1995) 

surface 

ch synchronization of 

S3Pas run by University of Sevilla (Judkoff and Neymark 1995) 

T zone air temper

TMY2 Typical Meteorological Year 2 

TSYS-BEL/BRE TRNSYS 13.1 run by Vrije Universiteit and BRE (Judkoff and Neymark 1995) 

TUD Technische Universitat Dresden (Dresden University of Technology) 

UIUC University of Illinois, Urbana/Champaign 

ULg University of Liège 

106
UR University of Reunion Island 

v. versus 

ubscripts 

max

tr 

trb 

trd 

AN A

Building

Hea g

AN A

Ana sis

efriger neers. 

ASHRAE. (2005). 2005 Handbook of Fundamentals, Atlanta, Georgia, US: American Society of Heating, 

Refrigerating and Air-Conditioning Engineers. 

VABI VABI Software BV 

VA114-CirBm VA114 with circumsolar diffuse radiation modeled as beam radiation 

VA114-CirDf VA114 with circumsolar diffuse radiation modeled as diffuse radiation 

WSA Welsh School of Architecture, Cardiff University 

S

A,B,C,D,E,F Zone designators 

b beam (direct normal) solar radiation 

bldg building 

B+C Sum of given value for Zone B and Zone C 

d diffuse solar radiation 

 maximum 

 transmitted solar radiation 

 transmitted beam (direct normal) solar radiation 

 transmitted diffuse solar radiation 

trh hourly transmitted solar radiation 

2.8 References for Part II 

André, P. (2008). Email communications from André (University of Liège, Liège, Belgium) to Neymark 

(Wheat Ridge, Colorado, US: J. Neymark & Associates) of April 1, 2008. 

SI/ SHRAE Standard 140-2004. Addendum b. Standard Method of Test for the Evaluation of 

 Energy Analysis Computer Programs. (2004a). Atlanta, Georgia, US: American Society of 

tin , Refrigerating and Air-Conditioning Engineers. 

SI/ SHRAE Standard 140-2004. Standard Method of Test for the Evaluation of Building Energy 

ly Computer Programs. (2004b). Atlanta, Georgia, US: American Society of Heating, 

R ating and Air-Conditioning Engi

 

ANSI/ASHRAE Standard 140-2007. Standard Method of Test for the Evaluation of Building Energy 

Analysis Computer Programs. (2007). Atlanta, Georgia, US: American Society of Heating, Refrigerating

and Air-Conditioning Engineers. 

ANSI/ASHRAE/IESNA (2007). ANSI/ASHRAE/IESNA Standard 90.1-2007, Energy Standard for 

Buildings Except Low-Rise Residential Buildings. Atlanta, Georgia, US: American Society of Heating, 

Refrigerating and Air-Conditioning Engineers.

107
EnergyPlus. (2008). U.S. Department of Energy, Energy Efficiency and Renewable Energy, Office of 

Building Technologies. www.energyplus.gov

European Union. (2002). On the Energy Performance of Buildings. Directive 2002/91/EC of the 

European Parliament and of the Council, Official Journal of the European Communites, December. 

ESRU. (2008). ESP-r web site. See www.esru.strath.ac.uk. Glasgow, Scotland, UK: University of 

Strathclyde, Energy Systems Research Unit. 

Felsmann, C. (2008). Email communications from Felsmann (Dresden University of Technology, 

Dresden, Germany) to Neymark (Wheat Ridge, Colorado, US: J. Neymark & Associates) of April 3 and 

April 11, 2008. 

Internal Revenue Service (IRS). (2008). Amplification of Notice 2006-52, Deduction for Energy Efficient 

ommercial Buildings. IRS Notice 2008-40. Appears in Internal Revenue Bulletin (IRB) No. 2008-14, 

able 

nergy Laboratory, Golden, CO. www.nrel.gov/docs/legosti/old/6231.pdf

C

April 7, 2008. Washington, D.C., US: United States Department of Treasury, Internal Revenue Service. 

Judkoff, R. (1988). “Validation of Building Energy Analysis Simulation Programs at the Solar Energy

Research Institute.” Energy and Buildings, 10 (3) 235. Lausanne, Switzerland: Elsevier Sequoia. 

Judkoff, R.; Neymark, J. (1995). International Energy Agency Building Energy Simulation Test 

(BESTEST) and Diagnostic Method. NREL/TP-472-6231. Golden, Colorado, US: National Renew

E

Jud f idation and Testing: The Methodological Foundation of 

ASH A RAE Transactions, Volume 112 (2) 367–376. Atlanta, Georgia, US: 

Am ican Society of Heating, Refrigerating and Air-Conditioning Engineers. 

udkoff, R.; Wortman, D.; O'Doherty, B.; Burch, J. (2008). A Methodology for Validating Building 

ne Colorado, US: National Renewable Energy 

Lab t

SERI T

McC n osoft Press, 

p. 5 

0152.pdf

kof , R.; Neymark, J. (2006). “Model Val

R E Standard 140.” ASH

er

 

J

E rgy Analysis Simulations. NREL/TP-550-42059. Golden, 

ora ory. Based on unpublished report of 1983 with same authors and title, previously referenced as 

/ R-254-1508. 

o nell, S. (2004). Code Complete: A Practical Handbook of Software Construction. Micr

02.

Myers, G. (2004). The Art of Software Testing. Hoboken, New Jersey, US: John Wiley & Sons, p. xiii. 

Neymark, J.; Judkoff, R. (2002). International Energy Agency Building Energy Simulation Test and 

Diagnostic Method for Heating, Ventilating, and Air-Conditioning Equipment Models (HVAC 

BESTEST) Volume 1: Cases E100-E200. NREL/TP-550-30152. Golden, Colorado, US: National 

Renewable Energy Laboratory. www.nrel.gov/docs/fy02osti/3

Neymark, J.; Judkoff, R. (2004). International Energy Agency Building Energy Simulation Test and 

Diagnostic Method for Heating, Ventilating, and Air-Conditioning Equipment Models (HVAC BESTEST

Vol. 2: Cases E300-E545. NREL/TP-550-36754. Golden, Colorado, US: National Renewable Energy 

Laboratory. 

), 

www.nrel.gov/docs/fy05osti/36754.pdf. 

108
Neymark, J.; Judkoff, R.; with Beausoleil-Morrison, I; Ben-Nakhi, A.; Crowley, M.; Deru, M.; 

enninger, R.; Ribberink, H.; Thornton, J.; Wijsman, A.; Witte, M. (2008). International Energy Agency 

gnostic Cases for 

-43388. Golden, 

rado, US newable Energy Laboratory. 

, A Literature Review. Lund, Sweden: Lund Institute of 

, I. (2003). Building Energy Simulation Test and Diagnostic Method for 

ired Furnace 

a: Natural Resources Canada, CANMET Energy Technology Centre. www.ieaH

Building Energy Simulation Test and Diagnostic Method (IEA BESTEST) In-Depth Dia

Ground Coupled Heat Transfer Related to Slab-On-Grade Construction. NREL/TP-550

Colo : National Re

Poirazis, H. (2007). Double Skin Facades

Technology, Lund University. 

Purdy, J.; Beausoleil-Morrison

Heating, Ventilating, and Air-Conditioning Equipment Models (HVAC BESTEST): Fuel-F

Test Cases. Ottawa, Canad

shc.org/task22/deliverables.htm

Strachan, P. (2008). Email communication with J. Neymark. 31 March 2008. University of Strathclyde, 

 of Wisconsin. (2 n 16.00.0037), A Transient System Simulation 

am. Ma ratory, University of Wisconsin, Wisconsin, 

. 

ing Multi-Zone. Natori, Japan: Institutes of 

nology; Ashikaga, Japan: Ashikaga Institute of Technology. In conjunction 

nnex 43, Project B. Draft, June 2008. 

ite. www.vabi.nl

Scotland, U.K. 

University 005). TRNSYS 16 (versio

Progr dison, Wisconsin, US: Solar Energy Labo

United States

Utsumi, Y.; Mitamura, T. (2008). Air Flow Test Cases includ

National Colleges of Tech

with IEA: SHC Task 34/ECBCS A

VABI Software. (2008). VABI web s . Delft, The Netherlands: VABI Software BV. 

s with J. Neymark. 19 May – 03 June 2008. Delft, The 

rlands: V

n, A. ( MZ320-MZ360, VA114 Version 2.25. Delft, 

March 2008. Included with Section 2.9, Appendix II-F, of this 

rt. 

Wijsman, A. (2008a). Email communication

Nethe ABI Software BV. 

Wijsma 2008b). Modeler Report for BESTEST Cases 

The Netherlands: VABI Software BV. 

final repo

109
2.9 APPENDIX II: Simulation Modeler Reports 

In Appendix II, we present reports written by the modelers for each simulation program. The modelers were 

asked to document: 

• Modeling assumptions (required inputs not explicitly described in the test specification) 

• Modeling options (alternative modeling techniques) 

• Difficulties experienced in developing input files for the test cases with their programs 

• Bugs, faulty algorithms, documentation problems, and input errors uncovered during the field trials 

• Source code or input modifications made because of the diagnostic results 

• Comments on agreement or disagreement of results compared to other simulation results 

• Any odd results obtained with their programs 

• Sensitivity studies conducted to further understand the sources of differences between their 

programs and the others 

• Conclusions and recommendations about their simulation models, the test specification, or both. 

110
Appendix II-A 

Modeler Report for BESTEST Cases MZ320 – MZ360 

EnergyPlus Version 2.1.0.012 

by 

Robert Henninger and Michael Witte 

GARD Analytics, Inc. 

United States 

 

March 2008 

1. Introduction 

Software: EnergyPlus Version 2.1.0.012 

Authoring Organization: U.S. Department of Energy 

 Energy Efficiency and Renewable Energy 

 Office of Building Technologies 

Authoring Country: USA 

This report describes the modeling methodology and results for Round 3 of testing done for the IEA 

BESTEST Multi-Zone Conduction Cases: MZ320 – MZ360 which were simulated using the EnergyPlus 

software. The specifications for the test suite are described in Proposed IEA BESTEST Multi-Zone NonAirflow In-Depth Cases: MZ320 – MZ360, IEA: SHC Task 34 / ECBCS Annex 43, August 2006 (referred 

to as the BESTEST Multi-Zone specification in this report). 

2. EnergyPlus Shading Module 

When assessing heat gains in buildings due to solar radiation, it is necessary to know how much of each 

part of the building is shaded and how much is in direct sunlight. The sunlit area of each surface changes 

as the position of the sun changes during the day. The purpose of the EnergyPlus shadow algorithm is to 

compute such sunlit areas. Predecessors to the EnergyPlus shadowing concepts include the BLAST and 

TARP shadowing algorithms. The EnergyPlus shadow algorithm is based on coordinate transformation 

methods similar to Groth and Lokmanhekim and the shadow overlap method of Walton. 

Shading surfaces are entities outside of the building that may cast shadows on the building’s heat transfer 

surfaces. These entities do not typically have enough thermal mass to be described as part of the 

building’s thermal makeup. 

The most important effect of shading surfaces is to reduce solar gain in windows that are shadowed. 

(However, in some cases, shading surfaces can reflect solar onto a wall or window and increase solar 

gain.) 

There are two kinds of shading surfaces in EnergyPlus: detached and attached. A detached shading 

surface, such as a tree or neighboring building, is not connected to the building. An attached shading 

surface is typically an overhang or fin that is attached to a particular base surface of the building, usually 

a wall; attached shading surfaces are usually designed to shade specific windows. 

111
EnergyPlus creates “bi-directional” shades from each shading surface entered. This means that the shade 

you input will cast a shadow no matter which side of the shade the sun is on. For example, a vertical fin 

will cast a shadow whether the sun is on the left side or right side of the fin. 

It is important to note that EnergyPlus will automatically account for “self-shading” effects — such as in 

L-shaped buildings — in which some of the building’s wall and roof surfaces shade other parts of the 

building, especially windows. This means that you need to describe only shading elements that aren’t 

building heat-transfer surfaces. 

Shading surfaces can also reflect solar radiation onto the building. This feature is simulated if you 

choose FullExteriorWithReflections or FullInteriorAndExteriorWithReflections in the Building input 

object (ref: Building - Field: Solar Distribution). In this case, you specify the reflectance properties of a 

shading surface with the Shading Surface Reflectance input object. 

Shading surfaces also automatically shade diffuse solar radiation (and long-wave radiation) from the sky. 

 And they will automatically shade diffuse solar radiation from the ground if Solar Distribution Field = 

FullExteriorWithReflections or FullInteriorAndExteriorWithReflections in the Building input object. 

Otherwise, shading surfaces will not shade diffuse radiation from the ground unless you enter a reduced 

value for View Factor to Ground for those building surfaces that are shaded (ref: Surface:HeatTransfer - 

Field: View Factor to Ground and Surface:HeatTransfer:Sub - Field: View Factor to Ground). 

3. Initial Distribution of Diffuse Solar Transmitted through Exterior and Interior Windows 

EnergyPlus calculates the distribution of short-wave radiation in the interior of each thermal zone. This 

radiation consists of beam solar radiation, diffuse solar radiation, and short-wave radiation from electric 

lights. The program determines the amount of this radiation that is (1) absorbed on the inside face of 

opaque surfaces, (2) absorbed in the glass and shading device layers of the zone’s exterior and interior 

windows, (3) transmitted through the zone’s interior windows to adjacent zones, and (4) transmitted back 

out of the exterior windows. 

The algorithm for the distribution of diffuse solar has been improved in EnergyPlus Version 2.1. 

Previously, all diffuse solar entering the zone was distributed over all surfaces in the zone using a 

weighted distribution based on area and solar absorptance for opaque surfaces or reflectance for windows. 

 For shallow zones with large windows, such as Case MZ360, this method caused a significant portion of 

the diffuse solar to incorrectly leave the zone through the windows. The new algorithm, described below 

(excerpted from EnergyPlus Engineering Reference, version 2.1.0, p.103), has corrected this problem. 

“As of Version 2.1 the treatment of diffuse solar transmitted first through exterior windows and 

subsequently through interior windows has been improved. Diffuse solar (from sky and ground sources) 

transmitted through exterior windows is first distributed to the interior heat transfer surfaces in the zone 

containing the exterior windows. This initial distribution apportions the transmitted diffuse solar to 

interior surfaces using the approximate view factors described above in ‘LW Radiation Exchange Among 

Zone Surfaces.’ The amount of this initially distributed diffuse solar absorbed by each interior surface, 

and each window material layer, is calculated and later added to the ‘short-wave radiation absorbed’ 

values described below. The amount of this initially distributed diffuse solar that is reflected is 

accumulated for each zone and redistributed uniformly as part of the QD calculation described below. 

The amount of this initially distributed diffuse solar that is transmitted by interior windows to adjacent 

zones is initially distributed to the interior heat transfer surfaces in the adjacent zone in the same manner 

as just described. This new treatment of diffuse solar is intended to more accurately account for the initial 

112

absorption, transmittance, and reflection of short-wave radiation prior to the uniform distribution.” 
4. Diffuse Sky Model 

In EnergyPlus the calculation of diffuse solar radiation from the sky incident on an exterior surface takes 

into account the anisotropic radiance distribution of the sky. For this distribution, the diffuse sky 

irradiance on a surface is given by 

 AnisoSkyMult(SurfNum) * DifSolarRad 

 where DifSolarRad is the diffuse solar irradiance from the sky on the ground and 

 SurfNum is the number of the surface. 

 AnisoSkyMult is determined by surface orientation and sky radiance distribution, and 

 accounts for the effects of shading of sky diffuse radiation by shadowing surfaces such 

 as overhangs. It does not account for reflection of sky diffuse radiation from shadowing 

 surfaces. 

The sky radiance distribution is based on an empirical model based on radiance measurements of real 

skies, as described in Perez et al. 1990. In this model the radiance of the sky is determined by three 

distributions that are superimposed 

• An isotropic distribution that covers the entire sky dome 

• A circumsolar brightening centered at the position of the sun 

• A horizon brightening. 

The proportions of these distributions depend on the sky condition, which is characterized by two 

quantities, clearness factor and brightness factor, defined below, which are determined from sun position 

and solar quantities from the weather file. 

The circumsolar brightening is assumed to be concentrated at a point source at the center of the sun 

although this region actually begins at the periphery of the solar disk and falls off in intensity with 

increasing angular distance from the periphery. 

The horizon brightening is assumed to be a linear source at the horizon and to be independent of azimuth. 

 In actuality, for clear skies, the horizon brightening is highest at the horizon and decreases in intensity 

away from the horizon. For overcast skies the horizon brightening has a negative value since for such 

skies the sky radiance increases rather than decreases away from the horizon. 

For further details regarding the EnergyPlus diffuse sky model refer to the EnergyPlus Engineering 

Reference Manual and the section titled Sky and Solar/Shading Calculations. 

5. Modeling Assumptions 

The following comments are provided in regards to user inputs that were used with EnergyPlus to model 

each of the cases described in the BESTEST multi-zone specification. Except where discussed below, all 

other requirements of the specification were met. 

113
Case MZ320 

a) The exterior and interior surface solar absorptance could not be set to 0.0. EnergyPlus requires 

that this input have a value > 0.0. Accordingly, the solar absorptance was set to 0.000001 for 

both the exterior and interior surfaces. 

b) The exterior surface roughness was not specified and was set to VerySmooth. 

c) Number of timesteps per hour was set to 4. 

d) Building outdoor terrain was set to FlatOpenCountry. 

Case MZ340 

a) To simulate external walls which were adiabatic and massless and because the exterior and 

interior absorptance of the exterior wall surfaces were different, the exterior wall had to be 

described as two layers of fiberglass insulation each with a thermal resistance of 500000 m2

K/W 

as follows: 

MATERIAL:Regular-R, 

 Wall-ExteriorLayer, !- Name 

 VerySmooth, !- Roughness 

 500000.00, !- Thermal Resistance {m2-K/W} 

 0.000001, !- Absorptance:Thermal 

 0.000001, !- Absorptance:Solar 

 0.000001; !- Absorptance:VisibleMATERIAL:Regular-R, 

MATERIAL:Regular-R, 

 Wall-InteriorLayer, !- Name 

 VerySmooth, !- Roughness 

 500000.00, !- Thermal Resistance {m2-K/W} 

 0.000001, !- Absorptance:Thermal 

 1.000000, !- Absorptance:Solar 

 1.000000; !- Absorptance:Visible 

CONSTRUCTION, 

 ExtWall, !- Name 

 Wall-ExteriorLayer, !- Outside Layer 

 Wall-InteriorLayer; !- Layer #2 

b) The common wall separating zones was defined as follows: 

CONSTRUCTION, 

 ComWall, !- Name 

 Wall-InteriorLayer, !- Outside Layer 

 Wall-InteriorLayer; 

114
c) All opaque exterior surfaces except for the west walls, which contained windows and all common 

walls, were made to see themselves so that they would be truly adiabatic and did not see external 

weather conditions. 

d) The west walls, which contained windows had to see external weather conditions including the 

sun and so had to be treated differently. For this case the ExtWall CONSTRUCTION of double 

layer insulation described above was used to simulate adiabatic conditions. 

e) The ideal windows were simulated as described by input objects below. Transmittance values 

had to < 1.0 and reflectance, IR emittance and conductivity values had to be > 0.0. 

MATERIAL:WINDOWGLASS, 

IDEAL GLASS, !- Name 

SpectralAverage, !- Optical Data Type 

, !- Name of Window Glass Spectral Data Set 

0.003175, !- Thickness {m} 

0.99999999, !- Solar Transmittance at Normal Incidence 

0.000000001, !- Solar Reflectance at Normal Incidence: Front Side 

0.000000001, !- Solar Reflectance at Normal Incidence: Back Side 

0.99999999, !- Visible Transmittance at Normal Incidence 

0.000000001, !- Visible Reflectance at Normal Incidence: Front Side 

0.000000001, !- Visible Reflectance at Normal Incidence: Back Side 

0.0, !- IR Transmittance at Normal Incidence 

0.000000001, !- IR Hemispherical Emissivity: Front Side 

0.000000001, !- IR Hemispherical Emissivity: Back Side 

0.000000001; !- Conductivity {W/m-K} 

CONSTRUCTION, 

 IDEAL WINDOW, !- Name 

 IDEAL GLASS; !- Outside LayerCONSTRUCTION, 

Case 350 

a) Case 350a with the shading device associated with the Zone C window could not be simulated 

with EnergyPlus. Windows in EnergyPlus are considered sub-surfaces of exterior heat transfer 

surfaces and therefore any shading devices must be defined as being associated with the exterior 

heat transfer surface. 

b) Case 350b was simulated using the Surface:Shading:Attached object where the shading surface 

was associated with the Zone C exterior wall. Although attached to the Zone C window it can 

cast shadows on other surfaces of the building. 

c) Case 350c was simulated using the Surface:Shading:Detached:Fixed object where the shading 

surface is exterior to and separated from the building. If the building is rotated this shading 

surface will remain stationary. 

d) Case 350d was simulated using the Surface:Shading:Detached:Building object where the shading 

surface is exterior to and separated from the building but if the building is rotated the shading 

surface rotates with it. 

115
Case 355 

a) No exceptions taken with the specification 

Case 360 

a) No exceptions taken with the specification 

6. Modeling Options 

Variations modeling options as far as simulating adiabatic surfaces, simulating exterior surfaces that have 

different radiation properties for the external and internal surfaces, and simulating shading surfaces were 

discussed in the Section 2. 

7. Modeling Difficulties 

EnergyPlus was not able to fully simulate windows with ideal properties as discussed above in Section 2. 

Evidence of this was seen in Cases MZ340, MZ350, MZ355, and MZ 360 where the hourly transmittance 

of the glass ranged from 0.989 to 1.007. 

8. Results 

Results for each test tested are presented in an Excel spreadsheet provided with the BESTEST multi-zone 

test suite. The EnergyPlus results have been provided in a spreadsheet named EnergyPlus-Round3-MZOutput092607-2.1.0.012Unlinked.xls. 

For cases MZ340, MZ350, MZ355, and MZ360 where all exterior walls and common walls are massless, 

although each of the simulations were successful and produced results, EnergyPlus gave the following 

“severe warning”: 

** Severe ** This building has no thermal mass which can cause an unstable solution. 

** ~~~ ** Use MATERIAL:REGULAR for all opaque material types except very light 

 insulation layers. 

This severe error message is normal when the building is entirely made up of R-layers. In some cases that 

can result in an unstable solution, but it is not a problem for these test cases. 

For Case MZ360 with internal windows between zones, EnergyPlus is calculating diffuse solar in both 

directions through internal windows. For example, on March 15 at 12:00, EnergyPlus shows results as 

follows: 

 Zone A: Zone Transmitted Solar (W) 28190.74 

 Zone A: Zone Beam Solar from Exterior Windows (W) 22198.48 

 Zone A: Zone Beam Solar from Interior Windows (W) 0 

 Zone A: Zone Diff Solar from Exterior Windows (W) 5992.25 

 Zone A: Zone Diff Solar from Interior Windows (W) 2553.10 

 Zone B: Zone Transmitted Solar (W) 0 

 Zone B: Zone Beam Solar from Exterior Windows (W) 0 

 Zone B: Zone Beam Solar from Interior Windows (W) 7935.66 

116
117

 Zone B: Zone Diff Solar from Exterior Windows (W) 0 

 Zone B: Zone Diff Solar from Interior Windows (W) 103.31 

 Zone C: Zone Transmitted Solar (W) 0 

 Zone C: Zone Beam Solar from Exterior Windows (W) 0 

 Zone C: Zone Beam Solar from Interior Windows (W) 0 

 Zone C: Zone Diff Solar from Exterior Windows (W) 0 

 Zone C: Zone Diff Solar from Interior Windows (W) 677.09 

Some of the solar gain which enters Zone B returns to Zone A through the interior window between 

Zones A and B. This is reported as “ Zone A: Zone Diff Solar from Interior Windows.” For Zone A, it is 

clear what has entered through the exterior window and what has come back through the interior window. 

For Zone B, solar will enter through the AB interior window, some will leave through the BC interior 

window, and some will return through the BC interior window. It is not clear what components are 

summed for the “Zone B: Zone Diff Solar from Interior Windows.” The Zone Transmitted Solar numbers 

are the ones that were recorded in the results spreadsheet and appear to be the NET amount not the 

GROSS as required by the specification. THERE CURRENTLY ARE NO ENERGYPLUS OUTPUT 

REPORT VARIABLES THAT ALLOW US TO REPORT WHAT IS REQUIRED. A LATER 

VERSION OF ENERGYPLUS WILL HAVE THIS CAPABILITY. 

Prior to EnergyPlus 2.1.0.012 the diffuse radiation entering an exterior window (Window AO) was 

evenly distributed to all surfaces within the zone, even the inside of the exterior window. 

The methodology for handling solar diffuse through a window was completely reworked in EnergyPlus 

2.1.0.012 and was changed uniform interior distribution of transmitted diffuse solar to distribution based 

on approximate view factors between transmitting windows and zone heat transfer surfaces. This 

improved EnergyPlus results compared to the results of other programs participating in this IEA 

BESTEST Multi-Zone Non-Airflow test suite. 
118
Appendix II-B 

Modeler Report for BESTEST Cases MZ320 – MZ360 

ESP-r Version 11.5 

by 

Paul Strachan 

Energy Systems Research Unit, University of Strathclyde 

United Kindom 

 

March 2008

1. Introduction 

 ESP-r, Version 11.5 of March/April 2008 with some modifications for shading as described below 

 Open Source software. Authors are Energy Systems Research Unit, University of Strathclyde, 

Scotland, UK 

 Finite volume, with user-selectable timesteps. 

2. Modelling Algorithms and Assumptions 

ESP-r uses the Perez 1990 anisotropic diffuse sky model for calculating diffuse radiation. Direct and diffuse 

transmission, glazing absorption and internal zone distribution are calculated separately. In the models 

mz340 and mz350c this is not important as the windows have 100% transmittance and all radiation is 

absorbed in the zone, with none re-transmitted out of the window. For model mz360, ray tracing is used to 

allocate the direct solar transmittance to the appropriate internal surface for both zones. Diffuse radiation 

passing through the window is allocated to surfaces not in the same plane as the window based on surface 

area and absorptivity. After the first bounce, direct radiation is treated as diffuse and added to the reflected 

diffuse radiation. This is iteratively spread to all internal zone surfaces based on the area and absorptivity (in 

the case of opaque surfaces) or the absorptances and transmittances (in the case of transparent constructions) 

until all radiation is accounted for. 

As mentioned in section 4, shading for the mz350c test is calculated using the daylight coefficient method 

and the link to Radiance. Daylight coefficients are pre-calculated for each sensor point - each window was 

set up with 80 sensor points. 

During simulation, the irradiance is calculated for each sensor point and averaged for the window, with 

direct and diffuse radiation held separately. Simulations were carried out at 15 minute timesteps. 

3. Modelling Options 

4. Modelling Difficulties and Enhancements 

Solar data provided were half-hour centred, whereas ESP-r has traditionally used hour-centred data. Code 

modifications were made to allow a flag to be set to indicate that the solar data are either hour or half-hour 

centred. This code change was incorporated in the versions of ESP-r starting at 11.2, allowing users the 

option (although it should be noted climate data sets vary in their time intervals). 

119
The windows cannot be modelled as adiabatic because this would not allow radiation through in ESP-r's 

definition of adiabatic. Therefore windows are given low conductivity (0.0001) and low surface heat transfer 

coefficients (0.001). All optical properties are included as specified. 

The relative humidity cannot be set to 0% because this causes errors in ESP-r’s external longwave algorithm 

for sky radiation. It was set to 50%. This should not matter in the tests MZ320 – MZ360 because external 

surface emissivity is set to (close to) zero and humidity does not influence the other processes considered. 

 

For the mz350c tests, use was made of an enhancement to ESP-r based on the daylight coefficient method, 

with work by Christoph Reinhart and Denis Bourgeois of NRC in Canada. In this [method], the ESP-r export 

to Radiance is used, Radiance is used to generate the coefficients for a discrete sky patches (145 in the 

current implementation for diffuse radiation and 2035 for direct radiation) for direct and diffuse radiation as 

a pre-computation, and then at each simulation timestep the appropriate radiation is calculated in ESP-r for 

direct and diffuse radiation. The facility was originally developed for lighting control purposes but has been 

extended from calculating illuminance data to also calculate irradiance data. It can be extended for complex 

shading systems and for complex internal radiation distributions. The current version is a beta version and it 

is likely that further tests and refinements will take place in the next few months. Nevertheless, the results to 

date are considered reasonable. Because most of the results of interest are a comparison of the unshaded case 

(mz340) with the unshaded case (mz350), the daylight coefficient method was used for both models. This 

results in a small decrease (less than 2%) in the annual solar loads in the rooms for the unshaded case 

compared to ESP-r's usual calculation. The reason for this will be investigated, but the effect on differences 

between the mz340 and mz350 cases should be negligible. 

5. Software Errors Discovered and Comparison between Different Versions of the Same 

Software 

As noted in the last section, a software modification was made to allow half-hour centred solar data. In these 

tests, where there are large west-facing windows, the difference is significant (in the order of 12% increase 

in cooling load if it is assumed that the data are hour-centred instead of half-hour centred). The differences 

are much smaller in the case of south-facing windows. 

Results differ for test MZ360 compared to the previous submission in the internal distribution of direct solar 

radiation. The total solar entering the building is unchanged, but there are some, mostly small, changes to the 

insolation distribution, which has the effect of changing the amount of direct radiation passing from Zone A 

to Zone B and from there to Zone C. 

6. Results 

Attached as MZ-Output310308_esp-r.xls 

 

7. Other (optional) 

8. Conclusions and Recommendations 

Adding shading blocks with different reflectances could be used to extend the series of tests. 

120
9. References 

 

The daylight coefficient method is documented in Bourgeois D, Reinhart C F and Ward G, “Standard 

Daylight Coefficient Model for Dynamic Daylighting Simulations”, Building Research and Information, 

36(1), January 2008, pp68-82. 

121
Appendix II-C

Modeler Report for BESTEST Cases MZ320 – MZ360 

HTB2 Version 2.20AD 

by 

Don Alexander 

Welsh School of Architecture, Cardiff University 

United Kindom 

 

March 2008 

1. Introduction

 HTB2 is a research based thermal modelling code. 

 Current version: 2.20AD. 

 Authors: Welsh School of Architecture, Cardiff University, Cardiff UK. 

• Explicit finite-difference fabric model is used for all fabric transfer, including internal partitions 

and glazing. 

• Inter-zone air transfer can be specified or calculated, or treated as an interzone conductance. 

• Surface shading calculated using a preprocessor (hshade 2.0). Shading effect specified to HTB2 

as a “Sky Mask” (further described below) in 10 degree sectors, rather than as geometric 

structures. Hshade 2.0 considers finite fins and overhangs. 

• Diffuse solar gain is determined through isotropic sky model. 

• Calculation timestep variable; typically in range 10-180 seconds. For these cases, a 90 second 

timestep was used, with integrated hourly data output. 

 

2. Modeling Assumptions

The specification of massless fabric is not feasible in this code. External fabric material required 

specification of thermal capacity as 1 J/m3

K for stability at timestep used. There were no changes in result 

values if capacity specified as 0.1 or 10.0. 

As external surfaces were to be modeled, adiabatic walls were specified using a very low conductance 

material. 

Radiant calculation modules disabled for MZ320 test, with surface transfer specified using combined 

coefficients. Radiant calculation modules were required for other tests, in order to calculate solar gains. 

Combined surface transfer coefficients again used, but surface emissivity set to 0 to disable longwave 

calculations. 

MZ320 test disabled meteorological input, setting fixed external conditions. Other tests utilized TM2 data 

reformatted to HTB2 format. 

MZ360 modelling of internal glazing requires precalculated transfer ratio (amount of direct solar passing 

through external window that falls on internal window). This was calculated from relative area ratios of 

internal glass and its surround. Other surface areas were assumed not to receive direct solar. 

122
Transmission, reflection and absorption of internal window are calculated for an incidence angle based on 

the solar ray and the orientation of the internal window. Diffuse radiation through external window is 

sent to all surfaces in zone (area weighted); including the internal window, which allows it to be 

transmitted, reflected and absorbed. Solar reflected off the internal window becomes diffuse solar in the 

source zone. A second pass is used to estimate the diffuse transmission back through the internal window 

to the source zone (n.b. all beam radiation not absorbed (or transmitted by surfaces becomes diffuse). 

Solar lost from the first window is a separate, fixed ratio. It is not calculated from the geometry. In this 

case, Solar lost for the external window was left at the default value, 0. 

For modeling shading, the sky mask model describes the view factor from a sector of the sky to a surface 

area; if a shading device obstructs the surface from the sector then no radiation from that sector reaches 

the surface. For direct solar, the sector the sun is in is determined at the recalculation time, and this factor 

is applied to the beam radiation. Diffuse shading is determined by integrating the mask with the sky 

brightness. Shading is determined for the whole surface (e.g. not subdivided) during the precalculation phase 

(hshade 2.0); shading effect for a surface is fraction 0-1 of unshaded incident direct and diffuse; ground 

reflection is not shaded. 

Solar geometry and shading effect are calculated on a meteorological interval (e.g. 60 minute default), when 

shading is changed (schedule), and on an inner 10 minute (default) loop. 

3. Modeling Options

No options specific to multi-zone modeling apply. 

4. Modeling Difficulties

 MZ320 - no problems 

 MZ340 - no problems, though specification of fixed external heat transfer coefficient revealed bug, 

 described below. 

Beam transmission not available in output. Values quoted are determined from TotalDiffuse. 

MZ350 - method to determine shading effect seems to best match option d – “other”; in HTB2 

cumulative shading effect of external objects (whether fins, overhangs, trees or self shading) 

are specified for each element (e.g. window) as a sky mask. Results submitted under 

MZ350d only. 

MZ355 - As shading of neighboring zones is not an automatic calculation, no results are submitted 

for MZ355. 

MZ360 - Current version allows for two windows in series. Not capable of three windows in series. 

Therefore the two zone alternative modeling spec used for this case. 

Cannot break transmission down to beam and diffuse. Gross diffuse transmission is not held in output data, 

only net diffuse transmission is available (from zone data, not per window). Per window data saved is total 

transmission (beam and diffuse combined). Therefore diffuse transmission to Zone B was available, but 

beam transmission to Zone B was calculated from Total transmission to zone B less Diffuse component. 

Zone A net transmission calculated similarly. Zone A Gross transmission calculated from Zone A net + Zone 

B net. 

123
5. Software Errors Discovered and Comparison between Different Versions of the Same 

Software

Three faults in code identified: 

• Initial specification of fixed external combined coefficients, for case MZ320 initially, led to 

disagreement with hand-calculated results. The difference was traced to the default external 

coefficient algorithm still being used; the override values specified were being ignored. 

Initialization code was altered to allow the proper detection and use of external coefficient override 

values. This fault applied only to external coefficients; override values for internal coefficients 

were detected and used properly in original code. This fault has been fixed in the latest version. 

• The case MZ340 required the use of zero emissivity for all surfaces in a zone, the original code 

failed when the total emissivity of a zone was zero. This was traced to an undetected divide- byzero. The code was altered to allow zero emissivity zones. (This was not detected in earlier cases as 

radiant calculations were turned off in order to treat the required combined coefficients; however, 

this would also disable solar calculations needed in the later cases.) 

• Case MZ355 was originally defined incrementally from Case MZ350, using a feature to “Skip” 

unwanted elements (e.g. the windows for Zones C and F). This “Skip” feature was originally 

intended as a convenience feature, in order to allow incremental testing or changes to fabric to be 

undertaken without affecting index codes. When “Skipped”, an element is removed from fabric 

calculations. Used in this case, solar gains were still found in zones C and F. It was determined that 

the skip logic had not been applied to solar calculations for transparent elements. In order to 

complete the case, the Case MZ355 files were re-edited to explicitly remove the unwanted window 

elements. This has fault has been flagged for correction in a future version. 

Also, in the hourly output of solar gain and cooling for Case MZ340 it is noted that there is a slight 

difference between the two for each hour. This is not a fault in the internal energy balance (the balance is 

adequate over a longer period (e.g. 1 day), but rather a “feature” of the reporting accounting. At the end of 

an accounting period, there remains, at the time of the report, uncertainty of one timestep (e.g. at the time of 

the report energy from some sources is left over for the next timestep loop, but from others it has already 

been applied). Therefore in this instance the cooling load is one timestep (e.g. 90 seconds) delayed 

compared to the solar gains. Within the overall structure of the model, this effect would be difficult to 

remove; it is not considered to be a “bug”, but the cause of the effect will be considered more carefully in 

future revisions. 

While this effect has been investigated further, a solution is not yet forthcoming. This effect is also evident 

in the MZ360 results; in both it may be mistaken as representing thermal mass; however, it is an accounting 

problem in the reporting procedure. Internally, verified by debugging inspection, there is a much closer 

energy balance between incoming solar and cooling. The effect reduces significantly if shorter timesteps for 

calculation or reporting are used. There is a slight residual thermal mass effect, on the order of 10W during 

peak changes of solar incoming. 

Recent detailed inspection of the dataflow in the model has lead to the conclusion that the solar data, as 

generated by the Meteorological and Solar transmission modules, and the surface insolation data, as used by 

the Fabric module, were one timestep out of phase when the fabric calculations were made. As of version 

2.20AB, the ordering of the calculation modules has been altered; no changes were made to algorithms, 

parameters or data. This appears to have solved the problem described above; the solar gains and cooling 

124
loads of a zone are now essentially identical in the MZ340 and MZ360 tests. The change has made little 

difference to other MZ results apart from those for peak cooling. 

During inspection of the shading preprocessor output prior to running latest revisions, anomalous behaviour 

(e.g. discontinuous “jumps” in the angular data) in the shading factors for high altitude angles was noticed 

visually in the data text. This was traced to faulty logic in determining the shadow overlap cases in the 

Hshade preprocessor which wrongly excluded a valid case triggered at acute vertical angles. This was 

corrected and better (more smoothly varying factors) were produced; this version has been used in these 

results. Although this error was present in the previous round of results, the larger fin size exacerbated the 

problem and made it more noticeable. Differences in results were generally small (< 2% of cooling energy) 

but notable in some of the hourly solar data. Results obtained for case MZ350 with the buggy shading code 

is in file “HTB2_badshading_MZ-Output082205.xls” for interest. 

 Investigation into the “late afternoon” lump observed in the HTB2 shaded results for the original case 350 

indicated that the time and spatial interpolation used for shading were too coarse for the test. Current 

version changed to increase shading recalculation interval and new interpolation algorithm used to 

estimate arbitrary shading values from user fixed data (set at 10 degree steps). 

 Investigation of the initial MZ360 case comparisons lead to discovery of issue in code dealing with 

internal windows; cosine of incidence angle was effectively accounted for twice in the calculation of 

transmission through the internal glazing case, the result appeared as a reflection back into zone A. This 

problem removed and case rerun (Code version 2.20AD) with no changes to input parameters; results 

appear more consistent with other models. (NB Greater agreement could be achieved through 

manipulation of the input factors (transfer rations discussed in section 2), but as this could not have been 

done blind, the original estimates were kept for this submission.) 

For the final results for MZ360, the hourly results for Oct 14 (dominated by diffuse solar) indicate that 

the cooling load for Zone B using the alternative spec for HTB2 (comparable to Zones B + C for the other 

programs) is less than the Zone-B-only results for the other programs. This difference is attributable to the 

relatively simplified method of modeling internal windows using assigned user-input transfer ratios based 

on the geometry of the case; e.g. relative areas of window and wall surfaces. Additionally, this 

disagreement is only seen for diffuse solar; the direct-solar dominated day has better agreement. To 

improve the result it is possible to “tune” the input parameters. The results were not changed as they may 

represent what a user may be more likely to obtain without the benefit of comparison with other models. 

For the final results for the MZ340-MZ350 hourly shading sensitivity for March 15 (dominated by direct 

normal solar), a disagreement occurs for hour 17. The suspected source of the difference may be a 

limitation of the sky mask model. The problem is likely that the sectoring is too coarse for this sensitive 

problem. Currently the descriptions are given in steps of 10 degrees (a fairly arbitrary decision made at 

least 20 years ago); the solar position is updated every 15 minutes. Some interpolation is done using 

neighbouring sectors, but if the shadow is sharp edged, the result would be fuzzy. At hour 17, the sun 

may be just passing the shade, so the coarseness of the mask may introduce an error. It is possible to 

increase the mask resolution (to 5 and 2 degrees), to see if that improves the result, and this issue has been 

flagged to check for a future update. 

6. Results

n/a 

125
7. Other (optional) 

Noted a potential for conflict in specification data in case MZ340 onwards: external dimensions for walls are 

specified, with allowance for walls of 0.1m thick, but specified zone volumes appear to be calculated using 

those external dimensions. If e.g. 0.1m walls are specified, then zone volume would be 189.93 m3. This 

would make no difference in these cases, but in potential future cases with free-floating temperatures or 

ventilation flows, this would introduce an area for disagreement. 

 

8. Conclusions and Recommendations

A resolution for the accounting problem in the output will be sought, and has been provisionally solved in 

this latest revision, as described in section 5 above. 

9. References

 

 

126
127

Appendix II-D 

Modeler Report for BESTEST Cases MZ320 – MZ360 

TRNSYS-TUD 

by 

Clemens Felsmann 

Dresden University of Technology 

Germany 

 

April 2008 

1. Introduction

All calculations have been performed with the program TRNSYS-TUD. This program is originally based 

on TRNSYS 14.2 (distributed by TRANSSOLAR, Germany) but a lot of major revisions and additions 

were made at TUD, especially in the multi-zone model. 

The multi-zone heat transfer through walls is always calculated with the transfer factor method (TFM). 

The simulation time step in the multi zone test cases was 0.05h. 

2. Modeling Assumptions

The solar modeling was originally done with the Reindl model [1], [2] because it is more accurate than 

the rather simple isotropic sky model. The Reindl model accounts for isotropic diffuse, circumsolar 

radiation and for horizontal brightening to estimate sky diffuse radiation. But in addition to that the 

isotropic sky model had to be used to guarantee consistency between building models with (MZ350) and 

without (MZ340) a shading device. So the Reindl model is available but isotropic model was used for the 

final results reported for MZ340, MZ350, and MZ360. See Chapters 4 and 5 for more detailed 

information about this issue. In both cases – isotropic and Reindl model - the input data for the solar 

processor are total horizontal and direct normal radiation taken from the TMY weather file. 

The fin shading in case MZ350 was modelled with six identical side fins associating each fin with one of 

the windows. This approach is necessary because the geometrical relation between a window and the 

given side fin is different for each window. It is not possible to associate a single fin to several windows. 

The fin shading definitions of case MZ350 can be used also to model the shading by another building 

zone as defined in MZ 355 when at the same time incident radiation for completely blinded surfaces 

(walls and windows) is fixed to zero. 

 

3. Modeling Options

The heat transfer through walls between zones is calculated with an identical mathematical approach than 

for all other walls in the model (TFM). 

Furthermore the simulation model asks the user for two basic options: 

a.) The transfer factor method also accounts for the thermal history of the wall. The program 

asks for a so called time base that indicates a discrete time interval for updating thermal 
128

history of the wall. Normally TRNSYS works with a time base of 1hr. But for these multizone tests the time base is 0.1hr for the exterior walls and 0.05 hr for the internal walls. 

b.) The user has to make a decision between two different approaches to calculate longwave 

radiation exchange: a normally used but simplified calculation method (star network by 

SEEM) or a more accurate one (view factors). For these multi-zone tests the more accurate 

approach has been used. 

4. Modeling Difficulties

No problems were encountered with representing any of the specifications in the TRNSYS-TUD model, nor 

problems with interpreting the User's Manual. All inputs required for the model were described in the input 

specification. 

The only problem has occurred when the Reindl model for calculating the solar radiation and a fin shading 

device should be used together in the same model. The conflict is caused by the assumption that both diffuse 

and ground reflected radiation on a shaded window area are isotropic whereas walls and windows without a 

shading device are correlated to the diffuse radiation calculated with the Reindl model. Thus the comparison 

of building energy loads of shaded (MZ350) and not shaded (MZ340) buildings will lead to some additional 

differences caused by different diffuses radiation models. The only solution to solve this modeling problem 

was to always use the isotropic sky model when predicting the solar radiation. 

5. Software Errors Discovered and/or Comparison between Different Versions of the Same 

Software

There are three kinds of errors and curiosities that were discovered: 

1. Although it was assumed that interior walls do not reflect any solar radiation (solar absorptance = 1) 

and ideal windows do neither reflect nor absorb any solar radiation (solar transmittance = 1) the 

zone cooling load was not equal to the net transmitted solar radiation. The reason for this error was 

that in the program transmitted solar radiation was originally distributed to the interior surfaces 

(walls and windows) accordingly to solar distribution factors that were calculated as follows: 

 

 ∑ − ρ

α =

surfaces

d s s

s s

sol s A

A f (1 ) ,

, (1). 

The solar energy absorbed at interior surfaces was then calculated as 

 abs s tot sol s q I f , = , & (2). 

Within a zone, i.e. after passing the window, solar radiation was treated to be diffuse. As seen from 

equation (1) a certain amount of transmitted solar radiation is not taken into account for energy 

balances and goes lost this way. To avoid this problem the calculation procedure for solar 

distribution was revised. In the current program version only solar radiation that was reflected at 

interior surfaces (walls and windows) will be distributed based on above mentioned factors. 

2. TRNSYS-TUD offers the opportunity to use ray tracing for direct solar radiation that enters the 

room through an external window. Only multi-zone test case MZ360 was calculated with this 

program feature. The computation revealed a loop-error in the calculation routine that only occurred 

if there are at least two zones in a building. This error was already fixed. 
129

The comparison between a solar distribution model that assumes any solar radiation entered the 

room to be diffuse and a ray tracing model for the direct part of solar radation on the basis of 

MZ360 shows big differences in solar transmission through internal windows, annual cooling loads 

and in dynamic load profiles. In Figure 2D-1 the annual transmitted solar radiation of each zone as 

calculated from the models with and without ray tracing are compared. While transmittance into 

zone A must be the same in both approaches transmittance through internal window into zone B is 

much higher if the ray tracing model is used. This consequently also has an impact on annual 

cooling load. By looking at Figure 2D-2 it can be seen that annual cooling load is lower in zone A 

and higher in Zone B if when using the ray tracing method the annual transmitted solar radiation 

into zone B is higher, too. The total annual cooling load of the building is not affected at all. Figures 

2D-3 and 2D-4 are useful to check load profiles. Figure 2D-4 also depicts that there is an impact of 

solar distribution models only if a direct part of solar radiation occurs. 

3. The calculation of solar shading effects of a fin is done with TRNSYS-Type 34 “Overhang and 

Wingwall Shading.” The solar radiation incident on the shaded windows consists of beam, diffuse 

and ground reflected components, which depend on view factors. The sky and ground radiation 

view factors are calculated assuming radiation to be isotropic. For that reason only simulation results 

based on an isotropic sky model have been reported for all test cases to be consistent for shaded and 

un-shaded test cases. 

6. Results

In general results of TRNSYS-TUD simulations agree very well to results of other participants. But for 

MZ360 there are some differences to others, which could be caused by two facts: 

a.) The ray tracing method used to calculate solar paths from outside to the most inner zone C only 

works fine for external windows. See Figures 2D-1 through 2D-4 for more details of impact of ray 

tracing on cooling loads. 

b.) Solar radiation is assumed to be 100% diffuse when transmitted trough an internal window. 

7. Other (optional) 

 

8. Conclusions and Recommendations 

The multi-zone test cases are very useful to detect program and modeling errors that mainly occur within a 

multi zone building: 

− Addressing of solar heat gains 

− Multi-zone partly shading effects

− Heat transfer through inner walls 

− Internal windows. 

It is recommended to have a further look at 

− Distribution of solar radiation within the building (internal shadings, several windows vis-àvis,...etc) 

− Interzonal air change. 

 

9. References

[1] Reindl, D.T., Beckmann, W.A., Duffie, J.A., 1990. Diffuse fraction correlations. Solar Energy 

45:1-7 

[2] Reindl, D.T., Beckmann, W.A., Duffie, J.A., 1990. Evaluation of hourly tilted surface radiation 

models. 31 Solar Energy 45:9-17 
130

10. Figures

Figure 2D-2. MZ360, Comparison of annual cooling loads 

Figure 2D-1. MZ360, Comparison of annual transmitted solar radiation 
131

Figure 2D-3. MZ360, comparison of transmitted solar and cooling loads 

in Zone A on March 15

Figure 2D-4. MZ360, comparison of transmitted solar and cooling loads 

in Zone A on October 14
132

Appendix II-E 

Modeler Report for BESTEST Cases MZ320 – MZ360 

TRNSYS-16 

by 

Julien L’Hoest, Christophe Adam, Corinne Rogiest and Philippe André 

University of Liège 

Belgium 

 

April 2008 

1. Introduction 

This report presents the major results of the application of the IEA-BESTEST Multi-zone Non-Airflow 

cases MZ320 – MZ360 to the TRNSYS software. TRNSYS [1] (“Transient System Simulation”) is a 

transient system simulation program with a modular structure, with each component of the simulated 

system being defined as a “Type”. The modular nature of TRNSYS gives the program tremendous 

flexibility, and facilitates the addition to the program of mathematical models not included in the standard 

TRNSYS library. TRNSYS is well suited to detailed analyses of systems whose behavior is dependent on 

the passage of time. 

The TRNSYS version is TRNSYS 16.01.0002 developed by Solar Energy Laboratory (University of 

Wisconsin-Madison) in Madison, USA (February 2005). 

This validation exercise made use of the following TRNSYS types: 

Type 56: Multizone Building model 

Type 34: Overhang and wingwall shading 

Type 109: Data reader and weather processing. 

Additional types like equations and on-line plotters were used in the simulation. 

The building model used in this work is TYPE 56 developed by TRANSSOLAR Energietechnik GmbH 

in Stuttgart, GERMANY. The TYPE 56 version is the version which is included in the TRNSYS 

16.01.0002 version. TRNFLOW isn’t used. This version of TYPE 56 is opened. 

To model the window, the window library has been implemented with WINDOW 5.2 [2]. The exported 

file was corrected with the “Notepad” editor (in order to impose the specifications). 

The simulation time step is 1 hour. 

2. Modeling Assumptions 

The required inputs which are not described in the specifications are: the sky temperature (for TYPE 56) 

and the ground reflectance (for TYPE 109: Data Reader and Radiation Processor). 

It was specified there is no heat transfer by radiation. So the sky temperature is arbitrarily fixed to 0°C 

and the view factor to sky is fixed to 0, which eliminates any radiation. The ground reflectance is also 

fixed to 0. 
133

3. Modeling Options 

• TYPE 56 (version 16) can evaluate the convection heat transfer coefficients for vertical and 

horizontal surfaces. As it was specified to use constant combined surface coefficients to eliminate 

the disagreements that might be caused by different convective and/or radiative surface heat 

transfer models, these internal calculations have not been used. Instead, constant combined 

coefficients were used with the following values: 29.844 for inside conditions and/or 109.754 

kJ/h.m2.K for outside conditions. 

• TYPE 56 uses a Transfer Function approach[4] to calculate the dynamic behaviour of walls and 

doesn’t accept zero-conductance walls. The greatest accepted resistance value is 1999 h.m2.K/kJ 

(for the massless layer) which corresponds to 0.001801 W/m2.K. TRNBuild which is the new 

building editor (TRNSYS 16) does not accept decimal values. 

• In the MZ355-case the zone G was not simulated, because there is no window. In this case the 

walls are zero-conductance walls. So, we decided to simulate only the zones A to F. The same 

configuration like MZ350-case was used for zones A, B, D, E. The external walls of the zones C 

and F are limited to the real external boundaries with the ambient. That means the windows of the 

zones C and F were not simulated. The surface area of the western walls was limited to 4.05 m2 

(1.5 m × 2.7m). 

4. Modeling Difficulties 

• Simulation of ideal windows

We started from the “without glass” window which is supplied in the Trnsys window library. The 

optical properties of that window are the same as the ideal window. Then the thermal properties was 

directly changed into the text file generally generated by WINDOW 5.1. 

No use of WINDOW 5.1 was made, the text file containing the window properties can be found in 

the appendix [“annex” at the end of this modeler report]. 

• Sky model

Type 16 provides four models for estimating the total radiation on a tilted surface. Each model 

requires knowledge of total and diffuse (or beam) radiation on a horizontal surface as well as the 

sun's position. In general the total tilted surface radiation is calculated by estimating and adding 

beam, diffuse and reflected radiation components on the tilted surface. All tilted surface radiation 

models use the same techniques for projecting the beam and ground reflected radiation onto a tilted 

surface; they differ only in the calculation of diffuse radiation on a tilted surface. 

The contribution of diffuse radiation on a tilted surface is determined by using one of the four 

models provided in Type109 Tilted Surface Radiation Mode (equivalent to the models contained in 

the Type 16). 

o Tilted Surface Radiation Mode 1 uses the isotropic sky model. This model was used. 

o Tilted Surface Radiation Mode 2 uses a model developed by Hay and Davies. 

o Tilted Surface Radiation Mode 4 uses a version of the tilted surface model developed 

by Perez, et al. 

o The Tilted Surface Radiation Mode 3 is a model developed by Reindl based on the 

work of several previous authors. This model adds a horizon brightening diffuse term to 

the Hay and Davies model. The horizon brightening is lumped with the isotropic diffuse 

term and its magnitude is controlled by a modulating factor. 
134

• Shading model

This part of the specification was treated by Type 34 “Overhang and wingwall shading”. Solar 

radiation incident on a shaded receiver consists of beam, diffuse and ground reflected 

components. (Solar radiation reflected from the overhang or wingwalls onto the receiver is not 

considered in this model, and is suppressed in the multi-zone test specification.) 

= + − + ρ FIFIfII −GAgnddSAbTibTST )(

Total = Beam + Diffuse + Reflected 

The fraction of the receiver area irradiated by direct beam, , is a function of shading geometry i f

and the position of the sun relative to the receiver. The irradiated fraction is given by 

i f = Ai

An ASHRAE algorithm [5] that determines is used in TYPE 34 to compute . Ai i f

Sky and ground radiation view factors are calculated assuming diffuse and reflected radiation to 

be isotropic. For unshaded vertical surfaces, the receiver radiation view factors of the sky and 

ground are both equal to one half. These view factors are reduced when wingwalls or an 

overhang are present. The view factor between the receiver and the wingwall, FA-W is computed 

by integrating the differential receiver area radiation view factor of the wingwall over the receiver 

area. 

 

Figure 2E-1. shading geometry Figure 2E-2. Radiation geometry
135

The receiver radiation view factor of the wingwall is given by 

Where FdA-A1 and FdA-A2 are given by Siegel and Howell [3] as 

Type 34 uses numerical integration to compute the view factor at the first time step of the 

simulation.

The table below shows the amount of time (in hours) during which the glazing is partially or 

totally shaded over the year. The second column shows the ratio of the time during which the 

window is totally shaded on the time during which it’s irradiated by the sun (2258 hours). 

Table 2E-1. Percentage of shaded radiation on the different windows 

 Partially or totally shaded Totally shaded 

 Hours % Hours % 

Window A 1008 44.64 690 30.56 

Window B 1494 66.16 1105 48.94 

Window C 524 23.21 254 11.25 

Window D 939 41.59 571 25.29 

Window E 1453 64.35 1007 44.60 

Window F 524 23.21 239 10.58 

• Treatment of diffuse radiation

In TRNSYS, direct and diffuse radiation are not treated the same. Direct radiation distribution can 

be specified by the user whereas sky diffuse radiation cannot. 

The incoming (primary) direct solar radiation is distributed according to the distribution 

coefficients (Geosurf) defined in the building description. These values are distribution factors 

related to the total direct solar radiation entering the zone and not related to a surface area. The 

sum of Geosurf values given for all inside surfaces of a zone should sum up to 1 at all times. 

The fraction of incoming direct solar that is absorbed by any surface i is given by the product of 

solar absorptance αs value times the Geosurf value given for this surface s. If the Geosurf 

values for all surfaces of a zone are set to zero, all direct solar radiation entering this zone is 

treated as diffuse radiation and distributed with the absorptance-weighted area ratios described 

below. 

With the Geosurf values, solar beam radiation might be distributed even when passing internal 
136

windows between zones up to two passages. After passing the second internal window all solar 

radiation is treated as diffuse radiation. 

The incoming diffuse solar radiation and reflected primary direct solar radiation is distributed 

according to absorptance-weighted area ratios. The fraction of diffuse solar that is absorbed by 

any surfaces is 

( ) ssd

surfaces

ss

ssdif

A

A f

.1

.

,

,,

ρ

α

−

=

∑

where 

 

α s is the solar absorptance of the surface (defined in the building description) 

ρ ,sd is the reflectance for diffuse solar of the surface 

For wall surfaces, where 

= 0 s τ , ( ) ρ ,sd 1−= α s . 

In this case, the absorptance of all surfaces was set to 1 for walls and 0 for windows. Then, the 

distribution of the direct radiation was only governed by the Geosurf value. If the Geosurf value is 

let to zero, then the solar radiation is distributed among all surfaces of the zone, including the 

windows. That’s a realistic hypothesis when wall absorptance is around 0.6 but in our case, it’s 

equal to 1 and then no solar radiation is reflected by the walls. 

Therefore, Geosurf value was set so that solar radiation was distributed among all surfaces except 

the window by which it entered the zone. Therefore, geosurf values were calculated according to the 

ratio between each surface and the total of the surfaces of each zone, excluding the window by 

which the solar radiation entered the zone. 

The values which were used in test MZ360 are given by Table 2E-2. 

Table 2E-2. Calculation of “geosurf” coefficients for the 3 zone of Case MZ-360 

Geosurf Zone A Zone B Zone C 

Front 0.02419191 0.13253012 0.18026565

Left 0.06098801 0.10843373 0.13662239

Right 0.06098801 0.10843373 0.13662239

Back 0.22362269 0.28614458 0.27324478

Floor 0.06098801 0.10843373 0.13662239

Ceiling 0.06098801 0.10843373 0.13662239

Inside 

window 0.50823338 0.14759036 0

Sum 1 1 1

In order to have a better control on the diffuse radiation, it was added to the direct radiation so the 
137

total incoming radiation was considered as direct for all experiments (MZ 340, 350 and 360). 

Otherwise a part of the initially transmitted solar diffuse radiation would be lost back out of the 

“external” window. 

As shown in Figure 2E-3, when diffuse radiation is taken into account as direct radiation, the 

outgoing solar radiation is null contrary to when it’s taken into account as diffuse, although 

transmitted radiation is equal. The absorbed radiation by the walls is directly affected. 

-50000.000

0.000

50000.000

100000.000

150000.000

200000.000

250000.000

5000.000 5100.000 5200.0

Time

Solar radiation (kJ/h)

Q_Transmis_Diffuse_as_Diffuse kJ/h Q_Abs_Tot_Diffuse_as_Diffuse kJ/h Q_Out_Win_Diffuse_as_Diffuse kJ/h

Q_Transmis_Diffuse_as_Direct kJ/h Q_Abs_Tot_Diffuse_as_Direct kJ/h Q_Out_Win_Diffuse_as_Direct kJ/h

Figure 2E-3. Comparison between diffuse solar radiation taken into account as diffuse or as direct 

5. Changes since first set of results (august 2006) 

• The perfect window was modeled correctly. 

• The diffuse radiation was entered as direct radiation and the Geosurf parameter was used to 

control the distribution of solar radiation among the interior walls. 

6. Software Errors Discovered and Comparison between Different Versions of the Same Software 

The incident solar radiation on March 15 hour 19 calculated by Type 109 is different from the one from 

type 16g and from other software tested in the subtask B. It differs usually at the end of the day and not 

for everyday, it could be due to a programming error. 

7. Results 

See the associated output file. 

8. Other Results 

[None] 
138

Type 109 

Type 16g 

Figure 2E-4. March 15 west incident radiation by Type 109-TMY2 and Type 16g 

9. Conclusions and Recommendations 

TRNSYS (TYPE 56) is a very powerful software to solve real building problems. It calculates the heat 

transfer by conduction into the walls, by convection between walls and air and by radiation between wall 

surfaces. The number of walls is not a problem. The developers have limited the software to the resolution of 

generic problems with wall emittance equal to one and without geometrical description. The principal 

objective of this BESTEST was to define a multi-zone-building calorimeter for measuring cooling loads 

caused by transmitted solar radiation. We were able to simulate the ideal window but we had to use a trick to 

have a better control on diffuse radiation so as to complete the exercise. 

Additional TRNSYS types like TYPE 34 allow the introduction of overhang and wingwall shading. That 

kind of type requires a geometrical description that is enough to simulate only perpendicular external 

shading, not parallel. With this TYPE 34, we have generated good results, which could be compared to the 

MZ340 reference. The MZ355 case cannot be simulated with TRNBuild because TRNBuild doesn’t 

integrate the geometrical description of the building. 

10. References 

[1] Solar energy laboratory – February 2005 - TRNSYS 16 (version 16.00.0037), A Transient System 

Simulation Program - Solar energy laboratory, University of Wisconsin (Madison), Madison WI 

53706 USA. 

[2] Window & Daylighting Group – December 2004 - WINDOW 5.2 (5.2.17), for analyzing window 

thermal and optical performance - Window & Daylighting Group, Building Technologies 

Program, Environmental Energy Technologies Department, Lawrence Berkeley National 

Laboratory, Berkeley, CA 94720 USA. 

[3] Siegel, R. and Howell, J. Thermal Radiation Heat Transfer – McGraw Hill, 1972 

[4] John Ervin Seem - 1987 - Modeling of heat transfer in building - A thesis submitted in partial 

fulfillment of the requirements for the degree of Doctor of Philosophy (Mechanical Engineering) 

at the University of Wisconsin-Madison. 
139

[5] Sun, Tseng-Yao, 'SHADOW 1', Procedure for Determining Heating and Cooling Loads for 

Computerizing Energy Calculations, ASHRAE Task Group on Energy Requirements, 1975, pp. 

48–56. 

Annex

Listing: BESTEST_win.lib 

*Name Description ID Slope u-Val g-val Hin Hout FFrame UFrame ABSFRAME RISh. 

RESh. REFLISh. REFLOSh. CCISh. 

BESTEST :BESTEST ;1001, 90, 0.0, 1.000, 109.754, 109.754, 0.01, 0.01, 0.01, 0, 

0, 0.0, 0.0, 0.500, 

_EXTENSION_WINPOOL_START_ 

WINDOW 4.1 DOE-2 Data File : Multi Band Calculation 

Unit System : SI 

Name : TRNSYS 14.2 WINDOW LIB 

Desc : Keine Glasscheibe = offen 

Window ID : 10001 

Tilt : 90.0 

Glazings : 1 

Frame : 11 2.270 

Spacer : 1 Class1 2.330 -0.010 0.138 

Total Height: 1219.2 mm 

Total Width : 914.4 mm 

Glass Height: 1079.5 mm 

Glass Width : 774.7 mm 

Mullion : None 

Gap Thick Cond dCond Vis dVis Dens dDens Pr dPr 

1 0 0 0 0 0 0 0 0 0 

2 0 0 0 0 0 0 0 0 0 

3 0 0 0 0 0 0 0 0 0 

4 0 0 0 0 0 0 0 0 0 

5 0 0 0 0 0 0 0 0 0 

Angle 0 10 20 30 40 50 60 70 80 90 Hemis 

Tsol 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 0.999 

Abs1 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.001 

Abs2 0 0 0 0 0 0 0 0 0 0 0 

Abs3 0 0 0 0 0 0 0 0 0 0 0 

Abs4 0 0 0 0 0 0 0 0 0 0 0 

Abs5 0 0 0 0 0 0 0 0 0 0 0 

Abs6 0 0 0 0 0 0 0 0 0 0 0 

Rfsol 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 

Rbsol 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 

Tvis 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 0.999 

Rfvis 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 

Rbvis 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 

SHGC 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 0.000 1.000 

SC: 1.0 

Layer ID# 9052 0 0 0 0 0 

Tir 0.000 0 0 0 0 0 

Emis F 1.000 0 0 0 0 0 

Emis B 1.000 0 0 0 0 0 

Thickness(mm) 0.001 0 0 0 0 0 

Cond(W/m2-C )0.001 0 0 0 0 0 

Spectral File None None None None None None 

Overall and Center of Glass Ig U-values (W/m2-C) 

Outdoor Temperature -17.8 C 15.6 C 26.7 C 37.8 C 

Solar WdSpd hcout hrout hin 

(W/m2) (m/s) (W/m2-C) 

 0 0.00 12.25 3.42 8.23 0 0 0 0 0 0 0 0 

 0 6.71 25.47 3.33 8.29 0 0 0 0 0 0 0 0 

 783 0.00 12.25 3.49 8.17 0 0 0 0 0 0 0 0 

 783 6.71 25.47 3.37 8.27 0 0 0 0 0 0 0 0 

*** END OF LIBRARY *** 

_EXTENSION_WINPOOL_END_ 
140

Appendix II-F 

Modeler Report for BESTEST Cases MZ320 – MZ360 

VA114 Version 2.25 

by 

Aad Wijsman 

VABI Software BV 

The Netherlands 

 

March 2008 

July 03, 2007 (final, seventh draft) 

September 12, 2006 (sixth draft) 

February 01, 2006 (fifth draft) 

August 29, 2005 (fourth draft) 

August 25, 2005 (third draft) 

June 30, 2005 (second draft) 

May 02, 2005 (first draft)

VA114 

VABI Software BV 

P.O. Box 29 

2600 AA Delft 

The Netherlands 
141

Remark:

This report is the seventh, final draft. Observations done at the last meeting (Golden, March 2007) were 

studied. Extra information has been added to the Modeler Report. No re-runs were done, so results are the 

same as for September 2006 (6th draft) 

Heat Exchange within a Zone and between Zones 

1. Introduction

The building simulation program VA114 is developed and distributed by VABI Software bv. The current 

version is 2.25. 

The program calculates the demand, the supply, the distribution and the generation of heat and cold for a 

building with its energy supply system. Moreover the internal comfort temperature and overheating are 

calculated. 

VA114 is a multi-zone program (up to 30). 

The time step applied in VA114 is 1 hour. 

The boundary conditions, that are possible in VA114 are: 

- bounded to ambient 

- bounded to a neighbour zone 

- bounded to a mirror zone 

- bounded to the underground. 

The current program VA114 models: 

- heat exchange within a zone 

- heat exchange between zones by conduction 

- heat exchange between zones by airflow (ventilation) 

- solar gain and solar exchange between zones 

- solar shading 

- and other processes. 

The simulation program VA114 passed the BESTEST [1],[2],[3]. In the summer of 2005 the simulation 

program was subjected to the new IEA-34/43 tests [4] (MZ320, MZ340, MZ350, MZ355 and MZ360). In 

August 2005 revised test specs were received. The runs were done again and reported. A first comparison 

with the other programs was made (Aalborg-meeting). This led to some observations: 

- there is a time shift for VA114 

- unshaded hourly diffuse shows an afternoon “hump” on October 14 

- the MZ350c seems to have “double” shading 

- VA114 treats circumsolar diffuse radiation as beam radiation, whereas other programs count 

this solar component to diffuse radiation. 

The “problems” were countered (time shift and double shading were caused by input errors made by tester 

A. Wijsman) and re-runs were done. For results see draft 5 (February 2006). Results both for circumsolar 

diffuse radiation counted to diffuse radiation (as other programs do) and counted to direct radiation (as 

VA114 usually does).
142

In August 2006 some dimensions in the test specifications (zone height, window area, fin size, ...) were 

adjusted and the test runs were done again. The results for the adjusted dimensions were reported in 

September 2006 (see draft 6). 

This report is the seventh, final draft. Observations done at the last meeting (Golden, March 2007) were 

studied. Extra information has been added to the Modeler Report. No re-runs were done, so results are the 

same as for September 2006 (6th draft) 

This Modeler Report starts with a brief description of the software. 

Remark:

VABI Software bv is developing the simulation program VA114. In 2004 VA114 has undergone a lot of 

changes: the solar distribution is calculated by a new method (Ray-tracing), internal window is implemented, 

integration of solar shading and solar distribution was done, acceleration of these ‘solar’ methods to reduce 

the computing time took place. Old ‘solar’ methods should stay available. A new version of VA114 was 

distributed to its users (about 200) by the end of June 2005. Before the distribution of this new version it was 

tested extensively. First by running the Bestest cases (1995) again and after that by running the new IEA34/43 test cases. Both tests cycles led us to errors in the software. The errors were repaired and tests were 

done again and again until we had enough confidence in the results. 

In the autumn of 2005 again many modifications were made to the program VA114. The new version 

VA114-vs 2.20 was subjected to the Bestest, to the EDR and to the IEA34/43-MZ-tests. 

In February 2006 this new version was distributed. 

2. Model description 

The current program VA114 models: 

- heat exchange within a zone 

- heat exchange between zones by conduction 

- heat exchange between zones by airflow (ventilation) 

- solar gain and solar exchange between zones 

- solar shading 

- and other processes. 

In more detail: 

- heat exchange within a zone 

The zone air is described by one node. Between this zone air node and the internal surfaces heat exchange 

takes place by convection. The convection coefficient is user given and can be specific for each surface. 

Heat exchange between the surfaces happens by long wave radiation. This heat exchange is dependent on the 

view factors and emittance factor of the internal surfaces. 

Remark: there is an option in the model the value of the convection coefficient can switch between two 

values. 

Remark: the view factors are calculated. Simple by VIEWA (area-weighted) or detailed by VIEW0 (an 

analytical method - for cases with rectangular zones) or by VIEW (Ray-tracing method – for cases with 

other shapes of zones). 
143

- heat exchange between zones by conduction 

Internal and external walls are simulated by a number of nodes. Each with a heat capacity and with heat 

resistances in between. 

- heat exchange between zones by airflow (ventilation) 

Air exchange takes place between ambient and the zone and between neighbouring zones. This air exchange 

can be user given or calculated according to a network node model. 

- solar gain and solar exchange between zones 

Solar radiation enters a zone by windows. This solar radiation is absorbed in the zone or can leave the zone 

through windows, to ambient or to a neighbouring zone. In Appendix A detailed information is given about 

the modelling aspects of this process. 

- solar shading 

Solar shading happens by surrounding buildings, by external façade parts, by own buildings parts and by 

setback of the window. In Appendix B detailed information is given about the modelling aspects of this 

process. 

- and other processes 

Like: internal heat production (by persons, equipment and lighting), mechanical ventilation, .... 

3. Modeling Assumptions

Per test case the modeling assumptions are discussed. 

Case MZ320 

Geometry 

All dimensions were assumed to be centre – centre dimensions, so whole building is 8,0 x 18,0 x 2,7 m. 

Volumes are determined without taking wall thickness into account, so 3 x 129,6 m3

. 

Interior infrared emittance 

This value was put on 0,01 (see 6. Modeling Errors). So the radiative surface coefficient is 0,06 W/(m2

.K). 

Interior Combined Surface Coefficients 

The convective surface coefficients were put on the required values minus 0,06 W/(m2

.K) (= radiative surface 

coefficient) 

Interior solar absorptance 

This value was put on 0,01 (see 6. Modeling Errors) 

Sensible cooling 

Was simulated by cooling element with convective fraction = 1.0 

Case MZ340 

Geometry 

All dimensions were assumed to be centre – centre dimensions. Zone height = 5,0 m instead of 2,70 m 

(volume per zone = 240 m3

 ). Remark: Window area = 16,0 m2 instead of 6,0 m2 in earlier tests. 
144

Walls are mass less 

Specific mass was put on 0,01 kg/m3

. Zero is not possible. 

Walls are adiabatic 

Thermal conductance was put on 0,00001. Zero is not possible. 

Windows 

Window physical properties are ideal (according to specifications): thermal conductance = 0,0 , transmittance 

= 1,0 and is independent of incidence angle. 

Windows are modelled by two panes with convective and radiative heat transfer coefficients in between: to 

achieve thermal conductance = 0,0 W/(m2

.K) the radiative heat transfer coefficient was put on 0,00 W/(m2.K) 

and the two convective heat transfer coefficients were put on 0,001 W/(m2

.K) (so 0,001 // 0,001). Zero 

convective heat transfer coefficient is not possible 

Interior infrared emittance was put on 0,01 (see Modeling Difficulties). So the radiative surface coefficient is 

0,06 W/(m2

.K).

Solar transmittance was put on 1,000 and the angular modifier was put on 1,000 (for all angles of incidence) 

Mechanical system 

In all zones there should be a sufficient cooling capacity. In case there is no or insufficient cooling capacity 

the zone temperatures become ‘infinite’ (because the heat losses of the zones are close to 0,0) and the program 

stops by error. 

Ground reflectivity Rho 

VA114 works with a hard-coded Rho = 0.20. Because of these IEA- tests it was put to 0.0. 

 

Case MZ350 

Geometry of the zones is not different from case MZ340. The dimensions of the shading fin changed from 12 

x 18 m in earlier tests to 24 x 24 m. 

Case MZ355 

Geometry of the zones is not different from cases MZ340 and MZ350. The dimensions of the shading 

building (zone G) changed from 12 x 18 x 5 m in earlier tests to 24 x 24 x 5 m. 

Case MZ360 

The geometry of the zone B changed: depth was 5 m in earlier tests and is now 3 m. 

No further assumptions had to be made. 
145

4. Modeling Options

First the modelling options are discussed in general and then what options are applied per test. 

Modeling options in general 

Infrared heat exchange (see chapter 2) 

Infrared heat exchange within a zone works with view factors between the internal surfaces and with 

emittances of that internal surfaces. 

For the calculation of the view factors 3 methods are available: 

- VIEWA - simple area-weighted method – if only areas of surfaces are available 

- VIEW0 - detailed analytical method – only applicable for rectangular zones 

- VIEW - detailed Ray-tracing method – applicable for all shapes of zones. 

Remark: sum of view factors from surface I to all the other surfaces should be 1,000 exactly; for the raytracing method this is not valid, it is almost 1,000 (i.e. 0,996–1,004). 

Solar distribution over the internal surfaces (see chapter 2) 

Direct radiation and diffuse radiation are treated separately. 

For the direct radiation it is calculated which internal surfaces are hit; such a surface absorbs a part of that 

direct radiation and reflects the rest diffusely. For the calculation of the direct distribution 3 methods are 

available: 

- PZONI0 – simple method – all direct radiation hits the floor 

- PZONI1 – detailed projection method – only applicable for rectangular zones 

- PZONI2 – detailed Ray-tracing method – applicable for all shapes of zones (See appendix 

C). 

The distribution of the diffuse radiation (through windows and the reflected direct radiation by internal 

surfaces) is calculated by the view factors (see the 3 models above) and by the reflections (= 1,0 – 

absorptance) of the internal surfaces. 

Solar shading (see chapter 2) 

Surrounding buildings cause shading of the direct solar radiation, not of the diffuse solar radiation. Two 

models (SCHADUW1) are available: 

- level 1: only in 1 point of a window (the centre) shading (= 0/1) is determined 

- level 2: in 5 points of a window (the centre and 4 corners) shading (= 0/1) is determined; 

shading of the window is the average shading (0,0-0,2-0,4-0,6-0,8-1,0). 

External façade parts, own building parts and set back of window cause both shading of the direct solar 

radiation and shading of the diffuse solar radiation. For the direct shading two models are available: 

- SCHADUW2: detailed projection method – only applicable for rectangular shapes 

- SCHADUW3: detailed Ray-tracing method – applicable for all shapes of zones (remark: 

SCHADUW3 is integrated in PZONI2). 

For the diffuse shading 1 model is available: 

- SCHADW2D: detailed Ray-tracing method – applicable for all shapes of zones. 

Remark: Method is used to determine the view factors to the shading objects, the ground and the sky. 

In Table 2F-1 is given what models can be used for a certain shape of a zone (Ishape = –1, 0, 1): 

Ishape = –1 in case only the areas of surfaces are known 

 = 0 rectangular zones 

 = 1 all shapes of zones . 

Remark: the distributed new version of VA114 works with Ishape = 1. 
146

Table 2F-1. Models that can be used for a given shape of a zone (Ishape = –1, 0, 1) 

Process Ishape = –1 Ishape = 0 Ishape = 1 

Infrared heat exchange 

VIEWA – area-weighted X x 

VIEW0 – analytical method X 

VIEW – Ray-tracing method x X 

Solar distribution direct radiation 

PZONI0 – 100% on floor X x 

PZONI1 – projection method X 

PZONI2 – Ray-tracing method x X 

Solar shading – Surrounding buildings 

SCHADUW1 

Level=1 – 1 point on window X x 

Solar direct 

Level=2 – 5 points on window X X 

Solar diffuse N/A 

Solar shading – External façade parts, other 

Solar direct SCHADUW2 – projection m. X X 

SCHADUW3 – Ray-tracing x X 

Solar diffuse SCHADW2D – Ray-tracing x X X 

 Note: ‘X’ = the model that is applied in VA114 

 ‘x’ = an alternative model that can be selected in VA114 

So in principle for Ishape = 0 (rectangular zones) all models can be applied. 

Modeling options per test 

Case MZ320 

For the infrared heat exchange the models VIEWA, VIEW0 and VIEW were tested. 

The comfort module calculates the radiative temperature on the 6 surfaces of a comfort cube. It works, 

depending on Ishape with VIEWCA, VIEWC0 and VIEWC. 

Case MZ340 

No options. 
147

Case MZ350 

Several options:

Î Shading by external façade parts, own buildings part, setback of window, and other 

MZ350a0 – Ishape = –1 

 Solar distribution according to PZONI0 

 Shading by external shading parts: direct shading SCHADUW2 

 diffuse shading SCHADW2D 

MZ350a1 – Ishape = 0 

 Solar distribution according to PZONI1 

 Shading by external shading parts: direct shading SCHADUW2 

 diffuse shading SCHADW2D 

MZ350a2 – Ishape = 1 

 Solar distribution according to PZONI2 

 Shading by external shading parts: direct shading SCHADUW3 

 diffuse shading SCHADW2D 

Î Shading by surrounding buildings 

MZ350c0 – Ishape = –1 

 Solar distribution according to PZONI0 

 Shading by external shading parts: direct shading SCHADUW1, level 1 

 diffuse shading – N/A 

MZ350c1 – Ishape = 0 

 Solar distribution according to PZONI1 

 Shading by external shading parts: direct shading SCHADUW1, level 2 

 diffuse shading – N/A 

MZ350c2 – Ishape = 1 

 Solar distribution according to PZONI2 

 Shading by external shading parts: direct shading SCHADUW1, level 2 

 diffuse shading – N/A 

So shading by surrounding buildings is without diffuse shading. 

Remark: the circumsolar diffuse radiation component is treated as direct solar radiation. 

Case MZ355 

SCHADUW3 (direct solar shading) and SCHADW2D (diffuse solar shading) have shading by own building 

parts. In principle the results should be the same as case MZ350a. 

Case MZ360 

Internal window: no options. 
148

5. Modeling Difficulties

Per test case the modeling difficulties are discussed. 

No specific modelling difficulties occurred. See chapter 3, 4 and 6. 

6. Software errors discovered and comparison between different versions of the same software.

Deviating test results can be caused by: 

- input errors made by the tester 

- errors in the software 

- the modelling approach. 

Î Input errors by the tester: 

During the Aalborg meeting (October 2005) a first comparison was made between the results of VA114 and 

the results of the other programs. This led to some observations: 

- there is a time shift for VA114 

- unshaded hourly diffuse shows an afternoon “hump” on October 14 

- the MZ350c seems to have “double” shading 

- VA114 treats circumsolar diffuse radiation as beam radiation, whereas other programs count 

this solar component to diffuse radiation. 

The first three “problems” were countered as input errors made by the tester: 

- the time shift because of the longitude (–80,267/15 = –5,35) and the time zone (= –5) was 

not taken into account. It is only a difference of –0,35 hour (21 minutes), but it has a rather 

big influence. By taking this time shift into account the newly calculated diffuse radiation 

on the horizontal (Total – Direct on horizontal) is very close to the diffuse radiation on the 

tape (hourly). So the incident solar on orientation West became 804 kWh/m2

 (instead of 

886), which is much closer to the other programs. 

- Case MZ350c treats a fin as surrounding building. The tester switched this option ‘ON’, but 

did not switch ‘OFF’ the option ‘fin treated as external building part’. So shading was 

calculated in two ways (Fshading1 and Fshading2). “Double” shading occurred because 

both options calculate shading individually and integrate them simple by the relation: 

 Fshading = 1 – (1 – Fshading1) * (1 – Fschading2). 

Remark: VA114-users use VA114 in the VABI-Uniforme Omgeving (Uniform 

Environment) and can not make this mistake. This environment treats each obstruction (also 

a surrounding building) as an external building part and does a real integrated shading 

calculation. In this way shading of diffuse radiation is also taken into account for a 

surrounding building. 

Remark: VA114 treats circumsolar diffuse radiation as beam radiation, whereas other programs count this 

solar component to diffuse radiation. This is not an error but a difference in the way of modelling. To make a 

comparison with the other programs easier calculations are done for both ways of modelling: 

- circumsolar diffuse radiation treated as ‘beam’ (as VA114 does) 

- circumsolar diffuse radiation treated as ‘diffuse’ (as other programs do). 
149

To conclude: 

by taking away 

- the input error in the time shift DTIME 

- the input error that caused “double shading” 

and by treating circumsolar diffuse radiation as diffuse radiation instead of beam radiation many of the 

remarks in the “Aalborg” spreadsheet are countered now. 

Î Errors in the software: 

The following software errors were discovered and corrected. 

Case MZ320 

For the infrared heat exchange the models VIEWA, VIEW0 and VIEW were tested. It was observed, that for 

low emittances (< 0,20 - all internal surfaces have the same emittance) the test with model VIEW (Raytracing) gives deviations: sum of exchange factors becomes > 1,0 (1,02 for emittance = 0,20 and 1,45 for 

emittance = 0,01; overflow at 0,001). 

Remark: if not all emittances are so low than this problem does not occur. 

Remark: a correction to the heat exchange model UITWIS (works with VIEW and emittances) was made; for 

emittances > 0,01 it is OK now. 

The same happened to model UITWISA (works with VIEW and absorptances), that is applied for the 

distribution of the diffuse solar radiation. 

Remark: a correction to the model UITWISA (works with VIEW and absorptances) was made; for 

absorptances > 0,01 it is OK now. 

The comfort module works, depending on Ishape with VIEWCA, VIEWC0 and VIEWC. It was found that 

after the modifications of last year the position of the comfort cube was in a wrong coordinate system for 

VIEWCA and VIEWC0. 

Case MZ340 

Thermal conductance of a construction layer can not be 0,000. Now a warning will be given if thermal 

conductance < 0,00001. 

Case MZ350 

Cases MZ350a0 and a1 differed strongly from a2. It was found the old model SCHADUW2 was by-passed 

(no shading of direct solar) after the new extensions for SCHADUW3. 

Cases MZ350c0 and c1 differed strongly from c2. It was found the old model SCHADUW1 was by-passed 

(no shading of direct solar) after the new extensions for SCHADUW3. 

Remark: after correction of the errors a1 and a2 give the same results (within the last digit); the same is valid 

for c1 and c2. Results are presented in one: a12 and c12. 
150

Case MZ355 

SCHADUW3 (direct solar shading) and SCHADW2D (diffuse solar shading) have shading by own building 

parts. In principle the results should be the same as case MZ350a. 

First results showed a big difference: shading was not observed!! Results were the same as MZ340. 

Two errors were found: 

- SCHADUW2 was not called because the switch was at 0 in case there were no external 

façade parts or there was no setback of window. 

- An error, that occurred both in SCHADUW3 and SCHADUW2D. 

After correction of this error the results of MZ355 are the same as for MZ350a. 

Remark: This is valid for the earlier tests with smaller dimensions of the fin (12 m width and 18 m height). 

However for the later tests with larger fin dimensions (24 m width and 24 m height) a small difference occurs: 

between March 12th and March 17th at hour 16 there is a difference between MZ350a and MZ355. Hour 16 is 

the moment the sun is coming from behind the fin, so at the very edge of the fin. It was found it has to do with 

the shading of beam radiation: MZ350 says at that hour it is partly shaded (as the 2–3 hours before) and 

MZ355 says it is completely shaded (whereas the 2–3 hours before it is partly shaded; numbers are exactly the 

same as MZ350). To our opinion in both cases the same shading subroutines are used .... 

Because it happened around March 15th (Spring) it was expected to find the same problem around October 1st

(Autumn) .... It was not found (even on no other days in the entire year it was found). At the moment the 

cause of the difference is not yet found. 

Case MZ360 

Internal window worked well, but the total cooling was a few % lower than the total incident solar radiation 

on that orientation (area * total solar in kWh/m2

). It was found, that in UITWISA (calculates the distribution 

of the diffuse solar radiation) the reflection of the window was fixed at 0,10 (a hard-coded value until now). 

So 10% of the solar (direct and diffuse) incident on an internal window is reflected. So also partly reflected 

through the external window in zone A to ambient. The solar reflection should be 0,0 for this case. It was put 

to the (1,0-transmittance) of the window (user given transmittance = 1,000 for this case). 

Î The modelling approach 

The following observations were done during this subtask: 

- It looks like VA114’s solar processor predicts a somewhat higher solar radiation incident on 

the façade than other programs do. 

- In daily profiles on some hours VA114 shows deviating results with respect to the other 

programs. 

It looks like VA114’s solar processor predicts a somewhat higher solar radiation incident on the façade 

than other programs do. 

In this subtask MZ (Multi-Zone-Non air), but also in subtask DSF (Double-Skin-Façade) this was observed. A 

description of VA114’s solar processor was made and distributed among the other participants. Comments 

and suggestions were obtained. Until now no direct cause could be found. Some checks still have to be done. 

In appendix D this information is available. 
151

Remark: from the latest DSF-results it was found VA114 is not so very different as seemed to be earlier (after 

3 iterations programs came closer and closer ..... and the incident solar radiation predicted by VA114 did not 

change during those iterations). 

In daily profiles VA114 shows on some hours deviating results with respect to the other programs 

In the Figure 2F-1 this can be seen for the hours 16 and 17. To our opinion this is caused by the modelling 

approach: 

The external window is divided in 100 points (10 rows by 10 columns). A sun ray (beam radiation) 

through each point is followed. Counted is the number of points through which a sun ray reaches a 

certain surface in zone B respectively zone C. It is found that in spite of the 100 points the method is 

somewhat discontinuous (see also appendix C). Figure 2F-2 shows the fraction of incident solar that 

reaches zone B respectively zone C for March 15; Figure 2F-3 shows the same, but then for the 

period March 15 – 31. 

Figure 2F-2 shows that the fraction that reaches zone B is 0,64 for hour 14 and 15 and 0,81 for hour 

16 and 17; the fraction that reaches zone C is respectively 0,12 – 0,24 – 0,30 – [0,]36 for the hours 14 

to 17. 

Figure 2F-3 shows that these fractions are on the same level for a number of days and jumps then to 

another level. 

These figures show the discontinuity in the solar radiation. 

Remark: by this effect the solar radiation that stays in zone B (what enters from zone A minus what 

leaves to zone C) is influenced too. That can be seen from the cooling load qB in that zone B: at hour 

14 the fraction is 0,52 ( = 0,64 – 0,12) of incident solar, at hour 15 fraction 0,40 ( = 0,64 – 0,24), at 

hour 16 fraction 0,51 and hour 17 fraction 0,45. This was observed from the comparison (see Figure 

2F-4). 

B
152

BESTEST Multi-Zone: MZ360 Internal Windows

March 15 (high dn) Hourly Transmitted Solar, Window "AB" (Zone B)

0

20000

40000

60000

80000

100000

120000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Transmitted Solar Radiation (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS16/Liege VA114-CirDf/VABI VA114-CirBm/VABI

Figure 2F-1: Daily profile of transmitted solar with deviating results for VA114 

Fraction Pzoni during day - March 15

0,000

0,100

0,200

0,300

0,400

0,500

0,600

0,700

0,800

0,900

1,000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour of the day

Fraction Pzoni

DirB / DirA

DirC / DirA

 Figure 2F-2: Daily profile of fraction Pzoni – March 15 
153

Fraction Pzoni during day - Period March 15 - March 31

0,000

0,100

0,200

0,300

0,400

0,500

0,600

0,700

0,800

0,900

1,000

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour of the day

Fraction Pzoni

DirB / DirA

DirC / DirA

 Figure 2F-3. Daily profile of fraction Pzoni – period March 15 – March 31 

BESTEST Multi-Zone: MZ360 Internal Windows

March 15 (high dn) Hourly Cooling Load, Zone B

0

20000

40000

60000

80000

100000

120000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Cooling Load (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA (2-Zone) TRNSYS-TUD/TUD

TRNSYS16/Liege VA114-CirDf/VABI VA114-CirBm/VABI

 Figure 2F-4. Daily profile of cooling load in zone B on March 15 
154

7. Results

Results are given for two models: 

- Circumsolar diffuse radiation is treated as direct radiation (VA114’s model). Results in spreadsheet 

“MZ-output082205-VABI-difcir is beam-20060921A-output real beam and dif.xls”. 

- Circumsolar diffuse radiation is treated as diffuse radiation (other programs’ model). Results in 

spreadsheet “MZ-output082205-VABI-difcir is dif-20060921A.xls”. 

Some additional comments: 

Case MZ320 

Zone temperatures are 31,1 C (Zone A), 24,8 C (Zone B) and 15,0 C (Zone C). Cooling power is 1541 W. 

If ground reflection # 0,0 then there will be diffuse solar radiation on the back of the floor (floor is above air). 

It is necessary the solar absorptance at the outside is as prescribed 0,0. 

Case MZ340 

All zones have the same solar input and the same cooling. 

 

Case MZ350 

Remark: a0 has some lower cooling with respect to a1 and a2 because of solar loss through the window: 

simple VIEWA (area-weighted) leads with absorptances to distribution of diffuse radiation entering through 

the window on the internal surface of that window. The same is valid for c0 with respect to c1 and c2. 

Remark: after correction of the errors a1 and a2 give the same results (within the last digit); the same is valid 

for c1 and c2. Results are presented in one: a12 and c12. 

Remark: cases MZ350a are lower than MZ350c because MZ350a does have diffuse solar shading, MZ350c 

does not. 

Case MZ355 

SCHADUW3 (direct solar shading) and SCHADW2D (diffuse solar shading) have shading by own building 

parts. In principle the results should be the same as case MZ350a. 

After correction of the error the results of MZ355 are the same as for MZ350a (except for the earlier 

mentioned hour 16 for the days March 12 till March 17 – see chapter 6). 

Case MZ360 

The total cooling (Zone A + Zone B + Zone C = 129653) is not exactly the same as the net total incident solar 

(total incident solar minus loss through external window to ambient = 129595). 

The hourly results show a constant cooling load of –4 W (zone A), –2 W (zone B) and –1 W (Zone C) during 

the hours there is no solar input. A run without solar radiation incident on to the window gives the same flows 

for all hours. On annual basis this cooling load is 58 kWh; this is equal to the found imbalance between solar 

radiation and cooling load (0,04%). 

So above found imbalance is not caused by the solar calculation method, but by some other reason (probably 

the Infra-Red model, that becomes a little bit inaccurate at emissivities of 0,01). 

 
155

8. Other

Concerning circumsolar diffuse radiation 

Originally VA114 treats circumsolar diffuse radiation in the same way as beam radiation is treated. Other 

programs treat this component in the same way as diffuse radiation is treated. 

The beam and diffuse treatment differs on: 

- transmission by a window 

- shading by obstacles 

- distribution over the internal surfaces in a zone 

- transfer from one zone to a neighbour zone through an internal window 

- ...... 

On both options the tests were done and results were presented. 

Concerning shading by surrounding buildings 

Case MZ350c works with shading by surrounding buildings. It takes into account shading of beam radiation 

only. Diffuse radiation is not shaded. 

This modelling option was tested and observations were done. Finally the module was found without errors. 

Remark: To model diffuse shading by surrounding buildings, the surrounding buildings should be modelled 

as external facades parts. And then it works as MZ350a. 

No further optional work.

9. Conclusions and Recommendations

VABI Software BV does developments on the building simulation program VA114. 

In 2005 VA114 has undergone a lot of changes: the solar distribution is calculated by a new method (Raytracing), internal window is implemented, integration of solar shading and solar distribution was done, 

acceleration of these ‘solar’ methods to reduce the computing time took place. However old ‘solar’ methods 

should stay available. 

A new version of VA114 was distributed to its users/clients (about 200 in the Netherlands) by the end of 

June 2005. 

Before the distribution of this new version took place it was tested extensively. First by running the (old!!) 

Bestest cases (1995) [1] again and then by running the new IEA-34/43 test cases [4]. Both tests cycles led us 

to errors in the software. 

The errors were repaired and tests were done again and again until we had enough confidence in the results. 

For the old Bestest cases the exact results for VA114 were available (tests were done on earlier versions of 

VA114). After the modifications in 2005 we found a number of newly introduced errors. First the results of 

all cases were different. After the first errors were found and corrected only the shading cases still showed 
156

differences. And again we found errors. Correction left only one case (case960 with solar space) with a 

deviation from the original results. This error was found too!! Now all BESTEST-cases were the same 

(within a few explainable digits) as earlier results. 

With that version of VA114 we started with the new IEA-34/43 tests(MZ320, MZ340, MZ350, MZ355 

and MZ360). Again errors were found and corrected. The results were discussed at the Aalborg-meeting 

(October 2005). This led to some observations. These “problems” were countered and re-runs were done 

(see draft 5 of Modeller Report). 

Modeller Report – draft 6 contained the results for adjusted dimensions. 

In this final draft of the Modeller Report some observations done at the last meeting (Golden, March 2007) 

were studied. Extra information about these items has been added. No re-runs were done, so results are the 

same as for September 2006 (6th draft). 

Final remark:

The test cases are very useful during developments on the Building simulation program VA114. 

Modifications in / extensions on the software are first tested on “good physical understanding” and “good 

practice” of the developer. Also other internal users tested the new version by “working” with it. This led to 

errors and corrections. 

But that is not enough. Bestest and IEA-34/43 tests brought a number of new errors to the surface. This 

shows the importance of these test circles!! 

And still there will be errors in the software!! Development of new, specific test cases is of big importance!! 

A MUST: after modifications (even if they are minor) in the software all tests (Bestest, IEA-34/43, others 

tests) have to be done again to be sure no derivative errors are introduced. 

10. References

 

[1] Judkoff, R and Neymark, J 

 “International Energy Agency Building Energy Simulation Test (BESTEST) and Diagnostic 

Method”, IEA: SHC Task 12 / ECBCS Annex 21, February 1995. 

[2] Soethout, L. L. 

“BESTEST Kwalificatietesten uitgevoerd aan het gebouwsimulatieprogramma VA114, 

versienummer 1.35”. TNO-rapport 98-BBI-R0830, mei 1998. 

[3] Wijsman, A.J.Th.M.; Plokker, W. 

“Eerste thermische gebouwsimulatieprogramma’s ondergingen de keurmerktest”. 

TVVL Magazine, augustus 1999. 

[4] Neymark, J and Judkoff, R 

“Proposed IEA BESTEST Multi-Zone Non-Airflow In depth Cases: MZ320 – MZ360”, IEA: 

SHC Task 34 / ECBCS Annex 43, August 2006. 
157

Appendix A: Solar gain and solar exchange between zones 

Model description 

In subroutine "ZONINT" the solar gain and solar exchange between zones is simulated. In Figure 2FA-1 this 

is given very schematically. 

 \ \ \ 

 \ .----======----.------=======----.---======---. 

 \ | \ | \ | \| | 

 || \ | \| | - || 

 ||\ \ || - || || 

 || \| || || || 

 | - ||\ || | 

 \ | || \ || | 

 \ | || \| || | 

 || || - || || 

 ||\ || || || 

 || \| || || || 

 | - | | | 

 | | | | 

 | | | | 

 .--------------.-----------------.------------. 

 

Figure 2FA-1. Solar enters a zone by external windows and by internal windows. Windows can be present in 

the facades and in the roof. 

It is calculated what fraction of the solar gain of a zone: 

- is used for the evaporation by plants 

- comes sensible available to the air node 

- comes sensible available to the walls; the distribution over all surfaces within the zone is 

calculated. 

Direct and diffuse solar radiation are treated separately. 

Steps in the calculation process: 

. calculation of the solar gain of a zone 

External windows: 

SOMZON = Σ A(IV,IVLK)*TRANS(IV,IVLK)* 

 (Amdir*Gdir(IV,IVLK)+Amdif*Gdif(IV,IVLK)) 

 with 

SOMZON = solar gain 

A = area of the window 

TRANS = transmission of the window (incident angle 45o

) 
158

Amdir = Angular Modifier-direct radiation (= 1.000 at 45o

) 

Gdir = intensity direct solar radiation on the window 

Amdif = Angular Modifier-diffuse radiation (at 58o

) 

Gdif = intensity diffuse solar radiation on the window 

Internal Windows: 

The solar radiation, that enters the zone by internal windows is added to the solar gain SOMZON. 

. calculation of the latent and the sensible part of the solar gain

 Latent part (evaporation by plants) 

 SOMZONV = VZON(IV) * SOMZON 

Sensible part 

 SOMZONS = (1.0 – VZON(IV)) * SOMZON 

 The fraction VZON is an input of the model. 

. calculation of the convective part and the radiative part 

 Convective part (to the air node) 

 QZONL(IV) = CZON(IV) * SOMZONS 

Radiative part (to the wall surfaces) 

 QZONW(IV) = (1 – CZON(IV)) * SOMZONS 

 The fraction CZON is an input of the model. 

. Calculation of the internal distribution of the radiative part.

Many models are available here, from very simple ones (100% goes to the floor) to very detailed 

ones. 

For the calculation of the exchange between zones a detailed model, that calculates the actual solar 

distribution (so each time step) is applied. 

Detailed model for the internal solar distribution 

The distribution of the solar radiation is separately done for direct and for diffuse radiation and is dependent 

on the solar position, the geometry of the zone, the absorption / reflection of the internal surfaces bounding 

that zone. 

Each window is treated separately. 

The solar entering the zone by a window has two components: 

- a direct component 

- a diffuse component. 
159

Remark: a fraction FDIFRM of the direct radiation is converted into diffuse when it passes the window. 

The fraction FDIFRM is an input of the model (at this moment FDIFRM = 0.0). 

Remark: the circumsolar diffuse radiation component is treated as direct solar radiation. 

The internal distribution is calculated in subroutine ZABSVLK: the fraction of the radiative part of the 

solar gain that is absorbed by each surface. The part absorbed by the surface of a window is assumed to 

pass that window (to outdoors or to a neighbouring zone) for 100%. 

The direct component 

Subroutine PZONI2 calculates, based on the solar position, what internal surface(s) receive direct 

radiation, that enters the zone by a specific window (see Appendix C). A fraction (= absorption 

coefficient of the internal surface) of this direct radiation is absorbed, the rest (1 – absorption) is diffuse 

reflected. 

Remark: in case the internal surface is an internal window PZONI2 calculates also what internal 

surface(s) of the neighbouring zone receive this direct radiation. 

Remark: PZONI2 uses a Ray-tracing method; shading by external facade parts, by own building parts and 

by window setback is integrated in this method. 

Remark: for simpler cases (rectangular zones; no internal window) subroutine PZONI0 (100% of the 

direct radiation hits the floor) and subroutine PZONI1 (a projection method, that calculates where the 

direct solar radiation hits the internal surfaces) are available. 

The diffuse component 

The calculation of the distribution of the diffuse radiation (diffuse entered by the windows + the diffuse 

reflected direct radiation) happens by exchange factors. These exchange factors FUFACA(IV,I,J) are 

derived from the view factors and the reflection coefficients of all internal surfaces. 

Remark: for the surface of an opaque wall the reflection coefficient is equal to (1 – absorption of that 

surface), for the surface of a window the reflection is equal to (1 – transmission – absorption in the 

panes). 

Remark: in case of internal windows the solar radiation exchange between zones is calculated iteratively. 

Reason: the solar radiation goes in two directions – through a window the zone in and through a window 

the zone out. 

The result of this calculation is the solar absorbed by each internal surface. 

Final Remark: as can be seen from Figure 2FA-1 the following situations can occur: 

- a beam of rays hits a part of an internal window 

- a beam of rays hits more than one internal window 

- several beams of rays hit the same internal window. 

The model is able to handle these situations. 

Appendix B: Solar shading 

Model description 

In subroutine “ZONEXT” the solar radiation on external surfaces is simulated. Based on the orientation of 

each surface and the known solar radiation on each orientation. Both the unshaded direct component 
160

(Gdir(IV,IVLK)) and the unshaded diffuse components (Gdif(IV,IVLK)) are known. 

For solar shading a distinction is made between direct and diffuse solar shading. 

 

Direct solar shading 

Direct solar shading happens by surrounding buildings (subroutine ‘schaduw1’), by external facade parts, by 

own building parts and by setback of the window (subroutine ‘schaduw2’). 

Shading factors: 

 Pschv1 (IV,IVLK) surrounding buildings 

 Pschv2 (IV,IVLK) external facade parts, own building parts, setback window 

Remark: Factor = 0.0 is not shaded, factor = 1.0 is fully shaded. 

Remark: only windows have shading, shading of opaque walls is (until further notice) not taken into account. 

These factors are combined to one factor 

 Psch0(IV,IVLK) = 1. – ( 1.– Pschv1(IV,IVLK) ) * ( 1. – Pschv2(IV,IVLK) ) 

Diffuse solar shading 

Diffuse solar shading by surrounding buildings is not taken into account; diffuse solar shading by external 

facade parts, by own building parts and by setback of the window is (subroutine ‘schadw2d’). 

Shading factors: 

 Pschv1d (IV,IVLK) surrounding buildings (is not taken into account, i.e. = 0.0)

 Pschv2d (IV,IVLK) external facade parts, own building parts, setback window. 

Remark: Factor = 0.0 is not shaded, factor = 1.0 is fully shaded. 

Remark: only windows have shading, shading of opaque walls is (until further notice) not taken into account. 

These factors are combined to one factor 

 Psch1(IV,IVLK) = 1. – ( 1. – Pschv1d(IV,IVLK) ) * ( 1. – Pschv2d(IV,IVLK) ) 

Solar radiation, shading included 

The shaded solar radiation on external surfaces is given by: 

 Direct solar radiation Gdir(IV,IVLK) = (1.0 – Psch0(IV,IVLK)) * Gdir(IV,IVLK) 

 Diffuse solar radiation Gdif(IV,IVLK) = (1.0 – Psch1(IV,IVLK)) * Gdif(IV,IVLK) 

Remark: 

The circumsolar diffuse radiation component is treated as direct solar radiation. 

More details about the mentioned models (subroutine Schaduw1, Schaduw2 and Schadw2d) is given below. 

Direct solar shading by surrounding buildings 

Direct solar shading by surrounding buildings is simulated in subroutine ‘schaduw1’. 

The method

For a number of points on an external surface (see Figure 2FB-1.) the skyline is determined: 

 SKYH(IGR,IV,IPUNT) 

This is done once and for each external surface. 
161

 5.----------------.4 

 | | 

 | .1 | 

 | | 

 2.----------------.3 

Figure 2FB-1. External surface with 5 points to determine shading 

If the solar height at the given solar azimuth is below the skyline of a point then there is shading in that point 

(Psch = 1.0), if it is above there is no shading (Psch = 0.0). 

The shading factor for that surface is the average shading factor of the 5 points. 

 

Direct solar shading by external façade parts, own building parts and by setback of window 

Direct solar shading by external facade parts, by own building parts and by setback of the window is 

simulated in subroutine ‘schaduw2’. 

In Figures 2FB-2a and 2FB-2b the situation with obstructions is shown. 

 . . . . . . . . . . . . . . . . . 

 . . 

 . Surface IVLK . 

 . . 

 . 4. 1.-----------------------------.4 4. 

 . /| / . / /! 

 . / | / Obstruction 1 / / ! 

 . / | .-----------------------------. / ! 

 . / ! 2 . 3 / ! 

 . / ! . / ! 

 . 3. ! . 3. ! 

 . ! ! . ! ! 

 . ! ! . ! ! 

 . !Obs 2! . !Obs 3! 

 . ! ! . ! ! 

 . ! .1 . | .1 

 . ! / . ! / 

 . ! / . ! / 

 . . . .!. /. . . . . . . . . . . . ! / 

 ! / ! / 

 !/ !/ 

 2. 2. 

Figure 2FB-2a. External obstructions (facade parts) – side view 
162

 ---------------------------------------- 

 | . | 

 | IV = 1 . IV = 2 | 

 | . | 

 | Surface IVLK . | 

 ------==.==.==.==.==--------. . . . . . | 

 \ | | 

 \ | | 

 \ | IV = 3 | 

 \ | | 

 \ | | 

 Obstruction \ ----------- 

 

Figure 2FB-2b. External obstructions (facade parts) – top view 

The method

The projections of all obstructions and all surfaces of the building on a plane perpendicular to the solar rays 

are determined. The overlap between the projection of an obstruction and the projection of a surface gives 

information about the shading: 

- ‘no overlap’ means ‘no shading’ 

- ‘overlap’ means ‘shading’; the size of the overlap is a measure for the shading (0.0 – 1.0). 

Remark: another new method uses Ray-tracing to determine the shading factor; at the moment it is only in 

use for windows and is integrated with the calculation method for the internal solar distribution. For this 

method the window is divided into 10x10 points (see Appendix C). 

Diffuse solar shading 

Diffuse solar shading by external facade parts, by own building parts and by setback of the window is 

simulated in subroutine ‘schadw2d’. 

To the diffuse solar radiation belong the isotropic component, the component from the horizon and the 

ground reflection component. The circumsolar component is treated as direct solar radiation. 

In Figures 2FB-2a and 2FB-2b the situation with obstructions is shown. 

The method

The shading by an obstruction on a surface is determined by the view factor between that surface and that 

obstruction. 

The shading by setback of the window follows from the sum of the view factors between that surface and 

the edges around that surface: Fschzyv(IV,IVLK). 

The shading by own building parts follows from the sum of the view factors between that surface and the 

own building parts: Fschegd(IV,IVLK). 

The shading by other facade parts (obstructions) follows from the sum of the view factors between that 

surface and the several obstructions: Fschbel(IV,IVLK). 
163

Total shading:: 

 Fschdif = Fschzyv(IV,IVLK) + Fschegd(IV,IVLK) + Fschbel(IV,IVLK). 

Appendix C: PZONI2 – Detailed ray-tracing method 

Method 

For the direct (beam) radiation it is calculated which internal surfaces are hit; such a surface absorbs a part of 

that direct radiation and reflects the rest diffusely. 

The external window is divided in 100 points (10 rows by 10 columns). A sun ray (beam radiation) 

through each point is followed. Determined is what internal surface is hit. In case the hit internal surface 

is an internal window the ray will pass that window and will hit an internal surface in that neighbour 

zone. Counted is the number of points through which a sun ray reaches a certain internal surface (see 

Figure 2FC-1). 

The method is integrated with shading: in case the followed sun ray passed earlier an obstacle then there is 

shading and the sun ray will not reach any surface (dashed rays in Figure 2FC-1). 

Figure 2FC-1. The method schematically (in 2-D) 

Comments to this method: 

In Figure 2FC-1 it can be seen that 2 rays are shaded by the overhang and the rest of the rays enter zone A; 2 

rays pass zone A and enter zone B, 0 rays pass zone B and enter zone C. 

In case the sun position at this hour of the day becomes somewhat higher (next days in Spring) the 3rd ray 

(from the top) will be shaded and the 4th ray from the top will not pass the window AB. So in that case 3 rays 

are shaded by the overhang and the rest of the rays enter zone A; 0 rays pass zone A and enter zone B, 0 rays 

pass zone B and enter zone C. 

In case the sun position at this hour of the day becomes lower (next days in Autumn) only the first ray (from 

the top) will be shaded and the 5th ray from the top will also pass the window AB. So in that case 1 ray is 

shaded by the overhang and the rest of the rays enter zone A; 4 rays pass zone A and enter zone B, 0 rays 

pass zone B and enter zone C. 
164

In case the sun position at this hour of the day becomes still lower (days towards winter) the first ray (from 

the top) will not be shaded, passes zone A, passes window AB, passes zone B, passes window BC and enters 

zone C. So in that case no rays are shaded by the overhang and all the rays enter zone A; 5–6 rays pass zone 

A and enter zone B, 1 ray passes zone B and enters zone C. 

As can be seen from this 2-D explanation the fraction, that reaches a certain zone and stays in a certain zone 

changes not continuously. 

The method uses 100 points (10 x 10) , but still the change in fraction is very discontinuously (rays through a 

complete row of points stay in one zone or just pass through an internal window to another zone. In Figure 

2FC-2 that is shown as an example. 

Fraction Pzoni during day - March 15

0,000

0,100

0,200

0,300

0,400

0,500

0,600

0,700

0,800

0,900

1,000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour of the day

Fraction Pzoni

DirB / DirA

DirC / DirA

Figure 2FC-2. Daily profile of fraction Pzoni – March 15 

 

Conclusion: 

The method is very flexible, can handle all shapes of windows, shapes of zones, but on hourly bases the 

profile can be a little bit discontinuous. 

Appendix D: Solar processor of VA114 

Introduction 

In IEA34/43 subtask B1 (MZ = Multi Zone-non air) and subtask E (DSF = Double Skin Façade) tests on 

Building Performance Simulations programs are conducted, where the solar radiation impinging on the 

façade is the most important driving force. From first comparisons it seemed VA114 predicts a somewhat 

higher incident solar radiation on the façade starting from the same solar source on the horizontal surface. 

In this appendix the solar processor of VA114 is described in short to give the other task participants 

inside in that model. An earlier version of this appendix was distributed and reactions were gathered. A 

summary of these reactions is given. It did not lead directly to the cause, but the comments and 

suggestions given will be checked. That will be done in due time, but not as part of this IEA34/43 Task. 
165

The description of VA114’s solar processor 

Solar position 

Solar position is given by solar height (h) and solar azimuth (az). Both are calculated half way the hour. 

Used formulas: 

- hour angle OHM 

OHM = 2 * π / 24 * (12,5 – ST) 

with solar time ST 

ST = KL – DTIME 

In this formula 

KL = hour of the day 

DTIME = time shift in hours 

The time shift DTIME is given by 

DTIME = EQT/60 – (DLONGD/15 – ITIMEZ) 

with 

EQT = equation of time (in minutes); EQT depends on day of the year 

DLONGD = longitude of site (in degrees; East = positive) 

ITIMEZ = time zone (East = positive) 

- Solar height H and solar azimuth AZ 

Sinus of solar height (sinh) and cosinus of solar azimuth (cosaz) are both calculated based on 

solar declination, latitude of site and hour angle OHM. 

Splitting in direct and diffuse radiation 

For IEA-34/43 MZ (subtask Multi-Zone Non air) the GH (Global radiation on the horizontal) and GBN 

(Normal Beam radiation) is given on tape. With sinus of solar height (sinh) follows for the GBH 

(Horizontal Beam radiation): 

GBH = GBN * sinh 

and for the GDH (Horizontal Diffuse radiation) 

GDH = GH – GBH. 

For IEA-34/43 DSF (subtask Double Skin Façade) the GH (Global radiation on the horizontal) and GDH 

(Horizontal Diffuse radiation) is given on tape. For the GBH (Horizontal Beam radiation) follows: 

GBH = GH – GDH 

and with sinus of solar height (sinh) the GBN (Normal Beam radiation): 

GBN = GBH / sinh. 

Remark: 

GBN should be lower than a maximum value GBN,max that is based on the outer atmospheric normal 

radiation G0N and the air mass AIRM. Correction: 

IF (GBN > (GBN,max +55,6)) THEN GBN = GBN,max 

The corrected GBN results in a corrected GBH and with GDH = GH – GBH in a corrected GDH. 
166

Splitting diffuse on the horizontal in 3 components 

The diffuse on the horizontal surface is split into 3 components based on Perez [1]: 

- Isotropic component D1 

D1 = GDH * (1,0 – F1ACC) 

- Circumsolar component D2 

D2 = GDH * (F1ACC / CZET) 

- Component from the horizon D3 

D3 = GDH * F2ACC 

With 

F1ACC = new circumsolar brightness coefficient 

F2ACC = horizon brightness coefficient 

Remark:

F1ACC and F2ACC should be both between 0,0 and 1,0; circumsolar (D1) has as maximum value of 500 

W/m2

. 

If not values F1ACC, F2ACC or D1 are given the limit value and components are recalculated. 

Calculation of total solar radiation on a tilted surface 

By geometric formulas the contribution of the direct component, the 3 diffuse components and the ground 

reflected component to the total radiation on the tilted surface are calculated. 

The used formulas: 

- Direct solar radiation: 

GBT = GBN*COS(Teta) 

With 

GBN = Normal Beam radiation 

Teta = angle of incidence of solar radiation on the tilted surface 

- Diffuse isotropic radiation: 

GD1 = D1 * 0,5 * (1,0 + COS(Beta)) 

With 

D1 = diffuse isotropic component on horizontal 

Beta = tilt of surface 

- Diffuse circumsolar radiation: 

GD2 = D2*COS(Teta) 

With 

D2 = diffuse circumsolar component 

Teta = angle of incidence of solar radiation on the tilted surface 

- Diffuse radiation component from horizon: 

GD3 = D3 * SIN(Beta) 

With 

D3 = diffuse component from the horizon 

Beta = tilt of surface 
167

- Ground reflection: 

GRT = GH * RHO * 0,5 * (1,0 – COS(Beta)) 

With 

GH = total radiation on the horizontal 

RHO = ground reflectivity 

Beta = tilt of surface. 

Total radiation on tilted surface: 

GT = GBT + GD1 + GD2 + GD3 + GRT 

Remark

VA114’s solar processor is described. The big lines are given. If necessary more details can be provided, 

such as details about calculation of: 

- equation of time EQT 

- solar height and solar azimuth 

- outer atmospheric normal radiation G0N 

- Perez factors F1ACC and F2ACC; zenith angle ZET 

- Angle of incidence of solar radiation impinging on the tilted surface 

- ........ 

Reactions and suggestions from participants 

Valuable reactions were received from Joel Neymark (USA) and Paul Strachan (GB). 

Joel Neymark 

He read about the Perez 1987, 1988 anisotropic sky model in Duffie and Beckman (Solar Engineering of 

Thermal Processes, 1991) that there are a number of disagreements that could occur with respect to how 

the model details are implemented ... 

e.g. 

- for calculating circumsolar diffuse a maximum for cos(zenith angle) of cos(85) is shown (remark 

VABI: VA114 takes that into account). 

- the implementation of the brightness coefficients could easily be different among modelers (for 

those using a Perez model). 

 

Duffie and Beckman note that this Perez model generally predicts slightly higher total radiation on a tilted 

surface, so in the MZ work the VA114 results are consistent with that. Duffie and Beckman recommend 

Perez for surfaces with azimuth angle far away from 0 [which is common for many building vertical 

surfaces]. 

Paul Strachan 

Most of the calculations looked OK to him. 

One difference is that VA114 is using Perez 1987. Paul’s program ESPr was updated to the Perez 1990 

model (probably also used by TRNSYS-TUD and Energy+). His experience: it does make some 

difference, but not a huge amount. 
168

Paul (ESPr) supplied detailed results on direct and diffuse radiation for the comparative tests concerning 

solar radiation on the façade. For the period April 17 – April 30 a comparison between ESPr and VA114 

was made [2]: 

- concerning the solar sum over the period: 

- Direct - VA114 is 1,4% higher than ESPr 

- Diffuse - VA114 is 4,2% higher than EPSr 

- Total - VA114 is 2,8% higher than EPSr 

- daily plots show VA114 is somewhat higher in the peaks!!! 

Paul suggested another possibility for comparisons: compare with the detailed solar processing analysis 

that used the EMPA data set. It was published as: 

Loutzenhiser P G, Manz H, Felsmann C and Strachan P A, Frank T and Maxwell G M Empirical 

Validation of Models to Compute Solar Irradiance on Inclined Surfaces for Building Energy 

Simulation, Solar Energy, 81(2), Feb 2007, pp 254–267. 

All the measured data and the predictions are included on the IEA34/43 FTP site. Measured were direct 

normal as well as global horizontal and diffuse horizontal. 

Other comparisons by Vabi Software BV 

The solar results of the comparative and empirical DSF-tests were studied intensively. There were a lot of 

observations, concerning all programs [3]. But our conclusion about the VA114 solar processor is: 

On total radiation and direct radiation VA114 is close to the other programs. On diffuse radiation 

two groups of programs can be distinguished, a higher group and a lower group; VA114 belongs 

to the higher group and is the highest in that group. 

So the differences are much smaller than was found from the earlier comparisons. 

Remark: information about what model assumptions other solar processors are using is not available at 

the moment. The individual modeler’s reports should provide that information. Not all modeler’s reports 

are available at the moment. 

 

Resume 

In this appendix VA114’s solar processor is described in big lines. Valuable reactions / suggestions were 

received from task participants. It did not lead directly to the cause of the differences, but the suggestions 

given will checked. That will be done in due time, but not as part of this IEA34/43 Task. Until now it 

was concluded the differences between VA114 and the other programs are much smaller than was found 

from the first, earlier comparisons. 

Literature 

[1] Perez et al. 

“A new simplified version of the Perez diffuse irradiation model for tilted surfaces”, Solar Energy Voume 

30, No. 3, pp. 221–231, 1987. 

[2] Wijsman, A 

“Solar radiation VA114 versus ESPr”, Excel sheet, June 12th, 2007 

[3] Wijsman, A 

“Solar radiation predicted by the several programs”, May 31st, 2007 
169

Appendix II-G 

Modeler Report for BESTEST Cases MZ320 – MZ360 

CODYRUN 

by 

Harry Boyer, Frederic Maranville, Alain Bastide 

University of Reunion Island 

France 

March 2005 

1. Introduction

CODYRUN is a tool for the thermal and airflow simulation of buildings, mostly dedicated to passive 

building design; It has been developed and is currently maintained by Harry Boyer, who is the head of the 

Civil Engineering and Building Physics Research Team of the Industrial Engineering Laboratory. In this 

team, others researchers are involved in CODYRUN’s validation. A previous step was BESTEST IEA task 

12 cases for monozone cases a few years ago. Being involved in other research themes (renewable energy), 

this laboratory is a research component of the University of Reunion Island. 

Based on iteratively connected thermal, airflow and humidity models, this software is design for research 

and professional use. This goal is facilitated by a multi-model approach [3]. The thermal model is based on a 

finite difference scheme [1] and solved numerically by using a LU matrix inversion method. The airflow 

pressure model [2] is solved using a modified Picard/Newton-Raphson method. 

The time step is specified by the meteorological file. At the end of a simulation the modeler obtain a set of 

results (usable with a spreadsheet) including among other outputs temperatures, airflow rate, pressures, 

radiation and heat flux. 

2. Modeling Assumptions

The mathematical model elaborated with the software is based on a macroscopic description of the 

building and consider the air volume surrounded by the several walls constituting the building envelope 

as transparent (non participating media) and characterized by one temperature, the dry-air temperature. 

Moreover, a building is composed of several zones, each zone being essentially representative of a room. 

Once this description is made, the software is able to set up and solve the set of equations relatives to the 

thermal and airflow transfers taking place in the building. The inputs are the climatic data of the location 

chosen, the geometrical and physical characteristic values of the building. The specification of these data 

combined with the elaboration of a model of the building lead to the numerical simulation. 

3. Modeling Options

As previously mentioned, the software allows a multiple model approach. Different level of modeling are 

available for heat conduction, convective coefficients, short and long wave radiative exchanges, airflow 

transfers, humidity storage in the envelope and numerical methods. This has been initially designed for a few 

following major reasons. During building construction process, data base available is growing up. It allows 
170

only rough models at the beginning and detailed one at the end. Objectives of simulation can also be very 

different from one user to another (analysis of solar exposition, annual energy need, condensation risk, ...) 

and a single model’s monolithic tool is often disadvantaged in terms of precision or calculation time. At 

least, during software validation, this method was powerful in to highlight models limitations (for example 

surface temperatures are obviously unreachable with low quality conduction models). 

So, for each case of this benchmark, models involved were chosen as the closest in terms of physical 

hypothesis. 

4. Modeling Difficulties

The code was slightly modified in order to take into account more significant digits for long wave 

emissivities (it was previously limited to 0.01). 

Model modification was made to be able to specify individual wall exchange convective coefficients. So, the 

library model of convective models was enriched. 

Modifications were also made for permitting the input of specific values for the density and the specific heat 

of the air composing each thermal zone. 

No indications were given for diffuse transmitance. Value used in 1.0. Problems arise in the code when 

indoor absorbtivity is taken to 1.0. Used value is 0.99. 

Albedo was assumed to be 0.0. 

Shadow mask are supposed to minimize diffuse radiation, through view factors. 

[Editor’s note. University of Reunion Island’s comments regarding cases MZ350 and MZ360 relate to their 

simulations for earlier versions of the test specification. As they did not submit results for the final version of 

the test specification (see Part I), their results were not included in Part III.] 

For MZ350 case, two sets of results are provided. The first one corresponds to infinite vetical height of the 

shading fin and the second one to finite case (12 m height). 

For MZ360, we do not track direct couplings (because the building is not geometrically descripted). Our 

indoor short wave coupling allows only diffuse couplings through indoor windows. In a zone, our model 

makes the hypothesis of direct incident on the floor and eventually reflected. With absorptivity taken to 0.99, 

energy transmitted to zone B and C is certainly underestimated. To match energy loads, it would have to be 

much physical to modify indoor floor A absorptivity, but this would not have be the descripted case. 

LARGE DISCREPANCIES WILL APPEAR with other codes allowing direct couplings, especially if 

absorptivities = 1.0. 

Simulations could be done again, with much smaller absorptivity. 
171

5. Software Errors Discovered and Comparison between Different Versions of the Same 

Software

Once the preceding modification made in the software, no major error has been encountered. Nevertheless, 

comparing to the initial version of the software, the results obtained with the modified version have showed 

better agreement with the given results (analytical). 

6. Results

The code results can’t be compared with analytical results yet because data are not provided (first round is 

“blind”). 

7. Other (optional) 

8. Conclusions and Recommendations

After passing BESTEST task 12 for monozone cases, the heat transfer multizone cases is much less difficult. 

This cases were not available elsewhere, and this was for us a slight but a valuable step. Additional cases 

should be designed in order to test airflow transfers handling and prediction, including moisture taking into 

account. 

9. References

 

H. Boyer et al. 

Thermal building simulation and computer generation of nodal models 

Building and Environment, Vol. 31, n° 3, 1996, pp. 207–214 

H. Boyer, F. Garde, J.C. Gatina, J. Brau 

A multi model approach of thermal building simulation for design and research purposes 

Energy and Buildings, 28 (1998), 1, pp. 71–79 

H. Boyer, A.P. Lauret, L. Adelard, T.A. Mara 

Building ventilation : a pressure airflow model computer generation and elements of validation 

Energy and Buildings, 29 (1999), 283–292 
172

 

Appendix II-H 

Modeler Report for BESTEST Cases MZ320 – MZ360 

COMFIE 

by 

Bruno Peuportier 

Paris School of Mines 

France 

 

September 2005 

1. Introduction

PLEIADES + COMFIE 

Developers: Ecole des Mines de Paris (COMFIE simulation tool) and IZUBA Energies (PLEIADES 

interface), France 

Multizone heat transfer : 

- through walls (or floors/ceilings) with surface heat transfer coefficients (radiation + convection), 

conduction and heat storage in walls, 

- accounting for solar gains received by the wall in one zone and transmitted to the adjacent zone 

through the wall, 

- through ventilation, 

- accounting for possible multizone control, e.g. the thermostat controlling the heating/cooling system 

of one zone can be situated in another zone. 

Time step: from 6 to 60 minutes, 6 minutes has been used in this exercise. 

Solar radiation model 

Incident direct and diffuse radiation on the sloped surface are calculated from Duffie and Beckmann1

assuming isotropic sky. 

2. Modeling Assumptions

Each thermostat is assumed to be placed in the same room as the cooling system. 

Thermal bridges are assumed to be zero. 

Ventilation air flow rates between zones and from outside are assumed to be zero. 

3. Modeling Options

The simulation time step can be chosen from 6 to 60 minutes. In the steady state calculations concerned here, 

a one hour time step has been chosen because it is consistent with the climatic data. If a smaller time step is 

chosen, the climatic data is interpolated between 2 hours : the climatic data for hour h is assumed to 

correspond to an average from h – 30 minutes to h + 30 minutes. This does not correspond to the TMY file, 

1

 Solar engineering of thermal processes, Wiley, 1991 
173

where the value for hour h corresponds to h – 60 to h. Therefore a one hour time step has been chosen to 

avoid this interpolation. This induces small temperature / cooling load oscillations, which would not occur 

using a smaller time step (e.g. 1⁄4 h). 

4. Modeling Difficulties

The values for surface heat transfer coefficients cannot be chosen by the user in our software, which has 

been developed for building professionals (architects and engineers). 

The surface heat transfer coefficient h considered is obtained from : 

Energy and Architecture, the European Passive Solar Handbook, J. R. Goulding, J. O. Lewis and T.C. 

Steemers, Batsford for the Commission of the European Communities, London, 1992 

Surface resistance (vertical wall, internal side) 

R = 0.123 (high surface emissivity) and 0.304 (low emissivity) 

From this we derive h = 1 / R for the two levels of the emissivity ε 

And we consider h = 3.29 + 4.84 * ε / 0.9 

The convective part is thus 3.29 W/(m2.K) instead of 4 proposed in the exercise. 

For the inter-comparison exercise, we have modified the source code so that the surface heat transfer 

coefficients indicated in the specifications are used. 

The minimum U-value of a window is 0.01 W/(m2.K). 

A thin layer (e.g. 1 cm plywood) had to be added in walls. We have added this layer on the external part of 

the insulation. The insulation has also a little thermal mass, and 2m thickness has been used (cf. the data 

description in annex). 

Case MZ350a 

[Editor’s note. Ecole des Mines Paris’ comments regarding Case MZ350 relates to their simulations for 

earlier versions of the test specification. As they did not submit results for the final version of the test 

specification (see Part I), their results were not included in Part III.] 

If a vertical shading fin is applied to a window, the model considers a very high fin (cf. next picture) and 

some reflexion (such architectural components are usually not black). It would be time consuming to modify 

the source code, for a case that does not really occur in practice (black fin), therefore this case has not been 

performed. We assume that the reflected radiation equals the diffuse radiation that would be sent by the 

sky portion corresponding to the fin. i.e. the diffuse radiation considered is the same as without fin. The 

same assumption applies to all windows. 

This case has not been simulated in the exercise because the height of the fin (18m) is not infinite, 

therefore the calculation would be less precise than case b. 
174

Case MZ 350 b, azimuth and height angles of the shading fin seen from each window 

The fin is described for each shaded wall using 5 parameters (cf. next figure) : 

- the average height of the fin above the shaded wall (we used the average height above the middle of the 

window), 

- the left and right azimuth of the fin related to the normal incidence (this azimuth is +/– 90° on one side, 

where the fin is attached to the wall), 

- the left and right distances between the fin and the wall (this distance is zero on one side, where the fin is 

attached to the wall). 

Height angles are derived from the height and distance values, so that the shading effect can be represented 

in a solar path diagram providing, for the given latitude, the height angle of the sun in terms of the azimuth 

for a typical day of each month. This diagram shows when the direct solar radiation is blocked by the fin. 

In the thermal simulation, the position of the sun is calculated hourly (no typical day is used). 

The diffuse radiation is reduced according to the estimated proportion of the sky hidden by the fin. This 

proportion depends on the height of the fin, and the difference between right and left azimuth. 

No reflexion is considered at the surface of the fin (black surface). 

If a fin shades different walls, a shading object has to be defined for each wall because the height, distance 

and azimuth parameters may vary. These parameters are not automatically calculated and the shading object 

description is not automatically generated by a geometry description. If a zone of a building shades other 

zone walls, the shading object is also not automatically generated, therefore the case MZ355 has not been 

performed. 
175

ZONE A ZONE B 
176

ZONE C ZONE D 

ZONE E ZONE F

Case MZ350c 

The possibility to model a distant shading like a neighbouring building does not apply in our software to a 

shading fin attached to a wall (cf. next picture): it would be necessary to change the description for each 

window because the azimuth angles would vary. 
177

Therefore case MZ 350 c has not been performed: we have only studied the most appropriate way to 

describe a vertical fin in our software : MZ 350 b. 

The case MZ 360 is also very specific : in practice solar radiation enters very rarely a room through three 

successive windows. Our model is limited to 2 successive glazing, e.g. the first glazing corresponds to the 

external glazing of a sunspace or a double skin façade, the second glazing corresponds to a window between 

this sunspace (or double skin space) and the adjacent zone. We would prefer to perform a validation exercise 

in such a case. 

5. Software Errors Discovered and Comparison between Different Versions of the Same 

Software

We would not like to allow the user to choose surface heat transfer coefficients because is would make the 

interface more complex for professional users and we think that this is not necessary. 
178

6. Results

[Editor’s note. These results are for the August 2005 version of the test specification; only COMFIE results 

for Case MZ320 are included in Part III.] 

MZ 320 

MZ320 Steady State 

Results 

Cooling 

Zone Air 

Temperatures 

Load 

TA TBB TC qC

Case (°C) (°C) (°C) (W or Wh/h)

MZ320 31,06 24,8 15 1541 

The surface temperatures are not calculated in COMFIE-PLEIADES : the comfort indication is provided by 

a zone temperature (combination of surface and air temperatures). 

MZ 340 – MZ 350 b – MZ 355 

 

 Annual Cooling Loads 

QBldg QA QB QC QD QE QF 

Case (kWh) (kWh) (kWh) (kWh) (kWh) (kWh) (kWh) 

MZ340 27892 4649 4649 4649 4649 4649 4649

MZ350a 

MZ350b 21194 3756 2910 3780 3867 3032 3849

MZ350c 

MZ350d 

MZ355 n/a n/a 

MZ360 n/a n/a n/a 

Only the total radiation is an output, therefore we cannot provide separate values for beam and diffuse. 

 

West* 

Incident 

Solar 

 Transmitted Solar Radiation 

IA Itr,A Itr,B Itr,C Itr,D Itr,E Itr,F 

Case (kWh/m2) (kWh) (kWh) (kWh) (kWh) (kWh) (kWh) 

MZ340 773 4636 4636 4636 4636 4636 4636 

MZ350a n/a 

MZ350b n/a 3745 2902 3770 3857 3024 3839 

MZ350c n/a 

MZ350d n/a 

MZ355 n/a n/a n/a 

MZ360 n/a n/a n/a 
179

An ideal controller has been modelled. 

Annual Average Zone Temperatures 

TA TB TC TD TE TF 

Case (°C) (°C) (°C) (°C) (°C) (°C) 

MZ340 20 20 20 20 20 20 

MZ350a 

MZ350b 20 20 20 20 20 20 

MZ350c 

MZ350d 

MZ355 n/a n/a 

MZ360 n/a n/a n/a 

 

qBldg qA qB qC qD qE qF 

Case (Wh/h) (Wh/h) (Wh/h) (Wh/h) (Wh/h) (Wh/h) (Wh/h) 

MZ340 26522 4422 4421 4421 4420 4419 4419 

MZ350a 

MZ350b 25649 4388 4272 4362 4388 4275 4364 

MZ350c 

MZ350d 

MZ355 n/a n/a 

MZ360 n/a n/a n/a 

MZ340

-5000

-4000

-3000

-2000

-1000

0

1000

2000

3000

4000

5000

0 5 10 15 20 25 30

hour

Wh/h

qA march

Itrh,A march

Itrh,A august

Itrh,A october
180

MZ350b, March

-500

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 5 10 15 20 25 30

hour

Wh/h

Itrh,A

Itrh,B

Itrh,D

Itrh,E

7. Other (optional) 

 

 

8. Conclusions and Recommendations

 COMFIE could be improved by asking the height and reflexion coefficient of a shading fin 

attached to a window. 

9. References

 

Bruno Peuportier and Isabelle Blanc Sommereux, Simulation tool with its expert interface for the thermal 

design of multizone buildings , International Journal of Solar Energy, 1990. 

Bruno Peuportier and Isabelle Blanc Sommereux, COMFIE users manual, Ecole des Mines de Paris, 

1994. 
181

Appendix II-I 

Modeler Report for BESTEST Cases MZ320 – MZ360 

KoZiBu 

by 

Jean Noel 

JNLOG 

France 

 

March 2005 

1. Introduction

KoZiBu (CoDyBa) is a software, jointly developed by the CETHIL (INSA-Lyon Thermal Center) and a 

freelance engineer, without any state help. It is aimed for design offices, teaching and research 

organizations. 

The software is used to determinate the heat flows in a building. It permits to estimate the instant heating 

or cooling powers needed to maintain a given set-point, or to calculate the interior temperatures when the 

heating or cooling system is insufficient. Humidity is treated in the same way. 

The tool is aimed to conduct studies of heating and cooling strategy, air conditioning or ventilation 

options, insulating materials to be installed. The room occupancy is included. The software does not 

permit the study of the dynamic behaviour of a set of technological components : the main objective is to 

forecast the energy consumption and temperature evolution range. 

KoZiBu runs on classical PC. The building is described accurately and the building description is given 

by the use of a graphical interface. KoZiBu is based on simply bricks assembled to form a complex 

building with its equipment. The assembly is conducted in a form to minimise data size and calculation 

time. The physical models of KoZiBu are those commonly admitted, but numerical algorithms are 

specific. 

The organization that wrote the old version of the software (until 1995) is : 

 CETHIL - ETB 

 INSA de Lyon - Bât. Freyssinet 

 40 avenue des Arts 

 69100 Villeurbanne 

 France 

 The software is now developed by a free-lance, and its future name is KoZiBu : 

 Jean NOEL (JNLOG) 

 15 place Carnot 

 69002 Lyon 

 France 

 Web site : http://www.jnlog.com

 Mel : contact@jnlog.com 

 The time step used in the calculation is 15 minutes. 
182

2. Modeling Assumptions

For all materials : 

 conductivity = 0.00001 W/m.K 

 capacity = 0.1 J/K.kg 

 density = 0.1 kg/m3

3. Modeling Options

No options, standard version is used. 

4. Modeling Difficulties

Data were introduced as described in the document. 

5. Software Errors Discovered and Comparison between Different Versions of the Same 

Software

No error was discovered for the moment. 

6. Results

It seems that the fact that walls with no mass are present conducts to some numerical instabilities. I will do 

more trials to better understand this possible problem. 

7. Other (optional) 

 - 

 

8. Conclusions and Recommendations

 - 

9. References

 
3.0 Part III: Simulation Field Trial Results 

3.1 Introduction 

Here we present the simulation results for the field trials of cases MZ320 through MZ360; see 

Section 3.4 for graphs and tables. These are results after numerous iterations to incorporate 

clarifications to the test specification, simulation input deck corrections, and simulation software 

improvements. Where improvements to simulation programs or simulation inputs were made as a 

result of running the tests, such improvements must have mathematical and physical bases and 

must be applied consistently across tests. Also, all improvements were required to be documented 

in modeler reports (see Part II, Section 2.9). Arbitrary modification of a simulation program’s 

input or internal code just for the purpose of more closely matching a given set of results is not 

allowed. The diagnostic process of trapping bugs discussed in Section 2.4 of Part II also isolated 

input errors that were corrected, as noted there and in the modeler reports. 

Table 3-1 summarizes the following information for the nine programs that were used to generate 

the simulation results: model-authoring organization, model testing organization (“Implemented 

by”), and abbreviation labels used in the results graphs and tables. For three of the programs final 

results were generated only for Case MZ320, as noted in Table 3-1. For cases MZ340 through 

MZ360 the VA114 modelers provided results for two different modeling approaches for shading 

and solar radiation transmission through windows: modeling circumsolar diffuse radiation as 

beam radiation (“VA114-CirBm”), and modeling circumsolar diffuse radiation as diffuse 

radiation (“VA114-CirDf”). 

An electronic version of the results is included with the accompanying files MZ-ResultsAnnuals.xls and MZ- RESULTS-Hourlies.XLS, for annual and hourly results respectively. 

Navigation instructions are included with Sheet A within each of those files. 

3.2 Zone Cooling Load Versus Transmitted Solar Radiation Results for 

Cases MZ340 through MZ360 

For cases MZ340, MZ350, and MZ355, zone cooling load should be equal to the transmitted total 

(direct + diffuse) solar radiation because the test cases specify zones that act as calorimeters with: 

ideal glass (solar transmittance = 1 for all solar incidence angles, and thermal conductance = 0) 

and ideal walls (interior solar absorptance = 1, thermal conductance = 0). Similarly for Case 

MZ360, total building cooling load should be equal to total solar radiation transmitted through the 

exterior window (Window AO). 

For whole-building simulation programs that do not disaggregate transmitted total solar radiation 

in their output, zone cooling load results are directly comparable to the transmitted total (direct + 

diffuse) solar radiation results for cases MZ340, MZ350, and MZ355. Similarly, for Case MZ360, 

total building cooling load is comparable to total transmitted solar radiation through window AO. 

Minor differences in zone cooling load versus total transmitted solar radiation may occur if a 

simulation program: cannot model strictly zero-conductance walls and ceilings, but rather is 

applying the lowest thermal conductance the simulation allows; does not have perfect iterative 

tolerance limits; etc. 

183
Table 3-1. Participating Organizations and Models 

Simulation 

Program Authoring Organization Implemented by Abbreviation 

EnergyPlus 

2.1.0.012 

LBNL/UIUC/DOE-BT,a,b,c United 

States 

GARD Analytics, Inc., United 

States 

EnergyPlus/GARD 

ESP-r ESRU,d

 United Kingdom ESRU,d United Kingdom ESP-r/ESRU 

HTB2 WSA,e

 United Kingdom WSA, e United Kingdom HTB2/WSA 

TRNSYS-TUD University of Wisconsin/Dresden 

University of Technology, United 

States/Germany 

Dresden University of 

Technology, Germany 

TRNSYS-TUD/TUD 

TRNSYS-16 University of Wisconsin, United 

States 

University of Liège, Belgium TRNSYS-16/ULg 

VA114 2.25 VABI Software BV, The 

Netherlands 

VABI Software BV, The 

Netherlands 

VA114-CirBm/VABI 

VA114-CirDf/VABI 

Simulation 

Program 

(MZ320 Only) Authoring Organization Implemented by 

 

Abbreviation 

CODYRUN University of Reunion Island, 

France 

University of Reunion Island, 

France 

UR 

COMFIE EdMP/IZUBA,f,g France EdMP,f

 France EdMP 

KoZiBu INSA-Lyon/JNLOG,h,i JNLOG,i

 France JNLOG 

a

LBNL: Lawrence Berkeley National Laboratory, United States 

b

UIUC: University of Illinois Urbana/Champaign, United States c

DOE-BT: U.S. Department of Energy, Office of Building Technologies, Energy Efficiency and Renewable Energy, United 

States d

ESRU: Energy Systems Research Unit, University of Strathclyde, United Kingdom 

e

Welsh School of Architecture, Cardiff University, United Kingdom 

f

Ecole des Mines de Paris, France 

g

IZUBA Energies, France 

h

INSA-Lyon Thermal Center, France 

i

Jean Noel, France

3.3 Further Comments on Results for Multi-Zone Shading Cases MZ340, 

MZ350, and MZ355 

For the shading cases, the fundamental level of disagreement for transmitted solar radiation when 

a shading device is present begins with the disagreement for incident solar radiation, which is 

caused by differences among basic solar processing algorithms. The “delta” shading plots (for 

sensitivity cases MZ350–MZ340 and MZ355–MZ340) isolate differences among shading models. 

Absolute differences among programs in incident solar calculations tend to cancel out in this type 

of comparison. For comparison plots showing absolute transmitted solar radiation with shading 

present (cases MZ350 and MZ355), disagreements are related to both basic solar processing and 

shading models. 

184
Only EnergyPlus and VA114 were able to run Case MZ355 for building self-shading. For those 

cases the annual results shown in this section for zones A, B, D, and E match the results for Case 

MZ350 exactly, except for minor differences for VA114 that are noticeable in the tables but not 

in the graphs. For EnergyPlus the hourly results for Case MZ355 exactly match those for Case 

MZ350 (see MZ- RESULTS-Hourlies.XLS sheet tab “EnergyPlus”), and were unnecessary to 

include in the graphs because they would exactly overlay the MZ350 results. For VA114 the only 

instance where hourly results required for Case MZ355 do not exactly match those for Case 

MZ350 are for March 15, hour 16, for Zone A only. (Also see Section 2.4.4.7 and MZRESULTS-Hourlies.XLS sheet tabs “VA114-CirBm” and “VA114-CirDf”.) These VA114 results 

are included in the graph with header “BESTEST Multi-Zone: MZ350–MZ340, Delta HighBeam-Day Shading, March 15 (high dn) Hourly Shaded Solar, Zone A (Less Shaded).” All other 

results for VA114 for Case MZ355 were unnecessary to include in the graphs because they would 

exactly overlay the VA114 MZ350 results.

3.4 Results Graphs and Tables

This section presents graphs of all results followed by results tables. A full set of hourly results 

graphs is provided; however, summary tables of hourly results are too cumbersome to provide in 

printed format here, but are available electronically in Sheet A of MZ-RESULTS-Hourlies.XLS. 

The results tables include dates and hours of occurrences for hourly maxima and minima; times 

of occurrence are not indicated in the graphs depicting hourly maxima and minima. 

See Section 2.7 of Part II for definitions of the abbreviations and acronyms used in the graphs and 

tables. Case descriptions are summarized in Table 1-1 of Part I. 

185
 

IEA BESTEST Multi-Zone: MZ320 

Steady-State Zone C Sensible Cooling Load

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

Zone C

Sensible Cooling Load (W or Wh/h)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg COMFIE/EdMP

ESP-r/ESRU CODYRUN/UR VA114/VABI EnergyPlus/GARD

KoZiBu/JNLOG Analytical

IEA BESTEST Multi-Zone: MZ320 

Steady State Zone Air Temperatures 

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

Zone A Zone B Zone C

Temperature (°C)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg COMFIE/EdMP

ESP-r/ESRU CODYRUN/UR VA114/VABI EnergyPlus/GARD

KoZiBu/JNLOG Analytical

186
IEA BESTEST Multi-Zone: MZ340 

Annual Incident Total Solar Radiation, Facing West

0

100

200

300

400

500

600

700

800

900

Total (IA) Beam (IbA) Diffuse (IdA)

Incident Solar Radiation (kWh/m2

)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg ESP-r/ESRU

VA114-CirBm/VABI VA114-CirDf/VABI EnergyPlus/GARD

IEA BESTEST Multi-Zone: MZ340, MZ350, MZ355 

Annual Transmitted TOTAL Solar Radiation, All Zones

0

2000

4000

6000

8000

10000

12000

14000

MZ340 MZ350, MZ355

Zone B

MZ350, MZ355

Zone E

MZ350, MZ355

Zone A

MZ350, MZ355

Zone D

 MZ350 

Zone C

 MZ350 

Zone F

Transmitted Solar Radiation (kWh)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg

ESP-r/ESRU VA114-CirBm/VABI VA114-CirDf/VABI

EnergyPlus/GARD VA114-CirBm-MZ355/VABI VA114-CirDf-MZ355/VABI

EnergyPlus-MZ355/GARD

187
IEA BESTEST Multi-Zone: MZ340, MZ350, MZ355 

Annual Transmitted BEAM Solar Radiation, All Zones

0

2000

4000

6000

8000

10000

12000

14000

MZ340 MZ350, MZ355

Zone B

MZ350, MZ355

Zone E

MZ350, MZ355

Zone A

MZ350, MZ355

Zone D

 MZ350 

Zone C

 MZ350 

Zone F

Transmitted Solar Radiation (kWh)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg

ESP-r/ESRU VA114-CirBm/VABI VA114-CirDf/VABI

EnergyPlus/GARD VA114-CirB 355/ m-MZ VABI VA114-CirDf-MZ355/VABI

EnergyPlus-MZ355/GARD

IEA BESTEST Multi-Zone: MZ340, MZ350, MZ355 

Annual Transmitted DIFFUSE Solar Radiation, All Zones

0

2000

4000

6000

8000

10000

12000

14000

MZ340 MZ350, MZ355

Zone B

MZ350, MZ355

Zone E

MZ350, MZ355

Zone A

MZ350, MZ355

Zone D

 MZ350 

Zone C

 MZ350 

Zone F

Transmitted Solar Radiation (kWh)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg

ESP-r/ESRU VA114-CirBm/VABI VA114-CirDf/VABI

EnergyPlus/GARD VA114-CirBm-MZ355/VABI VA114-CirDf-MZ355/VABI

EnergyPlus-MZ355/GARD

188
IEA BESTEST Multi-Zone: MZ340, MZ350, MZ355 

Annual Sensible Cooling Load, Building

0

10000

20000

30000

40000

50000

60000

70000

80000

90000

MZ340 MZ350a MZ350b MZ350c MZ350d MZ355

Sensible Cooling Load (kWh)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg ESP-r/ESRU

VA114-CirBm/VABI VA114-CirDf/VABI EnergyPlus/GARD

MZ355 should be different from MZ350 for 

Qbldg, because Zones C, F have no load.

IEA BESTEST Multi-Zone: MZ340, MZ350, MZ355 

Annual Sensible Cooling Load, All Zones

0

2000

4000

6000

8000

10000

12000

14000

MZ340 MZ350, MZ355

Zone B

MZ35

Z

Z355 MZ350, MZ355

Zone D

 MZ350 

Zone F

Sensible Cooling Load (kWh)

0, MZ355

one E

MZ350, M

Zone A

 MZ350 

Zone C

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg

ESP-r/ESRU VA114-CirBm/VABI VA114-CirDf/VABI

EnergyPlus/GARD VA114-CirBm-MZ355/VABI VA114-CirDf-MZ355/VABI

EnergyPlus-MZ355/GARD

189
IEA BESTEST Multi-Zone: MZ340, MZ350, MZ355 

Annual Hourly Integrated Peak Cooling Load, All Zones

0

2000

4000

6000

8000

10000

12000

14000

16000

MZ340 MZ350, MZ355

Zone B

M MZ355

 A

MZ350, MZ

Zone D

 MZ350 

Zone F

Cooling Load (Wh/h)

Z350, MZ355

Zone E

MZ350,

Zone

355 MZ350 

Zone C

HTB2/WSA TRNSYS/TUD TRNSYS/ULg

ESP-r/ESRU VA114-CirBm/VABI VA114-CirDf/VABI

EnergyPlus/GARD VA114-CirBm-MZ355/VABI VA114-CirDf-MZ355/VABI

EnergyPlus-MZ355/GARD

 

IEA BESTEST Multi-Zone: MZ340, MZ350, MZ355 

Annual Hourly-Integrated Peak Sensible Cooling Load, Building

0

10000

20000

30000

40000

50000

60000

70000

80000

90000

MZ340 MZ350a MZ350b MZ350c MZ350d MZ355

Sensible Cooling Load (Wh/h)

HTB2/WSA TRNSYS/TUD TRNSYS/ULg ESP-r/ESRU

VA114-CirBm/VABI VA114-CirDf/VABI EnergyPlus/GARD

190
IEA BESTEST Multi-Zone: MZ340, MZ350, MZ355 

Annual Mean Air Temperature, All Zones

0

5

10

15

20

25

MZ340 MZ350, MZ355

Zone B

MZ350, MZ355

Zone E

MZ350, MZ355

Zone A

MZ350, MZ355

Zone D

 MZ350 

Zone C

 MZ350 

Zone F

Temperature (°C)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg

ESP-r/ESRU VA114-CirBm/VABI VA114-CirDf/VABI

EnergyPlus/GARD VA114-CirBm-MZ355/VABI VA114-CirDf-MZ355/VABI

EnergyPlus-MZ355/GARD

IEA BESTEST Multi-Zone: MZ340, MZ350, MZ355 

Annual Maximum Air Temperature, All Zones

0

5

10

15

20

25

MZ340 MZ350, MZ355

Zone B

MZ350, MZ355

Zone E

MZ350, MZ355

Zone A

MZ350, MZ355

Zone D

 MZ350 

Zone C

 MZ350 

Zone F

Temperature (°C)

HTB2/WSA TRNSYS/TUD TRNSYS/ULg

ESP-r/ESRU VA114-CirBm/VABI VA114-CirDf/VABI

EnergyPlus/GARD VA114-CirBm-MZ355/VABI VA114-CirDf-MZ355/VABI

EnergyPlus-MZ355/GARD

191
IEA BESTEST Multi-Zone: MZ350-MZ340, MZ355-MZ340 

Delta Annual Shaded TOTAL Solar Radiation, All Zones

-7000

-6000

-5000

-4000

-3000

-2000

-1000

0

one Zone C Zone F

Shaded Solar Radiation (kWh)

Zone B Z E Zone A Zone D

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg

ESP-r/ESRU VA114-CirBm/VABI VA114-CirDf/VABI

EnergyPlus/GARD VA114-CirBm-MZ355/VABI VA114-CirDf-MZ355/VABI

EnergyPlus-MZ355/GARD

 

 

IEA BESTEST Multi-Zone: MZ350-MZ340, MZ355-MZ340 

Delta Annual Shaded BEAM Solar Radiation, All Zones

-7000

-6000

-5000

-4000

-3000

-2000

-1000

0

Zone B Zone E Zone A Zone D Zone C Zone F

Shaded Solar Radiation (kWh)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg

ESP-r/ESRU VA114-CirBm/VABI VA114-CirDf/VABI

EnergyPlus/GARD VA114-CirBm-MZ355/VABI VA114-CirDf-MZ355/VABI

EnergyPlus-MZ355/GARD

192
IEA BESTEST Multi-Zone: MZ350-MZ340, MZ355-MZ340 

Delta Annual Shaded DIFFUSE Solar Radiation, All Zones

-7000

-6000

-5000

-4000

-3000

-2000

-1000

0

Zone B Zone E Zone A Zone D Zone C Zone F

Shaded Solar Radiation (kWh)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg

ESP-r/ESRU VA114-CirBm/VABI VA114-CirDf/VABI

EnergyPlus/GARD VA114-CirBm-MZ355/VABI VA114-CirDf-MZ355/VABI

IEA BESTEST Multi-Zone: MZ350/MZ340 

Annual Shaded/Unshaded Transmitted Solar Ratios, All Zones

0.000

0.100

0.200

0.300

0.400

0.500

0.600

0.700

0.800

0.900

1.000

Zone

B

Zone

E

Zone

A

Zone

D

Zone

C

Zone

F

Zone

B

Zone

E

Zone

A

Zone

D

Zone

C

Zone

F

Zone

B

Zone

E

Zone

A

Zone

D

Zone

C

Zone

F

Transmitted Solar Radiation Ratio (Dimensionless)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg ESP-r/ESRU

VA114-CirBm/VABI VA

E 355/GARD

TOTAL BEAM DIFFUSE 

nergyPlus-MZ

114-CirDf/VABI EnergyPlus/GARD

193
IEA BESTEST Multi-Zone: MZ350-MZ340, MZ355-MZ340 

Delta Annual Cooling Load, All Zones

-7000

-6000

-5000

-4000

-3000

-2000

-1000

0

Zone B Zone E Zone A Zone D Zone C Zone F

Shaded Solar Radiation (kWh)

Matches “Delta Annual Shaded 

TOTAL Solar Radiation, All Zones” 

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg

ESP-r/ESRU VA114-CirBm/VABI VA114-CirDf/VABI

EnergyPlus/GARD VA114-CirBm-MZ355/VABI VA114-CirDf-MZ355/VABI

EnergyPlus-MZ355/GARD

 

IEA BESTEST Multi-Zone: MZ350-MZ340, MZ355-MZ340

Delta Annual Sensible Cooling Load, Building

-50000

-45000

-40000

-35000

-30000

-25000

-20000

-15000

-10000

-5000

0

MZ350a-MZ340 MZ350b-MZ340 MZ350c-MZ340 MZ350d-MZ340 MZ355-MZ340

Sensible Cooling Load (kWh)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg ESP-r/ESRU

VA114-CirBm/VABI VA114-CirDf/VABI EnergyPlus/GARD

194
IEA BESTEST Multi-Zone: MZ350-MZ340, MZ355-MZ340 

Delta Annual Hourly Integrated Peak Cooling Load, All Zones

-12000

-10000

-8000

-6000

-4000

-2000

0

Zone B Zone E Zone A Zone D Zone C Zone F

Cooling Load (Wh/h)

HTB2/WSA

Peak loads occur when shading is minimal, 

about 12000 Wh/h for each zone; y-axis 

made “large” to appropriately scale the 

relative differences shown here. 

TRNSYS-TUD/TUD TRNSYS-16/ULg

ESP-r/ESRU VA114-CirBm/VABI VA114-CirDf/VABI

EnergyPlus/GARD VA114-CirBm-MZ355/VABI VA114-CirDf-MZ355/VABI

EnergyPlus-MZ355/GARD

 

IEA BESTEST Multi-Zone: MZ350-MZ340, MZ355-MZ340 

Delta Annual Hourly-Integrated Peak Sensible Cooling Load, Building

-80000

-70000

-60000

-50000

-40000

-30000

-20000

-10000

0

MZ350a-MZ340 MZ350b-MZ340 MZ350c-MZ340 MZ350d-MZ340 MZ355-MZ340

Sensible Cooling Load (Wh/h)

Peak loads occur when shading is minimal, 

about 72000 Wh/h for the building; y-axis 

made “large” to appropriately scale the 

relative differences shown here. 

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg ESP-r/ESRU

VA114-CirBm/VABI VA114-CirDf/VABI EnergyPlus/GARD

195
BESTEST Multi-Zone: MZ340 Unshaded

March 15 (high dn) Hourly Transmitted Solar, Zone A

0

2000

4000

6000

8000

10000

12000

14000

1 5 6 7 8 14 15 16 22 23 24

Transmitted Solar Radiation (Wh/h)

2 3 4 9 10 11 12 13 17 18 19 20 21

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

BESTEST Multi-Zone: MZ340 Unshaded

March 15 (high dn) Hourly Sensible Cooling Load, Zone A

0

2000

4000

6000

8000

10000

12000

14000

1 5 6 7 8 14 15 16 22 23 24

Cooling Load (Wh/h)

2 3 4 9 10 11 12 13 17 18 19 20 21

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

196
BESTEST Multi-Zone: MZ340 Unshaded

August 4 TOTAL Hourly Transmitted Solar, Zone A

0

2000

4000

6000

8000

10000

12000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Transmitted Solar Radiation (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

BESTEST Multi-Zone: MZ340 Unshaded

BEAM Hourly itted Solar, Zo

0

2000

4000

6000

8000

10000

12000

1 2 3 4 5 6 1 12 17 18 22 23 24

Transmitted Solar Radiation (Wh/h)

August 4 Transm ne A

7 8 9 10 1 13 14 15 16 19 20 21

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

197
BESTEST Multi-Zone: MZ340 Unshaded

August 4 DIFFUSE Hourly Transmitted Solar, Zone A

0

2000

4000

6000

8000

10000

12000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Transmitted Solar Radiation (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

BESTEST Multi-Zone: MZ340 Unshaded

October 14 (low dn) Hourly Transmitted Solar, Zone A

0

2000

4000

6000

8000

10000

12000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Transmitted Solar Radiation (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

198
BESTEST Multi-Zone: MZ350-MZ340, Delta High-Beam-Day Shading

March 15 (high dn) Hourly Shaded Solar, Zone B (Most Shaded)

-14000

-12000

-10000

-8000

-6000

-4000

-2000

0

1 2 3 4 5 6 1 12 17 1 22 23 24

Shaded Solar Radiation (Wh/h)

7 8 9 10 1 13 14 15 16 8 19 20 21

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

BESTEST Multi-Zone: MZ350-MZ340, Delta High-Beam-Day Shading

March 15 (high dn) Hourly Shaded Solar, Zone E (More Shaded)

-14000

-12000

-10000

-8000

-6000

-4000

-2000

0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Shaded Solar Radiation (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

199
VA114’s MZ355 results only vary 

versus MZ350 for Hour 16, and 

only for Zone A. All other MZ355 

hourly results for VA114 and all 

results for EnergyPlus exactly 

match their MZ350 results. 

BESTEST Multi-Zone: MZ350-MZ340, Delta High-Beam-Day Shading

March 15 (high dn) Hourly Shaded Solar, Zone A (Less Shaded)

-14000

-12000

-10000

-8000

-6000

-4000

-2000

0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Shaded Solar Radiation (Wh/h)

EnergyPlus/GARD

 

BESTEST Multi-Zone: MZ350-MZ340, Delta High-Beam-Day Shading

March 15 (high dn) Hourly Shaded Solar, Zone D (Least Shaded)

-14000

-12000

-10000

-8000

-6000

-4000

-2000

0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Shaded Solar Radiation (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

ESP-r/ESRU HTB2/WSA

TRNSYS-TUD/TUD TRNSY /ULg S-16 VA114-CirDf/VABI

VA114-CirBm/VABI VA114 f-MZ355/ -CirD VABI VA114-CirBm-MZ355/VABI

200
201

BESTEST Multi-Zone: MZ350-MZ340, Delta High-Beam-Mid-PM

August 4 Hourly Shaded Solar, Zone C (Back Side Shade)

-14000

-12000

-10000

-8000

-6000

-4000

-2000

0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Shaded Solar Radiation (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

BESTEST Multi-Zone: MZ350-MZ340, Delta High-Beam-Mid-PM

August 4 Hourly Shaded Solar, Zone F (Back Side Shade)

-14000

-12000

-10000

-8000

-6000

-4000

-2000

0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Shaded Solar Radiation (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI
BESTEST Multi-Zone: MZ350-MZ340, Delta High-Diffuse-Day Shading

October 14 (low dn) Hourly Shaded Solar, Zone B (Most Shaded)

-2000

-1800

-1600

-1400

-1200

-1000

-800

-600

-400

-200

0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Shaded Solar Radiation (Wh/h)

EnergyPlus/GARD

 

ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

BESTEST Multi-Zone: MZ350-MZ340, Delta High-Diffuse-Day Shading

October 14 (low dn) Hourly Shaded Solar, Zone E (More Shaded)

-2000

-1800

-1600

-1400

-1200

-1000

-800

-600

-400

-200

0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Shaded Solar Radiation (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

202
BESTEST Multi-Zone: MZ350-MZ340, Delta High-Diffuse-Day Shading

October 14 (low dn) Hourly Shaded Solar, Zone A (Less Shaded)

-2000

-1800

-1600

-1400

-1200

-1000

-800

-600

-400

-200

0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Shaded Solar Radiation (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

 

BESTEST Multi-Zone: MZ350-MZ340, Delta High-Diffuse-Day Shading

October 14 (low dn) Hourly Shaded Solar, Zone D (Least Shaded)

-2000

-1800

-1600

-1400

-1200

-1000

-800

-600

-400

-200

0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Shaded Solar Radiation (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

203
 

BESTEST Multi-Zone: MZ350-MZ340, Delta High-Diffuse-Day Shading

October 14 (low dn) Hourly Shaded Solar, Zone C (Back Side Shade)

-2000

-1800

-1600

-1400

-1200

-1000

-800

-600

-400

-200

0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Shaded Solar Radiation (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

BESTEST Multi-Zone: MZ350-MZ340, Delta High-Diffuse-Day Shading

October 14 (low dn) Hourly Shaded Solar, Zone F (Back Side Shade)

-2000

-1800

-1600

-1400

-1200

-1000

-800

-600

-400

-200

0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Shaded Solar Radiation (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

204
BESTEST Multi-Zone: MZ350 ABSOLUTE High-Beam Day

March 15 (high dn) Hourly Cooling Load, Zone B (Most Shaded)

0

1000

2000

3000

4000

5000

6000

7000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Cooling Load (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

MZ350 cooling loads = transmitted solar, 

see graph below 

BESTEST Multi-Zone: MZ350 ABSOLUTE High-Beam Day

March 15 (high dn) Hourly Transmitted Solar, Zone B (Most Shaded)

0

1000

2000

3000

4000

5000

6000

7000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Transmitted Solar Radiation (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

205
BESTEST Multi-Zone: MZ350 ABSOLUTE High-Diffuse Day

October 14 (high diffuse) Hourly Cooling Load, Zone B (Most Shaded)

0

1000

2000

3000

4000

5000

6000

7000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Cooling Load (Wh/h)

MZ350 cooling loads = transmitted solar, 

see graph below 

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

BESTEST Multi-Zone: MZ350 ABSOLUTE High-Beam Day

October 14 (high diff.) Hourly Transmitted Solar, Zone B (Most Shaded)

0

1000

2000

3000

4000

5000

6000

7000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Transmitted Solar Radiation (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

206
207

IEA BESTEST Multi-Zone: MZ360 

Annual Incident & Transmitted Solar Radiation

0

20000

40000

60000

80000

100000

120000

140000

SW Inc. x

11.8^2, I

Zone A,

ItrA

Zone B,

ItrB

Zone C,

ItrC

SW Inc. x

11.8^2, Ib

Zone A,

ItrbA

Zone B,

ItrbB

Zone C,

ItrbC

SW Inc. x

11.8^2, Id

Zone A,

ItrdA

Zone B,

ItrdB

Zone C,

ItrdC

Solar Radiation (kWh)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg ESP-r/ESRU

VA114-CirBm/VABI VA114-CirDf/VABI EnergyPlus/GARD

 

IEA BESTEST Multi-Zone: MZ360 

Transmitted Solar Radiation Ratios

0.000

0.100

0.200

0.300

0.400

0.500

0.600

0.700

0.800

Zones B/A 

(ItrB/ItrA)

Zones C/B

(ItrC/ItrB)

Zones C/A

(ItrC/ItrA)

Zones B/A

(ItrbB/ItrbA)

Zones C/B

(ItrbC/ItrbB)

Zones C/A

(ItrbC/ItrbA)

Zones B/A

(ItrdB/ItrdA)

Zones C/B

(ItrdC/ItrdB)

Zones C/A

(ItrdC/ItrdA)

Transmitted Solar Radiation Ratio (Dimensionless)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg ESP-r/ESRU

VA114-CirBm/VABI VA114-CirDf/VABI EnergyPlus/GARD

TOTAL BEAM DIFFUSE 

TOTAL BEAM DIFFUSE 
IEA BESTEST Multi-Zone: MZ360 

Annual Sensible Cooling Loads

0

20000

40000

60000

80000

100000

120000

140000

Building, Qbldg Zone A, QA Zone B, QB Zone C, QC QB + QC

Sensible Cooling Load (kWh)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg ESP-r/ESRU

VA114-CirBm/VABI VA114-CirDf/VABI EnergyPlus/GARD

IEA BESTEST Multi-Zone: MZ360 

Annual Hourly Integrated Peak Sensible Cooling Loads

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

200000

Building, qmax,bldg Zone A, qmax,A Zone B, qmax,B Zone C, qmax,C

Sensible Cooling Load (Wh/h)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg ESP-r/ESRU

VA114-CirBm/VABI VA114-CirDf/VABI EnergyPlus/GARD

208
IEA BESTEST Multi-Zone: MZ360 

Annual Mean Zone Temperature

0

5

10

15

20

25

30

Zone A, TA Zone B, TB Zone C, TC

Temperature (°C)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg ESP-r/ESRU

VA114-CirBm/VABI VA114-CirDf/VABI EnergyPlus/GARD

IEA BESTEST Multi-Zone: MZ360 

Annual Hourly Integrated Peak Zone Temperature

0

5

10

15

20

25

30

Zone A, Tmax,A Zone B, Tmax,B Zone C, Tmax,C 

Temperature (°C)

HTB2/WSA TRNSYS-TUD/TUD TRNSYS-16/ULg ESP-r/ESRU

VA114-CirBm/VABI VA114-CirDf/VABI EnergyPlus/GARD

209
BESTEST Multi-Zone: MZ360 Internal Windows

March 15 (high dn) Hourly Transmitted Solar, Window "AO" (Zone A)

0

20000

40000

60000

80000

100000

120000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Transmitted Solar Radiation (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

210

BESTEST Multi-Zone: MZ360 Internal Windows

March 15 (high dn) Hourly Transmitted Solar, Window "AB" (Zone B)

0

20000

40000

60000

80000

100000

120000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Transmitted Solar Radiation (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

EnergyPlus currently does not provide this 

output exactly as specified by the test cases.
211

BESTEST Multi-Zone: MZ360 Internal Windows

March 15 (high dn) Hourly Sensible Cooling Load, Zone B

0

20000

40000

60000

80000

100000

120000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Cooling Load (Wh/h)

EnergyPlus/GARD ESP-r/ESRU TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

HTB2 currently does not model the second 

internal window.

BESTEST Multi-Zone: MZ360 Internal Windows

March 15 (high dn) Hourly Transmitted Solar, Window "BC" (Zone C)

0

20000

40000

60000

80000

100000

120000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Transmitted Solar Radiation (Wh/h)

EnergyPlus/GARD ESP-r/ESRU TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

EnergyPlus currently does not provide this output exactly 

as specified by the test cases. 

HTB2 currently does not model the second internal window.
BESTEST Multi-Zone: MZ360 Internal Windows

October 14 (low dn) Hourly Transmitted Solar, Window "AO" (Zone A)

0

5000

10000

15000

20000

25000

30000

35000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Transmitted Solar Radiation (Wh/h)

212

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

BESTEST Multi-Zone: MZ360 Internal Windows

October 14 (low dn) Hourly Transmitted Solar, Window "AB" (Zone B)

0

5000

10000

15000

20000

25000

30000

35000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Transmitted Solar Radiation (Wh/h)

EnergyPlus/GARD ESP-r/ESRU HTB2/WSA TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

EnergyPlus currently does not provide this 

output exactly as specified by the test cases.
213

BESTEST Multi-Zone: MZ360 Internal Windows

October 14 (low dn) Hourly Sensible Cooling Load, Zone B

0

5000

10000

15000

20000

25000

30000

35000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Cooling Load (Wh/h)

16 17 18 19 20 21 22 23 24

EnergyPlus/GARD ESP-r/ESRU TRNSYS-TUD/TUD

TRNSYS-16/ULg VA114-CirDf/VABI VA114-CirBm/VABI

HTB2 currently does not model the second 

internal window.

BESTEST Multi-Zone: MZ360 Intern

October 14 (low dn) Hourly Transmitted Solar,

0

5000

10000

15000

20000

25000

30000

35000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Transmitted Solar Radiation (Wh/h)

al Windows

 Window "BC" (Zone C)

16 17 18 19 20 21 22 23 24

TRNSYS-16/ULg

EnergyPlus/GARD

VA114-CirDf/VABI

ESP-r/ESRU HTB2/W

VA114-

EnergyPlus currently does not provide this output exactly as 

specified by the test cases.

HTB2 currently does not model the second internal window.

CirBm/VABI

SA TRNSYS-TUD/TUD
Case MZ32

 Sta

0 Steady-State Zone Air Temperatures and Cooling Load

HTB2 TRNSYS-TUD TRNSYS-16 COMFIE ESP-r CODYRUN VA114 EnergyPlus KoZiBu A

214

nalytical 

TA (° 31.06 30

TB (° 24.80 24TC (° 15.00 15qC (Wh/h) 1541 15

WSA TUD U. Liège EdMP ESRU U. Reunion VABI GARD JNLOG

C) 31.06 31.06 30.99 31.06 31.06 31.93 31.10 31.06 31.06C) 24.80 24.80 24.76 24.80 24.80 24.65 24.80 24.80 24.80C) 15.00 15.00 15.00 15.00 15.00 15.00 15.00 15.00 15.00

1541 1541 1546 1541 1541 1517 1541 1541 1541
Summary Tables for Multi-Zone Shading Cases MZ340, MZ350, 

MZ355 

These are compilation summaries of “shading by model” raw results tables, which follow after 

the summary tables. 

 

MZ340, MZ350, MZ355 Calorimetry, Annual Sensible Cooling Load Summary: Zones, Building

Annual Sensible Cooling Load, Q (kWh/y) Statistics, All Results

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus (Max-Min)

WSA TUD U. Liège ESRU VABI VABI GARD Min Max /Mean

MZ340, Zone A 12353 12454 12501 12290 12846 12849 12431 12290 12849 4.5%

MZ350, Zone B 6247 6319 6317 5867 6425 6671 6052 5867 6671 12.8%

MZ350, Zone E 6460 6535 6534 6098 6685 6895 6291 6098 6895 12.3%

MZ350, Zone A 8337 8338 8323 8011 8625 8730 8258 8011 8730 8.6%

MZ350, Zone D 8702 8714 8696 8404 9044 9113 8642 8404 9113 8.1%

MZ350, Zone C 8567 8634 8667 8485 9388 8873 9193 8485 9388 10.2%

MZ350, Zone F 8639 8708 8732 8582 9452 8935 9264 8582 9452 9.8%

MZ355, Zone B 6420 6668 6053 6053 6668 9.6%

MZ355, Zone E 6685 6895 6291 6291 6895 9.1%

MZ355, Zone A 8620 8726 8259 8259 8726 5.5%

MZ355, Zone D 9034 9106 8642 8642 9106 5.2%

MZ340, Building 74117 74725 75005 73741 77079 77092 74585 73741 77092 4.5%

MZ350, Building 46953 47249 47268 45447 49619 49217 47701 45447 49619 8.8%

MZ355, Building 30802 31437 29245 29245 31437 7.2%

215

Note: sum of individual zone peak loads is greater than building peak load because individual 

zone peak loads are non-coincident whereas overall building peak load is based on coincident 

zone loads.

MZ340, MZ350, MZ355 Calorimetry, Annual Peak Cooling Load Summary: Zones, Building

Annual Peak Cooling Load, q (Wh/h) Statistics, All Results

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus (Max-Min)

WSA TUD U. Liège ESRU VABI VABI GARD Min Max /Mean

MZ340, Zone A 12197 12164 12254 12586 12839 12839 12609 12164 12839 5.4%

MZ350, Zone B 11015 11556 11652 11413 12550 12242 12001 11015 12550 13.0%

MZ350, Zone E 11020 11572 11652 11483 12556 12256 12004 11020 12556 13.0%

MZ350, Zone A 11658 11633 12134 12005 12654 12427 12395 11633 12654 8.4%

MZ350, Zone D 11666 11642 12142 12020 12666 12453 12399 11642 12666 8.4%

MZ350, Zone C 12017 11981 12056 11111 12532 12176 12400 11111 12532 11.8%

MZ350, Zone F 12019 11983 12059 11118 12535 12182 12401 11118 12535 11.8%

MZ355, Zone B 12550 12241 12001 12001 12550 4.5%

MZ355, Zone E 12556 12256 12004 12004 12556 4.5%

MZ355, Zone A 12654 12427 12395 12395 12654 2.1%

MZ355, Zone D 12666 12453 12399 12399 12666 2.1%

MZ340, Building 73182 72982 73525 75516 77028 77028 75652 72982 77028 5.4%

MZ350, Building 67053 69095 70006 67652 75426 73737 71278 67053 75426 11.9%

MZ355, Building 50424 49378 48156 48156 50424 4.6%
MZ350-MZ340, MZ355-MZ340 Delta Annual Cooling Load Summary: Zones, Building

Delta Annual Cooling Load, del Q (kWh/y) Statistics, All Results

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus (Max-Min)

WSA TUD U. Liège ESRU VABI VABI GARD Min Max /Mean

MZ350-MZ340, Zone B -6106 -6135 -6184 -6423 -6422 -6178 -6378 -6423 -6106 -5.1%

MZ350-MZ340, Zone E -5893 -5919 -5967 -6192 -6161 -5954 -6140 -6192 -5893 -5.0%

MZ350-MZ340, Zone A -4015 -4116 -4178 -4279 -4221 -4119 -4173 -4279 -4015 -6.3%

MZ350-MZ340, Zone D -3650 -3741 -3805 -3886 -3802 -3736 -3789 -3886 -3650 -6.2%

MZ350-MZ340, Zone C -3786 -3820 -3834 -3805 -3458 -3976 -3238 -3976 -3238 -19.9%

MZ350-MZ340, Zone F -3714 -3746 -3769 -3708 -3394 -3914 -3166 -3914 -3166 -20.6%

MZ355-MZ340, Zone B -6427 -6181 -6378 -6427 -6181 -3.9%

MZ355-MZ340, Zone E -6161 -5954 -6140 -6161 -5954 -3.4%

MZ355-MZ340, Zone A -4226 -4123 -4172 -4226 -4123 -2.5%

MZ355-MZ340, Zone D -3812 -3743 -3788 -3812 -3743 -1.8%

MZ350-MZ340, Building -27164 -27476 -27737 -28294 -27460 -27875 -26884 -28294 -26884 -5.1%

MZ355-MZ340, Building -46277 -45655 -45340 -46277 -45340 -2.0%

 

MZ350-MZ340, MZ355-MZ340, Delta Hourly Annual Peak Cooling Load Summary: Zones, Building 

Delta Annual Peak Cooling Load, del q (Wh/h) Statistics, All Results

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus (Max-Min)

WSA TUD U. Liège ESRU VABI VABI GARD Min Max /Mean

MZ350-MZ340, Zone B -1183 -608 -602 -1173 -289 -597 -608 -1183 -289 -123.6%

MZ350-MZ340, Zone E -1177 -592 -602 -1103 -282 -582 -605 -1177 -282 -126.8%

MZ350-MZ340, Zone A -539 -531 -121 -581 -185 -412 -214 -581 -121 -124.8%

MZ350-MZ340, Zone D -531 -522 -112 -566 -172 -385 -210 -566 -112 -127.3%

MZ350-MZ340, Zone C -180 -183 -198 -1475 -307 -662 -209 -1475 -180 -281.9%

MZ350-MZ340, Zone F -178 -181 -195 -1468 -303 -656 -208 -1468 -178 -283.1%

MZ355-MZ340, Zone B -289 -598 -608 -608 -289 -64.0%

MZ355-MZ340, Zone E -282 -582 -605 -605 -282 -66.0%

MZ355-MZ340, Zone A -185 -412 -214 -412 -185 -84.0%

MZ355-MZ340, Zone D -172 -385 -210 -385 -172 -83.4%

MZ350-MZ340, Building -6129 -3887 -3519 -7864 -1602 -3291 -4374 -7864 -1602 -142.9%

MZ355-MZ340, Building -26604 -27650 -27496 -27650 -26604 -3.8%

Note: absolute value of sum of individual zone peak load differences is less than absolute value of 

building peak load difference because individual zone peak loads are non-coincident whereas 

overall building peak load is based on coincident zone loads (as noted on previous page).

216
MZ340 West-Facing Annual Incident Solar Radiation: Total, Beam, Diffuse

West-Facing Incident Solar, I (kWh/(m2y)) Statistics, All Results

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus (Max-Min)

WSA TUD U. Liège ESRU VABI VABI GARD Min Max /Mean

Total (IA) 772 778 781 768 804 804 782 768 804 4.6%

Beam (IbA) 371 371 361 361 361 369 361 371 2.8%

Diffuse (IdA) 408 411 408 443 443 414 408 443 8.4%

MZ340, MZ350, MZ355 Annual Transmitted Solar Summary: Total, Beam, Diffuse

Annual Transmitted TOTAL Solar, Itr (kWh/y) Statistics, All Results

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus (Max-Min)

WSA TUD U. Liège ESRU VABI VABI GARD Min Max /Mean

MZ340, Zone A 12353 12454 12504 12290 12844 12847 12429 12290 12847 4.4%

MZ350, Zone B 6247 6319 6317 5867 6423 6669 6052 5867 6669 12.8%

MZ350, Zone E 6460 6535 6534 6098 6683 6893 6290 6098 6893 12.2%

MZ350, Zone A 8337 8338 8323 8011 8623 8728 8257 8011 8728 8.6%

MZ350, Zone D 8702 8714 8696 8404 9041 9111 8641 8404 9111 8.1%

MZ350, Zone C 8567 8634 8667 8485 9386 8871 9192 8485 9386 10.2%

MZ350, Zone F 8639 8708 8732 8582 9450 8932 9263 8582 9450 9.8%

MZ355, Zone B 6418 6666 6052 6052 6666 9.6%

MZ355, Zone E 6683 6893 6290 6290 6893 9.1%

MZ355, Zone A 8618 8724 8257 8257 8724 5.5%

MZ355, Zone D 9032 9104 8641 8641 9104 5.2%

Annual Transmitted BEAM Solar, Itrb (kWh/y) Statistics, All Results

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus (Max-Min)

WSA TUD U. Liège ESRU VABI VABI GARD Min Max /Mean

MZ340, Zone A 5894 5933 5930 5768 5769 5769 5875 5768 5933 2.8%

MZ350, Zone B 2426 2431 2397 2397 2385 2385 2428 2385 2431 1.9%

MZ350, Zone E 2574 2579 2546 2541 2537 2537 2574 2537 2579 1.6%

MZ350, Zone A 3674 3625 3572 3556 3531 3531 3613 3531 3674 4.0%

MZ350, Zone D 3919 3873 3816 3796 3782 3782 3857 3782 3919 3.6%

MZ350, Zone C 5032 5056 5060 4602 4911 4911 4988 4602 5060 9.3%

MZ350, Zone F 5068 5095 5089 4631 4939 4939 5026 4631 5095 9.3%

MZ355, Zone B 2382 2382 2428 2382 2428 1.9%

MZ355, Zone E 2537 2537 2574 2537 2574 1.5%

MZ355, Zone A 3527 3527 3613 3527 3613 2.4%

MZ355, Zone D 3774 3774 3857 3774 3857 2.2%

Annual Transmitted DIFFUSE Solar, Itrd (kWh/y) Statistics, All Results

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus (Max-Min)

WSA TUD U. Liège ESRU VABI VABI GARD Min Max /Mean

MZ340, Zone A 6459 6521 6574 6522 7076 7078 6554 6459 7078 9.3%

MZ350, Zone B 3821 3888 3919 3470 4038 4284 3623 3470 4284 21.1%

MZ350, Zone E 3885 3956 3988 3557 4146 4355 3716 3557 4355 20.2%

MZ350, Zone A 4664 4713 4751 4455 5092 5197 4645 4455 5197 15.5%

MZ350, Zone D 4784 4841 4880 4608 5259 5329 4784 4608 5329 14.6%

MZ350, Zone C 3535 3578 3607 3883 4475 3960 4204 3535 4475 24.1%

MZ350, Zone F 3570 3614 3643 3951 4511 3994 4238 3570 4511 23.9%

MZ355, Zone B 4036 4284 3623 3623 4284 16.6%

MZ355, Zone E 4146 4355 3716 3716 4355 15.7%

MZ355, Zone A 5091 5197 4645 4645 5197 11.1%

MZ355, Zone D 5258 5329 4784 4784 5329 10.6%

217
218

MZ350-MZ340, MZ355-MZ340, Delta Annual Shaded Solar: Total, Beam, Diffuse 

Annual Shaded TOTAL, del Itr (kWh/y) Statistics, All Results

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus (Max-Min)

WSA TUD U. Liège ESRU VABI VABI GARD Min Max /Mean

MZ350-MZ340, Zone B -6106 -6135 -6187 -6423 -6421 -6178 -6377 -6423 -6106 -5.1%

MZ350-MZ340, Zone E -5893 -5919 -5970 -6192 -6161 -5954 -6139 -6192 -5893 -5.0%

MZ350-MZ340, Zone A -4015 -4116 -4181 -4279 -4221 -4119 -4172 -4279 -4015 -6.3%

MZ350-MZ340, Zo -3736 -3788 -3886 -3650 -6.2%

MZ350-MZ340, Zo -3976 -3237 -3976 -3237 -20.0%

MZ350-MZ340, Zo 6 -3772 -3708 -3394 -3915 -3165 -3915 -3165 -20.6%

MZ355-MZ340, Zo -6426 -6181 -6377 -6426 -6181 -3.9%

MZ355-MZ340, Zone E -6161 -5954 -6139 -6161 -5954 -3.4%

MZ355-MZ340, Zone A -4226 -4123 -4172 -4226 -4123 -2.5%

MZ355-MZ340, Zone D -3812 -3743 -3788 -3812 -3743 -1.8%

Annual Shaded BEAM, del Itrb (kWh/y) Statistics, All Results

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus (Max-Min)

WSA TUD U. Liège ESRU VABI VABI GARD Min Max /Mean

MZ350-MZ340, Zone B -3468 -3502 -3532 -3371 -3384 -3384 -3447 -3532 -3371 -4.7%

MZ350-MZ340, Zone E -3320 -3354 -3384 -3227 -3232 -3232 -3301 -3384 -3227 -4.8%

MZ350-MZ340, Zone A -2220 -2308 -2358 -2212 -2238 -2238 -2262 -2358 -2212 -6.5%

MZ350-MZ340, Zone D -1975 -2060 -2113 -1972 -1987 -1987 -2018 -2113 -1972 -7.0%

MZ350-MZ340, Zone C -862 -877 -870 -1166 -858 -858 -887 -1166 -858 -33.8%

MZ350-MZ340, Zone F -826 -838 -841 -1137 -830 -830 -849 -1137 -826 -35.4%

MZ355-MZ340, Zone B -3387 -3387 -3447 -3447 -3387 -1.8%

MZ355-MZ340, Zone E -3232 -3232 -3301 -3301 -3232 -2.1%

MZ355-MZ340, Zone A -2242 -2242 -2262 -2262 -2242 -0.9%

MZ355-MZ340, Zone D -1995 -1995 -2018 -2018 -1995 -1.1%

Annual Shaded DIFFUSE, del Itrd (kWh/y) Statistics, All Results

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus (Max-Min)

WSA TUD U. Liège ESRU VABI VABI GARD Min Max /Mean

MZ350-MZ340, Zone B -2638 -2633 -2655 -3052 -3038 -2794 -2930 -3052 -2633 -14.8%

MZ350-MZ340, Zone E -2573 -2565 -2586 -2965 -2930 -2838 -2965 -2565 -14.6%

MZ350-MZ340, Zone A -1795 -1808 -1823 -2067 -1984 -1909 -2067 -1795 -14.4%

MZ350-MZ340, Zone D -1675 -1681 -1694 -1914 -1817 -1770 -1914 -1675 -13.6%

MZ350-MZ340, Zone C -2924 -2943 -2967 -2639 -2601 -2350 -3118 -2350 -27.5%

MZ350-MZ340, Zone F -2889 -2907 -2931 -2571 -2565 -2316 -3084 -2316 -27.9%

MZ355-MZ340, Zone B -3040 2794 -2930 -3040 -2794 -8.4%

MZ355-MZ340, Zone E -2930 2723 -2838 -2930 -2723 -7.3%

MZ355-MZ340, Zone A -1985 1881 -1909 -1985 -1881 -5.4%

MZ355-MZ340, Zone D -1818 1749 -1770 -1818 -1749 -3.9%

ne D -3650 -3741 -3808 -3886 -3803

ne C -3786 -3820 -3837 -3805 -3458

ne F -3714 -374

ne B

-2723

-1881

-1749

-3118

-3084

-

-

-

-
MZ340, MZ350, MZ355 Calorimetry, Annual Mean Zone Air Temperature Summary

Annual Mean Zone Air Temperature, T (°C) Statistics, All Results

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus (Max-Min)

WSA TUD U. Liège ESRU VABI VABI GARD Min Max /Mean

MZ340 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 0.0%

MZ350, Zone B 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 0.0%

MZ350, Zone E 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 0.0%

MZ350, Zone A 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 0.0%

MZ350, Zone D 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 0.0%

MZ350, Zone C 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 0.0%

MZ350, Zone F 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 0.0%

MZ355, Zone B 20.00 20.00 20.00 20.00 20.00 0.0%

MZ355, Zone E 20.00 20.00 20.00 20.00 20.00 0.0%

MZ355, Zone A 20.00 20.00 20.00 20.00 20.00 0.0%

MZ355, Zone D 20.00 20.00 20.00 20.00 20.00 0.0%

219

 

Annual Hourly-Integrated Maximum Zone Air Temperature Summary

Annual Maximum Zone Air Temperature, Tmax (°C) Statistics, All Results

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus (Max-Min)

WSA TUD U. Liège ESRU VABI VABI GARD Min Max /Mean

MZ340 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 0.0%

MZ350, Zone B 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 0.0%

MZ350, Zone E 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 0.0%

MZ350, Zone A 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00 0.0%

MZ350, Zone D 20.00 20.00 20.00 20.00 20.00 00 20.00 20.00 20.00 0.0%

MZ350, Zone C 20.00 20.00 20.00 20.00 20.00 00 20.00 20.00 20.00 0.0%

MZ350, Zone F 20.00 20.00 20.00 20.00 20.00 00 20.00 20.00 20.00 0.0%

MZ355, Zone B 20.00 00 20.00 20.00 20.00 0.0%

MZ355, Zone E 20.00 00 20.00 20.00 20.00 0.0%

MZ355, Zone A 20.00 00 20.00 20.00 20.00 0.0%

MZ355, Zone D 20.00 00 20.00 20.00 20.00 0.0%

20.

20.

20.

20.

20.

20.

20.

219
Shading-by-Model Raw Data Tables for Cases MZ340, MZ350, MZ355

MZ340, MZ350, MZ355 Calorimetry, Annual Sensible Cooling Loads

Building, Qbldg (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf E

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 74117 74725 75005 73741 77079 77092 74585

MZ350a 47249 49619 49217

MZ350b 47701

MZ350c 47268 45447 47701

MZ350d 46953 47701

MZ355 30802 31437 29245

Zone A, QA (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESPnergyPlus

r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 12353 12454 12501 12290 12846 12849 12431

MZ350a 8338 8625 8730

MZ350b 8258

MZ350c 8323 8011 8258

MZ350d 8337 8258

MZ355 8620 8726 8259

Zone B, QB (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 12353 12454 12501 12290 12847 12849 12431

MZ350a 6319 6425 6671

MZ350b 6052

MZ350c 7

MZ350d 6247

MZ355 668 6053

Zone C, QC (kWh)

6317 586 6052

6052

6420 6

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 12353 12454 12501 12290 12846 12849 12431

MZ350a 8634 9388 8873

MZ350b 9193

MZ350c 8667 8485 9193

MZ350d 8567 9193

MZ355 n/a n/a n/a n/a n/a n/a n/a

Zone D, QD (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 12353 12454 12501 12290 12846 12849 12431

MZ350a 8714 9044 9113

MZ350b 8642

MZ350c 8696 8404 8642

MZ350d 8702 8642

MZ355 9034 9106 8642

Zone E, QE (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 12353 12454 12501 12290 12846 12849 12431

MZ350a 6535 6685 6895

MZ350b 6291

MZ350c 6534 6098 6291

MZ350d 6460 6291

MZ355 6685 6895 6291

Zone F, QF (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 12353 12454 12501 12290 12846 12849 12431

MZ350a 8708 9452 8935

MZ350b 9264

MZ350c 8732 8582 9264

MZ350d 8639 9264

MZ355 n/a n/a n/a n/a n/a n/a n/a

220
MZ340, MZ350, MZ355, Annual Hourly Integrated Peak Sensible Cooling Loads

Building, qmax,bldg (Wh/h)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CriBm EnergyPlus

WSA Date Hr. TUD Date Hr. U. Liege Date Hr. ESRU Date Hr. VABI Date Hr. VABI Date Hr. GARD Date Hr.

MZ340 73182 15-Mar 17 72982 15-Mar 17 73525 15-Mar 17 75516 15-Mar 17 77028 21-Mar 17 77028 21-Mar 17 75652 03/15 17:00

MZ350a 69095 19-Apr 17 75426 19-Apr 17 73737 19-Apr 17

MZ350b 71278 04/19 17:00

MZ350c 70006 19-Apr 17 67652 19-Apr 17 71278 04/19 17:00

MZ350d 67053 19-Apr 17 71278 04/19 17:00

MZ355 50424 19-Apr 17 49378 19-Apr 17 48156 04/19 17:00

Zone A, qmax,A (Wh/h)

HTB2 TRNSYS-TUD TRNSYS-16 ESPVA114-CirDf

r VA114-CriBm VA114-CirDf EnergyPlus

WSA Date Hr. TUD Date Hr. U. Liege Date Hr. ESRU Date Hr. VABI Date Hr. VABI Date Hr. GARD Date Hr.

MZ340 12197 15-Mar 17 12164 15-Mar 17 12254 15-Mar 17 12586 15-Mar 17 12839 21-Mar 17 12839 21-Mar 17 12609 03/15 17:00

MZ350a 11633 19-Apr 17 12654 21-Mar 17 12427 19-Apr 17

MZ350b 12395 03/15 17:00

MZ350c 12134 15-Mar 17 12005 19-Apr 17 12395 03/15 17:00

MZ350d 11658 19-Apr 17 12395 03/15 17:00

MZ355 12654 21-Mar 17 12427 19-Apr 17 12395 03/15 17:00

Zone B, qmax,B (Wh/h)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CriBm VA114-CirDf EnergyPlus

WSA Date Hr. TUD Date Hr. U. Liege Date Hr. ESRU Date Hr. VABI Date Hr. VABI Date Hr. GARD Date Hr.

MZ340 12197 15-Mar 17 12164 15-Mar 17 12254 15-Mar 17 12586 15-Mar 17 12839 21-Mar 17 12839 21-Mar 17 12609 03/15 17:00

MZ350a 11556 19-Apr 17 12550 19-Apr 17 12242 19-Apr 17

MZ350b 12001 04/19 17:00

MZ350c 11652 19-Apr 17 11413 19-Apr 17 12001 04/19 17:00

MZ350d 11015 7-May 17 12001 04/19 17:00

MZ355 12550 19-Apr 17 12241 19-Apr 17 12001 04/19 17:00

Zone C, qmax,C (Wh/h)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CriBm VA114-CirDf EnergyPlus

WSA Date Hr. TUD Date Hr. U. L Date ate Hr. r. GARD Date Hr.

MZ340 12197 15-Mar 17 12164 15-Mar 17 1225 15-Mar 17 17 12609 03/15 17:00

MZ350a 17 12176 19-Apr 17

MZ350b 12400 03/15 17:00

MZ350c 12056 15-Mar 17 11111 15-Mar 17 12400 03/15 17:00

MZ350d 12017 15-Mar 17 12400 03/15 17:00

MZ355 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a

Zone D, qmax,D (Wh/h)

HTB2 TRNSYS-TUD TRNSYS-16 ESPiege Date Hr. ESRU Hr. VABI D VABI Date H

4 15-Mar 17 12586 17 12839 21-Mar 12838 21-Mar

11981 15-Mar 17 12532 21-Mar

r VA114-CriBm VA114-CirDf EnergyPlus

WSA Date Hr. TUD Date Hr. U. Liege Date Hr. ESRU Date Hr. VABI Date Hr. VABI Date Hr. GARD Date Hr.

MZ340 12197 15-Mar 17 12164 15-Mar 17 12254 15-Mar 17 12586 15-Mar 17 12838 21-Mar 17 12838 21-Mar 17 12609 03/15 17:00

MZ350a 11642 19-Apr 17 12666 21-Mar 17 12453 19-Apr 17

MZ350b 12399 03/15 17:00

MZ350c 12142 15-Mar 17 12020 19-Apr 17 12399 03/15 17:00

MZ350d 11666 19-Apr 17 12399 03/15 17:00

MZ355 12666 21-Mar 17 12453 19-Apr 17 12399 03/15 17:00

Zone E, qmax,E (Wh/h)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CriBm VA114-CirDf EnergyPlus

WSA Date Hr. TUD Date Hr. U. Liege Date Hr. ESRU Date Hr. VABI Date Hr. VABI Date Hr. GARD Date Hr.

MZ340 12197 15-Mar 17 12164 15-Mar 17 12254 15-Mar 17 12586 15-Mar 17 12838 21-Mar 17 12838 21-Mar 17 12609 03/15 17:00

MZ350a 11572 19-Apr 17 12556 19-Apr 17 12256 19-Apr 17

MZ350b 12004 04/19 17:00

MZ350c 11652 19-Apr 17 11483 19-Apr 17 12004 04/19 17:00

MZ350d 11020 7-May 17 12004 04/19 17:00

MZ355 12556 19-Apr 17 12256 19-Apr 17 12004 04/19 17:00

Zone F, qmax,F (Wh/h)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CriBm VA114-CirDf EnergyPlus

WSA Date Hr. TUD Date Hr. U. Liege Date Hr. ESRU Date Hr. VABI Date Hr. VABI Date Hr. GARD Date Hr.

MZ340 12197 15-Mar 17 12164 15-Mar 17 12254 15-Mar 17 12586 15-Mar 17 12838 21-Mar 17 12838 21-Mar 17 12609 03/15 17:00

MZ350a 11983 15-Mar 17 12535 21-Mar 17 12182 19-Apr 17

MZ350b 12401 03/15 17:00

MZ350c 12059 15-Mar 17 11118 15-Mar 17 12401 03/15 17:00

MZ350d 12019 15-Mar 17 12401 03/15 17:00

MZ355 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a

221
MZ350-MZ340, MZ355-MZ340 Delta Annual Sensible Cooling Loads 

Building, del Qbldg (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -27476 -27460 -27875

MZ350b-MZ340 -26884

MZ350c-MZ340 -27737 -28294 -26884

MZ350d-MZ340 -27164 -26884

MZ355-MZ340 -46277 -45655 -45340

Zone A, del QA (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -4116 -4221 -4119

MZ350b-MZ340 -4173

MZ350c-MZ340 -4178 -4279 -4173

MZ350d-MZ340 -4015 -4173

MZ355-MZ340 -4226 -4123 -4172

Zone B, del QB (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -6135 -6422 -6178

MZ350b-MZ340 -6378

MZ350c-MZ340 -6184 -6423 -6378

MZ350d-MZ340 -6106 -6378

MZ355-MZ340 27 -6378

Zone C, del QC (kWh)

NSY 6 E

-64 -6181

HTB2 TR S-TUD TRNSYS-1 SP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -3820 -3458 -3976

MZ350b-MZ340 -3238

MZ350c-MZ340 -3834 -3805 -3238

MZ350d-MZ340 -3786 -3238

MZ355-MZ340

Zone D, del QD (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -3741 -3802 -3736

MZ350b-MZ340 -3789

MZ350c-MZ340 -3805 -3886 -3789

MZ350d-MZ340 -3650 -3789

MZ355-MZ340 -3812 -3743 -3788

Zone E, del QE (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -5919 -6161 -5954

MZ350b-MZ340 -6140

MZ350c-MZ340 -5967 -6192 -6140

MZ350d-MZ340 -5893 -6140

MZ355-MZ340 -6161 -5954 -6140

Zone F, del QF (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -3746 -3394 -3914

MZ350b-MZ340 -3166

MZ350c-MZ340 -3769 -3708 -3166

MZ350d-MZ340 -3714 -3166

MZ355-MZ340

222
MZ340, MZ350, MZ355 Calorimetry, Delta Hourly Integrated Peak Sensible Cooling Loads 

Building, del qmax,bldg (Wh/h)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -3887 -1602 -3291

MZ350b-MZ340 -4374

MZ350c-MZ340 -3519 -7864 -4374

MZ350d-MZ340 -6129 -4374

MZ355-MZ340 -26604 -27650 -27496

Zone A, del qmax,A (Wh/h)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -531 -185 -412

MZ350b-MZ340 -214

MZ350c-MZ340 -121 -581 -214

MZ350d-MZ340 -539 -214

MZ355-MZ340 -185 -412 -214

Zone B, del qmax,B (Wh/h)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -608 -289 -597

MZ350b-MZ340 -608

MZ350c-MZ340 - -608

MZ350d-MZ340 -1183 -608

MZ355-MZ340 9 -598 -608

Zone C, del qmax,C (Wh/h)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-

-602 1173

-28

r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -183 -307 -662

MZ350b-MZ340 -209

MZ350c-MZ340 -198 -1475 -209

MZ350d-MZ340 -180 -209

MZ355-MZ340

Zone D, del qmax,D (Wh/h)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -522 -172 -385

MZ350b-MZ340 -210

MZ350c-MZ340 -112 -566 -210

MZ350d-MZ340 -531 -210

MZ355-MZ340 -172 -385 -210

Zone E, del qmax,E (Wh/h)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -592 -282 -582

MZ350b-MZ340 -605

MZ350c-MZ340 -602 -1103 -605

MZ350d-MZ340 -1177 -605

MZ355-MZ340 -282 -582 -605

Zone F, del qmax,F (Wh/h)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -181 -303 -656

MZ350b-MZ340 -208

MZ350c-MZ340 5 -208

MZ350d-MZ340 -178 -208

MZ355-MZ340

-19 -1468

223
MZ340, MZ350, MZ355 Annual Transmitted Solar Radiation: Zones A, B

Transmitted Total Solar, Zone A, Itr,A (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 12353 12454 12504 12290 12844 12847 12429

MZ350a 8338 8623 8728

MZ350b 8257

MZ350c 8323 8011 8257

MZ350d 8337 8257

MZ355 8618 8724 8257

Transmitted Beam Solar, Zone A, Itrb,A (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 5894 5933 5930 5768 5769 5769 5875

MZ350a 3625 3531 3531

MZ350b 3613

MZ350c 3572 3556 3613

MZ350d 3674 3613

MZ355 3527 3527 3613

Transmitted Diffuse Solar, Zone A, Itrd,A (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 6459 6521 6574 6522 7076 7078 6554

MZ350a 4713 5092 5197

MZ350b 4645

MZ350c 4751 4455 4645

MZ350d 4664 4645

MZ355 5091 5197 4645

Transmitted Total Solar, Zone B, Itr,B (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 12353 12454 12504 12290 12844 12847 12429

MZ350a 6319 6423 6669

MZ350b 6052

MZ350c 6317 5867 6052

MZ350d 6247 6052

MZ355 6418 6666 6052

Transmitted Beam Solar, Zone B, Itrb,B (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 5894 5933 5930 5768 5769 5769 5875

MZ350a 2431 2385 2385

MZ350b 2428

MZ350c 2397 2397 2428

MZ350d 2426 2428

MZ355 2382 2382 2428

Transmitted Diffuse Solar, Zone B, Itrd,B (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 6459 6521 6574 6522 7076 7078 6554

MZ350a 3888 4038 4284

MZ350b 3623

MZ350c 3919 3470 3623

MZ350d 3821 3623

MZ355 4036 4284 3623

224
225

MZ340, MZ350, MZ355 Annual Transmitted Solar Radiation: Zones C, D

Transmitted Total Solar, Zone C, Itr,C (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 12353 12454 12504 12290 12844 12847 12429

MZ350a 8634 9386 8871

MZ350b 9192

MZ350c 8667 8485 9192

MZ350d 8567 9192

MZ355 n/a n/a n/a n/a n/a n/a n/a

Transmitted Beam Solar, Zone C, Itrb,C (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 5894 5933 5930 5768 5769 5769 5875

MZ350a 5056 4911 4911

MZ350b 4988

MZ350c 5060 4602 4988

MZ350d 5032 4988

MZ355 n/a n/a n/a n/a n/a n/a n/a

Transmitted Diffuse Solar, Zone C, Itrd,C (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 6459 6521 6574 6522 7076 7078 6554

MZ350a 3578 4475 3960

MZ350b 4204

MZ350c 3607 3883 4204

MZ350d 3535 4204

MZ355 n/a n/a n/a n/a n/a n/a

Transmitted Total Solar, Zone D, Itr,D (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 12353 12454 12504 12290 12844 12847 12429

MZ350a 8714 9041 9111

MZ350b 8641

MZ350c 8696 8404 8641

MZ350d 8702 8641

MZ355 9032 9104 8641

Transmitted Beam Solar, Zone D, Itrb,D (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 5894 5933 5930 5768 5769 5769 5875

MZ350a 3873 3782 3782

MZ350b 3857

MZ350c 3816 3796 3857

MZ350d 3919 3857

MZ355 3774 3774 3857

Transmitted Diffuse Solar, Zone D, Itrd,D (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 6459 6521 6574 6522 7076 6554

MZ350a 4841 5259 5329

MZ350b 4784

MZ350c 4880 4608 4784

MZ350d 4784 4784

MZ355 5258 5329 4784
MZ340, MZ350, MZ355 Annual Transmitted Solar Radiation: Zones E, F

Transmitted Total Solar, Zone E, Itr,E (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 12353 12454 12504 12290 12844 12847 12429

MZ350a 6535 6683 6893 0

MZ350b 6290

MZ350c 6534 6098 6290

MZ350d 6460 6290

MZ355 6683 6893 6290

Transmitted Beam Solar, Zone E, Itrb,E (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 5894 5933 5930 5768 5769 5769 5875

MZ350a 2579 2537 2537

MZ350b 2574

MZ350c 2546 2541 2574

MZ350d 2574 2574

MZ355 2537 2537 2574

Transmitted Diffuse Solar, Zone E, Itrd,E (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 6459 6521 6574 6522 7076 7078 6554

MZ350a 3956 4146 4355

MZ350b 3716

MZ350c 3988 3557 3716

MZ350d 3885 3716

MZ355 4146 4355 3716

Transmitted Total Solar, Zone F, I (kWh) tr,F

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 12353 12454 12504 12290 12844 12847 12429

MZ350a 8708 9450 8932

MZ350b 9263

MZ350c 8732 8582 9263

MZ350d 8639 9263

MZ355 n/a n/a n/a n/a n/a n/a n/a

Transmitted Beam Solar, Zone F, Itrb,F (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 5894 5933 5930 5768 5769 5769 5875

MZ350a 5095 4939 4939

MZ350b 5026

MZ350c 5089 4631 5026

MZ350d 5068 5026

MZ355 n/a n/a n/a n/a n/a n/a n/a

Transmitted Diffuse Solar, Zone F, Itrd,F (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 6459 6521 6574 6522 7076 6554

MZ350a 3614 4511 3994

MZ350b 4238

MZ350c 3643 3951 4238

MZ350d 3570 4238

MZ355 n/a n/a n/a n/a n/a n/a n/a

226
MZ350-MZ340, MZ355-MZ340, Delta Annual Transmitted TOTAL Solar 

Total Solar Zone A, del ItrA (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -4116 -4221 -4119

MZ350b-MZ340 -4172

MZ350c-MZ340 -4181 -4279 -4172

MZ350d-MZ340 -4015 -4172

MZ355-MZ340 -4226 -4123 -4172

Total Solar Zone B, del ItrB (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -6135 -6421 -6178

MZ350b-MZ340 -6377

MZ350c-MZ340 -6187 -6423 -6377

MZ350d-MZ340 -6106 -6377

MZ355-MZ340 -6426 -6181 -6377

Total Solar Zone C, del ItrC (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -3820 -3458 -3976

MZ350b-MZ340 -3237

MZ350c-MZ340 -3837 -3805 -3237

MZ350d-MZ340 -3786 -3237

MZ355-MZ340 n/a n/a n/a n/a n/a n/a n/a

Total Solar Zone D, del ItrD (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -3741 -3803 -3736

MZ350b-MZ340 -3788

MZ350c-MZ340 -3808 -3886 -3788

MZ350d-MZ340 -3650 -3788

MZ355-MZ340 -3812 -3743 -3788

Total Solar Zone E, del ItrE (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -5919 -6161 -5954

MZ350b-MZ340 -6139

MZ350c-MZ340 -5970 -6192 -6139

MZ350d-MZ340 -5893 -6139

MZ355-MZ340 -6161 -5954 -6139

Total Solar Zone F, del ItrF (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -3746 -3394 -3915

MZ350b-MZ340 -3165

MZ350c-MZ340 -3772 -3708 -3165

MZ350d-MZ340 -3714 -3165

MZ355-MZ340 n/a n/a n/a n/a n/a n/a n/a

227
MZ350-MZ340, MZ355-MZ340, Delta Annual Transmitted BEAM Solar 

Beam Solar Zone A, del ItrbA (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -2308 -2238 -2238

MZ350b-MZ340 -2262

MZ350c-MZ340 -2358 -2212 -2262

MZ350d-MZ340 -2220 -2262

MZ355-MZ340 -2242 -2242 -2262

Beam Solar Zone B, del ItrbB (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -3502 -3384 -3384

MZ350b-MZ340 -3447

MZ350c-MZ340 -3532 -3371 -3447

MZ350d-MZ340 -3468 -3447

MZ355-MZ340 -3387 -3387 -3447

Beam Solar Zone C, del ItrbC (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -877 -858 -858

MZ350b-MZ340 -887

MZ350c-MZ340 -870 -1166 -887

MZ350d-MZ340 -862 -887

MZ355-MZ340 n/a n/a n/a n/a n/a n/a n/a

Beam Solar Zone D, del ItrbD (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -2060 -1987 -1987

MZ350b-MZ340 -2018

MZ350c-MZ340 -2113 -1972 -2018

MZ350d-MZ340 -1975 -2018

MZ355-MZ340 -1995 -1995 -2018

Beam Solar Zone E, del ItrbE (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -3354 -3232 -3232

MZ350b-MZ340 -3301

MZ350c-MZ340 -3384 -3227 -3301

MZ350d-MZ340 -3320 -3301

MZ355-MZ340 -3232 -3232 -3301

Beam Solar Zone F, del ItrbF (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -838 -830 -830

MZ350b-MZ340 -849

MZ350c-MZ340 -841 -1137 -849

MZ350d-MZ340 -826 -849

MZ355-MZ340 n/a n/a n/a n/a n/a n/a n/a

228
229

MZ350-MZ340, MZ355-MZ340, Delta Annual Transmitted DIFFUSE Solar 

Diffuse Solar Zone A, del ItrdA (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -1808 -1984 -1881

MZ350b-MZ340 -1909

MZ350c-MZ340 -1823 -2067 -1909

MZ350d-MZ340 -1795 -1909

MZ355-MZ340 -1985 -1881 -1909

Diffuse Solar Zone B, del ItrdB (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -2633 -3038 -2794

MZ350b-MZ340 -2930

MZ350c-MZ340 -2655 -3052 -2930

MZ350d-MZ340 -2638 -2930

MZ355-MZ340 -3040 -2794 -2930

Diffuse Solar Zone C, del ItrdC (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -2943 -2601 -3118

MZ350b-MZ340 -2350

MZ350c-MZ340 -2967 -2639 -2350

MZ350d-MZ340 -2924 -2350

MZ355-MZ340 n/a n/a n/a n/a n/a n/a n/a

Diffuse Solar Zone D, del ItrdD (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -1681 -1817 -1749

MZ350b-MZ340 -1770

MZ350c-MZ340 -1694 -1914 -1770

MZ350d-MZ340 -1675 -1770

MZ355-MZ340 -1818 -1749 -1770

Diffuse Solar Zone E, del ItrdE (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -2565 -2930 -2723

MZ350b-MZ340 -2838

MZ350c-MZ340 -2586 -2965 -2838

MZ350d-MZ340 -2573 -2838

MZ355-MZ340 -2930 -2723 -2838

Diffuse Solar Zone F, del ItrdF (kWh)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ350a-MZ340 -2907 -2565 -3084

MZ350b-MZ340 -2316

MZ350c-MZ340 -2931 -2571 -2316

MZ350d-MZ340 -2889 -2316

MZ355-MZ340 n/a n/a n/a n/a n/a n/a n/a
MZ340, MZ350, MZ355 Calorimetry, Annual Mean Zone Air Temperatures

SA TUD U. Liège ESRU VABI VABI GARD

MZ340 20.00 20.00 20.00 20.00 20.00 20.00 20.00

MZ350a 20.00 20.00 20.00

MZ350a 20.00 20.00 20.00

MZ350b 20.00

MZ350c 20.00 20.00 20.00

MZ350d 20.00 20.00

MZ355 20.00 20.00 20.00

Zone C, TC (°C)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 20.00 20.00 20.00 20.00 20.00 20.00 20.00

Z350a 20.00 20.00 20.00

Z350b 20.00

MZ350c 20.00 20.00 20.00

MZ350d 20.00 20.00

MZ355 n/a n/a n/a n/a n/a n/a n/a

Zone D, TD (°C)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 20.00 20.00 20.00 20.00 20.00 20.00 20.00

MZ350a 20.00 20.00 20.00

MZ350b 20.00

MZ350c 20.00 20.00 20.00

MZ350d 20.00 20.00

MZ355 20.00 20.00 20.00

Zone E, TE (°C)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 20.00 20.00 20.00 20.00 20.00 20.00 20.00

MZ350a 20.00 20.00 20.00

MZ350b 20.00

MZ350c 20.00 20.00 20.00

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 20.00 20.00 20.00 20.00 20.00 20.00 20.00

MZ350a 20.00 20.00 20.00

MZ350b 20.00

MZ350c 20.00 20.00 20.00

MZ350d 20.00 20.00

MZ355 n/a n/a n/a n/a n/a n/a n/a

Zone A, TA (°C)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

W

MZ350b 20.00

MZ350c 20.00 20.00 20.00

MZ350d 20.00 20.00

MZ355 20.00 20.00 20.00

Zone B, TB (°C)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD

MZ340 20.00 20.00 20.00 20.00 20.00 20.00 20.00

M

M

MZ350d 20.00 20.00

MZ355 20.00 20.00 20.00

Zone F, TF (°C)

230
MZ340, MZ350, MZ355, Annual Hourly Integrated Maximum Zone Air Temperatures

Zone A, Tmax,A (°C)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CriBm VA114-CirDf EnergyPlus

WSA Date Hr. TUD Date Hr. U. Liege Date Hr. ESRU Date Hr. VABI Date Hr. VABI Date Hr. GARD Date Hr.

MZ340 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 15 20.00 1-Jan 15 20.00 06/12 20:00

MZ350a 20.00 1-Jan 1 20.00 2-Jan 8 20.00 2-Jan 8

MZ350b 20.00 05/22 20:00

MZ350c 20.00 1-Jan 1 20.00 1-Jan 1 20.00 05/22 20:00

MZ350d 20.00 1-Jan 1 20.00 05/22 20:00

MZ355 20.00 1-Jan 8 20.00 1-Jan 8 20.00 05/22 20:00

Zone B, Tmax,B (°C)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CriBm VA114-CirDf EnergyPlus

WSA Date Hr. TUD Date Hr. U. Liege Date Hr. ESRU Date Hr. VABI Date Hr. VABI Date Hr. GARD Date Hr.

MZ340 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 12 20.00 1-Jan 12 20.00 06/12 20:00

MZ350a 20.00 1-Jan 1 20.00 1-Jan 9 20.00 1-Jan 9

MZ350b 20.00 06/28 20:00

MZ350c 20.00 1-Jan 1 20.00 1-Jan 1 20.00 06/28 20:00

MZ350d 20.00 1-Jan 1 20.00 06/28 20:00

MZ355 20.00 1-Jan 9 20.00 1-Jan 9 20.00 06/28 20:00

Zone C, Tmax,C (°C)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CriBm VA114-CirDf EnergyPlus

WSA Date Hr. TUD Date Hr. U. Liege Date Hr. ESRU Date Hr. VABI Date Hr. VABI Date Hr. GARD Date Hr.

MZ 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 11 20.00 1-Jan 11 20.00 06/12 20:00

MZ350a 20.00 1-Jan 1 20.00 1-Jan 11 20.00 1-Jan 11

MZ350b 20.00 08/16 20:00

MZ350c 20.00 1-Jan 1 20.00 1-Jan 1 20.00 08/16 20:00

MZ350d 20.00 1-Jan 1 20.00 08/16 20:00

MZ355 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a

Zone D, Tmax,D (°C)

HTB2 TRNSYS-TUD TRNSYS-16 ESP340

r VA114-CriBm VA114-CirDf EnergyPlus

WSA Date Hr. TUD Date Hr. U. Liege Date Hr. ESRU Date Hr. VABI Date Hr. VABI Date Hr. GARD Date Hr.

MZ340 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 1 20.00 2-Jan 10 20.00 2-Jan 10 20.00 06/12 20:00

MZ350a 20.00 1-Jan 1 20.00 1-Jan 13 20.00 1-Jan 13

MZ350b 20.00 06/28 20:00

MZ350c 20.00 1-Jan 1 20.00 1-Jan 1 20.00 06/28 20:00

MZ350d 20.00 1-Jan 1 20.00 06/28 20:00

MZ355 20.00 2-Jan 13 20.00 2-Jan 13 20.00 06/28 20:00

Zone E, Tmax,E (°C)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CriBm VA114-CirDf EnergyPlus

WSA Date Hr. TUD Date Hr. U. Liege Date Hr. ESRU Date Hr. VABI Date Hr. VABI Date Hr. GARD Date Hr.

MZ340 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 12 20.00 1-Jan 12 20.00 06/12 20:00

MZ350a 20.00 1-Jan 1 20.00 1-Jan 16 20.00 1-Jan 16

MZ350b 20.00 06/28 20:00

MZ350c 20.00 1-Jan 1 20.00 1-Jan 1 20.00 06/28 20:00

M 20.00 1-Jan 1 20.00 06/28 20:00

M

Z

Z350d

Z355 20.00 1-Jan 15 20.00 1-Jan 15 20.00 06/28 20:00

one F, Tmax,F (°C)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CriBm VA114-CirDf EnergyPlus

WSA Date Hr. TUD Date Hr. U. Liege Date Hr. ESRU Date Hr. VABI Date Hr. VABI Date Hr. GARD Date

Z340 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 1 20.00 2-Jan 15 20.00 2-Jan 15 20.00

Z350a 20.00 1-Jan 1 20.00 1-Jan 15 20.00 1-Jan 15

Hr.

M 06/12 20:00

M

MZ350b 20.00 01/21 19:00

MZ350c 20.00 1-Jan 1 20.00 1-Jan 1 20.00 01/21 19:00

MZ350d 20.00 1-Jan 1 20.00 01/21 19:00

MZ355 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a

231
232

Case MZ360 (Internal Windows) Results 

 

MZ360 Calorimetry, Annual Cooling Loads, Incident and Transmitted Solar, Zone Air Temperatures

Annual Sensible Cooling Loads (kWh/y) Statistics, All Results

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus (Max-Min)

WSA TUD U. Liège ESRU VABI VABI GARD Min Max /Mean

Building, Qbldg 121816 122534 123497 125312 129647 129653 120538 120538 129653 7.3%

Zone A, QA 59734 48025 60817 47177 43529 43480 51113 43480 60817 34.3%

Zone B, QB 63512 54130 57988 58213 57751 59411 54130 63512 16.0%

Zone C, QC 10997 8550 20147 27905 28421 10015 8550 28421 112.4%

QB + QC 62082 74509 62679 78135 86118 86172 69425 62082 86172 32.5%

Annual Southwest-Facing Incident Unshaded Solar (kWh/(m2

y)) Statistics, All Results

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus (Max-Min)

WSA TUD U. Liège ESRU VABI VABI GARD Min Max /Mean

Total (IA) 875 880

Beam (IbA) 472 477 466 464 464 469 464

887 905 931 931 905 875 931 6.2%

477 2.7%

Diffuse (IdA) 408 411 438 467 467 436 408

Annual Transmitted Solar, Zone A (kWh/y) Statistics, 

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD Min

Total (ItrA) 121816 122534 123569 125312 129589 129595 125148 121816 129595

Beam (ItrbA) 65822 65782 66358 64605 64578 64578 65065 64578

467 13.6%

All Results

(Max-Min)

Max /Mean

6.2%

66358 2.7%

Diffuse (ItrdA) 55994 56752 57211 60707 65011 65017 60083 55994

Annual Transmitted Solar, Zone B (kWh/y) Statistics, 

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD Min

Total (ItrB) 62082 74509 62802 78135 86092 86147 62082

Beam (ItrbB) 45417 45665 33725 46668 43095 43095 43257 33725

65017 15.0%

All Results

(Max-Min)

Max /Mean

86147 32.1%

46668 30.1%

Diffuse (ItrdB) 16665 28843 29076 31467 42997 43052 16665

Annual Transmitted Solar, Zone C (kWh/y) Statistics, 

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD Min

Total (ItrC) 10997 9269 20147 27898 28415 9269

Beam (ItrbC) 0 4978 15505 13769 13769 0 0

43052 82.4%

All Results

(Max-Min)

Max /Mean

28415 99.0%

15505 193.7%

Diffuse (ItrdC) 10997 4291 4642 14130 14646 4291

Annual Mean Zone Air Temperatures (°C) Statistics, 

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD Min

Zone A, TA 20 20 20 20 20 20 20 20

Zone B, TB 20 20 20 20 20 20 20 20

14646 106.3%

All Results

(Max-Min)

Max /Mean

20 0.0%

20 0.0%

Zone C, TC 20 20 20 20 20 20 20 20 0.0%

MZ360 Calorimetry, Annual Cooling Loads, Incident and Transmitted Solar, Zone Air Temperatures

Annual Sensible Cooling Loads (kWh/y) Statistics, All Results

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus (Max-Min)

WSA TUD U. Liège ESRU VABI VABI GARD Min Max /Mean

Building, Qbldg 121816 122534 123497 125312 129647 129653 120538 120538 129653 7.3%

Zone A, QA 59734 48025 60817 47177 43529 43480 51113 43480 60817 34.3%

Zone B, QB 63512 54130 57988 58213 57751 59411 54130 63512 16.0%

Zone C, QC 10997 8550 20147 27905 28421 10015 8550 28421 112.4%

QB + QC 62082 74509 62679 78135 86118 86172 69425 62082 86172 32.5%

Annual Southwest-Facing Incident Unshaded Solar (kWh/(m2

y)) Statistics, All Results

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus (Max-Min)

WSA TUD U. Liège ESRU VABI VABI GARD Min Max /Mean

Total (IA) 875 880 887 905 931 931 905 875

Beam (IbA) 472 477 466 464 464 469 464

931 6.2%

477 2.7%

Diffuse (IdA) 408 411 438 467 467 436 408

Annual Transmitted Solar, Zone A (kWh/y) Statistics, 

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD Min

Total (ItrA) 121816 122534 123569 125312 129589 129595 125148 121816 129595

Beam (ItrbA) 65822 65782 66358 64605 64578 64578 65065 64578

467 13.6%

All Results

(Max-Min)

Max /Mean

6.2%

66358 2.7%

Diffuse (ItrdA) 55994 56752 57211 60707 65011 65017 60083 55994

Annual Transmitted Solar, Zone B (kWh/y) Statistics, 

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD Min

Total (ItrB) 62082 74509 62802 78135 86092 86147 62082

Beam (ItrbB) 45417 45665 33725 46668 43095 43095 43257 33725

65017 15.0%

All Results

(Max-Min)

Max /Mean

86147 32.1%

46668 30.1%

Diffuse (ItrdB) 16665 28843 29076 31467 42997 43052 16665

Annual Transmitted Solar, Zone C (kWh/y) Statistics, 

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD Min

Total (ItrC) 10997 9269 20147 27898 28415 9269

Beam (ItrbC) 0 4978 15505 13769 13769 0 0

43052 82.4%

All Results

(Max-Min)

Max /Mean

28415 99.0%

15505 193.7%

Diffuse (ItrdC) 10997 4291 4642 14130 14646 4291

Annual Mean Zone Air Temperatures (°C) Statistics, 

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CirBm VA114-CirDf EnergyPlus

WSA TUD U. Liège ESRU VABI VABI GARD Min

Zone A, TA 20 20 20 20 20 20 20 20

Zone B, TB 20 20 20 20 20 20 20 20

14646 106.3%

All Results

(Max-Min)

Max /Mean

20 0.0%

20 0.0%

Zone C, TC 20 20 20 20 20 20 20 20 0.0%
233

MZ360

Peak Sensib 

, Annual Hourly Integrated Maximum Cooling Loads and Zone Air Temperatures

le Cooling Loads (Wh/h)

HTB2 TRNSYS-TUD TRNSYS-16 ESP-r VA114-CriBm

WSA Date Hr. TUD Date Hr. U. Liege Date Hr. ESRU Date Hr. VABI Date Hr.

, qmax,bldg 111067 3-Jan 16 110956 3-Jan 16 118770 26-Feb 17 113850 21-Dec 15 118713 26-Feb 1

 qmax,A 35461 3-Jan 16 32346 3-Jan 16 58484 26-Feb 17 32140 15-Jan 15 39257 26-Feb 1

 qmax,B 67675 8-Feb 16 52067 26-Feb 17 54782 8-Feb 15 55795 21-Dec 1

VA114-CirDf EnergyPlus 

VABI Date Hr. GARD 

Building 6 118713 26-Feb 16 105575 Zone A, 5 39057 26-Feb 15 40913 Zone B, 4 55176 21-Dec 14 57806 

Zone C, qmax,C 11718 8-Feb 16 8220 26-Feb 17 48060 26-Feb 17 41854 8-Feb 1

one Air Temperatures (°C)

HTB2 TRNSYS-TUD TRNSYS-16 ESP6 41037 8-Feb 16 7100 

Maximum Z 

r VA114-CriBm

WSA Date Hr. TUD Date Hr. U. Liege Date Hr. ESRU Date Hr. VABI Date Hr.

 Tmax,A 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 1

 Tmax,B 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan

VA114-CirDf EnergyPlus 

VABI Date Hr. GARD 

Zone A, 6 20.00 1-Jan 16 20.00 

Zone B, 9 20.00 1-Jan 9 20.00 

Zone C, Tmax,C 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 1 20.00 1-Jan 8 20.00 1-Jan 8 20.00 
F1147-E(09/2007) 

REPORT DOCUMENTATION PAGE Form Approved 

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PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ORGANIZATION.

1. REPORT DATE (DD-MM-YYYY)

September 2008 

2. REPORT TYPE

Technical Report 

3. DATES COVERED (From - To)

 

5a. CONTRACT NUMBER

DE-AC36-99-GO10337 

5b. GRANT NUMBER

4. TITLE AND SUBTITLE

International Energy Agency Building Energy Simulation Test and 

Diagnostic Method (IEA BESTEST) Multi-Zone Non-Airflow In-Depth 

Diagnostic Cases: MZ320 – MZ360 

5c. PROGRAM ELEMENT NUMBER

5d. PROJECT NUMBER

NREL/TP-550-43827 

5e. TASK NUMBER

BEC76051 

6. AUTHOR(S)

J. Neymark and R. Judkoff, 

Contributors: 

D. Alexander, C. Felsman, P. Strachan, and A. Wijsman 

5f. WORK UNIT NUMBER

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

National Renewable Energy Laboratory 

1617 Cole Blvd. 

Golden, CO 80401-3393 

8. PERFORMING ORGANIZATION 

REPORT NUMBER

NREL/TP-550-43827 

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NREL 

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12. DISTRIBUTION AVAILABILITY STATEMENT

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13. SUPPLEMENTARY NOTES

14. ABSTRACT (Maximum 200 Words)

This report documents a set of in-depth diagnostic test cases for multi-zone heat transfer models that do not include 

the heat and mass transfer effects of airflow between zones. These test cases represent an extension to IEA 

BESTEST, which originally focused on a single-zone configuration except for one test case. 

15. SUBJECT TERMS

iea; international energy agency; bestest; building energy simulation test 

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a. REPORT 

Unclassified 

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