NAT L INST. OF STAND & TECH

NBSIR 85-3194

Opportunities for Full-Scale

Testing of Residential Building

Interactions in Environmental

Chambers

Reference

Andrew K. Persily

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Center for Building Standards

Gaithersburg, MD 20899

December 1985

I- QC

Prepared for: Architectural and Engineering Systems Branch

artment of Energy

on. DC 20585

100

• U56

85-3194

1985

NBSIR 85-3194

OPPORTUNITIES FOR FULL-SCALE

TESTING OF RESIDENTIAL BUILDING

INTERACTIONS IN ENVIRONMENTAL

CHAMBERS

fisSE&RCH INFORMATION CENTER "2^- AJSS

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fi/o . W

Andrew K. Persily

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Center for Building Technology

Gaithersburg, MD 20899

December 1985

Prepared for: Architectural and Engineering Systems Branch

U.S. Department of Energy

Washington, DC 20585

U.S. DEPARTMENT OF COMMERCE. Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS. Ernest Ambler, Director

Abstract

Much building energy performance research has been concerned with individual

components such as space conditioning equipment, controls, and building

envelopes. Less work has been done on how these various components interact on

the whole-building scale to determine energy use and other factors. As the

understanding of component performance has increased through measurement and

modelling, our lack of understanding of the interactions among these individual

items has become more apparent. It is difficult to examine these interactions

in real homes due to the physical complexity of homes, the uncontrollable nature

of the weather, and effects of occupants. This report focuses on opportunities

for full-scale testing of residential building interactions in environmental

chambers, where one has control of weather conditions and occupant effects.

Such research will increase our understanding of the physical nature of these

interactions and their effects on energy use, comfort, cost, and other factors.

In this report we review past and current research in the area of full-scale

testing in environmental chambers and other related work. Based on this review,

further research is proposed in several important areas of residential building

performance

.

Key words: building performance; energy conservation; environmental chambers;

f u ll~scale testing; residential buildings; whole building performance
.
TABLE OF CONTENTS

1. INTRODUCTION 1

2. PAST AND CURRENT FULL-SCALE TESTING STUDIES 2

2.1 Testing of Prototype Buildings in Environmental Chambers 2

2.2 Testing of Prototype Buildings in the Outdoors 4

2.3 Testing of Residential Buildings in Environmental Chambers 5

2.4 Other Relevant Research in Residential Building Interactions 5

3. EXISTING ENVIRONMENTAL CHAMBERS 8

4. PROPOSED FULL-SCALE TESTING RESEARCH 8

4.1 Effects of Building Design and Equipment Installation on the

Performance of Heating Equipment 8

4.1.1 Envelope Infiltration and Combustion Appliances ....9

4.1.2 Forced-Air Duct Leakage and Thermal Load Effects.. 9-

4.1.3 High R- Value Envelopes and Space Conditioning Equipment 10

4.1.4 Thermal Loads Associated with Infiltration and Ventilation 10

4.2 Full-Scale Testing of Interactions in Manufactured Housing 10

4.3 Building Envelope Characteristics, Air Conditioner Performance and

Indoor Humidity Control 10

4.4 Effects of Thermal Mass, Envelope Heat Loss and Equipment Type on Temperature Setback Savings 11

4.5 Whole Building Performance of Mechanical Ventilation Systems 11

4.6 Interactive Effects of Insulation Quality 12

5. PROPOSED RECONFIGURABLE TEST FACILITY 12

6.

REFERENCES 13
.
1. INTRODUCTION

The thermal performance of residential buildings is quite complex due to the

interaction of building envelope components, mechanical equipment, controls, the

environment, and occupant activities. While research has been conducted over

the years concerning these individual elements, the study of their relation to

whole-building performance is much more difficult. The interactions of the

physical elements of a building, the variability of weather conditions, and

occupant behavior make it difficult to isolate causes and effects when

conducting full-scale field studies of residential buildings. These

difficulties can be avoided by testing prototype buildings (undersized, simple

structures) and actual buildings in environmental chambers where one can control, and accurately repeat, exterior weather conditions. This report

discusses the potential for full-scale residential building research in

environmental chambers. Several examples of past work are discussed to

demonstrate the value of such research and to identify problems appropriate for

chamber testing.

Many studies have been conducted in environmental chambers, benefitting from the

ability to control weather conditions in these facilties. The use of prototype

buildings offers the further advantage of concentrating on only those features

of the building which are important to the study and avoiding complications

arising from the existence of superfluous building features. Several prototype

buildings have been studied in the large environmental chamber at the National

Bureau of Standards (NBS) to validate the NBSLD computer model for predicting

indoor temperature and space conditioning loads (Burch, Peavy and Powell 1974;

Kusuda and Bean 1981). Because of the advantages inherent in this experimental

approach, these studies revealed the potential for undesirable furnace

oversizing when steady-state theory is used to predict heating loads as compared

to calculations that consider dynamic thermal response. In addition, several

energy conserving cooling strategies for use in hot climates were evaluated with

a degree of detail and control not achievable in field studies of real homes.

This same chamber has also been extremely useful in infiltration studies because

of the absence of wind effects and the ability to repeat tests under identical

weather conditions. Although infiltration is a highly variable quantity,

dependent on many factors, this research was able to establish a linear

dependence of building infiltration rates on inside-outside temperature

difference and quantify the contribution to whole-building leakage of various

building components (Hunt and Burch 1975; Hunt, Treado , and Peavy; Silber stein

1980). The study of the contribution to leakage of specific building

components, such as windows, requires infiltration measurements under identical

weather conditions with and without the windows sealed. The repetitive

establishment of identical conditions can be easily accomplished in a chamber

but is impossible to achieve in the field. Similarly, environmental chamber

testing enables evaluation of specific components on the whole-building scale

through the testing of a reconfigured building under identical weather

conditions. The value of environmental chamber testing has been demonstrated

many times, as discussed in detail below, and great potential remains for

studying additional aspects of building performance.

In addition to describing past demonstrations of the value of environmental

chamber testing, other research suggestive of chamber testing is also discussed.

These additional topics include full-scale testing of manufactured housing,

studies of the effects of thermal mass on heating loads and thermal comfort, and

1
research into cooling equipment performance in hot, humid climates. Based on

this review of past research, several topics which merit consideration for

environmental chamber testing are presented. For example, testing of prototype

and actual buildings is proposed to study the interaction of building envelope

characteristics, air conditioner performance, and indoor humidity control.

Full-scale testing of manufactured housing is also proposed to study important

issues including HVAC design, installation and control, and energy conserving

construction options. The installed performance of heating equipment as it is

affected by installation and building design characteristics is another area which would benefit greatly from environmental chamber testing. In addition, a reconf igurable test facility is proposed for use in chamber and full-scale

testing.

2. PAST AND CURRENT FULL-SCALE TESTING STUDIES

Several studies have been done involving full-scale testing of both prototype

and actual buildings in environmental chambers and exposed to outside weather

conditions. In this section we review several examples of this work to

demonstrate the usefulness of chamber testing and to point out specific

residential building interactions requiring additional study. The review is

divided into four sections, i.e. prototype buildings in environmental chambers,

prototype buildings outdoors, actual buildings in chambers and actual buildings

outdoors. The latter section includes only those studies of actual buildings

which are suggestive of the research projects proposed later in this report.

2.1 Testing of Prototype Buildings in Environmental Chambers

There have been several studies of prototype buildings in environmental chambers

to investigate aspects of building performance such as heat transfer, wall

thermal mass effects, HVAC controls, thermal comfort, and air movement within

rooms. The prototype buildings are very simple structures with one or two

rooms, located within larger environmental chambers with controllable

temperature and humidity. In this section we briefly discuss some examples of

prototype testing in environmental chambers.

The first examples are tests conducted in the large environmental chamber at

NBS. One case involved a masonry structure consisting of a single cell with a 6 by 6 m base and a height of 3 m (Peavy, Powell and Burch 1973; Burch, Peavy and

Powell 1974). Tests were made of its dynamic thermal performance with and

without wall insulation, with the insulation located on the inside and outside

of the walls, with and without interior thermal mass, and with various amounts

of fenestration. The tests were made under various outside temperature cycles

to simulate realistic exterior weather conditions. The experiments revealed

that the addition of insulation decreased the variation in interior temperature

over space and time, with exterior insulation resulting in the smallest

variations. Tests made with a thermostat controlling the interior temperature

showed that assumptions of steady state heat transfer lead to calculated maximum

heating loads 30 to 70% higher than measured under simulated diurnal weather

patterns or calculated with consideration of dynamic thermal response. This

finding has important implications for the sizing of heating equipment. While

the test conditions differed significantly from those of realistic buildings in

the field, the fact that the structure was simple, alterable, and located in a chamber with controllable ambient conditions enabled the study and understanding

of several important effects.

2
Another building, with a high level of thermal mass, was tested in the large

environmental chamber at NBS to study energy conserving cooling strategies and

to validate the NBSLD computer model for predicting interior temperatures and

space conditioning loads (Gujral, Clark, and Burch 1980 and 1982; Kusuda and

Bean 1981). The structure in this case was a single cell masonry building with

external insulation, about 6.4 by 5.2 m and 4.7 m high. Two cooling strategies

were evaluated in a simulated Saudi Arabian climate. One of the schemes was continuous nighttime cooling using a ceiling mounted cooling coil. Nighttime

cooling has the advantages that utility loads are low and the cooling equipment

is more efficient. During the daytime, when the cooling system was off, the

thermal mass of the building envelope was able to prevent overheating of the

interior. The other cooling strategy was nighttime cooling using natural

ventilation. Both strategies were evaluated and resulted in considerable

reductions in cooling energy requirements, compared to continuous cooling of

light-weight buildings, while still maintaining comfortable interior conditions.

Another small prototype building was tested in the large NBS chamber to study

attic condensation (Burch et al. 1984c).

A two-room test house was used to study the effects of residential HVAC controls

on energy use and thermal comfort in an environmental chamber at Portland State

University (Spolek and Peterson 1984). Each room was 3 by 3 m and 2.4 m high,

and the structure was of standard, lightweight wood-frame construction. In

these tests the chamber was cooled and the test structure was heated with

electric baseboards controlled by a standard thermostat. An alternative

controller to regulate heater cycling was also studied and resulted in marginal

energy savings and somewhat improved thermal comfort. The main thrust of this

work was to demonstrate the use of the test facility. Future work is planned

with other control strategies and forced-air heating systems.

The last example of prototype testing in environmental chambers is the use of

test rooms to study the effectiveness of air distribution, or ventilation

efficiency, in several Scandanavian laboratories (Malmstrom and Ahlgren 1982;

Sandberg 1984; Skaret and Mathisen 1982). The test facilities used in this work

consisted of one or two small rooms with controllable ventilation rates, supply

and exhaust vent locations, interior and supply air temperatures, and internal

loads. These controllable conditions allowed the evaluation of mechanical

ventilation strategies in terms of thermal comfort and effectiveness in

replacing room air with supply air. This research has revealed the existence of

significant stratification of air within spaces ventilated using techniques

common in modern office buildings. Under such conditions, the breathing zones

in these spaces have effective ventilation rates that are significantly lower

than both the design rates and the ventilation rates required for the health and

safety of the occupants. This research has provided, and continues to provide,

other valuable findings which could only be obtained in these simple and

controllable test facilities.

In summary, full-scale testing of prototype buildings in environmental chambers

has proven to be a useful test method. The use of simple structures allows the

study of specific aspects of building performance without the confounding

effects of irrelevant building features. Conducting the tests in environmental

chambers, where one can control climatic conditions, enables the detailed study

of the effects of ambient conditions and the comparison of a structure's

performance in different physical configurations.

3
2.2 Testing of Prototype Buildings in the Outdoors

While the testing of prototype structures in environmental chambers has the

advantages discussed above, such experimental work lacks the realistic

conditions of the outdoor environment such as wind, rain, and radiation effects.

In order to study these effects, there have been several cases of full-scale

testing of prototype buildings in the outdoors. Three examples of such research

are discussed in this section. The first involves six, one-room test buildings

at NBS, the so-called "thermal mass" buildings. These buildings are 6 by 6 m

with 2.3 m ceilings, and are of identical floor plan and orientation. The only

difference is in their wall construction, with variation in the types of

materials used and in the amount of insulation and thermal mass. The structures

have been used to study the effects of wall mass on heating loads and thermal

comfort (Burch, Krintz and Spain 1984b). These experiments found a significant

thermal mass effect on heating loads during the intermediate heating season when

solar and other internal heat gains caused the indoor temperature to rise above

the thermostat setpoint. The more massive buildings were better able to store

this heat and use it later in the day than were the less massive structures.

Also, the wall mass reduced overheating during the day, leading to improved

thermal comfort. The fact that the buildings were identical except for wall

construction made this study and the quantification of the results possible.

Four of these structures were also used to study the effects of thermal mass on

the energy savings due to night temperature setback (Burch et al 1984a). While

computer simulations predicted greater savings in the less massive buildings,

these measurement results exhibited too much variability to determine whether or not differences in thermal mass caused significant differences in the setback

savings

.

Another prototype structure exposed to the outdoors was used to study envelope

heat transfer, air infiltration, and the effectiveness of an air-to-air heat

exchanger (Persily 1982a and 1982b). This structure, located at Princeton

University, was a single cell about 2.4 by 2.4 m and 5.5 m high. It was extremely airtight and of lightweight wood-frame construction with

reconf igurable window systems. It was used to study the effects of night sky

radiation on envelope heat loss and the relation of fan pressurization test

results to natural infiltration rates induced by weather. The Princeton chamber

was also used to determine the heat recovery effectiveness of an air-to-air heat

exchanger. Because the heat loss characteristics of the chamber were so well

understood, the tests enabled precise measurements of the device's heat recovery

efficiency including effects of heat conduction through the device. This fullscale testing approach was more realistic than a laboratory testing approach in

which the heat exchanger is installed in a system of ductwork, and provided more

accuracy than would be achievable in a house with its uncontrolled air leakage

and complex heat loss characteristics.

The last example of outdoor testing of a prototype structure involves the Mobile

Infiltration Test Unit (MITU), constructed at the Lawrence Berkeley Laboratory

(LBL), to study the predictive ability of the LBL infiltration model and to

examine the physical assumptions on which the model is based (Modera, Sherman

and Levin 1983). MITU is an airtight, wood-frame structure 4.9 by 2.4 m and 2.4 m high with sixteen locations available for the installation of calibrated

leakage panels. The fact that the experimenters know the location and

characteristics of the leaks enabled studies of infiltration that would not have

been possible in an actual home, in which leakage sites are not at all well

characterized in terms of location and magnitude.

4
2.3 Testing of Residential Buildings in Environmental Chambers

There have been a small number of full-scale tests of actual buildings in

environmental chambers that have combined controlled weather with real

buildings. Examples of this type of full-scale testing are described in this

section.

There have been several tests of manufactured housing in the large environmental

chamber at NBS (Hunt, Treado and Peavy 1976; Tietsma and Peavy 1978; Silberstein

1980). The first study considered several aspects of the thermal performance of

a two-bedroom modular house with a floor area of 56 m^. This work included

studies of the part-load efficiency of the heating plant and the effect of

furnace sizing on net efficiency. The latter aspect of the study required

testing with three different furnaces under identical exterior temperature

conditions, which could only be achieved in such a chamber. The temperature

difference dependence of the infiltration rate of this modular structure was

also studied and a clear linear dependence was found. Another modular house was

tested in the NBS chamber in an earlier study of air leakage (Hunt, Treado and

Peavy 1976). The testing included an examination of the dependence of

infiltration on temperature difference and the effects of storm windows, door

openings, and furnace fan operation on the infiltration rate. The fact that the

tests were made in the chamber under controlled and repeatable temperature

conditions enabled the demonstration of the linear dependence of infiltration on temperature difference and the unexpectedly small effects on infiltration of

storm windows and the opening of doors.

A dramatic example of full-scale testing in an environmental chamber involved a full-sized, four-bedroom townhouse installed in the large chamber at NBS (Peavy

et al 1975). This building was a factory produced structure of modular design

with a floor area of 110 m^. These thermal performance tests were made under

simulated daily temperature cycles for two cities and with simulated occupancy

patterns. The testing was designed in part to evaluate the capability of the

NBSLD model for predicting maximum heating and cooling loads, interior

conditions, and daily energy requirements. There were also infiltration

experiments in the house that demonstrated the linear dependence of infiltration

on temperature difference and revealed that leaks associated with doors and door

openings had a small effect on the total infiltration rate (Hunt and Burch

1975).

Such testing of residential buildings in environmental chambers allows the

detailed study of the performance of realistic structures. The fact that the

tests are made in a temperature controlled chamber allows direct comparisons of

different furnaces and different envelope airtightness configurations.

Infiltration studies are particularly well suited to chambers where temperature

effects can be examined without the confounding factors of wind speed and

direction encountered in the field.

2.4 Other Relevant Research in Residential Building Interactions

In this section we discuss past and current examples of full-scale field testing

of residential building interactions. This discussion is limited to that

research relevant to the projects proposed later in this report, and is not

intended as a complete review of full-scale testing of resiential buildings.

Tbs first example is ASHRAE SP43 , "Dynamic and Seasonal Performance of Central

Forced-Warm-Air Heating Systems" (Fischer et al 1984). This ongoing study,

5
being conducted by Battelle-Columbus Laboratories, involves the testing of two

unoccupied, conventional wood-frame houses typical of Midwest homes built in the

nineteen-fifties and sixties. The basic goal of the research is to develop and

verify a model to simulate dynamic interactions of the key components of a gasfired, forced-air heating system and the building structure in response to

weather. These components include the house structure, building envelope,

furnace, air distribution system, venting system, air infiltration, and

controls. Some of the equipment factors which are being varied include furnace

location, combustion air source, furnace efficiency rating, furnace sizing,

venting arrangement, ignition type, and control modes. As these and other

factors are varied, the dynamic response of temperatures, heat flows, and gas

usage are studied in order to understand the interactive processes occurring in

homes. This large and long-term effort suggests similar work with other types

of heating and distribution systems, with more consideration of envelope

features, and involving the use of prototype buildings, along with chamber

testing as a means of achieving additional experimental control.

Another important example of full-scale testing of residential building

interactions is a study of duct leakage and its effects (Orlando and Gamze

1980). This study in several U.S. homes involved the development of a technique

to measure the airflows involved and the effects of duct leakage on heat load.

The investigators studied the magnitude of duct leakage, where the associated

heat goes (i.e. how much ends up as useful heat in the living space), how the

distribution system impacts furnace efficiency and operation, and the effect of

the furnace fan on infiltration rates. While the research did not provide a complete characterization and explanation of the phenomena involved, it

revealed some interesting results and raised many important questions. For

example, this work identified increases in infiltration due to an imbalance

between the supply and return flows of the distribution system and effects on

furnace efficiency of lower return air temperatures due to duct leakage. As in

the previous research project, this work suggests the need for additional whole

building research as discussed later in the report.

There have also been several studies of manufacturer housing that have revealed

important issues in this area of significant construction activity. A study at

the Florida Solar Energy Center (1982) involved the side-by-side testing of two

unoccupied modular structures, one constructed with standard insulation levels

and the other with higher insulation levels and other improvements. This

research revealed a 10% difference in energy use between the two structures and

a six-year payback period for the energy conserving improvements. The addition

of an air barrier in the low-energy house was found to have no effect on infiltration. Such side-by-side testing of similar modular structures has

potential for use in evaluating alternative constructions and equipment

selection and installation, especially when conducted in environmental chambers.

Additional testing of modular structures, done by Science Applications, Inc.

(1980), involved the extensive study of two buildings and included the

installation of several different heating systems. This research considered

several important issues in modular housing energy use including equipment type,

sizing, and distribution. Several of the study's findings identified areas for

additional research. These findings include rates of interior temperature

change in excess of existing comfort standards, significant duct leakage, wide

variation in heat delivery to registers, awkward and illogical register

locations, excessive furnace noise, and inappropriate thermostat locations.

Additional research into these and other issues is required, and the use of

environmental chambers is an appropriate means for understanding these important

6
questions

.

There have also been studies of residential building interactions involving

modelling but little or no field testing. Instances where modelling has

suggested important effects of interactions between building features, or where

some controversy exists as to the net results of these interactions, are candidates for full-scale experimental work in environmental chambers. One

important example involves the interaction of envelope thermal characteristics,

building thermal mass, and heat pump performance as they determine thermostat

setback savings. The question of setback savings with heat pumps has been

discussed for many years, with references being made to the importance of

envelope heat loss and thermal mass. Some modelling studies have demonstrated

energy savings using night setback with heat pumps (Ellison 1977; Schade 1978),

while others have shown increased energy use with setback (Zabinski and Parlange

1977; Air Conditioning Heating and Refrigeration News 1977; Bullock 1978;

Bartlett 1979). In all cases, the research has referred to the importance of

the envelope and thermal mass, but the effects of these factors have not been

studied. The whole question of setback with heat pumps has been subject to

little full-scale testing. More recently, alternative control techniques were

proposed to avoid large amounts of electric resistance heating during the warmup after the setback period (Backus 1982; Benton 1983). The latter study

included experiments in five homes. The experiments did show energy savings

with the new controls, but did not study interactive effects associated with the

building envelope and thermal mass. These building envelope issues are important to understanding this problem, and full-scale testing in chambers is an appropriate and useful experimental approach.

Another example of a problem which lends itself to full-scale testing in

environmental chambers has been studied at the Florida Solar Energy Center

(FSEC) and concerns cooling in hot, humid climates. The research has

concentrated primarily on modelling with limited field testing in occupied and

unoccupied homes. One issue concerns the interaction of cooling load (sensible

and latent), air-conditioner efficiency, envelope heat transfer, and indoor

humidity control (Khattar 1984; Khattar and Swami 1984). As air conditioner

efficiencies increase, the ratio of sensible to total cooling of the device

(SHR) also increases, and thus the control of indoor humidity may suffer. The

problem arises from the fact that both more efficient equipment and improved

thermal integrity of building envelopes lead to shorter air conditioner on- times. Modelling done by FSEC has shown that undesirably high indoor humidity

levels can occur if the air conditioner is controlled by a thermostat alone and

is improperly sized regarding its SHR. Researchers at FSEC have also done

modelling and field testing of the importance of moisture storage in interior

furnishings and building materials. This work has important implications for

indoor humidity control and air conditioner energy use, especially when

considering the use of nighttime ventilation to decrease cooling energy

requirements. Humidity brought in during the night is absorbed within the house

and affects daytime humidity levels, cooling requirements, and net energy use. Full-scale testing in environmental chambers would assist in the development of

a more complete understanding of this issue.

7
3. Exisiting Environmental Chambers

In this section, several existing environmental chambers are described briefly,

including some details regarding size and range of ambient conditions.

NBS Environmental Chambers

There are seven environmental chambers at NBS, ranging in floor area from about

8 to 180 m^. The temperature within the chambers can be varied from -45 to 65

°C and the dewpoint from -15 to 32 °C. These interior conditions can be varied

according to predetermined cycles to simulate diurnal patterns. Two sets of two

chambers have a common insulated wall so that indoor and outdoor environments

can be created to impose a differential thermal load on components such as windows or heat pumps. The large chamber has a 9.4 m ceiling and a volume of

2.000 dP, and is capable of holding an entire house.

Portland State University Chamber

This chamber (Spolek and Peterson 1984) has a floor area of about 65 m^ and a height of 4.9 m for a volume of about 320 m^. It presently contains a two room

test house (each room 3 x 3 x 2.5 m) , and is being used to study residential

HVAC controls.

Owens-Corning Thermal Research Facility

This is a large environmental chamber with dimensions of 11 x 21 x 7.6 m for a floor area of about 230 m^ and a volume of about 1,700 m3 ( Mumaw 1980). It

contains a metering pit (4 x 6 m) for testing horizontal building elements such

as floors, ceiling and roofs, or more complex elements such as attics (Wilkes

1981 and 1983). The temperature within the chamber can be controlled within -45

and 65 °C.

4. PROPOSED FULL-SCALE TESTING RESEARCH

In this section several specific research topics are proposed for full-scale

testing in environmental chambers. Some of the research is related to past and

current experimental work described earlier, while other topics are based on questions posed by past modelling studies. Some of the research is proposed to

address whole building interactions important to today's most pressing building

research issues such as cooling in hot/humid climates, manufactured housing, and

indoor air quality. The full-scale testing research includes both prototype

structures and real buildings to be tested in environmental chambers, with the

possibility of additional testing in the outdoors. Based on the potential

associated with prototype building experiments, the design and construction of a reconf igurable test structure is proposed for use in both chamber and outdoor

testing. While many of the questions discussed below have been raised

previously, the determination of their quantitative significance requires

additional study.

4.1 Effects of Building Design and Equipment Installtion on the Performance of

Space Conditioning Equipment

This research topic is similar to ASHRAE SP43 , but is meant to include other

types of heating equipment and distribution systems, to give more consideration

to envelope and building mass effects, and to employ controlled testing in

8
environmental chambers. The basic thrust of the project is to understand the

various ways in which the building structure, thermal envelope, heating

equipment, and distribution system interact to determine the in situ performance

of the space conditioning system in terms of energy use and comfort. More

emphasis could be given to envelope and mass effects by using a reconf igurable,

prototype building in an environmental chamber, rather than structures with

constant envelope characteristics, such as those involved in the ASHRAE study.

Also, the use of environmental chamber testing will enable more detailed and

controlled experiments than have been possible in SP43. While ASHRAE SP43 has

concentrated on gas-fired, forced-air heat, this research could include oil,

electric resistance, heat pump, wood and other systems and distribution by hot

water, steam, radiant panels and other means. Gas-fired steam, hot water

heating, and individual room heating also merit consideration, as well as cooling equipment.

In addition to equipment questions such as sizing, design, location, venting,

and combustion air source, this research would consider the interaction of the

equipment with the rest of the building envelope and distribution system. These

interactions include the effects of equipment, duct and register location on

heat delivery and heat flow within the house, the effect of control strategies

on equipment performance, and the effect of infiltration rates and internal air

flows on heating performance and vice versa. The experimental design of SP43 can serve as a useful model for the development of this proposed research. The

proposed project includes the study of a number of smaller issues, several of

which are described below.

4.1.1 Envelope Infiltration and Combustion Appliances

The central questions of this topic are how combustion appliances affect

building infiltration and how the tightness of the building envelope affects the

performance of combustion appliances. The first part of the issue includes the

increase in building infiltration rates due to combustion air requirements, offcycle flows up the flue, and furnace fan operation. A small amount of data on

these questions exists as part of previous infiltration studies (Shaw and Brown

1982), and some relevant modelling work has also been done (Warren and Webb

1978). Full -scale, controlled experiments are necessary to quantify and

understand the issues involved. The other side of this topic is the effect of

envelope tightness on combustion appliance performance due to inadequate

combustion air supply under certain situations. The combinations of weather

conditions, envelope tightness, and internal air flows which can cause problems

need to be investigated and understood. The use of dedicated outside air

supplies (i.e. sealed combustion) or other strategies for alleviating these

problems also calls for full-scale testing of their effectiveness and impact.

4.1.2 Forced-Air Duct Leakage and Thermal Load Effects

This project is intended to build on the previous work by Orlando and Gamze

(1980) which studied the magnitude of duct leakage in several homes. Testing of

prototype structures is needed to determine the connection between the leakage

location and magnitude, and the associated increase in heating or cooling loads.

In addition, the effect of changes in return air temperature on space

conditioning equipment efficiencies needs to be studied. The existence and

effect of imbalances between the supply and return air flows is another

important area where full-scale research is needed. These problems also relate

to the heat flows, by conduction and convection, between the living space, the

9
furnace location, and any other spaces where ducts are located.

4.1.3 The Relation of High R-Value Envelopes and Space Conditioning Equipment

As more homes are built with extremely high R-value envelopes, questions are arising as to the most appropriate ways to heat these structures. In such

"superinsulated" buildings, the heating loads are so small that the capital

cost, sizing, and efficiency of the equipment must be examined from a new

perspective. High efficiency equipment may not make economic sense due to the

low heating loads. It may be difficult to find properly sized equipment, and

operating efficiencies may be affected by the low demand. Research is needed to

study the performance of various heating systems in superinsulated homes, and to

determine if and when critical points occur where particular types of equipment

are no longer appropriate for specific combinations of insulation level and

climate. Full-scale testing is also needed to study the creation and

alleviation of previously nonexistent cooling loads in these buildings.

4.1.4 Thermal Loads Associated with Infiltration and Ventilation

The thermal loads associated with the rate of infiltration or ventilation have

never been studied on the whole building scale, except for some limited tests in

a prototype building (Persily 1982a). These loads are generally assumed to be

directly proportional to the infiltration rate and the inside-outside

temperature difference. This assumption has not been studied in the detail

appropriate to its importance, especially in the area of coolings loads where

latent heat is so significant. Unexpected relations between infiltration and

heat loss may occur due to mixing effects of the interior air or heat transfer

effects on the airstream as it flows through the building envelope. This

question needs study for both uncontrolled infiltration through the envelope and

mechanical ventilation.

4.2 Full-Scale Testing of Interactions in Manufactured Housing

Because of the large amount of construction activity in the area of modular

manufactured housing, questions regarding the full-scale thermal performance of

these structures is taking on increasing importance. Past research and

experience raise many important issues for which experimental evaluation in

environmental chambers would be quite useful. These include the location of

ductwork, registers, HVAC equipment and thermostats, duct leakage, equipment

sizing, influence of transportation on airtightness and heat loss, airtightness

and insulation integrity of the connection between the two halves of double-wide

units, comfort, noise, and energy conserving construction options. Side-by-side

chamber testing of units with specific differences between them is one appropriate experimental strategy. Another strategy is the systematic variation

of a reconf igurable modular house.

4.3 Building Envelope Characteristics, Air Conditioner Performance and Indoor

Humidity Control

This project is intended to provide full-scale testing of the questions raised

in the FSEC work described earlier. FSEC researchers have made calculations

showing that energy efficient air conditioners, especially when installed in

buildings with low thermal load envelopes, may not remove sufficient moisture to

control the indoor humidity. A complete understanding of this issue would

benefit from full-scale testing of prototype structures in chambers. FSEC has

10
also done calculations, and some limited measurements, on the absorption and

desorption of moisture in interior furnishings and building materials and the

importance of such moisture storage in determining indoor humidity levels. This

storage question is also appropriate to full-scale testing as another factor to

study in this project. FSEC has done some testing in a small number of

townhouses, but these studies did not include infiltration measurements that are

so crucial to the study of latent cooling loads and indoor humidity. This

research project should include testing of a prototype structure in an environmental chamber under different conditions of cooling equipment, control

schemes, infiltration rates, envelope heat loss, and intentional ventilation

strategies. Later chamber work can include interior furnishings for their

contribution to moisture storage effects.

4.4 Effects of Thermal Mass, Envelope Heat Loss and Equipment Type on Temperature Setback Savings

This work follows from two research issues described earlier, the experimental

work on the effects of building mass on setback savings (Burch et al 1984a) and

the issue of setback savings with heat pump systems. The first project

investigated the existence of differences in night setback energy savings due to

thermal mass in four one-room prototype buildings which were identical except

for wall construction, including insulation and thermal mass levels. Due to

excessive variability in the data, it was not possible to determine whether or not a mass effect existed, although computer simulations predicted an effect on setback savings. It is possible that research in an environmental chamber could

discern such an effect, and further work could be done on the effects of

internal mass (interior walls, furniture). The effects of air infiltration,

which is an instantaneous heat loss as opposed to conduction through a wall,

must also be considered. The heat pump issue has been the subject of

disagreement and characterized by a lack of consideration of the important

factors of envelope heat loss and thermal mass. Again, prototype testing in

environmental chambers will assist the study of this complicated issue. For

example, the heat pump equipment performance is affected by sizing, controls,

amount and staging of auxiliary strip heat, equipment balance point, and cycling

and defrosting effects, in addition to envelope interactions. Since there are

so many variables that must be considered, the use of simple structures in an environmental chamber will eliminate some of the complexity and assist in

achieving some understanding of the problem. Thus, we are proposing a general

study of the savings possible from temperature setback with consideration of the

effects of the building envelope and heating equipment, particularly thermal

mass and heat pump systems.

4.5 Whole Building Performance of Mechanical Ventilation Systems

Mechanical ventilation is becoming a more popular option for ventilating homes

as indoor air quality concerns increase. While the equipment is fairly well

understood, the whole building performance of mechanical ventilation systems on the residential scale has not been well studied. Important questions exist

concerning system design and sizing, vent location, balancing, weather effects,

control strategies, heat recovery, and integration with forced-air distribution

systems. Mechanical ventilation systems are being designed, installed and

operated with insufficient understanding of these issues and their performance,

and research is needed to provide design and operation guidelines.

11
4.6 Interactive Effects of Insulation Quality

The quality of the installation of insulation in a building envelope has

implications for more than just the space conditioning load of the structure.

The insulation quality affects interior surface temperatures, and therefore

thermal comfort, which are both important considerations in thermostat settings

and energy use. Also, defects in the insulation can lead to condensation

problems that can cause material failures and other deleterious results.

Distibution losses are also affected when ducts or pipes are installed in

envelope cavities that are intended to be well-insulated. The net effects of

all these factors should be studied on the whole building scale in both

prototype buildings and actual homes.

5. PROPOSED RE CONFIGURABLE TEST FACILITY

Many of the above projects could be studied in a proposed reconfigurable,

prototype building which would provide great flexibility in testing. The

structure would be roughly 6x6x3 m with replaceable wall and ceiling panels

in order to enable alteration of the envelope thermal properties. In addition,

the structure would have controllable infiltration and mechanical ventilation,

and several different modes of heating and cooling. Such a structure, installed

in an environmental chamber, would be extremely useful in all of the proposed

studies of residential building interactions.

1 2
6. REFERENCES

Air Conditioning Heating and Refrigeration News , "Utility Says Don't Set Back

Heat Pump Thermostats in Winter," August 1, 1977.

Backus, A.O., "Energy Savings through Improved Control of Heat Pump Setback,"

ASHRAE Transactions , Vol.88(l), 1982.

Bartlett, A.A. , '‘Temperature Setback and Energy Savings in Buildings Heated by

Heat Pumps," ASHRAE Transactions . Vol.85(2), 1979.

Benton, R., "Heat Pump Setback: Computer Prediction and Field Test Verification

of Energy Savings with Improved Control," ASHRAE Transactions , Vol.89(lB),

1983.

Bullock, C.E., "Energy Savings through Thermostat Setback with Residential Heat

Pumps," ASHRAE Transactions , Vol.84(2), 1978.

Burch, D.M., Johns, W.L., Jacobsen, T. , Walton, G.N., Reeve, C.P., "The Effect

of Thermal Mass on Night Temperature Setback Savings," ASHRAE Transactions , Vo 1.90( 2) , 1984a.

Burch, D.M., Krintz, D.F., Spain, S., "The Effects of Wall Mass on Heating Loads

and Indoor Comfort - An Experimental Study," ASHRAE Transactions , Vol.90( 1) , 1984b.

Burch, D.M., Lemay, M.R., Rian, B.J., Parker, E.J., "Experimental Validation of an Attic Condensation Model," ASHRAE Transactions , Vol.90(2), 1984c.

Burch, D.M., Peavy, B.A., Powell, F.J., "Experimental Validation of the NBS Load

and Indoor Temperature Prediction Model," ASHRAE Transactions , Vol.80(2),

1974.

Ellison, R.D. , "Savings in Energy Consumption by Residential Heat Pumps: The

Effects of Lower Indoor Temperatures and of Night Setback," ASHRAE Journal , February 1977.

Fischer, R.D., Jakob, F.E., Flanigan, L.J., Locklin, D.W., Cudnik, R.A.

,

"Dynamic Performance of Residential Warm-Air Heating Systems - Status of

ASHRAE Project SP43," ASHRAE Transactions , Vol.90(2), 1984.

Florida Solar Energy Center, "Instrumentation for Side-by-Side Testing of the

Energy Attributes of Mobile Homes," Final Report to the Residential

Conservation Program, Florida Public Service Commission, FSEC-CR-64-82(EA)

,

October 1982.

Gujral, P.S., Clark, R.J., Burch, D.M., "Transient Thermal Behavior of an Externally Insulated Massive Building," ASHRAE Transactions , Vol.86(2),

1980.

Gujral, P.S., Clark, R.J., Burch, D.M., "An Evaluation of Thermal Energy

Conservation Schemes for an Experimental Masonry Building," NBS Building

Science Series 137, National Bureau of Standards, 1982.

13
Hunt, C.M., Burch, D.M., "Air Infiltration Measurement in a Four-Bedroom

Townhouse Using Sulfur Hexafluoride as a Tracer Gas," ASHRAE Transactions . Vol.81(l), 1975.

Hunt, C.M., Treado, S.J., Peavy, B.A., "Air Leakage Measurements in a Mobile

Home," NBSIR 76-1063, National Bureau of Standards, 1976.

Khattar, M.K., "Residential Air-Conditioning Energy Calculations," ASHRAE

Transactions. Vol.90(2), 1984.

Khattar, M.K., Swami, M.V., "Impact of Passive Cooling Strategies on AirConditioner Performance in Warm, Humid Climates," ASME Solar Energy

Division Sixth Annual Technical Conference, Las Vegas, April 1984.

Kusuda, T., Bean, J.W., "Comparison of Calculated Hourly Cooling Load and Indoor

Temperature with Measured Data for a High Mass Building Tested in an Environmental Chamber," ASHRAE Transactions . Vol.87(l), 1981.

Malmstrom, T.-G., Ahlgren, A., "Efficient Ventilation in Office Rooms " Environment International . Vol.8, 1982.

Modera, M.P. , Sherman, M.H. , Levin, P.A. , "A Detailed Examination of the LBL

Infiltration Model Using the Mobile Infiltration Testing Unit," ASHRAE

Transact ions . Vol.89(2), 1983.

Mumaw, J.R., 'thermal Research Facility - A Large Calibrated Hot Box for

Horizontal Building Enclosures," in proceedings of the DOE/ASTM Conference

Thermal Insulation Performance (Tampa 1978), ASTM STP 718, 1980.

Orlando, J.A., Gamze, M.G., "Analysis of Residential Duct Losses," Final Report

1980, Gamze-Korobkin-Caloger , Inc., (NTIS PB80-228000) , 1980.

Peavy, B.A., Burch, D.M., Powell, F.J., Hunt, C.M., "Comparison of Measured and

Computer-Predicted Thermal Performance of a Four Bedroom Wood-Frame

Townhouse," NBS Building Science Series 57, National Bureau of Standards,

1975.

Peavy, B.A. , Powell, F.J., Burch, D.M. , "Dynamic Thermal Performance of an Experimental Masonry Building," NBS Building Science Series 45, National

Bureau of Standards, 1973.

Persily, A., "Evaluation of an Air-to-Air Heat Exchanger," Environment

International . Vol.8, 1982a.

Persily, A., "Understanding Air Infiltration in Homes," Center for Energy and

Environmental Studies Report No.129, Princeton University, 1982b.

Sandberg, M., "Ventilation Efficiency as a Guide to Design," ASHRAE

Transactions , Vol.89( 2), 1983.

Schade, G.R., "Saving Energy by Night Setback of a Residential Heat Pump

System," ASHRAE Transactions , Vol.84(l), 1978.

Science Applications, Inc., ''Mobile Home Heating, Cooling and Fuel-Burning

Systems," SAI Project No. 1-441-03-119-00, April 1980.

14
Shaw, C.Y., Brown, W.C., "Effect of a Gas Furnace Chimney on the Air Leakage

Characteristic of a Two-Storey Detached House," in Energy Efficient

Domestic Ventilation Systems for Achieving Acceptable Indoor Air Quality

proceedings of the Third Air Infiltration Centre Conference, London, 1982.

Silberstein, S., "Air Leakage Measurements of an Unpartitioned Mobile Home,"

NBSIR 80-2105, National Bureau of Standards, 1980.

Skaret, E., Mathisen, H.M., "Ventilation Efficiency," Environment

International ," Vol.8, 1982.

Spolek, G.A., Peterson, J.C., "A Full-Scale Experimental Facility for Testing

Residential HVAC Controls," ASHRAE Transactions . Vol.90(2), 1984.

Tietsma, G.J., Peavy, B.A., ’*The Thermal Performance of a Two-Bedroom Mobile

Home," NBS Building Science Series 102, National Bureau of Standards, 1978.

Warren, P.R. Webb, B.C., "Air Supply for Domestic Combustion Appliances,"

Building and Environment . Vol.ll, 1976.

Wilkes, K.E., "Modeling of Residential Attics," in proceedings of the

ASHRAE/ DOE-ORNL Conference Thermal Performance of the Exterior Envelopes of

Buildings (Kissimmee, FL 1979), ASHRAE SP 28, 1981.

Wilkes, K.E., "Dynamic Thermal Performance of Walls and Ceilings/Attics, " in

proceedings of the ASHRAE/DOE Conference Thermal Performance of the

Exterior Envelopes of Buildings II (Las Vegas 1982), ASHRAE SP 38, 1983.

Zabinski, M.P., Parlange, J.V., '^Thermostat Down, Fuel Consumption Up," ASHRAE

Journal . January 1977.
FORM NBS-1 14A (REV.l 1-84)

U.S. OEPT. OF COMM.

BIBLIOGRAPHIC DATA

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1. PUBLICATION OR

REPORT NO.

85-3194

2. Performing Organ. Report No. 3. Publication Date

4. TITLE AND SUBTITLE

Opportunities for Full-Scale Testing of Residential Building

Interactions in Environmental Chambers

5. AUTHOR(S)

Andrew K. Persily

6. PERFORMING ORGANIZATION (If joint or other than NBS. see in struction s)

NATIONAL BUREAU OF STANDARDS

U.S. DEPARTMENT OF COMMERCE

GAITHERSBURG, MD 20899

7. Contract/Grant No.

8. Type of Report & Period Coverea

9.

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State, ZIP)

Architectural and Engineering Systems Branch

U.S. Department of Energy

Washington, DC 20585

10.

SUPPLEMENTARY NOTES

Document describes a computer program; SF-185, FlPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bi bliography or literature survey, mention it here) Much building energy performance research has been concerned with individual components

such as space conditioning equipment, controls, and building envelopes. Less work has

been done on how these various components interact on the whole-building scale to

determine energy use and other factors. As the understanding of component performance

has increased through measurement and modelling, our lack of understanding of the

interactions among these individual items has become more apparent. It is difficult

to examine these interactions in real homes due to the physical complexity of homes,

the uncontrallable nature of the weather, and effects of occupants. This report

focuses on opportunities for full-scale testing of residential building interactions

in environmental chambers, where one has control of weather conditions and occupant

effects. Such research will increase our understanding of the physical nature of

these interactions and their effects on energy use, comfort, cost, and other factors.

In this report we review past and current research in the area of full-scale testing

in environmental chambers and other related work. Based on this review, further

research is proposed in several important areas of residential building performance.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semi colon s/ building performance; energy conservation; environmental chambers; full-scale

testing; residential buildings; whole building performance

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