Enhancement of the Virtual Cybernetic 

Building Testbed to Include a Zone Fire 

Model with HVAC Components

Cheol Park

Paul A. Reneke

Michael A. Galler

Steven T. Bushby

William D. Davis

NISTIR 7414

 

NISTIR 7414

Enhancement of the Virtual Cybernetic 

Building Testbed to Include a Zone Fire 

Model with HVAC Components

Cheol Park 

Paul A. Reneke 

Michael A. Galler 

Steven T. Bushby 

William D. Davis 

Building and Fire Research Laboratory 

Gaithersburg, MD 20899 

April 2007

U.S. Department of Commerce 

Carlos M. Gutierrez, Secretary 

Technology Administration 

Robert Cresanti, Under Secretary of Commerce for Technology 

National Institute of Standards and Technology 

 William Jeffrey, Director 
 1 
 i 

ABSTRACT 

Enhancement of the Virtual Cybernetic Building Testbed to Include a 

Zone Fire Model with HVAC Components 

Cheol Park, Paul A. Reneke, Michael A. Galler, Steven T. Bushby, and William D. Davis 

Building and Fire Research Laboratory, NIST, Gaithersburg, MD 20899 

As part of a Cybernetic Building Systems project at the NIST Building and Fire Research 

Laboratory, a whole building emulator called the Virtual Cybernetic Building Testbed 

(VCBT) has been developed. The VCBT combines simulation tools with commercial 

building automation system products in order to emulate the characteristics of a 

commercial building and its various systems and controls. The VCBT simulates in real 

time the building envelope, weather, the heating ventilating and air-conditioning (HVAC) 

system, the heating/cooling plant, the fire detection system, and the security system. The 

simulation is linked through a data acquisition system to commercial products for HVAC 

control, fire detection, access control and lighting control in order to study their 

performance and interactions. 

This report describes a new simulation tool developed for the VCBT that combines a fire 

simulator called the Zone Fire Model with building shell and HVAC components derived 

from HVACSIM+

. This new simulation tool is called the Zone Fire Model with HVAC 

components (ZFM-HVAC). Implementation of the ZFM-HVAC tool in the VCBT is 

described along with the results of emulation runs used to test its performance. 

Key words: BACnet, building automation and control, building management systems, 

cybernetic building systems, fire models, fire simulator, ZFM-HVAC 
 ii 

Table of Contents 

1. INTRODUCTION ........................................................................................................ 1

2. VCBT 2.0 ARCHITECTURE...................................................................................... 2

2.1 Center...................................................................................................................... 3

2.2 HVACSIM+

............................................................................................................. 5

2.3 Building Shell Model.............................................................................................. 7

2.4 Data Acquisition System........................................................................................ 8

2.5 Building System BACnet Controllers ................................................................ 10

2.6 BACnet Fire Panel ............................................................................................... 13

2.7 Biometric Devices for Security ........................................................................... 14

2.8 Sensor-Driven Fire Model (SDFM).................................................................... 14

3. ZFM-HVAC ................................................................................................................ 14

3.1 Zone Fire Model (ZFM) ...................................................................................... 15

3.2 HVAC Components from HVACSIM+ .............................................................. 15

3.2.1 Actuator (Type321).......................................................................................... 17 

3.2.2 Mixing box...................................................................................................... 19 

3.2.3 Temperature Sensor (Type301) ...................................................................... 20 

3.2.4 Humidity Sensor (Type302) ........................................................................... 21 

3.2.5 Flow rate Sensor (Type303)............................................................................ 22 

3.2.6 Static pressure Sensor (Type305) ................................................................... 22 

3.2.7 Motor drive (Type333) ................................................................................... 23 

3.2.8 Fan (Type350)................................................................................................. 23 

3.2.9 VAV Box (Type526) ...................................................................................... 24 

3.2.10 Fluid Resistance (Type341) .......................................................................... 26 

3.2.11 Add Heat (Type366) ..................................................................................... 26 

3.2.12 Merge Flow (Type422)................................................................................. 26 

3.2.13 Mix Flow (Type365)..................................................................................... 27 

3.2.14 Mass Flow Balance (Type425) ..................................................................... 27 

3.2.15 Coil & Valve (Type524) ............................................................................... 27 

4. ZFM-HVAC RUNS AND DISCUSSION ................................................................. 35

4.1 Case 1 Scenario .................................................................................................... 36

4.2 Case 2 Scenario .................................................................................................... 57

4.3 Case 3 Scenario .................................................................................................... 62

5. CONCLUSION ........................................................................................................... 68

6. REFERENCES............................................................................................................ 69

Appendix A. Sample BACnet Air-handling Unit Controller Object Database. ....... 71
 iii 

Appendix B. Sample BACnet VAV Box Controller Object Database...................... 72

Appendix C. Fire-related Input Data for Case 1_1. .................................................... 73

Appendix D. HVAC-side Configuration Input Data ................................................... 74

Appendix E. Sample AHU Input Data.......................................................................... 75

Appendix F. Sample VAV Input Data .......................................................................... 83

Appendix G. Sample AHU Initial Data ........................................................................ 86
1

1. INTRODUCTION 

As part of a Cybernetic Building Systems project at the Building and Fire Research 

Laboratory of National Institute of Standards and Technology (NIST), a whole building 

emulator called the Virtual Cybernetic Building Testbed (VCBT) has been developed. 

The VCBT combines simulation tools with commercial building automation system 

products in order to emulate the characteristics of a commercial building and its various 

systems and controls. The VCBT simulates in real time the building envelope, weather, 

the heating ventilating and air-conditioning (HVAC) system, the heating/cooling plant, 

the fire detection system, and the security system. The simulation is linked through a data 

acquisition system to commercial products for HVAC control, fire detection, access 

control and lighting control in order to study their performance and interactions. 

Simulation results are converted by the data acquisition system into electrical signals that 

appear to building automation system devices as input from real sensors. The control 

actions are captured and used by the simulation software to determine the response of the 

virtual building. The overall effect is that the building management system (BMS) 

controls the simulated building systems as if they were an actual building. 

In 1983, a simple building emulator was constructed at NIST to demonstrate the basic 

concept of a building emulator. The first emulator had a model that was too simple for 

testing algorithms quantitatively. Later a contractor for the U.S. Naval Civil Engineering 

Laboratory, with assistance from NIST, built a second building emulator with greater 

sophistication [1]. Since then the work on building emulators has continuously evolved 

[2-7]. The resulting VCBT 1.0 simulator employed the program, HVACSIM+ [8], which 

stands for HVAC SIMulation PLUS other systems to simulate the HVAC system 

components and simple building envelopes except for the BMS controllers. The VCBT 

has been used to study various types of building systems and technology including: 

interactions of HVAC system components with fire, HVAC system fault detection and 

diagnostics (FDD) technology [9], communication protocols for building automation and 

control networks (BACnet) [10, 11], and the sensor-driven fire model (SDFM) [12]. 

Since the VCBT 1.0 architecture was reported [7], several enhancements have been made 

including: a more advanced fire detection system panel, a biometric building access 

control system, newer HVAC controls, and a new simulation tool developed for the 

VCBT that combines a fire simulator called the Zone Fire Model with building shell and 

HVAC components derived from HVACSIM+. This new simulation tool is called the 

Zone Fire Model with HVAC components (ZFM-HVAC). 

This report reviews the overall structure of the VCBT and describes the implementation 

of the ZFM-HVAC tool including results of emulation runs used to test its performance. 

Details of the ZFM components are published elsewhere [12]. Details of the HVAC 

components used in ZFM-HVAC will be described in this report. 
2

2. VCBT 2.0 ARCHITECTURE 

The architecture of the VCBT version 2.0 is shown schematically in Figure 1. The VCBT 

consists of a Center that provides an overall control and coordinating function of the 

other components, some of which are implemented in software and others are real 

building automation system devices. Simulated components include weather data, a 

simple building envelope model implemented using HVACSIM+ called the Shell Model, 

a firefighter decision support tool called the Sensor-Driven Fire Model (SDFM), and a 

visualization tool that can depict the virtual building and its internal conditions 

implemented in Virtual Reality Modeling Language (VRML). Two options exist for 

simulating the building interior rooms and HVAC system. HVACSIM+ is used if the 

research requires very detailed simulation of HVAC system components. ZFM-HVAC is 

used if the research requires investigating fires in the building. Fire detectors are 

represented by a combination of simulated output from detectors and actual fire detection 

hardware. 

Physical components of the VCBT include a variety of BACnet HVAC controllers from 

several manufacturers, a BACnet fire alarm panel, and a biometric building access 

control system. The hardware components are linked to the software components through 

a commercial data acquisition system. Key simulated values are converted by the data 

acquisition system into voltage or current signals that are wired to the building 

automation system devices and appear as sensor inputs. Control actions are captured by 

the data acquisition system and converted to digital values that are fed into the next step 

of the simulation. Figure 2 is a photo of the VCBT hardware. 
3

Figure 1. Components of the VCBT distributed simulation environment. 

2.1 Center 

The Center is the heart of the VCBT. It is a computer program residing in a personal 

computer that uses the Common Object Request Broker Architecture (CORBA) [13] to 

provide communications between the distributed components of the VCBT. CORBA is a 

vendor-independent, object-oriented architecture that provides a way to link computer 

programs across a network. 

Using the graphical interface of the Center, configuration data are entered and output data 

from the simulations are displayed. The inputs and outputs from the building control 

system hardware are also monitored by the Center. The VCBT runs in real-time in a 

distributed, multi-platform environment. As seen in Figure 1, the Center communicates 

with the building management system hardware through the data acquisition system. 

Other components of the VCBT communicate directly with the Center using CORBA. 

Real BACnet Controllers ZFM-HVAC

Data Acquisition System

CENTER

Shell Model

VRML Browser

BACnet Fire Panel

Biometric Devices

SDFM

Hardware Software

HVACSIM+

Fire Sensors

Fire Sensors
4

 

Figure 2. VCBT controller hardware, data acquisition system, fire-related devices 

including fire-panel, and biometric devices. Workstations for the VCBT controllers 

are not shown. 

The Center controls the flow of data between all elements of the VCBT. It is also 

responsible for starting, initializing, and closing them. Individual components can be 

selected for use in a particular run of the VCBT, and the computer that these components 

will run on can be chosen at runtime. The Center runs on a 10 s cycle, during which data 

messages for each active component are created, transmitted, and any return messages 

evaluated. The amount of data currently being sent through the Center is only a fraction 

of its capability. 

The Center is responsible for storing every piece of data that is transferred between the 

various components of the VCBT. This is done by first creating a list of the objects (i.e., 

a variable air volume (VAV) box or a room) which have properties (i.e., temperature, 

humidity, set points) associated with them. The properties of each object are then created, 

and linked to their parent objects. For each component of the VCBT, the subset of object 

and property combinations that the component uses is stored in a list associated with that 
5

component. Separate lists are created for each component for data going to the 

component, and for data coming back from the component. The value of any property 

used in the VCBT can be viewed at the Center. Figure 3 is a screen image of the Center. 

Figure 3. The Center Interface is used to link the components of a particular 

emulation and to control their interaction. In this example only the Datalogger, the 

ZFM-HVAC and the shell components are used. 

2.2 HVACSIM+

HVACSIM+

 is a public domain computer simulation program developed by NIST for 

studying the dynamic interactions between building system components [8]. Most of the 

programs are written in Fortran 77. This program has been used extensively in the studies 

of fault detection and diagnostics (FDD) of building HVAC systems [9]. 
6

HVACSIM+ links component type models together to build an HVAC system simulation. 

The component models used in the VCBT were originally developed during the course of 

ASHRAE Research Project 825 [14]. A typical virtual building simulation consists of the 

building zones (rooms), some single-duct Variable Air Volume (VAV) air-handling units, 

VAV terminal boxes, and the associated valves, coils, dampers, and sensors. 

A schematic representation of a typical VCBT air-handling unit along with central plant 

facilities is shown in Figure 4. The figure illustrates the various dampers, valves, 

actuators, and fans that are to be controlled. The simulated sensor outputs that are to be 

used as inputs to the controllers for air-handling units are listed in Table 1. The 

component models of a central boiler, chiller, and cooling tower have not been utilized in 

the VCBT yet and are shown as dashed lines. Figure 5 is a schematic drawing of one of 

the single duct VAV boxes. 

Figure 4. A schematic representation of a VCBT air-handling unit. 

A A

A

A

C A

C C

C C C

C

C

A

C

Heating coil Cooling coil

Supply fan

Boiler Chiller Cooling tower

Supply air

Return air

Return fan Re-circulating air damper

Exhaust air damper

Outside air damper

Controller

Actuator

Mixing box
7

 Table 1. Simulated sensor outputs for Air-handling unit control. 

mixed air temperature 

outdoor air relative humidity 

outdoor air temperature 

return air relative humidity 

return air temperature 

return air volumetric flow rate 

supply air static pressure 

supply air temperature 

supply air volumetric flow rate 

 

 

 Figure 5. A schematic representation of the single duct VAV box. 

2.3 Building Shell Model 

The building shell model component of the VCBT is implemented using HVACSIM+

. 

The building shell model simulates heat gain or loss through the building envelope 

surfaces (walls, ceilings, floors, doors, and windows) as a function of outside conditions 

such as air temperatures, solar intensities, and wind speeds. Conduction heat transfer 

functions are used for calculation of heat fluxes through composite multi-layered surfaces 

in which each layer material is assumed to have uniform properties [15]. By varying the 

input weather data, the climate effects due to building location can be observed. 

A C

A

C

VAV box heating coil

Supply air to zone

VAV box damper

Controller

A Actuator

Hot water from boiler
8

Table 2 lists the variables associated with a typical building surface. The VCBT shell 

model has been enhanced to use ASHRAE WYEC2 hourly weather data [16]. The shell 

model assumes that weather conditions remain constant for 15-minute intervals. The 15-

minute data are generated from the hourly values by interpolation. February, July, and 

October are selected as representatives of three weather patterns for heating, cooling, and 

swing seasons, respectively. Internal load variations and solar heat gains through 

windows and facades are not yet considered in the current ZFM-HVAC, but the 

temperature and humidity of outside air are accounted for. 

Table 2. Building Surface Variables. 

Variable Description 

Inputs 

TIA Indoor air dry-bulb temperature 

TMR Mean radiant temperature 

TOSINF Outer surface temperature of unexposed wall 

FAHADW Shaded fraction of exposed surface 

 

Outputs 

TIS Inner surface temperature 

SOLINT Integrated solar influx on surface 

 

Parameters 

IZN Identification number of zone 

ID Identification number of surface 

IEXPOS Internal exposure 

0 = within zone, 1= between zones, 2=exposed to sun 

ISTR Identification number of the construct 

AS Surface area 

ORIENT Azimuth angle of normal to surface & south 

TILT Tilt angle: flat roof=0E, floor=180E

GRF Ground reflectivity 

IROFS Outer surface roughness index: 1=stucco, ... 

ABSOS Solar absorptance of outer surface 

ABSIS Short wave absorptance of inner surface 

EMITIS Emissivity of the inner surface 

TRANSM Transmittance of the glass window 

SC Shading coefficient of the glass window 

2.4 Data Acquisition System 

One of the computers used for the distributed simulation contains an interface card that 

communicates digitally with a commercial data acquisition system. This component is 

called the Datalogger in the system architecture. The simulated values that represent 

sensor inputs to the controllers are converted by the digital-to-analog converter of the 

data acquisition system into analog outputs represented by either DC voltages (0 to 5 V) 

or DC currents (4 to 20 ma). There is a capability to scale values to other ranges if 

needed. The output values of the BACnet controllers that represent inputs to the virtual 

building system component models are read by the digital voltmeter in conjunction with 
9

multiplexing scanners. The output voltage range of each controller is in between 0 V and 

10 V. Solid-state relay chips are employed for handling binary (digital) signals between a 

BACnet controller and the data acquisition system. 

Figure 6 shows the relationship between the data acquisition system with other 

components of the VCBT. “Hardwire” represents a pair of electrical wires. Other 

connections are digital communication using CORBA. After receiving data from the 

simulations, converting it into the analog values, and sending it to the controllers, the 

Datalogger waits 1 s, and then begins to read the controller outputs. The total cycle time 

is approximately 3 s to 4 s. 

Figure 6. Relationship of the data acquisition system for ZFM-HVAC with other 

units. 

ZFM 

HVAC Components 

AHU_1 

VAV_1 

VAV_2 

VAV_3 

AHU_2 

VAV_4 

VAV_5 

VAV_6 

AHU_3 

VAV_7 

VAV_8 

VAV_9 

Center Datalink 

Data Acquisition System 

AHU_1 VAV_1 VAV_2 VAV_3 

VAV_4 VAV_5 VAV_6 

AHU_3 VAV_7 VAV_8 VAV_9 

 

 

 

BACnet controllers 

Database 

VRML Browser 

AHU_1 

AHU_2 

BACnet 

Fire Panel 

 Shell Model CORBA 

Link 

Hardwire 

Hardwire 

Ethernet 

Software 

Hardware 

ZFM-HVAC 

+ 
10

2.5 Building System BACnet Controllers 

Commercially available BACnet controllers make up the building automation and control 

system of the virtual building. The controller input and output connections are wired to a 

patch panels that provides connections to the emulator. Various BACnet communication 

networks [10, 11] connect the controllers to each other. 

Figure 7 shows the network topology of the current BACnet system. For each local area 

network (LAN), the figure shows the type of network technology used and the BACnet 

network number. An Ethernet LAN serves as the backbone to the system. It connects 

three operator workstations and the supervisory controllers for the virtual building. These 

supervisory controllers provide scheduling capability, alarm processing, implementing 

reset schedules and also serve as routers to networks of unitary controllers. The unitary 

controllers reside on ARCNET or MS/TP LANs. 

Ethernet Backbone (Network 10)

Networking of BACnet Devices in the VCBT

Workstation 1

ID = 100

MAC = X'09'

AHU1

ID = 110

MAC = X'04'

Zone 1

ID = 101

MAC = X'10'

Zone 2

ID = 102

MAC = X'11'

Zone 3

ID = 103

MAC = X'12'

ID = 104

MAC = X'13'

ID = 105

MAC = X'14'

ID = 106

MAC = X'15'

Workstation 2

MS/TP Network 21

Fire Panel

ID = 24002

AHU2

ID = 310

MAC = X'00'

Zone 4

ID = 304

MAC = X'01'

Zone 5

ID = 305

MAC = X'02'

Zone 6

ID = 306

MAC = X'03'

MS/TP Network 23

ID = 200

MAC = X'01'

AHU3

ID = 210

MAC = X'03'

ARCNET Network 31

 Router

ID = 211 X'02'

Zone 7

ID = 207

MAC = X'01'

Zone 8

ID = 208

MAC = X'02'

Zone 9

ID = 209

MAC = X'03'

MS/TP Network 22

X'04'

Workstation 3

ID = 199 ID = 299 ID = 399

Gateway

Controller/Router Controller/Router Controller/Router

Figure 7. Network topology of the BACnet building automation and control system.
11

Products from three different control companies are used for HVAC controls. It is 

possible to monitor essential input and output values of all products from controller 

workstations using BACnet. 

Air-handling unit (AHU) controllers in the virtual building provide supply fan control, 

return fan control, supply air temperature control, enthalpy economizer control, and 

supply air temperature reset. Appendix A provides an example BACnet object database 

for the controller for AHU 1. AI, AO, AV, BI, BO, and BV denote analog input, analog 

output, analog value, binary (digital) input, binary output, and binary value objects 

respectively. There is some variation in the BACnet object databases and control 

implementation details of the BACnet components. These differences reflect the fact that 

product features vary from manufacturer to manufacturer. The ranges of sensors and 

analog values in Appendix A correspond to design assumptions about the building 

equipment operating conditions. These can be varied by AHU or by zone. 

Control of VAV boxes in the virtual building involves damper and reheat valve controls. 

The damper is controlled to modulate supply airflow to a zone, while the reheat valve 

coupled with the reheat coil enables the temperature of air supplied to the zone to be 

increased. Appendix B provides an example BACnet object database for a sample VAV 

box controller. 

Appendices A and B illustrate the kind of detailed information that is available through a 

BACnet interface to the VCBT. They also provide the object identifier details needed to 

access the data using BACnet messages and the scaling details of the connection to the 

data acquisition system. Proportional-integral control is used for most local loops. 

Some AHU and VAV box control strategies implemented in controllers are briefly 

described below. 

Supply Fan Control

A typical, pressure-independent VAV system maintains a constant pressure at the VAV 

box inlets by sensing and controlling the static pressure at the supply duct. The supply fan 

controller with a proportional-integral (PI) algorithm receives the static pressure sensor 

output and sends the control output to a variable frequency motor controller to vary the 

supply fan speed. 

The PI control is a feedback control to minimize the error signal e(t) . 

e(t) = SP − MV(t)

where SP = set point 

 MV (t) =measured value 

t = time 
12

A popular PI algorithm is expressed [17] as: 

( ) ] 1 ( ) [ ( )

0

* *

0 ∫ = + +

t

I

u t u Kc e t e t dt

τ

where u(t) = controller output 

 u0 = bias value 

 Kc = proportional gain 

 τ I = integral time or reset time 

 =*

t dummy variable of integration 

Return Fan Control

The airflow rates of the supply and the return systems are measured at the airflow 

stations. The return fan speed is controlled to maintain a constant flow rate difference 

between the supply airflow rate and the return airflow rate. A PI algorithm is employed. 

Supply Air Temperature Control

The supply air temperature controller receives the sensor output from the supply air 

temperature sensor, and determines the appropriate positions of the cooling coil valve, 

heating coil valve, and mixing box dampers. It is assumed that outside air, exhaust air, 

and re-circulating air dampers are linked together to be controlled by a single controller 

output signal. Whenever the supply fan is on, the cooling and heating coil valves operate 

in conjunction with mixing box air dampers to maintain the set point value of supply air 

temperature. A PI controller is used. 

Enthalpy Economizer Control

The sensor outputs from the outside air temperature, outside air relative humidity, return 

air temperature, and return air relative humidity sensors allow the enthalpy economizer 

controller to determine the damper openings. When the outside air enthalpy is greater 

than the return air enthalpy, the outside air damper is closed to its minimum position, and 

the cooling coil provides the required cooling. When the outside air enthalpy is less than 

the return air enthalpy and the outside air temperature is greater than the supply air 

temperature, the outside air damper is fully open, and the cooling coil supplements the 

required cooling. 

Supply Air Temperature Reset
13

Based upon data from individual zone VAV boxes, the set point for supply air 

temperature can be reset to satisfy the maximum cooling demand required each zone 

during cooling season. 

VAV terminal box controller 

The airflow rate of a VAV terminal unit is governed by the damper opening. The reheat 

coil provides heating. The amount of heat is determined by the reheat coil valve opening. 

Typically the VAV terminal box controller controls the VAV box with a reheat coil in the 

way as shown in Figure 8. The zone temperature, Tz , is to be maintained near the set 

points (Tcool,set for cooling and Theat,set for heating). 

Figure 8. VAV box control

When Tz ≥ Tcool,set , the damper opening modulates linearly until the maximum opening is 

reached. 

When Tz < Tcool,set , the damper opening is at the minimum. 

When Tz ≥ Theat,set , the reheat coil valve is fully closed. 

When Tz < Theat,set , the reheat coil valve modulates linearly until the maximum opening is 

reached. 

2.6 BACnet Fire Panel 

The old BACnet fire panel has been replaced with a new advanced fire panel. The 

previous fire panel could monitor addressable smoke detectors that were triggered by 

Reheat coil valve - fully closed

Reheat coil valve - fully open VAV damper - maximum open

VAV damper- minimum open

Zone air temperature Theat,set Tcool,set
14

on/off operation. The new product can obtain analog values in voltage from addressable 

smoke detectors and heat sensors. First responders can monitor the information in the fire 

panel remotely using BACnet via Ethernet. In the virtual cybernetic building emulation, 

zone temperatures and zone smoke concentrations are be generated by ZFM-HVAC, 

transmitted to the data acquisition system, converted into analog data in voltage, sent to 

sensors, and sent to the BACnet fire panel as shown in Figure 9 where T and V denote 

the temperature and the voltage, respectively. When a zone/zones condition is in an alarm 

state due to fire, the fire panel provides alarms. 

Figure 9. BACnet fire panel and ZFM-HVAC 

2.7 Biometric Devices for Security 

Biometric devices for eye recognition and hand recognition as security measures for door 

entry have been added to the VCBT [18]. All implemented devices are fully compatible 

with the BACnet protocol. 

2.8 Sensor-Driven Fire Model (SDFM) 

The sensor-driven fire is described elsewhere [12]. 

3. ZFM-HVAC 

In the previous version of the VCBT, fire simulation was performed using the 

Consolidated Model of Fire Growth and Smoke Transport (CFAST) [19], and building 

HVAC system simulation was done using the HVACSIM+ program separately. 

Communication between CFAST and HVACSIM+

 was accomplished by exchanging data 

through the Center using CORBA. CFAST and HVACSIM+

 had their own independent 

equation solving routines. 

The new program called ZFM-HVAC is a computer program that combines a newly 

developed zone fire model, ZFM, and the building HVAC components based on 

HVACSIM+

. 

ZFM-HVAC Center Data Scale

Conversion

Sensors

Work

Station Gateway Fire Panel

Ethernet Network

T T V V

Digital Analog

Smoke sensor

Heat sensor

Pull station

Ethernet EIA-232

D/A

Conversion
15

The primary purpose of developing the combination program, ZFM-HVAC, is to 

organize all the computations under a single solver to ensure convergence to the proper 

solution. This consolidation will also aid in making the simulation expandable to large 

buildings. 

3.1 Zone Fire Model (ZFM) 

The zone fire model is described elsewhere. An early version can be found in reference 

[12]. 

3.2 HVAC Components from HVACSIM+

A building HVAC system delivers conditioned air to building zones. The virtual HVAC 

system determines pressures, flow rates, temperatures and humidity values, while the 

controllers provide control signals. As mentioned previously, HVACSIM+

 solves a 

system of non-linear equations simultaneously; however HVAC-side equations of the 

ZFM-HVAC are solved sequentially. This sequential solving method was chosen, 

because there are many variables to be solved in the HVAC-side. The ZFM-side equation 

solver solves simultaneously only for zone/room-related variables such as layer 

temperature, pressure, density, and combustion product concentrations. Fire is modeled 

as a two-layer environment with a hot upper smoke layer and a cool lower layer. The 

time scale for these zone/room variables to change is short compared to the response of 

an HVAC system. The variables determined by HVAC-side are treated as pseudo-steady 

state variables due to the fact that most HVAC motor-driven actuators respond very 

slowly to control signals and final element components such as coils, and dampers are 

connected to the motor-driven actuators. 

Most component models used in the HVAC-side of ZFM-HVAC originated from 

ASHRAE 825-RP by Norford and Haves [14] as “TYPE” routines. Brief descriptions of 

the models will be made based upon the report and the computer source code. Figure 10 

shows a number of routines involved in the HVAC-side of ZFM-HVAC. Slightly 

modified HVAC component models of HVACSIM+

 are used except that the mixing box 

component model is greatly simplified and smoke mixing is added. The routine for merge 

flow (Type422) was also modified to add smoke mixing. Completely new routines for 

determining calculation sequences were developed solely for ZFM-HVAC using Fortran 

90. At present, input data structures similar to HVACSIM+

 are used. The equations that 

are valid within their operating limits are presented below. Beyond the limits, the 

equations may not be valid. Special treatments are provided in the computer code for the 

equations in invalid regions. 
16

 

Figure 10. Routines involved in the HVAC-side of ZFM-HVAC. 

Relationship of HVAC-Side Subprograms 

AHU mixing_box_call actuator type321

mixing_box (new)

coil_valve_call actuator type321

coil_valve type524

fan_call motor_drive type333

fan type350

fluid_resistance type341

add_heat_call add_heat type366

pressure_call pressure_sensor type305

flowrate_call flowrate_sensor type303

temp_call temp_sensor type301

humidity_call humidity_sensor type302

Flow_merge merge_flow_call merge_flow type422

mix_flow_call mix_flow type365

VAV rh_coil_valve_call actuator type321

coil_valve type524

vav_box_call vav_box type526

temp_zone_calll temp_sensor type301

massflow_balance_ massflow_balance type425

call
17

3.2.1 Actuator (Type321) 

The motor-driven actuator model calculates the position of a constant speed, motordriven actuator accounting for hysteresis, crank geometry and range mismatch. Detailed 

description can be found in reference [14]. 

At each time step, the dimensionless actuator drive shaft position, ), θ (t moves to next 

position according to the demand position, (t) θ D , and the state of movement of the 

motor. The possible states of the motor are backward motion (δ = −1), stationary 

(δ = 0 ), or forward motion (δ = +1). 

The maximum change of position during one time step, Δθ max , is: 

 

f

t

τ

θ Δ Δ max =

where Δt is the duration of time step, and f τ is the time required for the actuator to 

travel its full range from θ = 0 to θ = 1 . 

Three cases can be considered: 

If the actuator motor was stationary at the previous time step (δ (t −1) = 0 ), 

the new position remains at the previous position (θ (t) = θ (t −1)) and no 

movement occurs (δ (t) = 0 ). 

If the actuator motor was moving either forward or backward (δ (t −1) = +1 or 

δ (t −1) = −1), and max θ D (t −1) −θ (t −1) ≤ Δθ , the actuator moves to new 

position as demanded at the previous time step ( (t) = (t −1) θ θ D ) and the actuator 

motor stops (δ (t) = 0 ), if the demand position is attained. 

If the actuator motor was moving (δ (t −1) = ±1), but it could not reach the 

demanded position during the current time step ( max θ D (t −1) −θ (t −1) > Δθ ), the 

motor continues to move by Δθ max . The new position is 

max θ (t) = θ (t −1) + Δθ , if (t −1) ≥ (t −1) θ D θ

max θ (t) = θ (t −1) − Δθ , if (t −1) < (t −1) θ D θ

The motor moving direction at the end of previous time, ) δ e (t −1 , becomes 

 1 δ e (t −1) = , if (t −1) ≥ (t −1) θ D θ
18

 1 δ e (t −1) = − , if (t −1) < (t −1) θ D θ

The new motor moving direction at the current time, ) δ (t , is determined considering 

whether the motor was moving in the direction required to reduce the position error at the 

end of the previous time step. If the motor was in the desired state at the end of the 

previous time step, no change of state is made ( ) δ (t) = δ e (t −1 ). 

The rotational motion of a motor-driven actuator matches the rotation motion of a 

damper, but most of valves need translational motion of the valve stem either by means 

of a screw thread or by a crank. When a valve is driven by a screw, the relationship 

between the dimensionless rotation position, ) θ (t , and the dimensionless translational 

position, ) y(t , is linear. Thus, simply 

 ) y(t) = θ (t

However, if a crank on the drive shaft is used, non-linearity needs to be considered. 

Figure 11 illustrates a motor-driven actuator with a crank on it along with a flow valve 

and a linkage. The length of the crank, R , the angular range of the crank, α , the total 

vertical displacement due to the cranking, Y , and the length of linkage, L , are given. 

The vertical displacement of the crank, y

~ , corresponding to the angular position, θ

~ , is 

determined ignoring any bending of the linkage under the assumption that L >> R . 

From the figure, 

 ) Y = 2Rsin(α / 2

 ) / 2 ~ sin( / 2) sin( ~y = R α + R θ −α

Defining 

α

θ θ

~

= and 

Y

y y

~

= , the relationship of ) θ (t and ) y(t is determined. 

 

 2sin( / 2)

)) 2 sin( ( ( ) 1

2

1 ( )

α

α θ − = +

t

y t
19

Figure 11. A crank of motor-driven actuator, a linkage, and a flow valve. 

3.2.2 Mixing box 

Figure 12. An air-handling unit mixing box 

The mixing box of an air-handling unit consists of an outdoor damper, an exhaust 

damper, and a re-circulating damper as shown in Figure 4. Only one damper actuator is 

employed to control three dampers in responding to the PI control signal from the BMS 

Exhaust air damper

Outside air damper

Re-circulating air damper

mret &

mmix & moa &

mexh &

mrec &

Valve

Crank

Linkage

Valve stem

Y

R

Flow

Motor-driven 

Actuator

α/2

α/2

L

θ

~ y

~
20

While the exhaust and outside air dampers are closing/opening in phase, the recirculating damper is opening/closing. 

This mixing box model used in ZFM-HVAC is a simplified model that differs from the 

model used in HVACSIM+

. 

The return (or extracted) air mass flow rate, mret & , is assumed to be 

 mret mmix & = (1− β ) &

where 

 m& mix = mixed air mass flow rate from the mixing box 

 β = fractional factor of air flow leakage in the air delivery system 

Then the exhaust air mass flow rate, mexh & , and the mixed air mass flow rate are expressed 

by 

 mexh mret mrec & = & − & 

 mmix moa mrec & = & + &

where the subscriptions rec and oa represent re-circulation and outside, respectively. 

Assuming that the outside air mass flow rate is proportional to the outside air damper 

fractional opening, α , 

 moa mmix & = α &

 mexh mmix & = (α − β ) &

The mixed air temperature, Tmix , becomes 

 ( ) ,

, ,

p mix oa rec

p oa oa oa p rec rec rec

mix

c m m

c m T c m T

T & &

& &

+

+ = 

where p c is moist air specific heat. 

The smoke concentration in the mixed air flow, Cmix , can be computed in terms of the 

smoke concentration of the return air flow, Cret , since the outside air is smoke-free. 

 ) Cmix = Cret(1−α

3.2.3 Temperature Sensor (Type301) 
21

Temperature sensor is modeled by a first-order differential equation with a single time 

constant, t τ . 

The sensor output signal, o c , is give in terms of modified temperature input, i c . 

 

t

i offset

i G

T T

c − =

 o i

o

t c c

dt

dc

τ + =

 

where 

 Ti = temperature input 

Toffset = offset for the minimum allowable temperature 

 Gt = temperature sensor gain 

The differential equation is solved analytically at each time step,Δt . 

 i

t

o o i c t = c t − − c e + c −Δ τ ( ) [ ( 1) ]

The output sensor signal is bound between the maximum and minimum values. For each 

air-handling unit, there are four temperature sensors for the supply air, return air, mixed 

air, and outside air temperatures. These sensor outputs are inputs to the air-handling unit 

controller. One temperature sensor is also used in the return air duct of each zone to 

provide the input signal to the VAV controller for the zone. 

3.2.4 Humidity Sensor (Type302) 

Humidity sensor is modeled by a first-order differential equation similar to the 

temperature sensor model. 

The sensor output signal, o x , is give in terms of modified humidity input, i x . 

 

h

i offset

i G

h h

x − =

 o i

o

h x x

dt

dx

τ + =

 

where 

 hi = humidity ratio 

hoffset = offset 
22

 Gh = humidity sensor gain 

 τ h = humidity sensor time constant 

There are two humidity sensors for the return air and outside air for each air-handling 

unit. 

3.2.5 Flow rate Sensor (Type303) 

A first-order differential equation is used to model the flow rate sensor. 

The sensor output signal, Fo , is give in terms of modified flow rate input, Fi . 

 

m

i offset

i G

m m

F & − & =

 o i

o

m F F

dt

dF

τ + =

 

where 

 m&i = mass flow rate input 

 m& offset = offset 

 Gm = flow rate sensor gain 

 τ m = flow rate sensor time constant 

There are two flow rate sensors for the supply air and return air for each air-handling 

unit. 

3.2.6 Static pressure Sensor (Type305) 

The static pressure sensor output signal, Po , is give in terms of modified static pressure 

input, Pi . 

 

p

i offset

i G

p p P − =

 o i

o

p P P

dt

dP

τ + =

 

where 

 pi = static pressure input 

poffset = offset 

 Gp = pressure sensor gain 
23

 τ p = pressure sensor time constant 

Only one static pressure sensor for the supply air is employed for each air-handling unit. 

3.2.7 Motor drive (Type333) 

The motor drive receives a demanded fractional speed signal, ωd , from the BMS to 

determine the actual rotational speed, Ωa , of an ideal motor of a fan. Motor dynamics, 

drive hysteresis, and non-linearity are neglected. Power consumption or efficiency is not 

considered. 

The actual fractional speed, ) (t ωa , is determined depending on the difference between 

current fractional demanded speed, ) (t ωd , and previous actual fractional speed, 

(t −1) ωa . 

 max ωa (t) = ωa (t −1) + Δω , if ) ωd (t) ≥ωa (t −1

 max ωa (t) = ωa (t −1) − Δω , if ) ωd (t) <ωa (t −1

where Δω max is the maximum change in fractional speed in one time step given by 

 Ttrav

Δt Δω max = 

 

The travel time, Ttrav , is the time required for the motor drive to travel from lower to 

upper limit. 

With a given maximum rotational speed, Ωmax , the actual rotational speed is determined. 

 max Ωa (t) =ωa (t)Ω 

 At each air-handling unit, two motor drives are connected to the supply fan and the 

return fan, respectively. 

3.2.8 Fan (Type350) 

The fan model calculates a pressure rise, Δp , in terms of the dimensionless flow, Cf , 

defined by 

 

 3 D

m Cf Ω = ρ

&

 where 
24

m& = mass flow rate 

ρ = density of air 

Ω = rotational speed 

 D = diameter of fan blade 

 

The dimensionless pressure head function, hf , is obtained from dimensionless fan 

performance curves, and can be represented by the 4th order polynomials. 

 4

4

3

3

2

0 1 2 ( ) h f f f f Cf f C = a + a C + a C + a C + a

 

Coefficients, ai , are determined empirically. In the valid region of the performance 

curves, the pressure rise is expressed by 

h p D f 2 2 Δ = 0.001ρ Ω

Fan efficiency, η , is also represented by the 4th order polynomial equation as 

4

4

3

3

2

0 1 f 2 f f Cf η = e + e C + e C + e C + e

Coefficients, i e , are empirically determined. Within the range of validity of the efficiency 

polynomial, fan power consumption, Efan , is determined. 

 ρη

m p EfanΔ = &

3.2.9 VAV Box (Type526) 

A typical VAV box with a reheat coil is shown in Figure 5. This VAV box model 

represents a pressure-independent VAV terminal box. The reheat coil is excluded here, 

but the actuator is included. Only the zone supply airflow rate variation due to the VAV 

damper opening is considered. A VAV terminal box controller sends a signal of demand 

flow rate to a VAV box. In responding to the signal, the VAV damper opening varies. 

 

For a given size of VAV box as nominal volumetric flow rate, Vnom , fractional demand 

speed of actuator motor, ωd , is determined. 

 ( ) ωd = Kp Vd −Vm , ωd ,min ≤ωd ≤ 1.0

where 

Kp = proportional gain 

 Vd = fractional demand volumetric flow rate 

 ωd ,min = minimum fractional speed of motor 
25

The measured fractional volumetric flow rate at the previous time step, ) Vm (t −1 , is 

nom

m V

m t V t

ρ

( 1) ( 1) − − = & 

Taking the average fractional demand speed during the time step, ωd , new angular 

position of the actuator, ) θ (t , is 

 

trav

d T

t

t t

Δ θ ( , ) = θ ( −1) +ω o 0 ≤θ (t) ≤ 90 

The travel time, Ttrav , is the time required for the motor drive to travel from 0 ̊ to 90 ̊. 

In turbulent flow, the mass flow rate through the VAV box is given in terms of the 

pressure drop, Δp , and the total flow resistance, tot r . 

 

tot r

p m tΔ &( ) =

The total resistance is a sum of fixed system resistance, fix r , and damper positiondependent resistance, θr . 

 2 2 2 2

0.001

f

open

nom

open

fix A

k

V

p

r

ρ ρ − Δ =

where 

 Δpopen = pressure drop at normal flow with fully open damper 

 kopen = loss coefficient of fully open damper 

 Af = face area of damper 

Legg’s correlation is used to calculate the damper position-dependent resistance. 

 

 ) ln(k ) α βθ (t θ = + , o o 15 < θ < 55 for opposed blade damper 

 o o 15 <θ < 65 for parallel blade damper 

 

α and β are empirically determined constants. Using damper loss coefficient, θ k , 

 the damper resistance is represented as 

 C

e

r

kθ

θ =
26

where C is the conversion factor. 

 

3.2.10 Fluid Resistance (Type341) 

The flow resistance model is based on a square law relationship at high flow rates and a 

linear relationship at low flow rates. This routine calculates the inlet pressure, pi , for 

given outlet pressure, po , mass flow rate, m& , and flow resistance, r . 

 pi = po + rm& m& in turbulent flow 

 pi = po + rm& critm& in laminar flow 

where mcrit & is the critical mass flow rate, which is the lower limit of purely quadratic 

flow. 

 

3.2.11 Add Heat (Type366) 

The outlet temperature of a fan or a duct, To , is calculated by adding the temperature rise, 

ΔT , due to added heat and the inlet temperature, Ti . ΔT is obtained analytically from 

 c m

Q T

dt

d T

p

add

h &

& + Δ = Δ

τ 

where 

Qadd = & rate of heat addition 

 τ h = time constant 

 c p = specific heat of dry air 

3.2.12 Merge Flow (Type422) 

The outlet mass flow rate is the sum of the two inlet mass flow rates. 

 mo mi,1 mi,2 & = & + & 

 The outlet smoke concentration, Co , is calculated in a simple way. 

 

o

i i i i

o m

C m C m

C &

& & ,1 ,1 + ,2 ,2 = 
27

3.2.13 Mix Flow (Type365) 

When multiple moist air flow streams merge, the outlet mixed air temperature, Tmix and 

the humidity ratio, hmix , are obtained from 

 ∑= ∑

i

i i

mix

m

h m

h &

& , (i =1,n)

 ∑

∑

+

+ = ( )( )( )

i pa pg mix

i i pa pg i

mix

m c c h

mT c c h

T &

& , ) (i = 1,n

where pa c and pg c are the specific heat of dry air and the specific heat of water vapor. 

Only two flow streams are used for ZFM-HVAC. 

 

3.2.14 Mass Flow Balance (Type425) 

An assumption is made in ZFM-HVAC that no air leaks to outside from a zone, and the 

outlet mass flow rate from a zone, moutlet & , is the same as the inlet mass flow rate, minlet & . 

 moutlet minlet & = &

3.2.15 Coil & Valve (Type524) 

The combined model of heating/cooling coil and its three-way control valve is the most 

complex routine among the component models used in HVACSIM+

. The temperature and 

humidity of the airflow through heating or cooling coil are governed by the three-way 

coil valve, which is connected to a coil valve actuator. The actuator operates in 

responding to the control signal from the BMS. 

The coil model used is a finned-tube cross-flow heat-exchanger with both fluids 

unmixed. When the working fluid is chilled water, the coil acts as a cooling coil, whereas 

when the working fluid is hot water, the coil is a heating coil. On the air-side of the heatexchanger, the inlet air dry bulb temperature, Ta,i , inlet air humidity ratio, ha,i , and dry 

air mass flow rate, ma & , are given. On the water-side of the heat-exchanger, the inlet 

water Temperature, Tw,i , inlet water pressure, pw,i , and outlet water pressure, pw,o , are 

given. With these input conditions, the outlet air dry bulb temperature, Ta,o , outlet air 

humidity ratio, ha,o , outlet water temperature, Tw,o , primary circuit water mass flow rate, 

mw, prim & , water mass flow rate through the coil, mw & , and mixed return water temperature, 

Tw,ret , are determined. Using the outlet air pressure, pa,o , the inlet air pressure, pa,i , is 

also calculated. Figure 13 is a schematic diagram of the coil with external water circuits. 
28

The equations in a general case are presented, not exactly following the calculation logic 

flow of the routine. 

Figure 13. The cooling/heating coil and three-way valve. 

 

Outlet air dry bulb temperature of a dry coil (Ta,o ) 

 

pa a

a dry

a o a i

c m

Q T T &

& ,

, = , +

 

where 

 cpa = specific heat of dry air 

Qa,dry = & air-side heat transfer of a dry coil 

 ( ) (1 ) Qa,dry = Tcs − Ta,i Ca − Bf &

Tc,s = effective coil surface temperature 

mw,byp &

mprim &

mw Tw,o &

Tw,i Tw,ret

Three-way Valve

Cooling/Heating Coil

w i p , w o p ,

ma & Ta,i Ta,o

a i p , a o p a i , h , a o h ,

Air

Chilled/Hot Water

Tcs : Effective coil surface temperature
29

 Ca = air capacity rate = pa pgha i ma (c c ) & + ,

cpg = water vapor specific heat 

 Bf = coil by-pass factor 

Effective coil surface temperature (Tcs ) 

The effective coil surface temperature is obtained by solving the first-order differential 

equation. 

 =α cs + β cs T

dt

dT 

where 

HCcoil rr

r r

1 2

1 + 2 α = 

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ = +

2

,

1

1 ,

r

T

r

T

HC

a i w i

coil

β 

 HCcoil = heat capacity of coil = HCfin + HCtube + HCwater

(1 )

1

1 Ca Bf

r − =

min

2

1

C

r

HX ε =

Cmin = minimum heat capacity rate 

ε HX = heat-exchanger effectiveness 

Coil by-pass factor ( Bf ) 

 a a

ext

C r

A

f B e

−

= 

where 

Aext = heat-exchanger total heat transfer area on air-side 

 ra = air-side thermal resistance = 

ha fin ε ~

1
30

 ha = ~ air-side heat transfer coefficient = 

h

a a

D

Nu k

Nua = Nusselt number of air = 

3

2

Re Pr 1 0.04

0.0668Re Pr

3.66

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

+

+

coil

a a h

coil

a a h

L

D

L

D

Re Reynolds number of air = a =

free a

a h

A

m D

ν

&

 Pr Prantl number of air = a =

a

pa a

k

c ν

 ka = thermal conductivity of air 

 Dh = hydraulic diameter 

 Lcoil = length of coil 

Afree = heat-exchanger minimum free-flow area on air side 

 ν a = dynamic viscosity of air = 

a i

a i

T

T

,

1.5

,

6

383.4

1.458 10 (273.16 )

+

× + −

 ε fin = fin effectiveness 

 ⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ − ⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

+ = − γ

γ ε

tanh( ) 1 1

, ,

,

fin net tube net

fin net

fin A A

A 

 fin

fin i

fin o

fin fin

a H

R

R

k t

h

⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ = +

,

, 1 0.35ln

~

2

γ

 

 Afin,net = net fin heat transfer area 

Atube,net = net tube heat transfer area 

 k fin = thermal conductivity of fin material 

 tfin = fin thickness 

 Rfin,o = effective fin radius 

 Rfin,i = fin inside radius 
31

Heat-exchanger effectiveness ( HX ε ) 

The effectiveness of a compact cross-flow heat-exchanger with both fluids unmixed is 

calculated for a typical condition. 

 ( )

⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡− − = −

−

rr

C NTU

HX C

NTU e rr 0.78

1 1 exp

0.22

ε

where 

a

w

rr C

C C = for water is minimum 

w

a

rr C

C C = for air is minimum 

Cw = water heat capacity rate = pwmw c & 

cpw = specific heat of water 

NTU = number of transfer units = 

tot

ext

C r

A

min

rtot = sum of resistances of air-side, water-side, and material 

Outlet air dry bulb temperature of a wet coil (Ta,o ) 

 Ta,o = Ta,i + Q&

a,wetSHR

 

where 

SHR = sensible heat ratio = ( )

a wet

a a o est a i

Q

C T T

,

, , ,

&

−

Ta,o,est = estimated outlet air dry bulb temperature 

 ( ) Ta,o,est = Bf Ta,i − Tcs + Tcs

Qa,wet = & air-side heat transfer of a wet coil 

 ( ) (1 ) Qa,wet = Tcs − Twb,i Ca,sat − Bf &

 Twb,i = inlet air wet bulb temperature 
32

Ca,sat = saturated air capacity rate = p satma c & ,

 cp,sat = saturated air specific heat 

Outlet air humidity ratio ( ha,o ) 

 c T HFG

H c T

h

pg a o

a o pa a o

a o +

− =

,

, ,

,

 

where 

HFG = latent heat of vaporization 

 Ha,o = outlet air enthalpy = 

a

a wet

a i

m

Q H &

& ,

, +

Coil outlet water temperature (Tw,o ) 

 

w

w

w o w i C

Q T T &

, = , −

where 

Qw = & heat transfer on water-side = 

2

,

r

Tw i − Tcs

Mixed return water temperature (Tw,ret ) 

 ( )

w prim

w i w prim w w o w

w ret m

T m m T m

T

,

, , ,

, &

& − & + & =

where 

m& w, prim = primary circuit water mass flow rate 

 m& w = water mass flow rate through the coil 

 Tw,i = inlet water temperature 
33

Figure 14. Water flow control valve characteristics 

The water flow control valve characteristics used in the model in the general form is 

presented in Figure 14. The figure shows the relationship between the fractional flow rate 

through the control valve, ) f (x , and the valve stem position, x . A constant pressure is 

applied. There are three regions – cut-off, linear, and exponential. 

In the cut-off region, 

 L

l

L

V

C

x

x C

S f x +⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ = − 1 ( ) l 0 ≤ x ≤ x

 

In the linear region, 

 ( )

V

l

e l

V

e

S

x x

x x

S f

f x

1

1

( ) − +

⎟

⎟

⎟

⎟

⎠

⎞

⎜

⎜

⎜

⎜

⎝

⎛

−

−

= l e x < x ≤ x

In the exponential region, 

 1 ( ) − = x f x a 1 xe < x ≤

Linear

l x

f

x

1

e f

SV 1/

CL

e x

Exponential

Cut-off

1
34

where 

 

SV = rangeability – ratio of highest to lowest controllable flow 

CL = fractional leakage flow when the valve is fully closed 

 xl = break point between the linear and cut-off regions 

 xe = break point between the exponential and linear regions 

 a = curvature parameter for equal percentage characteristic 

f e = ) ( e f x 

 

The hydraulic resistance across the flow port of the control valve, w v f r , , , is expressed in 

terms of the fractional flow rate and valve capacity, KV . 

 ( )

1296 , , 2 2 K f x

r

V

w v f =

The resistance across the bypass port of the valve, w v byp r , , , is calculated from 

 (1 )

1296 , , 2 2 K f x

r

V

w v byp − =

Water flow rate through the coil (mw & ) 

 

w c w v f

w i w o

w r r

p p

m

, , ,

, ,

+

− & =

where 

pw,i = inlet water pressure 

pw,o = outlet water pressure 

 rw,c = hydraulic resistance through the coil 

By-pass water flow rate ( mw,byp & ) 

 

w byp w v byp

w i w o

w byp r r

p p

m

, , ,

, ,

, +

− & =

where 
35

rw,byp = hydraulic resistance through the by-pass water circuit 

Primary water flow rate ( mw, prim & ) 

 mw, prim mw mw,byp & = & + &

Return water temperature (Tw,ret ) 

 

w prim

w i w byp w o w

w ret m

T m T m

T

,

, , ,

, &

& + & =

Inlet air pressure of the coil ( pa,i ) 

 a i a o a cma ma p p r & & , = , + , above the critical bound 

 a i a o a cmcritma p p r & & , = , + , below the critical bound 

where 

m& crit = critical flow – lower limit of purely quadratic flow 

Figure 15 is a diagram showing the airflows through various building HVAC component 

models used here. The four big blocks are AHU, VAV, Flow merge, and Fire Model. Air 

pressure, air mass flow rate, air temperature, air humidity ratio, and smoke concentration 

are denoted by p, m, t, h, and o, respectively. The numbers following the characters are 

indices chosen for identification. A component model is identified by “Ty” plus the 

specific number for the TYPE routine in HVACSIM+

 as seen in Figure 10. No specific 

number is given to the new mixing box routine in ZFM-HVAC. The same configuration 

is applied to all the three AHUs. Some simplification was made to the models compared 

with the model using HVACSIM+

. Particularly, a constant static pressure in the air 

supply duct is assumed during emulation. 

As shown in the Figure 15, the fire model receives the supply air mass flow rate, supply 

temperature, supply pressure, and smoke concentration from HVAC duct as inputs to a 

zone. The fire model determines the zone outlet pressures, temperatures, and combustion 

product concentrations. No solar heat gain, nor internal heat gain in a zone is considered 

in normal status, which is no fire condition. 

4. ZFM-HVAC RUNS AND DISCUSSION 

 

Three scenarios were selected to demonstrate the use of ZFM-HVAC in the VCBT. 

Case 1: A virtual three-story building with nine conditioned zones and an unconditioned 

stairwell. Three AHUs and nine VAV boxes are involved. 
36

Case 2: A virtual single-story building with nine conditioned zones. Eight of nine zones 

are identically sized. Three AHUs and nine VAV boxes are used. 

Case 3: A virtual single-story building with nine conditioned zones with different sizes. 

Three AHUs and nine VAV boxes are involved. 

Figure 15. The airflow paths through various building HVAC components for all cases. 

4.1 Case 1 Scenario 

As an example run, a virtual three-story building as shown in Figure 16 was modeled. 

This virtual building has three zones on each floor and a stairwell. Figures 17 to 19 show 

the layouts for all three floors. As shown in Figure 20, three air-handling units serve three 

zones each. AHU1 serves Zones 1, 2, and 3; AHU2 serves Zones 4, 5, and 6; and AHU3 

serves Zones 7, 8, and 9, respectively. None of the AHUs serves the stairwell (Zone 10). 

Access doors to the stairwell are located at Zone 7, 8, and 9. Two access doors to outside 

are located in Zone 7. Airflow is allowed between zones. The AHUs supply and extract 

the airflows through ducts and VAV boxes. It should be emphasized that the ZFMHVAC was primarily designed to observe the effects on the zone air temperature and 

smoke concentration in the zones as well as HVAC system responses due to fire. 

VAV Box VAV Box VAV Box

Cooling Coil Fluid 

Resistance Supply Fan

Return Fan Fluid 

Resistance

Mixing Box

m(1,3) m(2,3) m(3,3)

m(0,29)

m(1,19)

m(0,30)

m(0,1)

m(0,2)

p(0,3) p(0,4) p(0,5)

p(1,16)

p(0,26) p(1,26) p(0,27)

p(0,28)

p(0,2)

p(0,29)

p(0,1)

Zone Zone Zone

t(0,1)

t(0,54)

t(0,2)

t(0,3) t(0,4)

t(1,5)

t(1,35)

t(0,53) t(0,54)

h(0,1)

h(0,16)

h(1,4)

h(0,2)

h(0,3)

m(0,47)

o(0,3)

o(0,8)

o(1,4)

p(0,47)

t(0,80)

h(0,17)

h(1,10)

t(2,5) h(2,4) t(3,5) h(3,4)

o(0,8)

t(2,35) t(3,35) h(2,10) h(3,10)

p(2,16) p(3,16) m(2,19) m(3,19)

o(2,4) o(3,4)

o(1,8)

p(2,26)

o(2,8)

m(1,29) m(2,29)

Heating Coil

Flow Merge Flow Merge Flow Merge

m(3,29)

(additional VAV boxes 

and zones in future)
37

Figure 16. A virtual three-story building in Case 1. 

No controller tuning, FDD, nor HVAC system energy consumption analysis is 

emphasized with ZFM-HVAC. In all the cases, the supply and return fans were set to run 

continuously at all times. 

Initially AHUs and VAV boxes operated in a normal mode in conjunction with the real 

BACnet HVAC controllers. Two different sizes of fire were used. The heat release rate 

determines the size of a fire. Figure 21 shows heat release rates in terms of time. These 

heat release rates were artificially imposed as input conditions. Case 1_1 and Case 1_2 

represent the small fire and the large fire respectively. Appendix C is the ZFM-side input 

data for Case 1_1. 

Not To Scale
38

1.00

8.53 17.37

6.40 9.14

1.83

0.91

Scale (m):

Zone 1 Zone 4

Zone 7

Ceiling height = 2.9 m

3.05

4.88

Stair Well

0.91

Zone 10 First Floor

Figure 17. The first floor layout of the virtual three-story building in Case 1. 

1.00

8.53 17.37

6.40 9.14

1.83

Scale (m):

Zone 2 Zone 5

Zone 8

Ceiling height = 2.9 m

3.05

4.88

Stair Well

Zone 10

Second Floor

Figure 18. The second floor layout of the virtual three-story building in Case 1. 
39

1.00

8.53 17.37

6.40 9.14

1.83

Scale (m):

Zone 3 Zone 6

Zone 9

Ceiling height = 2.9 m

3.05

4.88

Stair Well

Zone 10 Third Floor

Figure 19. The third floor layouts of the virtual three-story building in Case 1. 

Figure 20. Air distribution for nine conditioned zones of the virtual three-story building 

in Case 1. 

Zone 3 Zone 6

Zone 9

Zone 2 Zone 5

Zone 8

Zone 4

Zone 7

Zone 1

Z 10

Z 10

Z 10

AHU 1 AHU 2 AHU 3

Z 10 : Stairwell

1st Floor

2nd Floor

3rd Floor
40

Time after fire starts (s)

0 500 1000 1500 2000

Heat Release Rate (kW)

0

500

1000

1500

2000

2500

Large fire

Small fire

 Figure 21. Heat release rates for large and small fires. 

Appendix D shows the HVAC-side configuration input data, where n_ahu is the number 

of air-handling units and nbr is the number of flow branches for VAVs served by each 

air-handling unit. The files with extension ‘inp’ are input data files and those with ‘out’ 

are output files. Sample input data for AHU and VAV are given in Appendices E and F. 

The parameter data are actually used in computation. Others are for information. 

Appendix G lists initial data of the HVAC-side of ZFM-HVAC. 

First, the VCBT emulation results of Case 1_1 for the small fire is examined. At 7200 s 

from the beginning of emulation, a fire was set in Zone 1. For the AHU1 branch, the 

BACnet controllers involved are the AHU controller (ID = 100), and the VAV controllers 

(ID = 101, 102, and 103). Refer to Figure 7. The control strategies actually implemented 

in these controllers are much complicated than the general strategies described previously 

(See Section 2.5). For example, the VAV controller sets an alarm condition and limits the 

supply flow rate at the minimum when the zone air temperature becomes above 50  ̊C, 

although generally we might expect the maximum rate instead. Note that emulation 

results of this report reflect the responses of controllers of different companies in 

different ways. 
41

Figures 22 and 23 show the return air temperatures from zones, the air temperatures at 

AHU1, the flow rates of AHU1 branch, the damper opening demand by controllers of 

AHU1, the coil opening demand signals, and the reheat coil control signals. Referring to 

Figure 15, ZA_TMP_1 [t(1,35)], ZA_TMP_2 [t(2,35)], and ZA_TMP_3 [t(3,35)] 

represent the return air temperatures from Zone 1, 2, and 3, respectively. The bottom and 

top edges of rectangular return air ducts locate 1.5 m and 2.0 m from the floor 

respectively as shown in Appendix C. The fire side of the ZFM-HVAC program 

determines the return air temperatures. In this case, the changes in ZA_TMP_2 and 

ZA_TMP_3 are not noticeable, but ZA_TMP_1, which is the return air temperature from 

the fire zone, Zone 1, is very high as expected. The zone air temperatures on the 2nd and 

the 3rd floors are not much affected due to the small fire size. 

The supply air temperature of AHU1, mixed air temperature, return air (extracted air) 

temperature, and outdoor air temperature are denoted as SA_TMP [t(0,4)], MA_TMP 

[t(t(0,2)], RA_TMP [t(0,54)], and OA_TMP [t(0,1)], respectively. Although SA_TMP 

was maintained around the set point, MA_TMP and RA_TMP approached 100 ̊C during 

the fire. OA_TMP did not vary much in this emulation period. The flow rates in the flow 

branch served by AHU1 are plotted for SA_FLOW [m(0,2)], RA_FLOW [m(0,29)], 

ZFLOW_1 [m(1,3)], ZFLOW_2 [m(2,3)], and ZFLOW_3 [m(3,3)], which represent the 

supply airflow rate, return airflow rate, and the zone airflow rates of Zone1, 2, and 3, 

respectively. 

Demand control signals from BMS were observed. The AHU damper opening demand 

signal (DMP_DEM), the cooling coil valve opening demand signal (CC_DEM), and the 

heating coil valve opening demand signal (HC_DEM) are shown in Figure 23a. The 

actual damper opening (DMP_opening) is also shown on the same chart. It can be seen 

that DMP_opening value remained the same value of 0.15, which means that 

approximately 15 % of the AHU fresh (outdoor) air damper, 15 % of the exhaust air 

damper, and 85 % of the AHU re-circulation damper were open. It is because the 

DMP_opening was set to the constant value of 15 % in ZFM-HVAC overriding 

DMP_DEM that varied between 0.15 and 1.0. The AHU1 controller operated with the 

enthalpy economizer logic enabled. The VAV box damper opening demand signals 

(ZDMP_CTL_1, ZDMP_CTL_2, ZDMP_CTL_3) and the reheat coil valve opening 

demand signals (RHC_CTL_1, RHC_CTL_2, RHC_CTL_3) are shown in Figure 23b. 
42

(a) Temperatures at AHU1 and return air temperatures

 from zones 1, 2, and 3

Time (s)

4000 6000 8000 10000 12000 14000

Temperature (oC)

0

50

100

150

200

250

300

SA_TMP 

MA_TMP 

OA_TMP 

RA_TMP 

ZA_TMP_1 

ZA_TMP_2 

ZA_TMP_3 

Time (s)

4000 6000 8000 10000 12000 14000

Flow rate (m3 /s)

0.0

0.5

1.0

1.5

2.0

2.5

SA_FLOW 

RA_FLOW 

ZFLOW_1 

ZFLOW_2

ZFLOW_3

(b) Flow rates of AHU1 branch

Figure 22. Temperatures, and flow rates of AHU1 in Case 1_1. 
43

(a) Damper and coil opening demands by AHU1 controller

4000 6000 8000 10000 12000 14000

Control signal (-)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

DMP_DEM 

CC_DEM 

HC_DEM 

DMP Opening 

(b) VAV damper and reheat coil signals by VAV controllers

Time (s)

4000 6000 8000 10000 12000 14000

Control signal (-) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

ZDMP_CTL_1 

ZDMP_CTL_2 

ZDMP_CTL_3 

RHC_CTL_1 

RHC_CTL_2 

RHC_CTL_3 

Figure 23. Control signals of AHU1 in Case 1_1. (-) means dimensionless. 
44

In Case 1_2, the same building configuration as the previous case was applied, except 

that a large fire was set in the Zone 1 at 7,200 s after the start of emulation. Figure 24 

shows the same kind of plots for AHU1 branch similar to Case 1_1. Notice that 

ZA_TMP_1 went up to 1600  ̊C, and ZA_TMP_2 and ZA_TMP_3 approached 160  ̊C. 

The airflow through the stairwell and the AHU ducts could contribute to the temperature 

increases. Since DMP opening was set to the minimum value of 15 %, roughly 85 % of 

the extracted flow from zones (RA_FLOW) returned to zones as the supply airflow after 

mixing with the fresh air. The supply air temperature became quite high during the period 

of fire. The cooling coil model in ZFM-HVAC was programmed up to 100  ̊C. Beyond 

the limit, the cooling coil discharge temperature was set to equal the return air 

temperature ensuring that no cooling would occur. 

It is worthwhile to mention about why the reheat coils were activated by the VAV 

terminal box controller during the cooling season under no fire condition when the 

outdoor air temperature (OA_TMP) of the select weather condition was at 23.5  ̊C to 24.0 

 ̊C. The set point of the supply air temperature of the AHU was set at 12.8  ̊C, while the 

set point of the zone VAV controllers was 23.4  ̊C. No heat source (e.g., generated heat 

by person, equipment, or lighting, and heat transfer from ceiling, floor, or wall) in a zone 

was enabled. The only way the zone temperature could reach the set point value was 

reheating by the reheat coils. As a result, active reheat coil valve control signals can be 

observed. 

Figures 26 and 27 show temperatures, flow rates, and control signals of the air-handling 

unit AHU2 and the VAVs served by AHU2 in Case 1_2. ZA_TMP_4, ZA_TMP_5, and 

ZA_TMP_6 represent the return air temperatures from Zone 4, 5, and 6, respectively. See 

Figures 17 through 20. For the AHU2 branch, the BACnet device instances of the AHU 

controller and the VAV controllers are 310, 304, 305 and 306 as shown in Figure 7. 

Compared with Figure 24, the return air temperatures from zones were much lower. The 

peak value was about 150  ̊C. The flow rates as well as control loops for the AHU2 

branch quite fluctuated.

 

Figures 28 and 29 depict the similar plots as before for the AHU3 branch. Zones 7, 8, and 

9 have openings to Zone 1, 2, and 3. This would bring the return air temperatures higher 

than those of AHU2. ZA_TMP_7 went up to 500  ̊C and ZA_TMP_8 and ZA_TMP_9 

reach near 180  ̊C. Note that SA_TMP followed a similar pattern as MA_TMP or 

RA_TMP, which was near 260  ̊C at its peak. Here again as seen in Figure 29a, 

DMP_DEM was sometimes at 100 %, but the actual damper opening was set to 15 % at 

all times by ignoring the output signal, DMP_DEM, from the AHU enthalpy control. 
45

(a) Temperatures at AHU1 and return air temperatures

 from zones 1, 2, and 3

Time (s)

4000 6000 8000 10000 12000 14000

Temperature (oC)

0

200

400

600

800

1000

1200

1400

1600

1800

SA_TMP

MA_TMP 

OA_TMP 

RA_TMP 

ZA_TMP_1 

ZA_TMP_2 

ZA_TMP_3 

(b) Flow rates of AHU1 branch

Time (s)

4000 6000 8000 10000 12000 14000

Flow rate (m3/s)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

SA_FLOW 

RA_FLOW 

ZFLOW_1 

ZFLOW_2 

ZFLOW_3 

Figure 24. Temperatures, and flow rates of AHU1 in Case 1_2. 
46

(a) Damper and coil opening demands by AHU1 controller

Time (s)

4000 6000 8000 10000 12000 14000

Control signal (-) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

DMP_DEM 

CC_DEM 

HC_DEM 

DMP opening 

(b) VAV damper and reheat coil signals by VAV controllers

Time (s)

4000 6000 8000 10000 12000 14000

Control signal (-) 

0.0

0.2

0.4

0.6

0.8

1.0

ZDMP_CTL_1 

ZDMP_CTL_2 

ZDMP_CTL_3 

RHC_CTL_1 

RHC_CTL_2 

RHC_CTL_3 

Figure 25. Control signals of AHU1 in Case 1_2. 
47

(a) Temperatues at AHU2 and return air temperatures

 from zones 4, 5, and 6

Time (s)

4000 6000 8000 10000 12000 14000

Temperature (oC)

0

20

40

60

80

100

120

140

160

SA_TMP 

MA_TMP 

OA_TMP 

RA_TMP 

ZA_TMP_4 

ZA_TMP_5 

ZA_TMP_6 

(b) Flow rates of AHU2 branch

Time (s)

4000 6000 8000 10000 12000 14000

Flow rate (m3/s)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

SA_FLOW 

RA_FLOW 

ZFLOW_4 

ZFLOW_5 

ZFLOW_6 

Figure 26. Temperatures, and flow rates of AHU2 in Case 1_2. 
48

(a) Damper and coil opening demands by AHU2 controller

Time (s)

4000 6000 8000 10000 12000 14000

Control signal (-)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

DMP_DEM 

CC_DEM 

HC_DEM 

DMP opening 

(b) VAV damper and reheat coil signals by VAV controllers

Time (s)

4000 6000 8000 10000 12000 14000

Control signal (-)

0.0

0.2

0.4

0.6

0.8

ZDMP_CTL_4 

ZDMP_CTL_5 

ZDMP_CTL_6 

RHC_CTL_4 

RHC_CTL_5 

RHC_CTL_6 

Figure 27. Control signals of AHU2 in Case 1_2. 
49

(a) Temperatures at AHU3 and return air temperatures

 from zones 7, 8, and 9

Time (s)

4000 6000 8000 10000 12000 14000

Temperature (oC)

0

100

200

300

400

500

600

SA_TMP

MA_TMP 

OA_TMP 

RA_TMP 

ZA_TMP_7 

ZA_TMP_8 

ZA_TMP_9 

(b) Flow rates of AHU3 branch

Time (s)

4000 6000 8000 10000 12000 14000

Flow rate (m3/s)

0

1

2

3

4

5

6

SA_FLOW 

RA_FLOW 

ZFLOW_7 

ZFLOW_8 

ZFLOW_9 

Figure 28. Temperatures, and flow rates of AHU3 in Case 1_2. 
50

(a) Damper and coil opening demands by AHU3 controller

Time (s)

4000 6000 8000 10000 12000 14000

Control signal (-)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

DMP_DEM 

CC_DEM 

HC_DEM 

DMP opening 

(b) VAV damper and reheat coil signals by VAV controllers

Time (s)

4000 6000 8000 10000 12000 14000

Control signal (-)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

ZDMP_CTL_7 

ZDMP_CTL_8 

ZDMP_CTL_9 

RHC_CTL_7 

RHC_CTL_8 

RHC_CTL_9 

Figure 29. Control signals of AHU3 in Case 1_2. 
51

The fire model, ZFM, was developed based on the modeling approach used in CFAST 

[25], which models the fire gases as homogeneous upper (hot) and lower (cool) layers. 

The temperatures and smoke concentrations (or mass fraction) of upper and lower layers 

are shown in Figure 30 for Case 1_2. The labels Zone_1L, Zone_2L, and Zone_3L 

represent the lower layer temperatures of Zone 1, 2, and 3, respectively. Likewise 

Zone_1U, Zone_2U, and Zone_3U represent the upper layer temperatures. As expected, 

the upper layer temperature of Zone 1 was highest about 1580  ̊C, and the lower layer 

temperature of the same zone was 690  ̊C at its peak. The peak upper and lower layer 

temperatures of the other two zones were almost 160  ̊C. The peak values of other two 

zone’s layer temperatures appeared in delay compared with the peak time in Zone 1. The 

smoke concentrations of Zone 1 apparently were high, while those in other zones, which 

were located in the second and third floor, were insignificant in this virtual three-story 

building. 

Based upon Bouguer’s law, the transmitted light intensity, I , through the smoke is given 

by: 

 KcL

o I I e− =

where 

Io = incident light intensity 

K = extinction coefficient 

c = smoke density 

L = path length 

 

Thus, the path length is expressed as 

 Kc

I

I

L o

− =

ln( )

According to Mulholland and Johnson [20], the extinction coefficient for over-ventilated 

flaming combustion is 8.7 m / g

2 . Using the value of air density, 1294.3 3

g / m , the 

visibility limit or path length in meters that we see only 0.1 % of light is 

 8.7(1294.3 )

ln(0.001)

st

L − =

where st is the dimensionless smoke concentration. 

Figure 31 shows the visibility limits at the upper layers of the nine conditioned zones of 

the building and the unconditioned stairwell in Case 1_2. As seen in Figure 31, the 

visibility was low in zones at the 1st floor (Zone 1, 4, and 7) and the stairwell. U_1 in the 

figure represents the visibility limit of the upper layer in Zone 1. 
52

(a) Upper and lower layer temperatures

Time (s)

4000 6000 8000 10000 12000 14000

Layer temperature (oC)

0

200

400

600

800

1000

1200

1400

1600

1800

Zone_1L 

Zone_2L 

Zone_3L 

zone_1U 

Zone_2U 

Zone_3U 

(b) Smoke concentrations of upper and lower layers

Time (s)

4000 6000 8000 10000 12000 14000

Smoke concentration (g/g)

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

s1L 

s2L 

s3L 

s1U 

s2U 

s3U 

Figure 30. Layer temperatures and smoke concentrations of zones served by AHU1 in 

Case 1_2. 
53

Time (s)

7000 7500 8000 8500 9000

Visibility limit (m)

0

5

10

15

20

U1 

U2 

U3 

U4 

U5 

U6 

U7 

U8 

U9 

U10 

U9

U10 U7

U1

U4

U2

U3

U8

U6

U5

Figure 31. Visibility limits at the upper layers due to smoke in Case 1_2. 

An emulation run (Case 1_3) was performed with the same configuration as Case 1_2 

except that the AHU damper opening was allowed to obey the BMS enthalpy economizer 

command. Namely the restriction given to the damper opening to be 15 % at all times 

was removed. As a result, the AHU damper was opened fully whenever the return air 

enthalpy was greater than the outside air enthalpy. The temperatures, flow rates, and 

BMS control signals of AHU1 are shown in Figures 32 and 33. When ZA_TMP_2 and 

ZA_TMP_3 of Case 1_3 are compared with those of Case 1_2, quite different outcomes 

can be seen. 

The zone air temperatures in Case 1_3 other than in Zone 1 did not significantly increase. 

Since the most of the return air was exhausted and almost 100 % of fresh air entered into 

the mixing box when the AHU damper was fully open, the supply air temperature, 

SA_TMP, and the mixed air temperature, MA_TMP, were considerably lower despite the 

high temperature of the return air due to fire. Layer temperatures and smoke 

concentrations of the zones served by AHU1 in Case 1_3 are shown in Figure 34. 

Compared with Figure 30a, it can be seen that the upper and lower temperatures of Zone 

3 are much lower in this case. Those of Zone 1 also are slightly lower. Otherwise Figure 

34 is very similar to Figure 30. 
54

(a) Temperatures at AHU1 and return air temperatures

 from zones 1, 2, and 3

Time (s)

4000 6000 8000 10000 12000 14000

Temperature (oC)

0

200

400

600

800

1000

1200

1400

1600

SA_TMP

MA_TMP 

OA_TMP 

RA_TMP 

ZA_TMP_1 

ZA_TMP_2 

ZA_TMP_3 

(b) Flow rates of AHU1 branch

Time (s)

4000 6000 8000 10000 12000 14000

Flow rate (m3/s)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

SA_FLOW 

RA_FLOW 

ZFLOW_1 

ZFLOW_2 

ZFLOW_3 

Figure 32. Temperatures, and flow rates of AHU1 in Case 1_3. 
55

(a) Damper and coil opening demands by AHU1 controller

Time (s)

4000 6000 8000 10000 12000 14000

Control signal (-)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

DMP_DEM 

CC_DEM 

HC_DEM 

DMP opening 

(b) VAV damper and reheat coil signals by VAV controllers

Time (s)

4000 6000 8000 10000 12000 14000

Control signal (-)

0.0

0.2

0.4

0.6

0.8

1.0

ZDMP_CTL_1 

ZDMP_CTL_2 

ZDMP_CTL_3 

RHC_CTL_1 

RHC_CTL_2 

RHC_CTL_3 

Figure 33. Control signals of AHU1 in Case 1_3. 
56

(a) Upper and lower layer temperatures

Time (s)

4000 6000 8000 10000 12000 14000

Layer temperature (oC)

0

200

400

600

800

1000

1200

1400

1600

Zone_1L 

Zone_2L 

Zone_3L 

Zone_1U 

Zone_2U 

Zone_3U 

(b) Smoke concentrations of upper and lower layers

Time (s)

4000 6000 8000 10000 12000 14000

Smoke concentration (g/g)

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

s1L 

s2L 

s3L 

s1U 

s2U 

s3U 

Figure 34. Layer temperatures and smoke concentrations of zones served by AHU1 in 

Case 1_3. 
57

4.2 Case 2 Scenario 

Figure 35 shows a layout of a single-story virtual building. There are eight identically 

sized rooms (or zones) and a corridor. Each zone has a VAV box and each AHU serves 3 

VAV boxes. AHU 1 serves for Zones 1, 2 and 3; AHU 2 for Zones 4, 5 and 6; and AHU 

3 for Zones 7, 8 and 9, respectively as seen in Figure 36. 

A fire was set in Zone 1 at 7200 s of emulation time. The enthalpy economizer cycle 

signal from BACnet AHU controller was ignored and set to the minimum damper 

position. Since all the zones are on the same floor, the fire-spreading pattern appeared 

quite different from the Case 1. Figures 37 and 38 shows temperatures, airflow rates, and 

BMS control signals of AHU1. SA_TMP reached up to 960  ̊C, so did MA_TMP. The 

return air temperature, RA_TMP, went up to 1070  ̊C. 

Layer temperatures and smoke concentrations of zones served by AHU1 are shown in 

Figure 39. Obviously the configuration makes quite different form of distribution of 

temperature as well as smoke compared with the previous scenario. As seen in Figure 40, 

visibility limits were very low in all the zones. No data of AHU2 and AHU3 are 

presented here. 

Scale:

4.88 2.13

1.83

3.66

0.91

30.0

Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Zone 7 Zone 8

Zone 9

1.00

Unit: m

 

Figure 35. Floor layout of the virtual single-story building with eight identically sized 

zones in Case 2. 
58

Figure 36. Air distribution for the single-floor building with eight same-size zones in 

Case 2. 

Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Zone 7 Zone 8

Zone 9

AHU 1 AHU 2

AHU 3
59

(a) Temperatures at AHU1 and return air temperatures

 from zones 1, 2, and 3

Time (s)

4000 6000 8000 10000 12000 14000

Temperature (oC)

0

200

400

600

800

1000

1200

1400

1600

1800

SA_TMP 

MA_TMP 

OA_TMP 

RA_TMP 

ZA_TMP_1 

ZA_TMP_2 

ZA_TMP_3 

Time (s)

4000 6000 8000 10000 12000 14000

Flow rate (m3 /s)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

SA_FLOW 

RA_FLOW 

ZFLOW_1 

ZFLOW_2 

ZFLOW_3 

(b) Flow rates of AHU1 branch

Figure 37. Temperatures, and flow rates of AHU1 in Case 2. 
60

(a) Damper and coil opening demands by AHU1 controller

4000 6000 8000 10000 12000 14000

Control signal (-) 

0.0

0.2

0.4

0.6

0.8

1.0

1.2

DMP_DEM 

CC_DEM 

HC_DEM 

DMP Opening 

(b) VAV damper and reheat coil signals by VAV controllers

Time (s)

4000 6000 8000 10000 12000 14000

Control signal (-)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

ZDMP_CTL_1 

ZDMP_CTL_2 

ZDMP_CTL_3 

RHC_CTL_1 

RHC_CTL_2 

RHC_CTL_3 

Figure 38. Control signals of AHU1 in Case 2. 
61

(a) Upper and lower layer temperatures

Time (s)

4000 6000 8000 10000 12000 14000

Layer temperature (oC)

0

200

400

600

800

1000

1200

1400

1600

1800

Rm_1L 

Rm_2L 

Rm_3L 

Rm_1U 

Rm_2U 

Rm_3U 

(b) Smoke concentrations of upper and lower layers

Time (s)

4000 6000 8000 10000 12000 14000

Smoke concentration (g/g)

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

s1L 

s2L 

s3L 

s1U 

s2U 

s3U 

Figure 39. Layer temperatures and smoke concentrations of zones served by AHU1 in 

Case 2. 
62

Time (s)

7000 7500 8000 8500 9000

Visibility limit (m)

0.0

0.5

1.0

1.5

2.0

U1 

U2 

U3 

U4 

U5 

U6 

U7 

U8 

U9 

U1 U9

U4, U5, U6 

U7, U8

U2, U3

Figure 40. Visibility limits at the upper layers due to smoke in Case 2. 

4.3 Case 3 Scenario 

A virtual single-story building with nine zones with different sizes was considered. 

Figure 41 shows the floor layout and Figure 42 shows the air distribution by three air 

handling units. Each zone has a VAV box and each AHU serves three VAV boxes. 

AHU1 serves for Zone 1, 2, and 3; AHU2 for Zone 4, 5, and 6; AHU3 for Zone 7, 8, 9, 

respectively. Zone 8 is a corridor. As was done in Cases 1 and 2, fire was set in Zone 1, 

and the start time of fire was 7200 s of emulation time. The behavior of AHU1 is close to 

that in Case 2 as seen in Figures 43 and 44. Due to the different configuration, the time 

history of upper and lower layer temperature and smoke concentrations as shown in 

Figure 45 has some differences as expected. Quite low visibility in all zones can be seen 

in Figure 46. 
63

1.00 Scale:

6.40

8.53

6.40 6.40 12.80

8.53 2.13

0.91

Zone 1 Zone 2 Zone 3 Zone 7

Zone 8

Zone 4 Zone 5 Zone 6 Zone 9

1.83

Ceiling Height = 2.44 m

Unit : meter

Figure 41. Floor layout of the single-story building with different size zones in Case 3. 
64

Figure 42. Air distribution for the virtual single-floor building with different size zones 

in Case 3. 

Zone 1 Zone 2 Zone 3

Zone 4 Zone 5 Zone 6

Zone 7

Zone 8

Zone 9

AHU 1

AHU 2

AHU 3
65

(a) Temperatures at AHU1 and return air temperatures

 from zones 1, 2, and 3

Time (s)

4000 6000 8000 10000 12000 14000

Temperature (oC)

0

200

400

600

800

1000

1200

1400

1600

1800

SA_TMP 

MA_TMP 

OA_TMP 

RA_TMP 

ZA_TMP_1 

ZA_TMP_2 

ZA_TMP_3 

Time (s)

4000 6000 8000 10000 12000 14000

Flow rate (m3 /s)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

SA_FLOW 

RA_FLOW 

ZFLOW_1 

ZFLOW_2 

ZFLOW_3 

(b) Flow rates of AHU1 branch

Figure 43. Temperatures, and flow rates of AHU1 in Case 3. 
66

(a) Damper and coil opening demands by AHU1 controller

4000 6000 8000 10000 12000 14000

Control signal (-)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

DMP_DEM 

CC_DEM 

HC_DEM 

DMP Opening 

(b) VAV damper and reheat coil signals by VAV controllers

Time (s)

4000 6000 8000 10000 12000 14000

Control signal (-)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

ZDMP_CTL_1 

ZDMP_CTL_2 

ZDMP_CTL_3 

RHC_CTL_1 

RHC_CTL_2 

RHC_CTL_3 

Figure 44. Control signals of AHU1 in Case 3. 
67

(a) Upper and lower layer temperatures

Time (s)

4000 6000 8000 10000 12000 14000

Layer temperature (oC)

0

200

400

600

800

1000

1200

1400

1600

1800

Rm_1L 

Rm_2L 

Rm_3L 

Rm_1U 

Rm_2U 

Rm_3U 

(b) Smoke concentrations of upper and lower layers

Time (s)

4000 6000 8000 10000 12000 14000

Smoke concentration (g/g)

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

s1L 

s2L 

s3L 

s1U 

s2U 

s3U 

Figure 45. Layer temperatures and smoke concentrations in Case 3. 
68

Time (s)

7000 7500 8000 8500 9000

Visibility limit (m)

0.0

0.5

1.0

1.5

2.0

U1 

U2 

U3 

U4 

U5 

U6 

U7 

U8 

U9 

U1

U8

U9

U7

U4, U5, U6

U2, U3

Figure 46. Visibility limits at the upper layers due to smoke in Case 3. 

5. CONCLUSION 

The VCBT has been enhanced and the overall structure of the current VCBT is reviewed 

in this preliminary report. ZFM-HVAC was added to the VCBT, the component models 

used in the HVAC-side of ZFM-HVAC were described and three scenarios were 

emulated. Some of the emulation results are presented graphically along with brief 

discussion. Interaction between building HVAC system and fire was demonstrated. In 

this study, nine conditioned space cases were utilized, because of availability of real 

BACnet controllers. 

Recently, capability to dynamically configure the capacities of AHUs and VAVs based 

on the zone floor areas was added to ZFM-HVAC. Also simplification of input data to 

ZFM-HVAC was made. Additionally virtual AHU and VAV box controllers were added 

to the VCBT in order to emulate buildings with a large number of zones, not limited to 

nine zones as done this report. 
69

6. REFERENCES 

1. May, W.B. & C. Park, Building Emulation Computer Program for Testing of Energy 

Management and Control System Algorithms, NBSIR 85-3291, NIST, 1985. 

2. Kelly, G.E., C. Park, and J.P. Barnett, Using Emulators/Tester for Commissioning 

EMCS Software, Operator Training, Algorithm Development, and Tuning Local Control 

Loops, ASHRAE Trans., V. 97, Pt. 1, 1991. 

3. Kohonen, R., et al., Development of Emulation Methods, IEA Annex 17 Report, 

August 1993. 

4. Benninn, H., BACnet Virtual Building, Practical Training Report, University of 

Maryland, 1997. 

5. Decious, G.M., C. Park, & G.E. Kelly, A Low-Cost Building/HVAC Emulator, 

Heating/Piping/AirConditioning, HPAC, Jan. 1997. 

6. Fuhrmann, F., Integrating Multiple Programs over the Internet using CORBA, 

Practical Training Report, University of Maryland, 1999. 

7. Bushby, S.T., N.S. Castro, M. Galler, C. Park, and J.M. House, Using the Virtual 

Cybernetic Building Testbed and FDD Test Shell for FDD Tool Development, NISTIR 

6818, NIST, 2002. 

8. Park, C., D.R. Clark, and G.E. Kelly, An Overview of HVACSIM+

, A Dynamic 

Building/HVAC/Control Systems Simulation Program , Proceedings of the 1st Annual 

Building Energy Simulation Conf., Seattle, WA, August 21-22, 1985. 

9. Castro, N.S., J. Schein, C. Park, M.A. Galler, S.T. Bushby, & J.M. House, Results 

from Simulation and Laboratory Testing of Air Handling Unit and variable Air Volume 

Box Diagnostic Tools, NISTIR 6964, NIST, 2003. 

10. Bushby, S.T., Application Layer Communication Protocols for Building Energy 

management and Control Systems, ASHRAE Transactions 1988, V. 94, Pt. 2, ASHRAE, 

1988. 

11. Bushby, S.T., BACnet: A Standard communication Infrastructure for Intelligent 

Buildings, Automation in Construction, V. 6, No. 5-6, 1997. 

12. Reneke, P.A., R.D. Peacock, G.P. Forney, and W.D. Davis, ZFM Zone Fire Model 

(Version 1) Reference Guide, (to be published in NIST publication). 

13. Siegel, J., CORBA Fundamentals and Programming, John Wiley & Sons, 1996. 
70

14. Norford, L.K. and P. Haves, A Standard Simulation Testbed for the Evaluation of 

Control algorithms and Strategies, ASHRAE Report 825-RP, ASHRAE, 1997. 

15. Kusuda, T., Thermal Response Factors for Multilayer Structures of Various Heat 

Conduction Systems, ASHRAE Trans. V. 75, 1969, pp. 246-270. 

16. WYEC2 User’s Manual and Toolkit, ASHRAE contract 728-TRP, Augustyn+ 

Company, 1997. 

17. Seborg, D.E., T.F. Edgar, and D.A. Mellichamp, Process Dynamic and Control, John 

Wiley & Sons, 1989. 

18. Treado, S., S.C. Cook, & M. Galler, Distributed Biometric Access Control Testbed, 

NISTIR 7190, NIST, 2004. 

19. Peacock, R.D., G.P. Forney, P. Reneke, R. Portier, and W.W. Jones, CFAST, the 

Consolidated Model of Fire Growth and Smoke Transport, NIST Tech. Note 1299, NIST, 

1993. 

20. Mulholland, G.W., and E.L. Johnson, A New Smoke Concentration Meter, 3rd

International Conf. on Fire Research and Engineering, Chicago, IL, Oct. 4-8, 1999. 

 
71

Appendix A. Sample BACnet Air-handling Unit Controller Object Database. 

 BACnet Objects of a VAV Air-handling Unit Controller

Object Description Default Remarks

AI-0 Supply Air Temperature n/a 0 to 5 volts = 0 EF to 200 EF

AI-1 Supply Air Pressure n/a 0 to 5 volts = 0" to 5"

AI-2 Return Air Temperature n/a 0 to 5 volts = 0 EF to 100 EF

AI-3 Return Air Humidity n/a 0 to 5 volts = 0 % to 100 %

AI-4 Outside Air Temperature n/a 0 to 5 volts = -50 EF to 150 EF

AI-5 Outside Air Humidity n/a 0 to 5 volts = 0 % to 100 %

AI-6 Supply Flow Rate n/a 0 to 5 volts = 0 to 8000 CFM

AI-7 Return Flow Rate n/a 0 to 5 volts = 0 to 8000 CFM

AI-8 Mixed Air Temperature n/a 0 to 5 volts = -50 EF to 150 EF

BI-9 Supply Flow Proof n/a 0 volts = Fan ON, 5 volts = Fan OFF

BI-10 Return Flow Proof n/a 0 volts = Fan ON, 5 volts = Fan OFF

BO-0 Supply Fan n/a

BO-1 Return Fan n/a

AO-0 Supply Fan Speed 0 0 to 10 volts = 0 % to 100 %

AO-1 Cooling Coil 0 0 to 10 volts = 0 % to 100 %

AO-2 Heating Coil 0 0 to 10 volts = 0 % to 100 %

AO-3 Economizer 0 0 to 10 volts = 0 % to 100 %

AO-4 Return Fan Speed 0 0 to 10 volts = 0 % to 100 %

AV-0 Temperture Ctrl Signal 0

AV-28 OSA Enthalpy 0

AV-29 Return Enthalpy 0

AV-40 Min. Return Fan Speed 20

AV-41 Min. Supply Fan Speed 20

AV-42 Supply/Return CFM Differential 1000

AV-43 Dehumidifying Supply Temp. Setpoint 50

AV-44 Current Supply Temp. Setpoint 0

AV-45 Supply Temp. SP Reset Loop 0

AV-46 Highest Cooling Signal (from VAV's) 0

AV-47 Supply Pressure SP Reset Loop 0

AV-48 Current Supply Pressure Setpoint 0

AV-49 Highest Need More Air Signal (from VAV's) 0

AV-50 Supply Pressure Setpoint - Warmup 1.4

AV-51 Supply Pressure Setpoint - Hi Limit 2

AV-52 Supply Pressure Setpoint - Lo Limit 0.2

AV-53 Supply Pressure Setpoint - Manual/Startup 1

AV-55 Supply Temp. Setpoint - Hi Limit 65

AV-56 Supply Temp. Setpoint - Lo Limit 50

AV-57 Supply Temp. Setpoint - Manual/Startup 60

AV-58 Supply Temp. Setpoint - Warmup 160

AV-60 Supply Temp. Low Limit 50

AV-66 Econ Min. Position % 15

AV-80 Humidity Hi Limit 60

BV-20 Alarm Reset OFF

BV-26 Supply Fan Alarm OFF

BV-28 Return Fan Alarm OFF

BV-32 Economizer Lockout Status OFF ON = Econ. locked out

BV-40 Occupied Command OFF Starts AHU, Econ. to Min. Position

BV-41 WarmupCommand OFF Starts AHU, Econ. stays closed

BV-43 Return Fan Proof OFF Transferred from BI-9

BV-46 Supply Fan Proof OFF Transferred from BI-10

BV-47 Supply Pressure Setpoint Reset Switch OFF ON = Autoreset, OFF = Manual

BV-48 Supply Temp. Setpoint Reset Switch OFF ON = Autoreset, OFF = Manual

BV-49 Dehumidifying OFF Indicates system is dehumidifying
72

Appendix B. Sample BACnet VAV Box Controller Object Database. 

 BACnet Objects of a VAV Box Controller

Object Description Default Remarks

AI-0 n/a not used

AI-1 Room Temp. n/a 0 to 5 volts = 30 EF to 130 EF

AI-2 Discharge Air Temp. n/a 0 to 5 volts = 40 EF to 190 EF

AI-3 Airflow Rate n/a 0 to 5 volts = 0 to 4000 CFM

AO-0 Damper Command OFF 0 to 10 volts = Full closed to full open

AO-1 Heating Valve Command OFF 0 to 10 volts = Full closed to full open

AO-2 OFF not used

AV-0 Heating Signal 0

AV-1 Cooling Signal 0

AV-4 Desired Airflow - Cold 0 CFM

AV-6 Occupied Heating Setpoint 0

AV-7 Occupied Cooling Setpoint 0

AV-9 Cooling Damper Position % 0

AV-10 Need More Air - Clg 0

AV-14 Heating Valve Position % 0

AV-20 Windsock - Cold ( 0 to 1) 0

AV-64 Cooling Damper Time 60 seconds

AV-65 Heating Valve Time 60 seconds

AV-66 Reheat Air - CFM 300 Desired airflow when htg valve full open

AV-67 Max Airflow - CFM 1000

AV-68 Min. Airflow - CFM 100 Min. air applies only when occupied

AV-90 Occupied Setpoint 72 Limited by AV-91 and AV-92

AV-91 Occupied Setpoint - Hi Limit 80 Limit for AV-90

AV-92 Occupied Setpoint - Lo Limit 65 Limit for AV-90

AV-93 Cooling Offset 1

AV-94 Heating Offset 1

AV-95 Unoccupied Cooling Setpoint 85

AV-96 Unoccupied Heating Setpoint 55

AV-97 Afterhours Timer Limit 0 Duration for Microtouch

AV-98 Afterhours Timer (hr) 0 Automatically counts down to 0

AV-99 Current Cooling Setpoint 0 Calculated

AV-100 Current Heating Setpoint 0 Calculated

AV-101 Microset Room Temp. 0 Use DDC to transfer AI to this AV

AV-102 Humidity from Microset 0

AV-103 Outside Air Temp. 0 Transfer from Lsi

AV-104 Mictouch Lever Offset 0 Calculated from current lever position

AV-105 Mictouch Bias Limit 0 Assigned Offset for full stroke

AV-106 Demand Offset 0 Transfer from Lsi

BV-0 Bad Sensor Alarm OFF

BV-1 Heating/Cooling Mode: On= Heating OFF

BV-2 Persistent Communication Fail OFF

BV-7 Main Air Status - Cold OFF

BV-8 Warm Air in Duct OFF

BV-9 Force Min. Air - Cold OFF

BV-10 Force Reheat Air OFF

BV-11 Force Max. Air - Cold OFF

BV-12 Force Open - Cold OFF

BV-13 Force Closed - Cold OFF

BV-19 Day Mode 2 hour Delay OFF

BV-24 Space Too Warm OFF

BV-25 Space Too Cold OFF

BV-38 Heating Lockout OFF Used for demand control

BV-39 Cooling Lockout OFF Used for demand control

BV-40 Occupied Command OFF Typically sent from Lsi

BV-41 Optimum Start Heating OFF

BV-42 Optimum Start Cooling OFF

BV-64 Occupied SP's Command OFF Turns ON Micset and BV-67

BV-65 OFF Mode Enable OFF OFF button ends daymode

BV-66 Afterhour Timer Status OFF ON when AV-98 > 0, otherwise OFF

BV-67 Occupied Status OFF Determined by BV-64 to BV-66

BV-68 Field Service Lockout OFF ON = Field Service Locked out

BV-69 English/Metric display Swap OFF OFF = Use VLC Mode, ON = Swap

BV-70 Microset Present Flag OFF ON = Microset Present

BV-71 English/Metric VLC Mode OFF OFF = English, Read Only
73

 

Appendix C. Fire-related Input Data for Case 1_1.

File name: zfm-hvac.inp

ROOMS ! Case 1_1: Three-story building with a small fire 08/05/05 

10 

0.0 8.53 6.40 2.9 ! elevation, length, width, height 

2.9 8.53 6.40 2.9 

5.8 8.53 6.40 2.9 

0.0 17.37 6.40 2.9 

2.9 17.37 6.40 2.9 

5.8 17.37 6.40 2.9 

0.0 25.91 9.14 2.9 

2.9 25.91 9.14 2.9 

5.8 25.91 9.14 2.9 

0.0 3.05 4.88 8.7 

VENTS ! number of vents 

 11 ! from room#, to room#, bottom, top, width 

 7 0 0. 2. 0.91 ! from room 7 to outside (door) 

 7 0 0. 2. 0.91 

 7 10 0. 2. 0.91 

 7 1 0. 2. 0.91 

 7 4 0. 2. 0.91 

 8 10 0. 2. 0.91 

 8 2 0. 2. 0.91 

 8 5 0. 2. 0.91 

 9 10 0. 2. 0.91 

 9 3 0. 2. 0.91 

 9 6 0. 2. 0.91 

SOLVEPRODS 

FIRES 

1 ! nfires 

1 3 0.1 1 5.0e+7 0.002 0.5 0.2 ! room#, type, elevation, flag, heat_c, 

species(i=2,3,4) 

 6 ! number of points 

 0. 0. ! time, heat release rate(kW) 

 60. 100. 

 70. 200. 

 100. 350. 

 1800. 400. 

 1900. 000. 

HSIM 

9 ! number of HVAC paths 

1 1.5 2.0 1 1.5 2.0 ! supply room#, duct bottom, top, return room#, 

duct bottom, top 

1 1 1 ! AHU#, return path#, supply path# 

2 1.5 2.0 2 1.5 2.0 

1 2 2 

3 1.5 2.0 3 1.5 2.0 

1 3 3 

4 1.5 2.0 4 1.5 2.0 

2 1 1 

5 1.5 2.0 5 1.5 2.0 

2 2 2 

6 1.5 2.0 6 1.5 2.0 

2 3 3 

7 1.5 2.0 7 1.5 2.0 

3 1 1 

8 1.5 2.0 8 1.5 2.0 
74

3 2 2 

9 1.5 2.0 9 1.5 2.0 

3 3 3 

PLOT 

zfm-hvac 

TIME 

 0.0 50000.0 ! start time, end time 

 0.0 2.897 300. 300. ! pressure, layer height, lower layer temp, 

upper layer temp 

 0.0 2.897 300. 300. 

 0.0 2.897 300. 300. 

 0.0 2.897 300. 300. 

 0.0 2.897 300. 300. 

 0.0 2.897 300. 300. 

 0.0 2.897 300. 300. 

 0.0 2.897 300. 300. 

 0.0 2.897 300. 300. 

 0.0 8.697 300. 300. 

Appendix D. HVAC-side Configuration Input Data

File name: run_hvac.inp

 3 ! n_ahu 

 3, 3, 3 ! nbr 

AHU1.inp ! (1) AHU 1 

AHU2.inp ! (2) AHU 2 

AHU3.inp ! (3) AHU 3 

VAV1.inp ! (4) AHU 1 (Zone 3, 2, 1) 

VAV2.inp ! (5) AHU 2 (Zone 6, 5, 4) 

VAV3.inp ! (6) AHU 3 (Zone 9, 8, 7) 

AHU1init.inp ! (7) AHU 1 Initial data 

AHU2init.inp ! (8) AHU 2 Initial data 

AHU3init.inp ! (9) AHU 3 Initial data 

AHUout1.out ! (10) AHU 1, 2, & 3 Output data 

AHUout2.out ! (11) AHU 1, 2, & 3 Output data 
75

Appendix E. Sample AHU Input Data

File name: AHU1.inp

! AHU1.inp Changed for ZFM-HVAC model 

! Base data file: emuex29i.mod 

 UNIT 17 TYPE 321 ----- OA damper 

 Motor-driven actuator 

 1 INPUTS: 

 CONTROL 149 - demanded position 

 2 OUTPUTS: 

 CONTROL 38 - position of final control element 

 CONTROL 0 - motor position 

 CONTROL 133 - number of stops/starts/reversals 

 CONTROL 0 - total distance traveled by final control element 

 3 PARAMETERS: 

 1.00000 direction: 1=forward, -1=reverse, 0=stuck 

 0.00000 starting position (0-1) 

 125.000 travel time (lim-lim) (s) 

 0.00000 minimum change in demanded position for movement (-) 

 0.00000 hysteresis (-) 

 0.00000 crank travel angle (0 for linear) (deg) 

 1.00000 Upper limit of control element range on actuator scale 

 0.00000 Lower limit of control element range on actuator scale 

 UNIT TYPE ----- AHU 

 Mixing box (simplified) 

 1 INPUTS: 

 TEMPERATURE 1 - Outside air dry bulb temperature 

 HUMIDITY 1 - Outside air humidity ratio 

 TEMPERATURE 54 - Extract air dry bulb temperature 

 HUMIDITY 16 - Extract air humidity ratio 

 FLOW 29 - Extract air mass flow rate 

 CONTROL 38 - Outside air damper position (0=closed, 1=open) 

 OTHER 8 - incoming smoke concentration 

 2 OUTPUTS: 

 TEMPERATURE 2 - Mixed air dry bulb temperature 

 HUMIDITY 2 - Mixed air humidity ratio 

 FLOW 2 - Mixed air mass flow rate 

 FLOW 1 - Total outside dry air mass flow rate 

 FLOW 30 - Recirc air mass flow rate 

 FLOW 47 - Exhaust air mass flow rate 

 OTHER 3 - outgoing smoke concentration 

 3 PARAMETERS: 

 0.100000 leakage factor of zones (-) 

 0.000000 Economizer on = 1, off = 0 (-) 

 0.100000 Minimum damper opening (-) 

UNIT 67 TYPE 321 ----- Heating coil valve 

 Motor-driven actuator 

 

 1 INPUTS: 

 CONTROL 159 - demanded position 

 

 2 OUTPUTS: 

 CONTROL 85 - position of final control element 

 CONTROL 0 - motor position 

 CONTROL 83 - number of stops/starts/reversals 

 CONTROL 0 - total distance traveled by final control element 

 
76

 3 PARAMETERS: 

 1.00000 direction: 1=forward, -1=reverse, 0=stuck 

 0.00000 starting position (0-1) 

 125.000 travel time (lim-lim) (s) 

 0.00000 minimum change in demanded position for movement (-) 

 0.00000 hysteresis (-) 

 0.00000 crank travel angle (0 for linear) (deg) 

 1.00000 Upper limit of control element range on actuator scale 

 0.00000 Lower limit of control element range on actuator scale 

 

UNIT 68 TYPE 524 ----- Heating coil and valve 

 Coil + three port valve, calculates flow 

 

 1 INPUTS: 

 TEMPERATURE 2 - Inlet air dry bulb temperature 

 HUMIDITY 2 - Inlet air humidity ratio 

 PRESSURE 47 - Outlet air pressure 

 FLOW 2 - Dry air mass flow rate 

 TEMPERATURE 78 - Inlet water temperature 

 PRESSURE 48 - Inlet water pressure 

 PRESSURE 49 - Outlet water pressure 

 CONTROL 85 - Valve stem position 

 TEMPERATURE 79 - Effective coil surface temperature 

 

 2 OUTPUTS: 

 TEMPERATURE 79 - Effective coil surface temperature 

 TEMPERATURE 80 - Outlet dry bulb air temperature 

 HUMIDITY 17 - Outlet air humidity ratio 

 PRESSURE 0 - Inlet air pressure 

 TEMPERATURE 81 - Outlet water temperature 

 FLOW 0 - Primary circuit water mass flow rate 

 FLOW 48 - Water mass flow rate through coil 

 TEMPERATURE 0 - Mixed return water temperature 

 POWER 10 - Total heat transfer to the air 

 CONTROL 0 - Sensible heat ratio 

 CONTROL 0 - Coil effectiveness 

 CONTROL 0 - Coil by-pass factor 

 ENERGY 0 - Outlet air specific enthalpy 

 CONTROL 0 - Outlet air relative humidity 

 TEMPERATURE 0 - Outlet air wet-bulb temperature 

 

 3 PARAMETERS: 

 1.00000 Method : 0 = steady state, 1 = dynamic 

 0.00000 Fault : 0 for no faults, 1 = parallel flow (cooling co 

 0.00000 Psycho : 0 = no psychrometric output calcs, 1 = calcs 

 1.00000 Number of rows of tubes 

 18.0000 Number of tubes per row 

 18.0000 Number of parallel water circuits 

 0.600000E-01 Length of finned section in direction of flow (m) 

 1.37000 Height of finned section (m) 

 2.77000 Width of finned section (m) 

 0.159000E-01 Tube outside diameter (m) 

 0.787400E-03 Tube wall thickness (m) 

 2.00000 Tube material (Al=1,Cu=2,Fe=3,CaCO3=4) 

 0.212000E-02 Fin spacing (pitch) (m) 

 0.216000E-03 Fin thickness (m) 

 1.00000 Fin material (Al=1,Cu=2,Fe=3) 

 0.802500E-03 Flow resistance on air side (1000/kg.m) 

 0.600000 Coil water flow resistance (1000/kg.m) 

 0.100000E+07 By-pass water flow resistance (1000/kg.m) 

 1.00000 Valve type: 0=lin/lin, 1=eq%(flow)/lin(byp), 2=lin/eq% 

 5.43600 Valve capacity (Kv) (m3/hr @ 1 bar) 

 3.54000 Valve curvature parameter (0=linear) (-) 

 24.5100 Valve rangability (-) 

 0.100000E-03 Valve leakage (fractional flow) (-) 

 

 UNIT 20 TYPE 321 ----- Cooling coil valve 

 Motor-driven actuator 

 

 1 INPUTS: 
77

 CONTROL 150 - demanded position 

 2 OUTPUTS: 

 CONTROL 41 - position of final control element 

 CONTROL 0 - motor position 

 CONTROL 136 - number of stops/starts/reversals 

 CONTROL 0 - total distance traveled by final control element 

 3 PARAMETERS: 

 1.00000 direction: 1=forward, -1=reverse, 0=stuck 

 0.00000 starting position (0-1) 

 125.000 travel time (lim-lim) (s) 

 0.00000 minimum change in demanded position for movement (-) 

 0.00000 hysteresis (-) 

 0.00000 crank travel angle (0 for linear) (deg) 

 1.00000 Upper limit of control element range on actuator scale 

 0.00000 Lower limit of control element range on actuator scale 

 

 UNIT 41 TYPE 524 ----- Cooling coil 

 Coil + three port valve, calculates flow 

 

 1 INPUTS: 

 TEMPERATURE 80 - Inlet air dry bulb temperature 

 HUMIDITY 17 - Inlet air humidity ratio 

 PRESSURE 3 - Outlet air pressure 

 FLOW 2 - Dry air mass flow rate 

 TEMPERATURE 55 - Inlet water temperature 

 PRESSURE 32 - Inlet water pressure 

 PRESSURE 33 - Outlet water pressure 

 CONTROL 41 - Valve stem position 

 TEMPERATURE 57 - Effective coil surface temperature (same as 1st o/ 

 2 OUTPUTS: 

 TEMPERATURE 57 - Effective coil surface temperature 

 TEMPERATURE 3 - Outlet dry bulb air temperature 

 HUMIDITY 3 - Outlet air humidity ratio 

 PRESSURE 0 - Inlet air pressure 

 TEMPERATURE 56 - Outlet water temperature 

 FLOW 0 - Primary circuit water mass flow rate 

 FLOW 40 - Water mass flow rate through coil 

 TEMPERATURE 0 - Mixed return water temperature 

 POWER 3 - Total heat transfer to the air 

 CONTROL 0 - Sensible heat ratio 

 CONTROL 0 - Coil effectiveness 

 CONTROL 0 - Coil by-pass factor 

 ENERGY 0 - Outlet air specific enthalpy 

 CONTROL 0 - Outlet air relative humidity 

 TEMPERATURE 0 - Outlet air wet-bulb temperature 

 3 PARAMETERS: 

 1.00000 Method : 0 = steady state, 1 = dynamic 

 0.00000 Fault : 0 for no faults, 1 = parallel flow (cooling co 

 0.00000 Psycho : 0 = no psychrometric output calcs, 1 = calcs 

 3.00000 Number of rows of tubes 

 36.0000 Number of tubes per row 

 36.0000 Number of parallel water circuits 

 0.180750 Length of finned section in direction of flow (m) 

 1.37000 Height of finned section (m) 

 2.77000 Width of finned section (m) 

 0.159000E-01 Tube outside diameter (m) 

 0.787400E-03 Tube wall thickness (m) 

 2.00000 Tube material (Al=1,Cu=2,Fe=3,CaCO3=4) 

 0.212000E-02 Fin spacing (pitch) (m) 

 0.216000E-03 Fin thickness (m) 

 1.00000 Fin material (Al=1,Cu=2,Fe=3) 

 0.802500E-03 Flow resistance on air side (1000/kg.m) 

 0.600000 Coil water flow resistance (1000/kg.m) 

 0.100000E+07 By-pass water flow resistance (1000/kg.m) 

 1.00000 Valve type: 0=lin/lin, 1=eq%(flow)/lin(byp), 2=lin/eq% 

 16.3100 Valve capacity (Kv) (m3/hr @ 1 bar) 
78

 3.54000 Valve curvature parameter (0=linear) (-) 

 24.5100 Valve rangability (-) 

 0.100000E-03 Valve leakage (fractional flow) (-) 

 

 

 UNIT 14 TYPE 333 ----- Supply fan 

 Variable speed drive 

 

 1 INPUTS: 

 CONTROL 157 - demanded fractional speed 

 2 OUTPUTS: 

 OTHER 1 - actual rotation speed 

 3 PARAMETERS: 

 22.3330 maximum rotation speed (rev/s) 

 120.000 travel time (lim-lim) (s) 

 

 UNIT 26 TYPE 350 ----- Supply fan 

 Fan or pump 

 

 1 INPUTS: 

 FLOW 2 - mass flow rate of fluid 

 PRESSURE 4 - outlet pressure 

 OTHER 1 - fan or pump rotational speed 

 2 OUTPUTS: 

 PRESSURE 3 - inlet pressure 

 POWER 1 - fluid stream heat addition rate 

 POWER 29 - power consumption 

 

 3 PARAMETERS: 

 4.29040 1st pressure coefficient 

 -1.38700 2nd pressure coefficient 

 4.22930 3rd pressure coefficient 

 -3.92920 4th pressure coefficient 

 0.853400 5th pressure coefficient 

 0.116200 1st efficiency coefficient 

 1.54040 2nd efficiency coefficient 

 -1.48250 3rd efficiency coefficient 

 0.766400 4th efficiency coefficient 

 -0.197100 5th efficiency coefficient 

 0.685800 diameter (m) 

 1.00000 mode: air=1, water=2 

 1.00000 lowest valid normalized flow (-) 

 2.00000 highest valid normalized flow (-) 

 

 UNIT 15 TYPE 333 ----- Return fan 

 Variable speed drive 

 

 1 INPUTS: 

 CONTROL 158 - demanded fractional speed 

 2 OUTPUTS: 

 OTHER 2 - actual rotation speed 

 

 3 PARAMETERS: 

 8.00000 maximum rotation speed (rev/s) 

 120.000 travel time (lim-lim) (s) 

 UNIT 38 TYPE 350 ----- Return fan 

 Fan or pump 

 

 1 INPUTS: 

 FLOW 29 - mass flow rate of fluid 

 PRESSURE 27 - outlet pressure 

 OTHER 2 - fan or pump rotational speed 

 2 OUTPUTS: 

 PRESSURE 26 - inlet pressure 
79

 POWER 2 - fluid stream heat addition rate 

 POWER 30 - power consumption 

 

 3 PARAMETERS: 

 4.19370 1st pressure coefficient 

 -1.63370 2nd pressure coefficient 

 12.2110 3rd pressure coefficient 

 -23.9619 4th pressure coefficient 

 9.81620 5th pressure coefficient 

 0.619000E-01 1st efficiency coefficient 

 3.14170 2nd efficiency coefficient 

 -5.75510 3rd efficiency coefficient 

 6.16760 4th efficiency coefficient 

 -3.37480 5th efficiency coefficient 

 1.13000 diameter (m) 

 1.00000 mode: air=1, water=2 

 0.700000 lowest valid normalized flow (-) 

 1.00000 highest valid normalized flow (-) 

 

UNIT 69 TYPE 341 ----- AHU HC 

 Fluid resistance 

 

 1 INPUTS: 

 FLOW 2 - Mass flow rate 

 PRESSURE 47 - Outlet pressure 

 

 2 OUTPUTS: 

 PRESSURE 2 - Inlet pressure 

 

 3 PARAMETERS: 

 0.200000E-03 flow resistance (0.001/kg.m) 

 

UNIT 25 TYPE 341 ----- AHU duct and CC 

 Fluid resistance 

 

 1 INPUTS: 

 FLOW 2 - Mass flow rate 

 PRESSURE 3 - Outlet pressure 

 2 OUTPUTS: 

 PRESSURE 47 - Inlet pressure 

 

 3 PARAMETERS: 

 0.546000E-03 flow resistance (1000/kg.m) 

 

 UNIT 27 TYPE 341 ----- Supply duct 

 Fluid resistance 

 

 1 INPUTS: 

 FLOW 2 - Mass flow rate 

 PRESSURE 5 - Outlet pressure 

 2 OUTPUTS: 

 PRESSURE 4 - Inlet pressure 

 

 3 PARAMETERS: 

 0.164000E-03 flow resistance (1000/kg.m) 

 

 UNIT 39 TYPE 341 ----- Return duct 

 Fluid resistance 

 

 1 INPUTS: 

 FLOW 29 - Mass flow rate 

 PRESSURE 28 - Outlet pressure 

 2 OUTPUTS: 

 PRESSURE 27 - Inlet pressure 

 
80

 3 PARAMETERS: 

 0.118000E-03 flow resistance (1000/kg.m) 

 

UNIT 42 TYPE 366 ----- AHU 

 Ideal heating of fluid stream 

 

 1 INPUTS: 

 FLOW 2 - mass flow rate 

 TEMPERATURE 3 - inlet temperature 

 POWER 1 - rate of heat addition 

 

 2 OUTPUTS: 

 TEMPERATURE 4 - outlet temperature 

 

 3 PARAMETERS: 

 1.00000 fluid: 1 = air, any other value + water (-) 

 30.0000 time constant (s) 

 

UNIT 47 TYPE 366 ----- AHU return stream 

 Ideal heating of fluid stream 

 

 1 INPUTS: 

 FLOW 29 - mass flow rate 

 TEMPERATURE 53 - inlet temperature 

 POWER 2 - rate of heat addition 

 

 2 OUTPUTS: 

 TEMPERATURE 54 - outlet temperature 

 

 3 PARAMETERS: 

 1.00000 fluid: 1 = air, any other value + water (-) 

 30.0000 time constant (s) 

 

UNIT 62 TYPE 305 ----- Supply air 

 Static pressure sensor 

 

 1 INPUTS: 

 PRESSURE 5 - pressure 

 FLOW 2 - mass flow rate 

 2 OUTPUTS: 

 CONTROL 65 - sensor output 

 

 3 PARAMETERS: 

 1.00000 air = 1, water = 2 (-) 

 1.00000 cross-sectional area of duct or pipe (m2) 

 0.00000 offset: input for zero output (kPA) 

 1.00000 gain: change in input for 0->1 output (kPA) 

 1.00000 time constant (s) 

 5.00000 upper limit of output range (-) 

 -5.00000 lower limit of output range (-) 

 

UNIT 60 TYPE 303 ----- Supply air 

 Flow rate sensor 

 

 1 INPUTS: 

 FLOW 2 - mass flow rate 

 

 2 OUTPUTS: 

 CONTROL 63 - sensor output 

 

 3 PARAMETERS: 

 2.00000 mass flow=1, vol flow=2, vel=3, vel pres=4 (-) 

 1.00000 air = 1, water = 2 (-) 

 1.00000 cross-sectional area of duct or pipe (m2) 

 0.00000 offset: input for zero output (sensed quantity) 
81

 1.00000 gain: change in input for 0->1 output (sensed quantity) 

 1.00000 time constant (s) 

 20.0000 upper limit of output range (-) 

 -10.0000 lower limit of output range (-) 

 

 UNIT 61 TYPE 303 ----- Return air 

 Flow rate sensor 

 

 1 INPUTS: 

 FLOW 29 - mass flow rate 

 

 2 OUTPUTS: 

 CONTROL 64 - sensor output 

 

 3 PARAMETERS: 

 2.00000 mass flow=1, vol flow=2, vel=3, vel pres=4 (-) 

 1.00000 air = 1, water = 2 (-) 

 1.00000 cross-sectional area of duct or pipe (m2) 

 0.00000 offset: input for zero output (sensed quantity) 

 1.00000 gain: change in input for 0->1 output (sensed quantity) 

 1.00000 time constant (s) 

 20.0000 upper limit of output range (-) 

 -10.0000 lower limit of output range (-) 

 

 UNIT 54 TYPE 301 ----- SA 

 Temperature sensor 

 

 1 INPUTS: 

 TEMPERATURE 4 - temperature 

 

 2 OUTPUTS: 

 CONTROL 61 - sensor output 

 

 3 PARAMETERS: 

 0.00000 offset: input for zero output (C) 

 1.00000 gain: change in input for 0->1 output (K) 

 30.0000 time constant (s) 

 2000.0000 upper limit of output range (-) 

 0.00000 lower limit of output range (-) 

 

 UNIT 56 TYPE 301 ----- MA 

 Temperature sensor 

 

 1 INPUTS: 

 TEMPERATURE 2 - temperature 

 

 2 OUTPUTS: 

 CONTROL 68 - sensor output 

 

 3 PARAMETERS: 

 0.00000 offset: input for zero output (C) 

 1.00000 gain: change in input for 0->1 output (K) 

 30.0000 time constant (s) 

 2000.0000 upper limit of output range (-) 

 0.00000 lower limit of output range (-) 

 UNIT 53 TYPE 301 ----- OA 

 Temperature sensor 

 

 1 INPUTS: 

 TEMPERATURE 1 - temperature 

 

 2 OUTPUTS: 

 CONTROL 60 - sensor output 

 

 3 PARAMETERS: 

 0.00000 offset: input for zero output (C) 

 1.00000 gain: change in input for 0->1 output (K) 
82

 30.0000 time constant (s) 

 51.6700 upper limit of output range (-) 

 -40.0000 lower limit of output range (-) 

 UNIT 55 TYPE 301 ----- RA 

 Temperature sensor 

 

 1 INPUTS: 

 TEMPERATURE 54 - temperature 

 

 2 OUTPUTS: 

 CONTROL 62 - sensor output 

 

 3 PARAMETERS: 

 0.00000 offset: input for zero output (C) 

 1.00000 gain: change in input for 0->1 output (K) 

 30.0000 time constant (s) 

 2000.0000 upper limit of output range (-) 

 0.00000 lower limit of output range (-) 

UNIT 63 TYPE 302 ----- Outside air 

 Humidity sensor 

 

 1 INPUTS: 

 HUMIDITY 1 - humidity ratio 

 TEMPERATURE 1 - temperature 

 

 2 OUTPUTS: 

 CONTROL 66 - sensor output 

 

 3 PARAMETERS: 

 1.00000 HR=1, RH=2, DP=3, WB=4, deg sat=5, spec enthalpy=6 (-) 

 0.00000 offset: input for zero output (sensed quantity) 

 1.00000 gain: change in input for 0->1 output (sensed quantity) 

 30.0000 time constant (s) 

 1.00000 upper limit of output range (-) 

 0.00000 lower limit of output range (-) 

 

 UNIT 64 TYPE 302 ----- Return air 

 Humidity sensor 

 

 1 INPUTS: 

 HUMIDITY 16 - humidity ratio 

 TEMPERATURE 54 - temperature 

 2 OUTPUTS: 

 CONTROL 67 - sensor output 

 

 3 PARAMETERS: 

 1.00000 HR=1, RH=2, DP=3, WB=4, deg sat=5, spec enthalpy=6 (-) 

 0.00000 offset: input for zero output (sensed quantity) 

 1.00000 gain: change in input for 0->1 output (sensed quantity) 

 30.0000 time constant (s) 

 1.00000 upper limit of output range (-) 

 0.00000 lower limit of output range (-) 
83

Appendix F. Sample VAV Input Data

File name: VAV1.inp

! VAV1.inp Changed for ZFM-HVAC model 

! Base data file: emuex29i.mod 

 UNIT 30 TYPE 526 ----- zone 1 

 Motorized pressure-independent VAV box 

 

 1 INPUTS: 

 PRESSURE 5 - inlet pressure 

 PRESSURE 16 - outlet pressure 

 CONTROL 151 - demanded flow rate (normalized to nominal) 

 FLOW 3 - air mass flow rate 

 

 2 OUTPUTS: 

 FLOW 3 - air mass flow rate 

 CONTROL 77 - damper position (0=closed, 1=open) 

 CONTROL 0 - fractional motor velocity 

 CONTROL 143 - number of stops/starts/reversals 

 CONTROL 0 - total distance traveled by valve/damper 

 

 3 PARAMETERS: 

 0.565000 nominal volumetric flow rate (m3/s) 

 0.250000 face area of damper(s) (m2) 

 0.999000E-01 additional pressure drop at nominal flow (kPa) 

 100.000 actuator travel time (0-90 deg) (s) 

 0.00000 minimum fractional motor speed (-) 

 0.00000 hysteresis (-) 

 9.99000 controller gain (frac speed/frac error) 

 

 UNIT 21 TYPE 321 ----- RHC valve zone 1 

 Motor-driven actuator 

 

 1 INPUTS: 

 CONTROL 154 - demanded position 

 

 2 OUTPUTS: 

 CONTROL 42 - position of final control element 

 CONTROL 0 - motor position 

 CONTROL 137 - number of stops/starts/reversals 

 CONTROL 0 - total distance traveled by final control element 

 

 3 PARAMETERS: 

 1.00000 direction: 1=forward, -1=reverse, 0=stuck 

 0.00000 starting position (0-1) 

 125.000 travel time (lim-lim) (s) 

 0.00000 minimum change in demanded position for movement (-) 

 0.00000 hysteresis (-) 

 0.00000 crank travel angle (0 for linear) (deg) 

 1.00000 Upper limit of control element range on actuator scale 

 0.00000 Lower limit of control element range on actuator scale 

 UNIT 43 TYPE 524 ----- zone 1 

 Coil + three port valve, calculates flow 

 

 1 INPUTS: 

 TEMPERATURE 4 - Inlet air dry bulb temperature 

 HUMIDITY 3 - Inlet air humidity ratio 

 PRESSURE 16 - Outlet air pressure 

 FLOW 3 - Dry air mass flow rate 

 TEMPERATURE 58 - Inlet water temperature 

 PRESSURE 34 - Inlet water pressure 

 PRESSURE 35 - Outlet water pressure 

 CONTROL 42 - Valve stem position 

 TEMPERATURE 70 - Effective coil surface temperature (same as 1st o/ 

 
84

 2 OUTPUTS: 

 TEMPERATURE 70 - Effective coil surface temperature 

 TEMPERATURE 5 - Outlet dry bulb air temperature 

 HUMIDITY 4 - Outlet air humidity ratio 

 PRESSURE 0 - Inlet air pressure 

 TEMPERATURE 64 - Outlet water temperature 

 FLOW 0 - Primary circuit water mass flow rate 

 FLOW 41 - Water mass flow rate through coil 

 TEMPERATURE 0 - Mixed return water temperature 

 POWER 4 - Total heat transfer to the air 

 CONTROL 0 - Sensible heat ratio 

 CONTROL 0 - Coil effectiveness 

 CONTROL 0 - Coil by-pass factor 

 ENERGY 0 - Outlet air specific enthalpy 

 CONTROL 0 - Outlet air relative humidity 

 TEMPERATURE 0 - Outlet air wet-bulb temperature 

 

 3 PARAMETERS: 

 1.00000 Method : 0 = steady state, 1 = dynamic 

 0.00000 Fault : 0 for no faults, 1 = parallel flow (cooling co 

 0.00000 Psycho : 0 = no psychrometric output calcs, 1 = calcs 

 1.00000 Number of rows of tubes 

 16.0000 Number of tubes per row 

 1.00000 Number of parallel water circuits 

 0.275000E-01 Length of finned section in direction of flow (m) 

 0.457000 Height of finned section (m) 

 0.305000 Width of finned section (m) 

 0.127000E-01 Tube outside diameter (m) 

 0.406000E-03 Tube wall thickness (m) 

 2.00000 Tube material (Al=1,Cu=2,Fe=3,CaCO3=4) 

 0.254000E-02 Fin spacing (pitch) (m) 

 0.152000E-03 Fin thickness (m) 

 1.00000 Fin material (Al=1,Cu=2,Fe=3) 

 0.150000 Flow resistance on air side (0.001 kg.m) 

 25.0000 Coil water flow resistance (0.001 kg.m) 

 0.100000E+07 By-pass water flow resistance (0.001 kg.m) 

 1.00000 Valve type: 0=lin/lin, 1=eq%(flow)/lin(byp), 2=lin/eq% 

 0.500000 Valve capacity (Kv) (m3/hr @ 1 bar) 

 3.22000 Valve curvature parameter (0=linear) (-) 

 50.0000 Valve rangability (-) 

 0.200000E-03 Valve leakage (fractional flow) (-) 

 

UNIT 33 TYPE 425 ----- zone 1 

 Room air mass balance 

 

 1 INPUTS: 

 FLOW 3 - supply air mass flow rate (positive in) 

 PRESSURE 16 - room pressure 

 PRESSURE 30 - ambient pressure 

 TEMPERATURE 35 - room temperature 

 2 OUTPUTS: 

 FLOW 19 - return air mass flow rate (positive out) 

 FLOW 31 - leakage mass flow rate to ambient (positive out) 

 3 PARAMETERS: 

 1.00000 leakage resistance [0.001/(kg m)] 

 0.00000 local extract fan mass flow rate [kg/s] 

UNIT 57 TYPE 301 ----- zone 1 air temperature 

 Temperature sensor 

 

 1 INPUTS: 

 TEMPERATURE 35 - temperature 

 

 2 OUTPUTS: 

 CONTROL 70 - sensor output 

 

 3 PARAMETERS: 

 0.00000 offset: input for zero output (C) 
85

 1.00000 gain: change in input for 0->1 output (K) 

 10.0000 time constant (s) 

 2000.00 upper limit of output range (-) 

 0.00000 lower limit of output range (-) 

UNIT 37 TYPE 422 ----- From Zone 1 

 Flow merge with smoke 

 3 PARAMETERS: 

 0.263200E-03 Inlet resistance 1 (0.001/k.m) 

 0.263200E-03 Inlet resistance 2 (0.001/k.m) 

 0.263200E-02 Resistance of outlet (0.001/k.m) 

 

UNIT 46 TYPE 365 ----- AHU 

 Mixing of two moist air streams 

 3 PARAMETERS: 

 0.00000 (dummy) 
86

Appendix G. Sample AHU Initial Data

File name: AHU1init.inp

 

PRESSURE 1 -> 0.00000 (kPa) 

 PRESSURE 2 -> -0.09278 (kPa) 

 PRESSURE 3 -> -0.09375 (kPa) 

 PRESSURE 4 -> 0.25100 (kPa) 

 PRESSURE 5 -> 0.25000 (kPa) 

 PRESSURE 16 -> 0.01000 (kPa) 

 PRESSURE 26 -> -0.46000 (kPa) 

 PRESSURE 27 -> 0.06465 (kPa) 

 PRESSURE 28 -> 0.06465 (kPa) 

 PRESSURE 29 -> 0.06465 (kPa) 

 PRESSURE 30 -> 0.00000 (kPa) 

 PRESSURE 32 -> 39.0300 (kPa) 

 PRESSURE 33 -> 0.00000 (kPa) 

 PRESSURE 34 -> 38.1000 (kPa) 

 PRESSURE 35 -> 0.00000 (kPa) 

 PRESSURE 47 -> 0.00000 (kPa) 

 PRESSURE 48 -> 20.0000 (kPa) 

 PRESSURE 49 -> 0.00000 (kPa) 

 FLOW 1 -> 0.66100 (kg/s) 

 FLOW 2 -> 1.33000 (kg/s) 

 FLOW 3 -> 0.28300 (kg/s) 

 FLOW 19 -> 0.31200 (kg/s) 

 FLOW 28 -> 0.00000 (kg/s) 

 FLOW 29 -> 1.10000 (kg/s) 

 FLOW 30 -> 0.67300 (kg/s) 

 FLOW 31 -> 0.00000 (kg/s) 

 FLOW 40 -> 0.00000 (kg/s) 

 FLOW 41 -> 0.00000 (kg/s) 

 FLOW 47 -> 0.00000 (kg/s) 

 FLOW 48 -> 0.00000 (kg/s) 

 TEMPERATURE 1 -> 30.0000 (C) 

 TEMPERATURE 2 -> 20.0000 (C) 

 TEMPERATURE 3 -> 20.0000 (C) 

 TEMPERATURE 4 -> 20.0000 (C) 

 TEMPERATURE 5 -> 20.0000 (C) 

 TEMPERATURE 35 -> 25.0000 (C) 

 TEMPERATURE 53 -> 20.0000 (C) 

 TEMPERATURE 54 -> 20.0000 (C) 

 TEMPERATURE 55 -> 6.00000 (C) 

 TEMPERATURE 56 -> 6.00000 (C) 

 TEMPERATURE 57 -> 20.0000 (C) 

 TEMPERATURE 58 -> 80.0000 (C) 

 TEMPERATURE 64 -> 20.0000 (C) 

 TEMPERATURE 70 -> 20.0000 (C) 

 TEMPERATURE 78 -> 80.0000 (C) 

 TEMPERATURE 79 -> 20.0000 (C) 

 TEMPERATURE 80 -> 20.0000 (C) 

 TEMPERATURE 81 -> 20.0000 (C) 

 CONTROL 1 -> 1.0000 (-) 

 CONTROL 2 -> 1.0000 (-) 

 CONTROL 38 -> 0.0000 (-) 

 CONTROL 41 -> 0.0000 (-) 

 CONTROL 42 -> 0.0000 (-) 

 CONTROL 60 -> 30.0000 (-) 

 CONTROL 61 -> 20.0000 (-) 

 CONTROL 62 -> 20.0000 (-) 

 CONTROL 63 -> 6.17300 (-) 

 CONTROL 64 -> 5.25600 (-) 

 CONTROL 65 -> 0.223000 (-) 

 CONTROL 66 -> 0.153000E-01(-) 

 CONTROL 67 -> 0.750000E-02(-) 

 CONTROL 68 -> 20.0000 (-) 

 CONTROL 70 -> 22.2200 (-) 

 CONTROL 77 -> 0.00000 (-) 
87

 CONTROL 85 -> 0.00000 (-) 

 CONTROL 143 -> 0.00000 (-) 

 CONTROL 149 -> 0.10000 (-) 

 CONTROL 150 -> 0.26000 (-) 

 CONTROL 151 -> 0.70000 (-) 

 CONTROL 154 -> 0.00000 (-) 

 CONTROL 157 -> 0.50000 (-) 

 CONTROL 158 -> 0.20000 (-) 

 CONTROL 159 -> 0.00000 (-) 

 OTHER 3 -> 0.00000 (-) 

 OTHER 4 -> 0.00000 (-) 

 OTHER 8 -> 0.00000 (-) 

 POWER 1 -> 0.00000 (kW) 

 POWER 2 -> 0.00000 (kW) 

 POWER 3 -> 0.00000 (kW) 

 POWER 4 -> 0.00000 (kW) 

 POWER 10 -> 0.00000 (kW) 

 POWER 29 -> 0.00000 (kW) 

 POWER 30 -> 0.00000 (kW) 

 HUMIDITY 1 -> 0.162000E-01(kg/kg) 

 HUMIDITY 2 -> 0.162000E-01(kg/kg) 

 HUMIDITY 3 -> 0.162000E-01(kg/kg) 

 HUMIDITY 4 -> 0.162000E-01(kg/kg) 

 HUMIDITY 10 -> 0.162000E-01(kg/kg) 

 HUMIDITY 16 -> 0.162000E-01(kg/kg) 

 HUMIDITY 17 -> 0.162000E-01(kg/kg)