TRACE Load 700 Output Interpretation ManualTABLE OF CONTENTS

Click on a topic with your mouse to jump to that specific page.

CHAPTER 1. Overview................................................................................................................................................................................. 3 1.1 How to use this manual......................................................................................................................................................................... 3

CHAPTER 2. Output Reports 2.1 Summary Reports 2.1.1 Title Page....................................................................................................................................................................................... 5 2.1.2 Checksums (System, Zone, Room).............................................................................................................................................. 9 2.2 System Reports 2.2.1 Design Airflow Quantities........................................................................................................................................................... 13 2.2.2 Design Capacity Quantities......................................................................................................................................................... 17 2.2.3 Engineering Checks.................................................................................................................................................................... 26 2.3 Peak Load Summary Reports 2.3.1 Peak Cooling Loads..................................................................................................................................................................... 28 2.3.2 Peak Heating Loads..................................................................................................................................................................... 43 2.4 Psychrometric State Points (System, Zone, Room, Auxiliary)........................................................................................................... 53 2.5 Building Envelope Loads.................................................................................................................................................................... 63 2.6 Internal Loads...................................................................................................................................................................................... 77 2.7 Airflow Loads 2.7.1 Airflow Cooling Loads at Coil Peak........................................................................................................................................... 84 2.7.2 Airflow Heating Loads at Coil Peak............................................................................................................................................ 90 2.8 Airflow Heat Gain/Loss....................................................................................................................................................................... 96 2.9 Building Envelope Composition 2.9.1 Building U-Values..................................................................................................................................................................... 108 2.9.2 Building Areas........................................................................................................................................................................... 111 2.9.3 ASHRAE 90 Analysis............................................................................................................................................................... 114

CHAPTER 3. Echo Input Report 3.1 Project Information............................................................................................................................................................................ 117 3.2 Room Information............................................................................................................................................................................. 117 3.3 System Information........................................................................................................................................................................... 117

APPENDIX A. System Type Acronyms.................................................................................................................................................... 118

2This document contains excerpts from theTRACE 600 Output Interpretation Manual

(Trane order no. TRCE-UM-603), dated January 1992

The Trane Company, in offering the TRACE Load 700 computer program, accepts no responsibility or liability for the design of buildings ortheir support systems or for the accuracy of the building and system air conditioning load data. The building and system air conditioning loaddata are based on conventional engineering principles, plus engineering data supplied only by the program user. Trane further accepts noresponsibility or liability for the suitability of the building air conditioning system in providing the proper temperature control, humiditycontrol, infiltration, ventilation, air distribution, and quiet operation.

3Chapter 1 OVERVIEW

This document describes some of the algorithms used to generate output from the TRACE Load 700 program.

During the load calculation phase, the program takes the building information and stores the 24-hour load profile associated with eachroom's load components (external conduction, internal, and solar loads) for each month of the design simulation period.

The design phase uses this load profile information and system information to first find when each room and zone assigned to a particularsystem peaks, and then calculate the airflows and capacities using a psychrometric analysis.

The output consists of envelope, capacity and airflow summaries, peak load components, and cooling coil psychrometrics..

1.1 How to use this manual

1. Use the jumps in the Table of Contents to access the desired report. 2. The section lists every output field on the report, each containing a brief description and equations. The equations and algorithms

will typically be followed by a variable list with associated references. These references are prefixed with one of the two-letter codeslisted in Table 1.0 below.

3. Use Acrobats search capabilities to find all occurrences of the reference of interest.

Choose Find from the Tools menu (or press the Find button on the toolbar - the binoculars) Type in the string that you wish to search for in the Find What field:

Variable (i.e. SADB) Reference or Equation Number (i.e. Ref ##) Key Word or Phrase

Press the Find button. Continue to press the Find Again button to see other occurrences.

Table 1.0 TRACE Load 700 Reference Acronyms

EQ Equation numbered by reference within this manual (goto the Ref # with the same number, the value is calculated in the description of the Ref #)

RF Variable numbered by reference within this manual (goto the listed Ref #)

TB Table numbered by section within this manual TR * TRACE Load 700 input screen

(see Table 1.1 below for screen location) * The "TR" prefixes are followed by a 4-letter acronym representing a TRACE Load 700 program input screen. The screen acronyms arelisted in Table 1.1 that follows. For detailed descriptions of these screens or individual input fields, refer to the on-line Help.

Table 1.1 TRACE Load 700 Screen Acronyms

TR Acronym TRACE Load 700 Screen NameWTHR Weather OverridesGENL Create Rooms - Single Sheet

Create Rooms - RoomsSTAT Create Rooms - RoomsROOF Create Rooms - Single Sheet

Create Rooms - RoofsSKYL Create Rooms - RoofsWALL Create Rooms - Single Sheet

Create Rooms - WallsGLAS Create Rooms - Single Sheet

Create Rooms - WallsLSCH Create Rooms - Internal Loads

Create Rooms - AirflowsPLIT Create Rooms - Single Sheet

Create Rooms - Internal Loads Internal & Airflow Loads Library - Lighting

MISC Create Rooms - Single Sheet Create Rooms - Internal Loads Internal & Airflow Loads Library - Misc Equipment

4OACF Create Rooms - Single Sheet Create Rooms - Airflows

FNCF Create Rooms - AirflowsPART Create Rooms - Partitions/FloorsXFLR Create Rooms - Partitions/FloorsEXSH Shading Library - External ShadingINSH Shading Library - Internal ShadingSTYP Create Systems - Selection

Create Systems - OptionsSOPT Create Systems - OptionsFNSP Create Systems - Fan Static PressuresSADB Create Systems - Design TemperaturesFNOV Create Systems - Fan OverridesCLGC Create Systems - Cooling OverridesHTGC Create Systems - Heating OverridesTIME Load ParametersLSIM Load ParametersZNSS Assign Rooms and Zones

* Acronyms that may be included, but are not related to TRACE Load 700DAYL Daylighting Controls (TRACE 600 only)EMSH EMS/BAS Schedules (TRACE 600 only)ESIM Energy Simulation (TRACE 600 only)EQSH Equipment Schedules (TRACE 600 only)RUFS Resource Utilization (TRACE 600 only)

System Type acronyms are listed with the accompanying description in Appendix A of this manual. For detailed descriptions of theseSystem Types, refer to the on-line Help.

Additional documentation of the program algorithms is available in the TRACE 600 Engineering Manual (TRCE-UM-602.)

52.1.1 TITLE PAGE

The title page lists the project information, geographic and design weather information, and additional load parameters.

Ref #1. Project Information

The Project Name, Location, Building Owner, Program User, Company, and Comments entered on the Project Information screen areechoed exactly as entered by the user. The Dataset Name is the filename and location.

Ref #2. Weather Location

The weather location is selected by the user on the Weather Map screen.

Ref #3,4. Latitude/Longitude

The latitude and longitude are echoed from the Weather Library. The latitude and longitude will affect all solar and shading calculations.

Ref #5. Time zone

The time zone is echoed from the Weather Library. The time zone will affect all solar and shading calculations. Table 2.1 lists how theprogram assigns the time zone number and lists the North America time zones.

Table 2.1 Time ZonesTimeZone

Number

DegreesWestLongitude

DegreesEastLongitude

12 - 172 + 17211 + 172 + 15710 + 157 + 1429 (Alaskan) + 142 + 1278 (Pacific) + 127 + 1127 (Mountain

)+ 112 + 97

6 (Central) + 97 + 825 (Eastern) + 82 + 674 (Atlantic) + 67 + 523 + 52 + 372 + 37 + 221 + 22 + 70 + 7 - 7

- 1 - 7 - 22- 2 - 22 - 37- 3 - 37 - 52- 4 - 52 - 67- 5 - 67 - 82- 6 - 82 - 97- 7 - 97 - 112- 8 - 112 - 127- 9 - 127 - 142- 10 - 142 - 157- 11 - 157 - 172

Ref #6. Elevation

The elevation, in feet [m], is echoed from the Weather Library. Also see Ref #7.

6Ref #7. Barometric Pressure

The Design Barometric Pressure, DOAPS, is used to correct the properties of moist air for elevation. This value is equivalent to the totalpressure of the moist (supply) air. The barometric pressure is echoed from the Weather Library.

Ref #8, 9. Summer/Winter Clearness Number

The summer and winter clearness numbers are echoed from the Weather Library unless overridden by user entry on the WeatherOverrides screen. For northern latitudes the "summer" clearness number is applied to the months May through September and the"winter" clearness number to months October through April. For southern latitudes the periods switch. The summer and winter periodcan be changed by user entry on the Load Parameters screen.

The clearness number is a direct multiplier on the direct component of solar radiation; however, since the clearness number is divided intothe diffuse component of solar insolation, smaller values of clearness number will increase the diffuse solar component.

Ref #10, 11. Summer Design Dry Bulb/Wet Bulb

The summer design dry bulb (SDDB) and wet bulb (SDWB) are echoed from the Weather Library unless overridden by user entry on theWeather Overrides screen. This outside air condition represents the time of the hottest dry bulb occurring during the 12 months of thecooling design portion of the Weather Library.

Whenever the summer design dry bulb and wet bulb are overridden by user entry on the Weather Overrides screen, the summer months(defined by the "Summer Period" from the Load Parameters screen) cooling design data are modified for that particular run. The dry bulbsare multiplied by the ratio, DBRAT, defined below:

DBRAT = (SDDB new + TCNFAC) / (SDDB old + TCNFAC)

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 10 DBRAT Ratio used to normalize Weather Library data dry bulbs to user-entered SDDB, dimensionless TR WTHR SDDB new Summer design dry bulb entered by user on the Weather Overrides screen, F [C] RF 10 SDDB old Summer design dry bulb from the Weather Library, F [C] RF 10 TCNFAC Absolute temperature conversion constant = 459.67, [273.15]

The relative humidity profiles (and thus the wet bulbs and humidity ratios) are modified by normalizing the previous values of humidityratio by basing it on the new coincident SDDB/SDWB, i.e.,

If SDRH old > SDRH new Then RHRAT = (SDRH old - SDRH new) / SDRH old Else RHRAT = (SDRH new - SDRH old) / (100 - SDRH old)

For hourly values,

If SDRH old > SDRH new Then RH t,new = RHt,old - RHRAT * RH t,old Else RH t,new = RHt,old + RHRAT * (100 - RH t,old)

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 11 RHRAT Relative humidity normalizing ratio, decimal EQ 11 RH t,new New hourly value of relative humidity, % EQ 11 RH t,old Hourly values relative humidity from the Weather Library, % RF 11 SDRH old Summer design relative humidity; a function of SDWB old, SDDB old, and DOAPS, % RF 11 SDRH new Summer design relative humidity; a function of SDWB new, SDDB new, and DOAPS, %

Ref #12. Winter Design Dry Bulb

7The winter design dry bulb, WDDB, is echoed from the Weather Library unless overridden by user entry on the Weather Overridesscreen. The winter design dry bulb is used in the design of the heating coils and heating-only fans.

Ref #13, 14. Summer/Winter Ground Reflectance

The summer and winter ground reflectance numbers will default to 0.2 unless overridden by user entry on the Weather Overrides screen.For northern latitudes the "summer" clearness number is applied to the months May through September and the "winter" clearnessnumber to months October through April. For southern latitudes the periods switch. The summer and winter period can be changed byuser entry on the Load Parameters screen.

The ground reflectance, RGRND, is a direct multiplier on the direct component of solar radiation and represents the additional amount ofdirect solar reflected from the ground onto a vertical wall. A horizontal roof will receive no ground reflected radiation. A tilted wall orroof will receive an amount proportional to RGRND x cosine(90 deg - tilt angle).

Ref #15. Air Density

The density of moist air, AIRDEN, is the ratio of the total mass to the total volume, that is,

(Ma + Mw) 1 + SAW/CWRT C1 x (1 + SAW/CWRT) (DOAPS - PW) AIRDEN = --------- = ------------ = -------------------------------- V v Ra x (SADB + C2)

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 15 AIRDEN Supply air density, lbm/ft 3 [kg/m 3] RF 15 CWRT Humidity ratio conversion constant = 7000 [1], grains/(lbm/lbm) RF 15 C1 Conversion constant = 70.72 [1000], lbf/ft 2/in.H20 [N/m/kPa] RF 15 C2 Absolute temperature conversion constant = 459.6 [273.15], R [K] RF 7 DOAPS Barometric pressure, in.Hg [kPa] RF 15 Ma Mass of dry air within a given moist air volume, lbm [kg] RF 15 Mw Mass of water vapor within a given moist air volume, lbm [kg] RF 15 PW Partial pressure of moist air, in.Hg [kPa] RF 15 Ra Gas constant for dry air Equals 53.352 [287.05], ft-lbf/lbm-R [N-m/kg-C] SAW Supply air humidity ratio, grains SADB Supply air dry bulb, F [C] RF 15 V Total volume of moist air, ft 3 [m3] RF 15 v Moist air specific volume, ft 3/lbm dry air [m 3/kg dry air]

For calculation purposes, the air density is determined assuming SADB = 59 F [15 C] and SAW = 70 grains.

Ref #16. Air Specific Heat

The specific heat of moist air, CPAIR, is given by:

CPAIR = CPDRY + (CPWET x SAW) / CWRT

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 16 CPAIR Specific heat of moist air, Btu/lbm-F [kJ/kg-C] RF 16 CPDRY Specific heat of dry air = 0.24 Btu/(lbm-F) [1.0 kJ/(kg-C)] RF 16 CPWET Specific heat of water vapor = 0.444 Btu/(lbm-F) [1.805 kJ/(kg-C)] RF 16 CWRT Humidity ratio conversion constant = 7000 [1], grains/(lbm/lbm) RF 15 SAW Supply air humidity ratio, grains

8Ref #17. Density-Specific Heat Product

The Density-Specific Heat Product K, is a useful constant used in airflow and sensible energy calculations:

K = AIRDEN * CPAIR * CONVFC

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 15 AIRDEN Supply air density, lbm/ft 3 [kg/cu m] RF 17 CONVFC Conversion factor = 60 [1000], min/hr [J/kJ] EQ 16 CPAIR Specific heat of moist air, Btu/lbm-F [kJ/kg-C] EQ 17 K Density-specific heat product, Btu-min/(hr-ft 3-F) [J/(m 3-C)]

Ref #18, 19. Enthalpy Factor / Latent Heat Factor

The enthalpy factor, HFAC, and the latent heat factor, LFAC, are useful constants used in airflow and energy calculations.

HFAC = AIRDEN * CONVFC

LFAC = AIRDEN * HFG * CONVFC

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 15 AIRDEN Air density, lbm/ft 3 [kg/m 3] RF 17 CONVFC Conversion factor = 60 min/hr [1000 J/kJ] EQ 19 HFAC Enthalpy factor, lbm-min/(hr-ft 3) [J-kg/(kJ-m 3)] RF 19 HFG Energy content of 50% relative humidity water vapor at 75 F [24 C] less the energy content of water at 50 F [10 C] = 1076 Btu/lbm [2503 kJ/kg] RF 18 LFAC Latent heat factor, Btu-min/(hr-lbm-ft 3) [J/m 3]

Ref #20. Design Simulation Period

The design simulation period will default to months June through November unless overridden by user entry on the Load Parametersscreen. The program will calculate the building design cooling loads for the period using the design cooling weather days from theWeather Library. (Also see Reference's 10 and 11 for the effect of overriding the summer design dry bulb and wet bulb.)

Ref #22. Cooling Load Methodology

The cooling load methodology is selected by the user on the Load Parameters screen. For descriptions of the available Cooling LoadMethodologies, refer to the online Help or the TRACE 600 Engineering Manual (TRCE-UM-602.)

Ref #23. Heating Load Methodology

The heating load methodology is selected by the user on the Load Parameters screen. For descriptions of the available Heating LoadMethodologies, refer to the online Help or the TRACE 600 Engineering Manual (TRCE-UM-602.)

92.1.2 CHECKSUMS

A checksums report is created for every room, zone, and system defined for the project. This report is a single page overview of thecooling/heating loads and design information, including: cooling and heating space and coil peak loads, coil selection criteria, designairflows, engineering checks and design temperatures.

Note: For accurate design information, use the report at the same level as the component of interest. For example, if you want the designinformation for a room level heating coil, such as in a VAV box, refer to the Room Checksums report for that room.

System Type acronyms are listed with the accompanying description in Appendix A of this manual.

The Checksums report is divided into nine sections as follows:

Ref #53a. Cooling Coil Peak

This section summarizes the load components comprising the main cooling coil capacity as defined by the "Time of Coil Peak" resultsfrom the Peak Cooling Loads, Internal Loads, Building Envelope Loads, Airflow Loads, and Heat Gain/Loss reports. If the main coolingcoil sizing method is BLOCK or BLK-INT the Block Totals of the various reports are used; otherwise, the Peak Totals are used.

This section includes all load components at the time of the cooling coil peak regardless if those components were used in the calculationof cooling capacity; therefore, the sensible plus latent total may or may not match the main cooling coil capacity. For example, if the maincooling coil has been sized as SKIN, the internal loads are still printed out even though they were not used to size the cooling coil.

Ref #53b. Cooling Space Peak

This section summarizes the load components used to size the main cooling fan as defined by the "Time of Space Peak" results from thePeak Cooling Loads, Internal Loads, Building Envelope Loads, Airflow Loads, and Heat Gain/Loss reports. If the main cooling fan sizingmethod is BLOCK or BLK-INT the Block Totals of the various reports are used; otherwise, the Peak Totals are used.

This section includes all load components at the time of the cooling space peak regardless if those components were used in the calculationof fan size; therefore, the space sensible total may or may not match the value used to calculate fan size. For example, if the main coolingfan has been sized as SKIN, the internal loads are still printed out even though they were not used to size the main cooling fan.

Ref #53c. Heating Coil Peak

Column "Space Sensible": This section summarizes the load components used to size the main heating fan as defined by the "Time ofSpace Peak" results from the Peak Heating Loads, Internal Loads, Building Envelope Loads, Airflow Loads, and Heat Gain/Loss reports.If the main heating fan sizing method is BLOCK or BLK-INT the System Block Totals of the various reports are used; otherwise, thePeak Totals are used. (NOTE: all pre-built system types except induction assume PEAK.) This section includes all load components at thetime of the heating space peak regardless if those components were used in the calculation of fan size; therefore, the space sensible totalmay or may not match the value used to calculate fan size. For example, if the main heating fan has been sized as SKIN, the internal loadsare still printed out even though they were not used to size the main heating fan.

Column "Sensible Total": This section summarizes most of the main heating coil load components as defined by the "Time of Coil Peak"results from the Peak Heating Loads, Internal Loads, Building Envelope Loads, Airflow Loads, and Heat Gain/Loss reports. Note,however, that although these components are used to help size the main heating coil, the actual heating coil capacity is also a function ofthe heating coil location with respect to the preheat coil, i.e., the preheat coil is assumed to meet part or all of the return air and ventilationload components, depending on the design preheat coil leaving temperature. For any system types that have heating coils located at thezone or system level, the design heating coil temperature will automatically be sized to handle the worst case heating zone (or room)which may lead to oversizing. This is typically good design practice except for those instances in which 1) either the heating airflow or coiltemperature can be cycled to meet the load or 2) if air leakage between zones (or rooms) prevents temperature stratification between of theexistence of "air" walls or large doorways. To prevent oversizing for these special cases the Main Heating Coil Capacity can be user-defined as No Oversizing on the Create Systems - Heating Overrides screen.

Ref #53d. Cooling Coil Selection

For the convenience of the user, coil selection values can be printed for the room, zone, and system level even though the affected coilmay exist at only one of those levels. For example, a shutoff-VAV system has a single cooling coil located at the system level while a fancoil system has a coil located in each room. Only use the selection values that correspond to the coil level location; other values may beinappropriate as sum-totals or averages.

The three possible cooling coils are: Main Cooling, Auxiliary Cooling, and Optional Ventilation Cooling. Typically, only the main coolingcoil parameters are printed out.

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Main Cooling: See Ref #33 for a description of the associated coil selection parameters. Note that if the system type was a heating-onlysystem such as UV or RAD, the main cooling coil selection parameters will print out zeroes.

Auxiliary Cooling: See Ref #34 for a description of the associated coil selection parameters. However, none of the pre-built system typeshave an auxiliary cooling coil unless the user adds one by user entry on the Create Systems - Cooling Overrides screen).

Optional Ventilation Cooling: See Ref #35 for a description of the associated coil selection parameters. The optional ventilation coolingcoil line will print out zeroes unless a value is entered for SADBvc on the Create Systems - Options screen.

NOTE: When using these values in conjunction with a coil selection program, only use the capacity, coil airflow, and entering coilconditions. Do NOT use the estimated coil leaving values as these will vary depending on the type of coil selected.

Ref #53e. Areas

Floor: See Ref #186.

Partition: See Ref #187.

Exposed Floor: See Ref #188.

Roof (non-glass, glass, %glass): See Ref's 191, 189, and 190 respectively.

Wall (non-glass, glass, %glass): See Ref's 194, 192, and 193 respectively.

Ref #53f. Heating Coil Selection

The six possible heating coils are: Main Heating, Auxiliary Heating, Preheat, Reheat, Humidification, and Optional Ventilation Heating.Typically, only the main heating and preheat coils will print out non-zero values.

Main Heating: Note that if the system type uses radiation heating such as BPVAV, VAV or RAD, the entering and leaving coil selectionparameters will print out as zeroes. Except for the most basic systems (such as RAD), the main heating coil capacity is notsimply a sum of the heating load components printed under the Heating Coil Peak section of this report. If a preheat coil exists,it is assumed to handle some or all of the return air and ventilation components. Mixing systems with an economizer are sized tohandle the extra "reheat" load of the economizer air. (Also see the text for HEATING COIL PEAK above.) See Ref's #37 and#79 for a description of the associated coil selection parameters.

Auxiliary Heating: See Ref #34 for a description of the associated coil selection parameters. Only the system types VAVBSK andVAVFSK have an auxiliary heating coil unless the user adds one by user entry on the Create Systems - Heating Overridesscreen.

Preheat: Not all systems have preheat coils. For some systems the preheat and main heating coil are combined (i.e., they are one and thesame coil). If a preheat coil exists, it is assumed to handle some or all of the return air and ventilation components. See Ref #39for a description of the associated coil selection parameters.

Reheat: Not all systems have reheat coils. For some systems the reheat and main heating coil are combined (i.e., they are one and the samecoil). See Ref's #40 and #138 for a description of the associated coil selection parameters. Note that both VAV and BPVAVhave reheat coils located in the room (as baseboard radiation) while systems VRH and BPVRH have reheat coil located in eachroom's terminal box.

Humidification: This coil size defaults to zero unless the user explicitly enters a value for Minimum Room Relative Humidity on theCreate Systems - Design Temperatures screen. See Ref's #41 and #140 for a description of the associated coil selectionparameters. Note that the humidification capacity is a direct function of the heating infiltration and ventilation airflows; if bothof these quantities are zero for heating design, the humidification coil will be set to zero capacity regardless of the value enteredfor Minimum Room Relative Humidity. Another common error occurs when the calculated value for Design Room RelativeHumidity (entered on the Create Rooms - Rooms screen) is overridden by the Psychrometric algorithm and is lower than theMinimum Room Relative Humidity value. In this case, the Humidity Ratio Difference should also be entered on the CreateSystems - Design Temperatures screen. NOTE: THE ENTERING AND LEAVING CONDITIONS LISTED HERE ARE INTERMS OF GRAINS, NOT TEMPERATURES!

Optional Ventilation Heating: See Ref's #42 and #136 for a description of the associated coil selection parameters. The optional ventilationcooling coil line will print out zeroes unless a value is entered for SADBvh on the Create Systems - Options screen.

SUGGESTION: When using these values in conjunction with a coil selection program, only use the capacity, coil airflow, and enteringcoil conditions. Do NOT use the estimated coil leaving values as these will vary depending on the type of coil selected. For the case wherethe main heating and preheat coils are combined (i.e., they are one and the same coil), sum the two capacities to arrive at the actual

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combined capacity, the entering condition will equal the preheat coil entering condition while the leaving condition will equal the mainheating coil leaving condition.

Ref #53g. Airflows

Ventilation: This is the ventilation airflow at the time of the space peak. See Ref's #26, #123, and #133.

Infiltration: This is the infiltration airflow at the time of the space peak. See Ref #119.

Supply: This represents the design supply airflow used to size the main supply fan. See Ref's #27, #28, #58 and #72.

Mincfm: MINCFM represents the minimum operating supply airflow. The terminal box "minimum stop" (or "reheat minimum") nominalsetpoint is set equal to the larger of the two values. This value is used by system types with variable airflow to the space (i.e.,VAV, VAVBSK, VAVFSK, VRH, BPVAV, BPVRH, PFPVAV, PFPVAVRA, SFPVAV, 2FDDVV, DDVAV). For theterminal reheat system, TRH, the reheat minimum is set equal to 100% of design supply airflow.

Return: This represents the design airflow used to size the return fan. See Ref #29.

Exhaust: This represents the design airflow used to size the main exhaust fan. See Ref #30.

Room Exhaust: This represents the design airflow used to size the room exhaust fan. See Ref #32.

Auxiliary: This represents the design supply airflow used to size the auxiliary fan, if it exists.

Ref #53h. Engineering Checks

Capacity values are taken from Ref's #53d/#53f and airflows from Ref #53g. Any auxiliary coil/airflow is ignored. Also see Ref's #44-50.

Clg % OA: (Cooling Ventilation) / (Design Cooling Supply Airflow) x 100

Clg Cfm/Sqft: (Design Cooling Supply Airflow) / (Floor Area)

Clg Cfm/Ton: (Design Cooling Supply Airflow) / (Main Clg Cap + Opt Vent Clg Cap)

Clg Sqft/Ton: (Floor Area) / (Main Clg Cap + Opt Vent Clg Cap)

Number of People: from time of cooling space peak. See Ref #83.

Htg % OA: (Heating Ventilation) / (Design Heating Supply Airflow) x 100

Htg Cfm/Sqft: (Design Heating Supply Airflow) / (Floor Area)

Htg Btuh/Sqft: (Main Htg Cap + Opt Vent Htg Cap) / (Floor Area) x 1000.

Ref #53i. Temperatures, F [C]

SADB: design supply air dry bulbs used to size the fan supply airflow (from time of space peak). See Ref's #57 and #71.

Plenum (PLENDB) : Plenum temperature from time of coil peak. See Ref #91. If no plenum exists, PLENDB is set equal to the designroom cooling/heating dry bulb.

Return (RADBT) : Return air temperature from time of coil peak. See Ref #153.

Ret/OA (ROADB) : Return/outside air mixture temperature from time of coil peak. See Ref #159 for similar type calculation.

Runaround (RRDB) : Runaround temperature from time of coil peak. Typically equal to plenum temperature. Only relevant for TAB,PFPVAV, PFPVAVRA, SFPVAV, and 2FDDVV system types. See Ref #151.

FnMtrTD (MTRTD) : Main fan motor heat temperature difference. See Ref #160.

FnBldTD (BLDTD) : Main fan blade heat temperature difference. See Ref #160.

FnFrict (FDUCTD) : Main fan duct friction heat due to airstream kinetic energy translation. See Ref #160.

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2.2.1 DESIGN AIRFLOW QUANTITIES

This report lists design airflow quantities for the applicable fans in each system each calculated at its worst case condition ( sum-of-peaks or block). NOTE: These airflows may not necessarily be occurring at the same month and hour

System Type acronyms are listed with the accompanying description in Appendix A of this manual.

Ref #26. Outside Airflow (Main System)

Outside Airflow is a function of user entry on the Create Rooms - Single Sheet or Create Rooms - Airflows screens. The nominal value ofventilation airflow is given by:

OANOM = OAVAL * CONV air * PCTOA t

Ref# Variable Description -------- ------------- ----------------------------------------------- TB 2.2 CONV air Airflow conversion factor EQ 26 OANOM Nominal value of outside air this hour, cfm [cms] TR OACF OAUNIT Outside air unit TR OACF OAVAL Outside air value TR LSCH PCTOA t Scheduled percent of outside airflow from time of peak space cooling load sub-report or peak space heating sub-report. The larger of the two percents is used.

A value of zero can occur for any of the following reasons:

-- Units of air changes/hr have been specified but the floor-to-ceiling height and/or floor area is zero.-- The value of Ventilation air is equal to zero on the Create Rooms - Single Sheet or Create Rooms - Airflows screens.-- Units of airflow/person have been specified but the number of people for this system is zero.-- Units of % of room supply air have been specified but the supply airflow is zero.-- The ventilation schedule reads 0% for either the cooling and/or heating design period.

Table 2.2 Airflow Conversion Factors1Conversion Factor, CONV air

Units Acronym Description English SIACH-HR air chgs/hr VOLUME/60 VOLUME/1CFM ft3/min 1.0 1/2118CFM-P cfm/person NPEOP NPEOP/2118CFM-SF cfm/ft 2 AREAfl AREAfl/196.8M3\S m3/sec 2118 1.0M3\SPERS cms/person NPEOP*2118 NPEOPM3\SM2 cms/m2 AREAfl*196.8 AREAflPCT-MCLG % Main CFMC CFMC/100 CFMC/100PCT-MHTG % Main CFMH CFMH/100 CFMH/1001VOLUME = (FLFLHT - PLENHT) * AREAfl AREA = AREAfl; if airflow is infiltration AREA = AREAWT

Ref #27. Cooling Supply Airflow (Main System)

The Main Cooling Supply Airflow is taken from the Main System Peak Cooling Loads report. See Ref #58.

Ref #28. The Heating Supply Airflow (Main System)

The Main Heating Supply Airflow is taken from the Main System Peak Heating Loads report. See Ref #72.

Ref #29. Return Airflow (Main System)

The design main return airflow quantity will depend on the Return Fan Sizing Method defined by the System Library.

If (FNSIZE r = BALANCE) Then DSRACF = RACFMT c

If (FNSIZE r = SAME-CF) Then DSRACF = DSCFM c

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If (FNSIZE r = NO-FAN) Then DSRACF = 0

If (DSRACF < DSEXCF) Then DSRACF = DSEXCF

Ref# Variable Description -------- ------------- ----------------------------------------------- RF 30 BALANCE Acronym indicating that the return fan will be sized such that the system is in balance EQ 27 DSCFM c Design main cooling airflow, cfm [cms] EQ 30 DSEXCF Design system exhaust airflow, cfm [cms] EQ 29 DSRACF Design return airflow, cfm [cms] RF 29 FNSIZE r Return fan sizing Method (Default = BALANCE) RF 29 NO-FAN Acronym indicating that no return fan exists EQ 153 RACFMT c Total return airflow just prior to the main exhaust (at time of main cooling space peak), cfm [cms] RF 29 SAME-CF Acronym indicating that return fan size will equal the main cooling fan size

Ref #30. Exhaust Airflow (Main System)

The design main exhaust airflow quantity will depend on the Main Exhaust Fan Sizing Method defined by the System Library.

If (FNSIZE sx = BALANCE) Then DSEXCF = SYEXCF c

If (FNSIZE sx = SAME-CF) Then DSEXCF = DSCFM c

If (FNSIZE sx = SAME-HF) Then DSEXCF = DSCFM h

If (FNSIZE sx = OA-ONLY) Then DSEXCF = DSOACF + DSINCF

If (FNSIZE sx = OA-OR-CF) Then If (ECOTYP NONE) DSEXCF = DSCFM c * (OAMAX / 100.) If (ECOTYP = NONE) DSEXCF = DSOACF + DSINCF

If (FNSIZE sx = NO-FAN) Then DSEXCF = 0

Ref# Variable Description -------- ------------- ----------------------------------------------- RF 30 BALANCE Acronym indicating that the main exhaust fan will be sized such that the system is in balance EQ 30 DSEXCF Design system exhaust airflow, cfm [cms] EQ 27 DSCFM c Design main cooling airflow, cfm [cms] EQ 28 DSCFM h Design main heating airflow, cfm [cms] EQ 119 DSINCF Design infiltration airflow, cfm [cms] EQ 26 DSOACF Design outside air (ventilation) airflow, cfm [cms] TR SOPT ECOTYP Economizer type RF 30 FNSIZE sx Main exhaust fan sizing method (Default = OA-OR-CF) RF 30 NO-FAN Acronym indicating that no fan exists RF 30 NONE Acronym indicating that there is no economizer for this system TR SOPT OAMAX Maximum percent of design cooling airflow avail- able during economizer mode RF 30 OA-ONLY Acronym indicating that fan size is to equal the design ventilation airflow RF 30 OA-OR-CF Acronym indicating that fan size is equal to the design ventilation airflow is no economizer has been specified; otherwise, the fan size is equal to the design main cooling fan airflow RF 30 SAME-CF Acronym indicating that fan size is equal to the main cooling fan size RF 30 SAME-HF Acronym indicating that fan size is equal to the main heating fan size EQ 147 SYEXCF c Value of system exhaust airflow needed to

15

balance the system at the time of the main cooling space peak, cfm [cms]

Ref #31. Auxiliary System Supply Airflow

Typically, this value will be zero except for system types VAVFSK, VAVBSK, IND, and INDFP.

The design auxiliary airflow during the cooling mode is equal to the auxiliary cooling supply airflow at the time of the auxiliary coolingspace peak.

DSCFM ac = DSFNCF ac

The design auxiliary airflow during the heating mode is equal to the auxiliary heating supply airflow at the time of the auxiliary heatingspace peak.

DSCFM ah = DSFNCF ah

The design auxiliary fan airflow quantity will depend on the Auxiliary Fan Sizing Method defined by the System Library.

If (FNSIZE ax = SAME-ACC) Then DSCFM ax = DSCFM ac

If (FNSIZE ax = SAME-ACH) Then DSCFM ax = DSCFM ah

If (FNSIZE ax = LARGEST) Then If (DSCFM ah > DSCFM ac) DSCFM ax = DSCFM ah If (DSCFM ac DSCFM ah) DSCFM ax = DSCFM ac

If (FNSIZE ax = NO-FAN) Then DSCFM ax = 0

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 65 DSCFM ac Design auxiliary airflow during the cooling mode, cfm [cms] EQ 31 DSCFM ah Design auxiliary airflow during the heating mode cfm [cms] EQ 31 DSCFM ax Design auxiliary fan airflow TB 2.3 FNSIZE ax Auxiliary fan sizing method RF 31 LARGEST Acronym indicating that auxiliary fan is to be sized according to the larger of the auxiliary heating and cooling coil sizing methods RF 31 NO-FAN Acronym indicating that no fan exists RF 31 SAME-ACC Acronym indicating that the auxiliary fan size is equal to the design auxiliary cooling airflow RF 31 SAME-AHC Acronym indicating that the auxiliary fan size is equal to the design auxiliary heating airflow

Table 2.3 Auxiliary Fan CharacteristicsSystem Type Sizing Method Level Location Deck Location Fan ConfigBPVAV LARGEST ROOM RM-WALL BLOWBPVRH LARGEST ROOM RM-WALL BLOWBPMZ LARGEST ROOM RM-WALL BLOWCOMP LARGEST ROOM RM-WALL BLOWDD LARGEST ROOM RM-WALL BLOWDDVAV LARGEST ROOM RM-WALL BLOWFC LARGEST ROOM RM-WALL BLOWINCHP LARGEST ROOM RM-WALL BLOW1IND LARGEST ROOM RM-WALL BLOW1INDFP LARGEST ROOM RM-WALL BLOWMZ LARGEST ROOM RM-WALL BLOWPFPVAV LARGEST ROOM RM-WALL BLOW

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PFPVAVRA LARGEST ROOM RM-WALL BLOWPTAC LARGEST ROOM RM-WALL BLOWRAD LARGEST ROOM RM-WALL BLOWRTMZ LARGEST ROOM RM-WALL BLOWSFPVAV LARGEST ROOM RM-WALL BLOWSZ LARGEST ROOM RM-WALL BLOWTAB LARGEST ROOM RM-WALL BLOWTRH LARGEST ROOM RM-WALL BLOW2FDDVV LARGEST ROOM RM-WALL BLOWUV LARGEST ROOM RM-WALL BLOWVAV LARGEST ROOM RM-WALL BLOWVAVBSK LARGEST ROOM RM-WALL BLOW2VAVFSK LARGEST ROOM RM-WALL BLOWVRH LARGEST ROOM RM-WALL BLOWVTCV LARGEST ROOM RM-WALL BLOWWSHP LARGEST ROOM RM-WALL BLOW1Used to size the induced (secondary) airflow2Only this system will automatically size an auxiliary fan. It is optional for all other system types.

Ref #32. Room Exhaust Airflow

The design room exhaust airflow quantity will depend on the Room Exhaust Fan Sizing Method defined by the System Library.

If (FNSIZE rx = AS-INPUT) Then If (PCT rx,c > PCT rx,h) DSRXCF = RMEXVL * CONV air * (PCT rx,c / 100) If (PCT rx,h > PCT rx,c) DSRXCF = RMEXVL * CONV air * (PCT rx,h / 100)

If (FNSIZE rx = NO-FAN) Then DSRXCF = 0

Ref# Variable Description -------- ------------- ----------------------------------------------- RF 32 AS-INPUT Acronym indicating that the design room exhaust & EQ 27 airflow is equal to the value calculated at the time of the main cooling space peak as entered by the user TB 2.2 CONV air Airflow conversion constant EQ 32 DSRXCF Design room exhaust fan airflow, cfm [cms] TB 2.3 FNSIZE rx Room exhaust fan sizing method (Default = AS-INPUT) RF 32 NO-FAN Acronym indicating that no fan exists TR LSCH PCT rx,c Room exhaust percent utilization at time of main cooling coil peak, % TR LSCH PCT rx,h Room exhaust percent utilization at time of main heating coil peak, %

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2.2.2 DESIGN CAPACITY QUANTITIES

This report identifies design coil capacities for the applicable coils in each system each calculated at its worst case condition(sum-of-peaks or block). It also displays the block load for the entire building.

System Type acronyms are listed with the accompanying description in Appendix A of this manual.

Ref #33. Main Cooling Coil Capacity

The main cooling coil capacity is based on the coil sensible and coil latent components as printed in the Main System Peak Cooling Loadsreport, i.e.,

QCAP c = (QSENS cl,c + QLAT cl,c) / CONST

Ref# Variable Description -------- ------------- ------------------------------------------------------- RF 33 CONST Units conversion constant = 12,000 Btuh/ton [1000 W/kW] EQ 33 QCAP c Main cooling coil capacity, tons [kW] EQ 67 QLAT cl,c Main cooling coil latent component at time of coil peak, Btu/hr [W] EQ 66 QSENS cl,c Main cooling coil sensible component at time of coil peak, Btu/hr [W]

If the user has overridden this calculated value by user entry on the Create Systems - Cooling Overrides screen, the user-entered value isprinted here.

The coil airflow at the time of the coil peak, COILCF c, will also depend on the type of system as discussed by Ref #65.

The coil entering condition is a function of the return/outside condition at the time of the main cooling coil peak and is printed in theChecksums report.

CEDB c = ROADB c + CETD c

CEW c = DSRMW c

CEH c = (CEW c/CWRT) * (CPWET*CEDB c + HCONST) + CPDRY*CEDB c

The coil leaving dry bulb is equal to the cooling supply air temperature at the time of the coil peak minus the fan heat component whichoccurs downstream of the cooling coil:

CLDB c = SADB c - CLTD c

The approximate coil leaving humidity ratio is found by solving for CLWc in the enthalpy equation:

CLH c = (CLW c/CWRT) * (CPWET*CLDB c + HCONST) + CPDRY*CLDB c

CLW c = [(CLH c - CPDRY*CLDB c) / (CPWET*CLDB c + HCONST)] * CWRT

Ref# Variable Description -------- ------------- ------------------------------------------------------- RF 53d CEDB c Main cooling coil entering dry bulb, F [C] RF 33 CEH c Main cooling coil entering enthalpy, Btu/lbm [kJ/kg] RF 160 CETD c Temperature increase prior to coil due to supply fan heat, F [C] RF 53d CEW c Coil entering humidity ratio, grains [kg/kg] RF 53d CLDB c Coil leaving dry bulb at time of main cooling coil peak, F [C] RF 33 CLH c Main cooling coil leaving enthalpy, Btu/lbm [kJ/kg] RF 160 CLTD c Temperature increase due to fan heat after air leaves coil, F [C] RF 53d CLW c Coil leaving humidity ratio, grains [kg/kg] RF 33 CPDRY Specific heat of dry air = 0.24 Btu/(lbm-F) [1.0 kJ/(kg-C)] RF 33 CPWET Specific heat of water vapor = 0.444 Btu/(lbm-F) [1.805 kJ/(kg-C)] RF 33 CWRT Humidity ratio conversion constant = 7000 [1], grains/(lbm/lbm)

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RF 33 HCONST Enthalpy constant = 1061 Btu/lbm [2468 kJ/kg] RF 154d DSRMW c Design room humidity ratio at time of the main cooling space peak, lbm/lbm [kg/kg] RF 53i ROADB c Return/outside air mixture dry bulb at time of main cooling coil peak, F [C] RF 53i SADB c Cold deck supply air temperature at time of coil peak, F [C]

Ref #34. Auxiliary Cooling Coil Capacity

This value will normally be zero since only two of the standard system types (IND and INDFP) use an auxiliary cooling coil.

The auxiliary cooling coil capacity for a particular system is a function of the coil sizing method. For example, if the sizing method isdefined as SKIN, the system cooling capacity will be the sum of the room-level cooling capacities of the room assigned to that system.The nominal cooling capacity is taken from the Auxiliary System Peak Cooling Loads report by adding the auxiliary coil's sensible andlatent components, i.e.,

QCAP ac = (QSENS cl,ac + QLAT cl,ac) / CONST

Ref# Variable Description -------- ------------- ----------------------------------------------- RF 33 CONST Units conversion constant = 12,000 Btuh/ton [1000 W/kW] EQ 34 QCAP ac Auxiliary cooling coil capacity, Btu/hr [kW] EQ 67 QLAT cl,ac Auxiliary cooling coil latent component, Btu/hr [W] EQ 66 QSENS cl,ac Auxiliary cooling coil sensible component, Btu/hr [W]

If the user has overridden this calculated value by user entry to the Create Systems - Cooling Overrides screen, the user-entered value isprinted here.

The coil entering condition is a function of the room condition at the time of the coil peak.

CEDB ac = DSRMDB c + CETD ac

CEW ac = DSRMW ac

CEH ac = CEW ac * (CPWET*CEDB ac + HCONST) + CPDRY * CEDB ac

The coil leaving dry bulb is equal to the cooling supply air temperature at the time of the coil peak minus the fan heat component whichoccurs downstream of the cooling coil:

CLDB ac = SADB ac - CLTD ac

The approximate coil leaving humidity ratio is found by solving for CLWac in the enthalpy equation:

CLH ac = CLW ac * (CPWET*CLDB ac + HCONST) + CPDRY * CLDB ac

CLW ac = (CLH ac - CPDRY*CLDB ac) / (CPWET*CLDB ac + HCONST)

Ref# Variable Description -------- ------------- ----------------------------------------------- RF 53d CEDB ac Auxiliary cooling coil entering dry bulb, F [C] RF 34 CEH ac Auxiliary cooling coil entering enthalpy, Btu/lbm [kJ/kg] RF 160 CETD ac Temperature increase prior to coil due to supply fan heat, F [C] RF 53d CEW ac Auxiliary coil entering humidity ratio, grains [kg/kg] RF 53d CLDB ac Auxiliary coil leaving dry bulb, F [C] RF 34 CLH ac Auxiliary cooling coil leaving enthalpy, Btu/lbm [kJ/kg] RF 160 CLTD ac Temperature increase due to fan heat after air leaves coil, F [C] RF 53d CLW ac Coil leaving humidity ratio, grains [kg/kg] RF 34 CPDRY Specific heat of dry air = 0.24 Btu/(lbm-F) [1.0 kJ/(kg-C)]

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RF 34 CPWET Specific heat of water vapor = 0.444 Btu/(lbm-F) [1.805 kJ/(kg-C)] RF 34 CWRT Humidity ratio conversion constant = 7000 [1], grains/(lbm/lbm) RF 154d DSRMW ac Design room humidity ratio at time of auxiliary cooling space peak, grains [kg/kg] RF 34 HCONST Enthalpy constant = 1061 Btu/lbm [2468 kJ/kg] RF 34 ROADB ac Return/outside air mixture dry bulb at time of auxiliary coil peak, F [C] RF 64 SADB ac Cold deck supply air temperature at time of auxiliary coil peak, F [C]

Ref #35. Optional Ventilation Cooling Coil Capacity

The outside air condition at the time of the optional ventilation cooling coil peak is always going to equal the summer design point,SDDB/SDWB. The summer design point defaults to the values found in the Weather Library unless overridden by user entry on theWeather Overrides screen.

The coil entering and leaving conditions will depend on the location of the optional ventilation fan with respect to the coil bank, i.e.,

CEDB vc = SDDB + CETD ov

CEW vc = f(SDDB, SDWB)

CEH vc = (CEW vc/CWRT) * (CPWET*CEDB vc + HCONST) + CPDRY * CEDB vc

CLDB vc = SADB vc - CLTD ov

The coil leaving humidity ratio is found by following the coil curve from the coil entering point, CEDBvc/CEWvc, to the coil leavingdry bulb, CLDBvc.

CLW vc = f(CEDB vc, CEWvc, CLDB vc)

The corresponding coil leaving enthalpy is then given by:

CLH vc = (CLW vc/CWRT) * (CPWET * CLDB vc + HCONST) + CPDRY * CLDB vc

The design airflow through the optional ventilation coil is equal to the design value of outside airflow, but only if the optional ventilationcooling coil has been scheduled on during the time of the main cooling space peak.

COILCF vc = DSOACF

The nominal capacity of the coil is a function of the enthalpy difference between the entering and leaving airstreams:

QCAP vc = HFAC * COILCF vc * (CEH vc - CLH vc) / CONST

Ref# Variable Description -------- ------------- ----------------------------------------------- RF 53d CEDB vc Optional ventilation cooling coil entering dry bulb, F [C] EQ 35 CEH vc Auxiliary cooling coil entering enthalpy, Btu/lbm [kJ/kg] RF 35 CETD ov Temperature increase prior to coil due to supply fan heat (also see Ref #160), F [C] RF 53d CEW vc Optional ventilation cooling coil entering humidity ratio, grains EQ 53d CLDB vc Optional ventilation cooling coil leaving dry bulb, F [C] EQ 35 CLH vc Auxiliary cooling coil leaving enthalpy, Btu/lbm [kJ/kg] RF 35 CLTD ov Temperature increase due to fan heat after air leaves coil (also see Ref #160), F [C] RF 53d CLW vc Optional ventilation cooling coil leaving humidity ratio, grains RF 53d COILCF vc Optional ventilation cooling coil airflow cfm, [cms]

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RF 33 CONST Units conversion constant = 12,000 Btuh/ton [1000 W/kW] RF 16 CPDRY Specific heat of dry air = 0.24 Btu/(lbm-F) [1.0 kJ/(kg-C)] RF 16 CPWET Specific heat of water vapor = 0.444 Btu/(lbm-F) [1.805 kJ/(kg-C)] RF 35 CWRT Humidity ratio conversion constant = 7000 [1], grains/(lbm/lbm) EQ 26 DSOACF Design outside air (ventilation) airflow, cfm [cms] RF 35 HCONST Enthalpy constant = 1061 Btu/lbm [2468 kJ/kg] EQ 18 HFAC Enthalpy factor, lbm-min/(hr-ft 3) [J-kg/(kJ-m 3)] EQ 17 K Density-specific heat product, Btu-min/(hr-ft 3-F) [J/(m 3-C)] EQ 35 QCAP vc Optional ventilation cooling coil capacity, Btu/hr [W] TR STYP SADB vc Optional ventilation cooling coil design supply air dry bulb, F [C] RF 10 SDDB Summer design dry bulb from Weather Library, F [C] RF 11 SDWB Summer design wet bulb from Weather Library, F [C]

Ref #36. Cooling Totals

The Total Cooling Capacity, QCAPc,tot , is the sum of all the cooling coil capacities, i.e.,

QCAP c,tot = QCAP c + QCAP ac + QCAP vc

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 36 QCAP c,tot Total cooling coil capacity, Btu/hr [W] EQ 34 QCAP ac Auxiliary cooling coil capacity, Btu/hr [W] EQ 33 QCAP c Main cooling coil capacity, Btu/hr [W] EQ 35 QCAP vc Optional ventilation cooling coil capacity, Btu/hr [W]

Ref #37. Main Heating Coil Capacity

The main heating coil capacity is taken from the Main System Peak Heating Loads report. For an explicit calculation of the main heatingcoil capacity, see Ref #79.

Regardless of whether the main heating coil also handles preheat or reheat modes, the preheat and reheat capacities are printed outseparately. Therefore, if the user is installing a single heating coil to handle both preheat and main heating modes, the user must sum thetwo printed components manually.

If the user has overridden this calculated value by user entry on the Create Systems - Heating Overrides screen, the user-entered value isprinted here.

Ref #38. Auxiliary Heating Coil Capacity

This value will typically be zero since only a few of the standard system types (e.g., IND, INDFP, VAVBSK, and VAVFSK) utilize anauxiliary heating coil.

The auxiliary heating coil can only handle room-level space heat losses and cannot be sized to handle the outside air load if ventilation isbrought through the return/outside air deck.

The auxiliary heating coil capacity is taken from the Auxiliary System Peak Heating Loads report. See Ref #79.

If the user has overridden this calculated value by user entry on the Create Systems - Heating Overrides screen, the user-entry value isprinted here.

Ref #39. Preheat Coil Capacity

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The purpose of the preheat coil is typically to prevent the downstream cooling coil from freezing. The preheat coil capacity can becombined with the main heating coil to allow a single coil to be used for both the preheat and regular modes. Only the preheat mode isdescribed in this section.

The preheat coil airflow is assumed to be equal to the return/outside airflow, ROACFM c, at the time of the main cooling space peakunless ROACFM c is zero.

COILCF ph = ROACFM c IF (ROACFM c = 0) Then COILCF ph = ROACFM h

The preheat coil entering condition is based on the return/outside air condition at the time of the main heating coil peak.

IF (SADB vh is entered and SADB vh > WDDB) Then OADB vh = SADB vh Otherwise OADB vh = WDDB

IF (CLDECK ov = ROADK) Then ROADB h = [(ROACFM c - DSOACF)*RADBT h + DSOACF*OADB vh] / ROACFM c Otherwise ROADB h = RADBT h

CEDB ph = ROADB h

The design preheat coil leaving dry bulb, CLDBph, initially defaults to the preheat minimum control point, CLDBph,min ,specified on the Create Systems - Design Temperatures screen. If CLDBph,min is not entered or is less than the preheat maximumcontrol point, CLDBph,max , the value CLDBph is set equal to CLDBph,max . If neither CLDBph,min norCLDBph,max are entered, CLDBph will default to the design economizer control point, ECOPNT.

If (CLDB ph,min was entered) Then CLDB ph = CLDB ph,min

If (CLDB ph,max was entered and CLDB ph,max > CLDB ph,min ) Then CLDB ph = CLDB ph,max

If (Neither CLDB ph,min nor CLDB ph,max was entered) Then ECOPNT = DSADB c - (DRAWTD + BLOWTD + FDUCTD c + DUCTTD) CLDB ph = ECOPNT

CLW ph = CEW ph

If the outside air dampers are located on the ROA deck, the preheat capacity will have to offset the heating load imposed on the preheatcoil by the ventilation heating load. This portion of the preheat capacity is represented by:

IF (CLDECK ov = ROADK) Then QOAPH = K * DSOACF * (OADB vh - CLDB ph) Otherwise QOAPH = 0

The return air component of the preheat coil load is given by:

QRAPH = K * (ROACFM c - DSOACF) * (RADBT h - CLDB ph)

This component (QRAPH) may be a credit (heat gain) if the return air temperature is greater than the design preheat leaving temperature.However, for VAV fan cooling systems, the return air component is not allowed to reduce the preheat coil capacity since the returnairflow may be zero during actual TRACE 600 System Simulation of heating months (e.g., when the part load cooling airflow equals thedesign ventilation airflow).

IF (CTCNTL = VAV) Then QCAP ph = QOAPH IF (QRAPH ph < 0) QCAP ph = QOAPH + QRAPH

IF (CTCNTL does not = VAV) then QCAP ph = K * COILCF ph * (CEDB ph - CLDB ph)

If the preheat coil sizing method, CLSIZE ph, has been specified as "COMBINED", the preheat coil capacity -- although printed outseparately from the main heating coil capacity -- is included in the main heating coil capacity during the TRACE 600 System Simulation.

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 160 BLOWTD Fan temperature difference in supply air stream

22

prior to the main cooling coil, F [C] RF 53f CEDB ph Preheat coil entering dry Air bulb, F [C] RF 53f CEW ph Preheat coil entering humidity ratio, grains TR SADB CLDB ph,min Minimum preheat control point, F [C] CLDB ph,max Maximum preheat control point, F [C] RF 53f CLDB ph Preheat coil leaving dry bulb, F [C] TR STYP CLDECK ov Ventilation deck location (Default = ROADK except for Systems UV and RAD which default to ROOMDK). Can also be overridden by user entry on the Create Systems - Options screen. TB 2.4 CLSIZE ph Preheat coil sizing method RF 53f CLW ph Preheat coil leaving humidity ratio, grains RF 53f COILCF ph Preheat coil airflow, cfm [cms] RF 39 COMBINED Acronym indicating that preheat coil capacity is combined with that of the main heating coil TB 2.8 CTCNTL Cooling terminal control method EQ 161 DRAWTD Fan temperature difference in supply air stream after coil, F [C] EQ 57 DSADB c Design main cold deck supply air temperature, F [C] EQ 26 DSOACF Design outside air (ventilation) airflow, cfm [cms] EQ 165f DUCTTD Supply/return duct heat gain temperature difference, F [C] EQ 39 ECOPNT Design economizer control point, F [C] EQ 162f FDUCTD c Temperature increase in the supply air due to duct friction loss, F [C] EQ 17 K Density-specific heat product, Btu-min/(hr-ft 3-F) [J/( m3-C)] RF 39 OADB vh Ventilation deck winter design temperature, F EQ 39 QCAP ph Preheat coil capacity, Btu/hr [W] EQ 39 QOAPH Ventilation portion of preheat capacity, Btu-hr(W) EQ 39 QRAPH Return air portion of preheat capacity, Btu-hr(W) EQ 153 RADBT h Return air dry bulb at time of main heating coil peak, F [C] EQ 147 ROACFM c Supply airflow routed through the return/outside deck at the time of the main cooling space peak, cfm [cms] EQ 147 ROACFM h Supply airflow routed through the return/outside deck at time of heating peak, cfm [cms] RF 53i ROADB h Return/outside air mixture dry bulb at time of main heating coil peak, F [C] EQ 39 ROADK Acronym indicating that the outside air dampers are located on the return/outside air deck just prior to the main cooling/heating coil EQ 39 ROAW h Return/outside air mixture humidity ratio at the time of the main heating coil peak, grains RF 39 VAV Acronym indicating that terminal box is to be controlled like a VAV box EQ 12 WDDB Winter design dry bulb , F [C]

A sample calculation procedure follows using the system block information from the Design Airflow Quantities, Main System PeakCooling Loads, Building Envelope Loads, and System Psychrometrics reports.

The design preheat coil airflow for a PFPVAV system is equal to the return/outside airflow at the time of the main cooling space peak, i.e.,

COILCF ph = ROACFM c = DSCFM c (see RF 27)

The outside air dampers are located on the return/outside deck, so:

ROADB h = [(ROACFM c - DSOACF) * RADBT h + DSOACF * WDDB] / ROACFM c

these values are retrieved from the following sources

= [(RF 147) - (RF 26) * (EQ 153) + (RF 26) * (RF 12)] / (RF 147)

CEDB ph = ROADB h

If neither CLDBph,min nor CLDBph,max was entered:

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ECOPNT = DSADB c - (BLOWTD + DRAWTD + FRDUCT c + DUCTTD)

these values are retrieved from the following sources

= (RF 57) - [(RF 160) + (RF 161) + (RF 162) + (RF 165)]

CLDB ph = ECOPNT

The ventilation and return air components of the preheat capacity can then be found:

QOAPH = K * DSOACF * (WDDB - CLDB ph)

these values are retrieved from the following sources

= (RF 17) * (RF 26) * [(RF 12) - (EQ 39)]

and

QRAPH = K * (ROACFM - DSOACF) * (RADBT h - CLDB ph)

these values are retrieved from the following sources

= (RF 17) * [(RF 147) - (RF 26)] * [(EQ 153) - (EQ 39)]

Since PFPVAV is a variable air volume fan system, we ignore the QRAPH component if it is positive:

QCAP ph = QOAPH

If this had been a constant volume fan system, the preheat capacity would have been reduced by the positive QRAPH component, e.g.,

QCAP ph = QOAPH + QRAPH

As a check, use the following equation:

QCAP ph = K * COILCF ph * (CEDB ph - CLDB ph)

However, the heating load due to the return air load does not necessarily disappear since the preheat coil only heats the return outside air toCLDBph. Either a reheat coil (for VAV systems) or a main heating coil located further downstream must still reheat the leavingpreheat coil airflow to the design room heating dry bulb. See Ref #79.

Table 2.4 Preheat Coil CharacteristicsSystem Type Sizing Method Level Location Deck LocationBPVAV SEPARATE SAME-CC ROADKBPVRH SEPARATE SAME-CC ROADKBPMZ SEPARATE SAME-CC ROADKCOMP SEPARATE SAME-CC ROADKDD SEPARATE SAME-CC ROADKDDVAV SEPARATE SAME-CC ROADKFC COMBINED SAME-CC ROADKPFPVAV SEPARATE SAME-CC ROADKPFPVAVRA SEPARATE SAME-CC ROADKINCHP COMBINED SAME-CC ROADKIND SEPARATE SAME-CC ROADKINDFP SEPARATE SAME-CC ROADKMZ SEPARATE SAME-CC ROADKPFPVAV SEPARATE SAME-CC ROADKPFPVAVRA SEPARATE SAME-CC ROADKPTAC COMBINED SAME-CC ROADKRAD NO-COILRTMZ SEPARATE SAME-CC ROADKSFPVAV SEPARATE SAME-CC ROADK

24

SZ COMBINED SAME-CC ROADKTAB SEPARATE SAME-CC ROADKTRH SEPARATE SAME-CC ROADK2FDDVV SEPARATE SAME-CC ROADKUV NO-COILVAV SEPARATE SAME-CC ROADKVAVBSK SEPARATE SAME-CC ROADKVAVFSK SEPARATE SAME-CC ROADKVRH SEPARATE SAME-CC ROADKVTCV COMBINED SAME-CC ROADKWSHP COMBINED SAME-CC ROADK

Ref #40. Reheat Coil Capacity

The system reheat coil capacity is taken from the Airflow Heating Loads at Time of Coil Peak. See Ref #138.

If the reheat coil sizing method, CLSIZE rh, has been specified as "COMBINED" (see Table 2.5), the reheat coil capacity --although printed out separately -- is included in the main heating coil capacity during the TRACE 600 System Simulation.

If the user has overridden this calculated value by user entry on the Create Systems - Heating Overrides screen, the user-entered value isprinted here.

Ref #41. Humidification Capacity

The system humidification coil capacity is taken from the Airflow Heating Loads at Time of Coil Peak. See Ref #140.

Ref #42. Optional Ventilation Heating Coil Capacity

The system optional ventilation heating coil capacity is taken from the Airflow Heating Loads at Time of Coil Peak. See Ref #136.

Table 2.5 Reheat Coil CharacteristicsSystem Type Sizing Method Level Location Deck LocationBPVAV COMBINED ROOM ROOMDKBPVRH COMBINED ROOM SAME-CCBPMZ NO-COILCOMP COMBINED ROOM CDECKDD NO-COILDDVAV SEPERATE ROOM B-DECKSFC NO-COILINCHP NO-COILIND NO-COILINDFP NO-COILMZ NO-COILPFPVAV COMBINED ROOM B-DECKSPFPVAVRA NO-COILPTAC NO-COILRAD NO-COILRTMZ NO-COILSFPVAV COMBINED ROOM SAME-CCSZ NO-COILTAB COMBINED ROOM SAME-CCTRH COMBINED ROOM SAME-CC2FDDVV SEPARATE ROOM B-DECKSUV NO-COIL

25

VAV COMBINED ROOM ROOMDKVAVBSK SEPARATE ROOM SAME-CCVAVFSK SEPARATE ROOM SAME-CCVRH COMBINED ROOM SAME-CCVTCV NO-COILWSHP NO-COIL

Ref #43. Heating Totals

The Total Heating Capacity, QCAPh,tot, is the sum of all the heating coil capacities, i.e.,

QCAP h,tot = QCAP h + QCAP ah + QCAP ph + QCAP vh + QCAP rh + QCAP hm

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 38 QCAP ah Auxiliary heating coil capacity, Btu/hr [W] EQ 37 QCAP h Main heating coil capacity, Btu/hr [W] EQ 41 QCAP hm Humidification coil capacity, Btu/hr [W] EQ 39 QCAP ph Preheat coil capacity, Btu/hr [W] EQ 40 QCAP rh Reheat coil capacity, Btu/hr [W] EQ 43 QCAP h,tot Total heating capacity, Btu/hr [W] EQ 42 QCAP vh Optional ventilation heating coil capacity, Btu/hr [W]

Ref #200. Building Peak Month/Hour/Load

Above, the design cooling load is displayed for each system (based on sum-of-peaks or block load) along with the month and hour inwhich it occurred. Here, the block cooling load for the entire building is displayed. This would be used to design the capacity of acentral plant that serves multiple systems.

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2.2.3 ENGINEERING CHECKS

Use this report to quickly review general heating and cooling values for each room, zone, and system. These values are based on fan andcoil capacities relative to building floor area.

System Type acronyms are listed with the accompanying description in Appendix A of this manual.

Ref #44. Cooling and Heating Percent Outside (or Ventilation) Air

PCTOA = (DSOACF / DSCFM) x 100

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 27,28 DSCFM Supply air quantity, equal to DSCFM c for cooling only or cooling/heating systems, equal to DSCFM h for heating-only systems, cfm [cms] EQ 26 DSOACF Outside air quantity, cfm [cms] EQ 44 PCTOA Percent outside air, %

Ref #45. Cooling Airflow per unit floor area

This value will normally vary between 0.5 to 1.5 cfm/ft2 [.00025 - .0076 cms/m2].

VCPA = DSCFM c / AREA fl

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 51 AREA fl Floor area, ft 2 [m2] EQ 27 DSCFM c Cooling air quantity, cfm [cms] EQ 45 VCPA Cooling airflow per floor area, cfm/ft 2 [cms/m 2]

Ref #46. Cooling airflow per unit cooling capacity

This value will normally vary between 300 to 600 cfm/ton [.04 -.08 cms/kW].

VCPT = DSCFMc / (QCAP c + QCAP vc)

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 27 DSCFM c Cooling supply airflow, cfm [cms] EQ 33 QCAP c Main cooling coil capacity, tons [kW] EQ 35 QCAP vc Optional ventilation cooling coil capacity, Btu/hr [W] EQ 46 VCPT Airflow per unit cooling capacity, cfm/ton [cms/kW]

Ref #47. Floor Area per unit Cooling Capacity

This value typically varies between 350 to 500 ft2/ton [9.25 - 13.2 m2/kW].

APT = AREA fl / (QCAP c + QCAP vc)

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 51 AREA fl Floor area, ft 2 [m2] EQ 47 APT Area per unit cooling capacity, ft 2/ton [m 2/kW] EQ 33 QCAP c Main cooling coil capacity, tons [kW] EQ 35 QCAP vc Optional ventilation cooling coil capacity, Btu/hr [W]

Ref #48. Cooling Heat Gain per Unit Floor Area

This value normally varies between 24 to 34 Btuh/ft2 [75.7 - 107.2 W/m2].

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HGPA = (QCAP c + QCAP vc) x CONST / AREA fl

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 51 AREA fl Floor area, ft 2 [m2] RF 48 CONST Units conversion constant = 12,000 Btuh/ton [1000 W/kW] EQ 48 HGPA Heat gain per unit floor area, Btuh/ft 2 [W/m2] EQ 33 QCAP c Main cooling coil capacity, tons [kW] EQ 35 QCAP vc Optional ventilation cooling coil capacity, Btu/hr [W]

Ref #49. Heating Airflow per unit floor area

This value normally will vary between 0.25 to 0.75 cfm/ft2 [.00127 -.0038 cms/m2].

VHPA = DSCFM h / AREA fl

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 51 AREA fl Floor area, ft 2 [m2] EQ 28 DSCFM h Main heating airflow, cfm [cms] EQ 49 VHPA Heating airflow per floor area, cfm/ft 2 [cms/m 2]

Ref #50. Heat Loss per Unit Floor Area

This value normally varies between 10 to 50 Btuh/ft2 [31.5 - 158 W/m2].

HLPA = (QCAP h + QCAP vh) * CONST / AREA fl

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 51 AREA fl Floor area, ft 2 [m2] RF 50 CONST Units conversion constant = 1 [1000 W/kW] EQ 50 HLPA Heat loss per unit floor area, Btuh/ft 2 [W/m2] EQ 37,79 QCAP h Main heating coil capacity, Btuh [kW] EQ 42 QCAP vh Optional ventilation heating coil capacity, Btu/hr [W]

Ref #51. Floor Area

Floor area is the sum of the individual room floor areas serving a particular system. Since exposed floor area is already included inAREAfl it is ignored in the summation. Units are ft2 [m2]. Also see Ref #186.

28

2.3.1 PEAK COOLING LOADS

Ref #51. Floor Area

Floor area is the sum of the individual room floor areas serving a particular system. Since exposed floor area is already included inAREAfl it is ignored in the summation. Units are ft2 [m2]. Also see Ref #186.

Ref #54. Peak Month/Hour (at time of the space cooling peak)

This is the time of the year when the space sensible cooling component (defined in Ref #55) peaked. The time of the space peak isimportant since it is used to calculate design airflows and size the fan. This peak can only occur between the first and last months of thecooling simulation period defined on the Load Parameters screen. The hour of occurrence can be fixed by user entry on the LoadParameters screen (Peak Cooling Load Hour); otherwise, the program will determine the hour of the peak for each room, block zone, andblock system load.

If the time of the peak seems unusual (e.g. solar heat gain is occurring during the nighttime) it is likely that the latitude and longitude haveinadvertently been switched or an incorrect time zone number has been entered in a user-generated Weather Library.

Ref #55. Outside Air Condition (at time of the space cooling peak)

OADB sp,c Outside air dry bulb temperature at time of the space sensible cooling peak, F [C]

OAWB sp,c Outside air wet bulb temperature at time of the space sensible cooling peak, F [C]

The outside air condition at the time the space sensible peak may not equal the summer design condition since the ventilation load is notused directly in the calculation of the space sensible load. (The exception is when the ventilation air is dumped directly into the space, i.e.CLDECK ov = ROOMDK; however, if this ventilation air is pre-cooled, the space load effect will be a negative constant and thereforenot affect the time of the space peak.)

Even for skin-dominated buildings, the thermal flywheel effect combined with solar-influenced envelope temperatures may cause the peakload seen by the fan system to occur earlier or later than the time of the dry bulb peak. For solar-dominated buildings the room, zone, orsystem block peak will occur near the time of the solar peak. For example, a south-facing room in the northern hemisphere may peak inearly afternoon in September.

The internal loads will sometimes determine the time of the peak if scheduled on for only parts of a day or a portion of the year.

NOTE: The Ventilation Methodology option (user-definable on the Load Parameters screen) only affects the psychrometric calculation ofsupply air dry bulb and has no effect on the time of the room, zone, or system load peaks.

Ref #56. Design Room Dry Bulb for Cooling (at time of the space peak)

The Design Room Dry Bulb Cooling, DSRMDB c, is user defined on the Create Rooms - Rooms screen. If the room dry bulb variesby room within a particular system and the main cooling coil is located at either the zone or system level, the value of DSRMDB c usedduring psychrometrics will equal the average design room temperature weighted by the floor areas of the rooms assigned to that zone orsystem. The zone or system return air temperature, however, will be weighted by the return airflow from each room.

Ref #57. Supply Air Dry Bulb for Cooling (at time of the space peak)

Depending upon the type of Load and System information entered, the design cooling supply air dry bulb (DSADB c) may already beknown; for example, the supply air dry bulb may be fixed as a result of user entry on the Create Systems - Design Temperatures screen orthe supply airflow may be known as a result of user entry on the Create Rooms - Airflows screen. (The supply air dry bulb can also befixed at the room level if, for example, the cooling coil is located at the system level. In this case, all rooms and zones assigned to thatsystem will receive a fixed supply air temperature from the coil located at the system level. Zone-level cooling coils are treated in a similarmanner.) Each case is treated differently as illustrated in the text that follows.

Case I. Neither DSADB c nor DSCFM c is known.

1. The Psychrometric algorithm is called to determine the appropriate DSADB c and DSCFM c given the design room relativehumidity.

29

2. If the calculated value of DSCFM c is less than MINCFM c, DSCFM c is set equal to MINCFM c and Case III isprocessed.

Case II. DSADB c is known but DSCFM c is unknown.

1. The Psychrometric algorithm is called to determine the appropriate DSCFM c and a new value of design room relative humidity.

2. If the calculated value of DSCFM c is less than MINCFM c, DSCFM c is set equal to MINCFM c and Case IV isprocessed.

Case III. DSADB c is unknown, but DSCFM c is known.

1. The space sensible load, QSENSP sp,c, is calculated for the known value of DSCFM c.

2. DSADB c is calculated:

DSADB c = DSRMDB c - QSENSP sp,c / (DSCFM c * K)

3. The Psychrometric algorithm is called to determine the new value of design room relative humidity.

Case IV. Both DSADB c and DSCFM c are known.

1. If a reheat coil is available, the amount of over/undersizing, QSIZE, is calculated. QSIZE is added toQSENSP sp,c.

2. The Psychrometric algorithm is called to determine the a new value of design room relative humidity.

The psychrometric procedure is described in the TRACE 600 Engineering Manual (TRCE-UM-602).

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 57 DSADB c Design supply air temperature cooling, F [C] EQ 56 DSRMDB c Design room dry bulb cooling, F [C] EQ 58,27 DSCFM c Main cooling supply fan airflow, cfm [cms] EQ 17 K Density-specific heat product, Btu-min/(hr-ft 3-f) [J/m 3] EQ 59 QSENSP sp,c Cooling space sensible load, Btu/hr [W] EQ 132 QSIZE Over or under sizing energy, Btu/hr [W]

Ref #58. Space Cooling Airflow (at time of the space peak)

For main cooling airflow the room-level calculation sequence is as follows:

A minimum cooling supply airflow, MINCFM c, is defined whenever supply airflow units of ACH-HR, CFM-P, CFM-SF, LPS-P, orLPS-SM are specified, i.e.,

MINCFM c = FANVAL c * CONV air

Note that MINCFM c represents the minimum size of the terminal box rather than the minimum operating airflow, i.e., this valueis ignored by the TRACE 600 System Simulation.

If a minimum stop is located over the cold deck (RHTLOC = CDECK) during cooling design or over both decks (RHTLOC = B-DECKS), then the minimum supply airflow is compared against the reheat airflow. If the reheat airflow units have been entered as apercent, then this comparison is not done.

If RHCFM > MINCFM c then MINCFM c = RHCFM

If ventilation is routed through the ROA deck (CLDECK ov = ROADK), the current value of MINCFM c is compared to thevalue of ventilation airflow.

If OACFM > MINCFM c then MINCFM c = OACFM

If the main supply airflow units acronym is entered as "CFM" or "LPS" then DSCFM c = FANVAL c; otherwise, the main supplyairflow is calculated based on the Fan Sizing Method components listed in Table 2.6, i.e.,

30

DSCFM c = QSENSP sp,c / [K * (DSRMDB c - DSADB c)]

If DSCFM c is less than MINCFM c then DSCFM c is set equal to MINCFM c.

Ref# Variable Description -------- ------------- ----------------------------------------------- TB 2.2 CONV air Airflow conversion multiplier EQ 57 DSADB c Design supply air temperature cooling, F [C] EQ 56 DSRMDB c Design room dry bulb cooling, F [C] EQ 58,27 DSCFM c Main cooling supply fan airflow, cfm [cms] FANVAL c Main cooling fan airflow value EQ 17 K Density-specific heat product, Btu-min/(hr-ft 3-f) [J/m 3] RF 53g MINCFM c Minimum design value of main cooling airflow, cfm [cms] EQ 123 OACFM Outside air brought through the ROA deck, cfm [cms] TR LSCH PCTRH t Reheat utilization percent this hour, % EQ 59 QSENSP sp,c Cooling space sensible load, Btu/hr [W] EQ 137 RHCFM Reheat airflow, cfm [cms] TR OACF RHVAL Reheat airflow value

The value of cooling supply airflow may be different than the load-calculated value if any of the following conditions exist:

-- The heating supply airflow (see Ref #28) is greater for a single duct system (i.e. fan coils) since the same fan is used to handle both thecooling or heating needs.

-- The user-defined value of minimum airflow (cooling airflow units ACH HR, CFM-P, CFM-SF, LPS-P, or LPS-SM have been specified)is greater. (Also see Ref #58.)

-- The outside air dampers are located on the return/outside air deck (ROADK) and the outside air quantity is greater.-- The value of cooling supply airflow has been user defined on the Create Systems - Fan Overrides screen.-- The Block Fan Airflow has been user defined on the Create Systems - Fan Overrides screen. (This will only work when the fan sizing

method from Table 2.7 equals BLOCK or BLK-INT.)

A sample calculation procedure follows using the system block information from the Main System Peak Cooling Loads report. Thedesign cooling supply airflow for a PFPVAV system occurs at the time of the main cooling space peak, i.e.,

DSCFM c = QSENSP sp,c / [ K * (DSRMDB c - DSADB c)]

these values are retrieved from the following sources

= (RF 59) / (RF 17) * [(RF 56) - (RF 57)]

Had this been a constant volume fan system, the design cooling airflow calculation would have used the sum-of-the-peaksQSENSP sp,c.

Ref #59. Space Sensible Cooling Load (at time of the space peak)

The space sensible load, QSENSP sp,c, is used to calculate cooling supply airflow.

2 QSENSP sp,c = QSPACE c,i i=1

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 59 QSENSP sp,c Cooling space sensible load, Btu/hr [W] TB 2.6 QSPACE c,i Cooling space sensible load components, Btu/hr [W]

The room space sensible load (less skin conduction), QRMSLD sp,c, is given by:

QRMSLD sp,c = QPEOPS t + QMISC t,sp + QSOL sk,sp + QSOL gl,sp + QLITES t,sp + QINFS + QCEIL + QVENTS sp + QRSPAC

Ref# Variable Description -------- ------------- -----------------------------------------------

31

EQ 96 QCEIL Conduction load through ceiling, Btu/hr [W] Btu/hr [W] EQ 108 QSOL gl,sp Wall glass solar heat gain seen by space, Btu/hr [W] EQ 120 QINFS Infiltration sensible load, Btu/hr [W] EQ 80 QLITES t,sp Portion of lighting heat gain originally assigned as a space load, Btu/hr [W] EQ 86 QMISC t,sp Space sensible miscellaneous heat gain, Btu/hr [W] EQ 124 QVENTS sp Sensible ventilation load on space, Btu/hr [W] EQ 83 QPEOPS t People sensible heat gain, Btu/hr [W] EQ 97 QSOL sk,sp Skylight solar heat gain seen by space at the time of the cooling space peak, Btu/hr [W] EQ 59 QRMSLD sp,c Room (space) sensible load less skin conduction, EQ 66 QRSPAC Portion of return air heat gain (QRASLD) which becomes a space load if the total return airflow is zero, Btu/hr [W]

Table 2.6 Fan Load Components by Sizing MethodQSPACEc,i

Coil Type Sizing Method1 QRMSLDsp,c QWCONDsp,cMain BLOCK Yes Yes

BLK-INT Yes NoPEAK Yes YesPEAK-INT Yes NoSKIN No Yes

Aux BLOCK Yes YesBLK-INT Yes NoPEAK Yes YesPEAK-INT Yes NoSKIN No Yes

1Sizing Method default values are listed in Table 2.7

The external conduction load into the space, QWCOND sp,c, is the "skin" portion of the sensible space load. (NOTE:QWCOND sp,c does not include the ceiling load, QCEIL, which is included in the QINT component.)

QWCOND sp,c = QCOND wl,sp + QCOND gl,sp + QCOND sk,sp + QCOND rf,sp + QCOND pt + QCOND xf

Ref# Variable Description -------- ------------- ----------------------------------------------- EQ 111 QCOND gl,sp Wall glass space load, Btu/hr [W] EQ 117 QCOND pt Partition conduction load, Btu/hr [W] EQ 94 QCOND rf,sp Nonglass roof conduction load to space, EQ 102 QCOND sk,sp Skylight conduction load to space, Btu/hr [W] EQ 106 QCOND wl,sp Nonglass wall space load, Btu/hr [W] EQ 115 QCOND xf Exposed floor conduction load, Btu/hr [W] Btu/hr [W] EQ 59 QWCOND sp,c External conduction load into the space at the, time of the cooling space peak, Btu/hr [W]

Table 2.7 Cooling Fan Characteristics1System Main Cooling Fan Auxiliary. Cooling FanType Sizing

MethodLevel Location Deck Location Fan

ConfigSizing Method Deck Location Fan

ConfigBPVAV PEAK SAME-CC SAME-CC DRAW LARGEST RM-WALL BLOWBPVRH PEAK SAME-CC SAME-CC DRAW LARGEST RM-WALL BLOWBPMZ PEAK SAME-CC ROADK BLOW LARGEST RM-WALL BLOWCOMP PEAK SAME-CC ROADK DRAW LARGEST RM-WALL BLOWDD PEAK SAME-CC ROADK BLOW LARGEST RM-WALL BLOWDDVAV BLOCK SAME-CC ROADK BLOW LARGEST RM-WALL BLOW

32

FC PEAK SAME-CC SAME-CC BLOW LARGEST RM-WALL BLOWPFPVAV BLOCK SAME-CC SAME-CC DRAW LARGEST RM-WALL BLOWPFPVAVRA BLOCK SAME-CC SAME-CC DRAW LARGEST RM-WALL BLOWINCHP PEAK SAME-CC SAME-CC BLOW LARGEST RM-WALL BLOWIND SKIN SAME-CC SAME-CC DRAW LARGEST RM-WALL BLOWINDFP PEAK SAME-CC SAME-CC DRAW LARGEST RM-WALL BLOWMZ PEAK SAME-CC ROADK DRAW LARGEST RM-WALL BLOWPTAC PEAK SAME-CC SAME-CC BLOW LARGEST RM-WALL BLOWRAD NO-FAN LARGEST RM-WALL BLOWRTMZ PEAK SAME-CC ROADK DRAW LARGEST RM-WALL BLOWSFPVAV BLOCK SAME-CC SAME-CC DRAW LARGEST RM-WALL BLOWSZ PEAK SAME-CC SAME-CC DRAW LARGEST RM-WALL BLOWTAB PEAK SAME-CC SAME-CC DRAW LARGEST RM-WALL BLOWTRH PEAK SAME-CC SAME-CC DRAW LARGEST RM-WALL BLOW2FDDVV BLOCK SAME-CC SAME-CC DRAW LARGEST RM-WALL BLOWUV NO-FAN LARGEST RM-WALL BLOWVAV BLOCK SAME-CC SAME-CC DRAW LA