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Validation of the HVAC Engineering Book modules

HVAC Engineering Toolkit modules were validated against the test examples in ASHRAE Handbook Fundamentals 2005 /1/ and ASHRAE Standard Thermal Environmental Conditions for Human Occupancy /2/. The summaries of the testing results are presented in this article.

Module 'Design Loads'

ParameterTest sourceUnitsActualSimulatedDeviation
Solar irradiance Single-room example, p.30.32 /1/ Btu/h/ft2 205.4 205.4 0%
Solar-temperature same oF 156 156.4 0%
Lighting cooling load same Btu/h 1122 1123 0%
Wall cooling load same Btu/h 602 572 5.2%
Cooling load of windows without blinds same Btu/h 5636 5542 1.4%
Cooling load of windows with blinds same Btu/h 4310 4254 1.1%
Room heat loss same Btu/h 8495 8513 -0.2%

Module 'Water Flow'

Friction loss rates in ft w.c./100ft at 60oF water flow rate 10 US gal/min
Duct diameter, in.Test sourceSource valueBy module (Galvanized steel)By module (Uncoated carbon steel)
¾ Friction chart /1/ 25.0 23.9 20.8
1 same 7.0 7.04 6.32
1 ¼ same 1.8 1.79 1.65
1 1/2 same 0.9 0.83 0.78
Duct diameter, in.Test sourceActualBy module (Galvanized steel)By module (Uncoated carbon steel)
2 Friction chart /1/ 19 19.06 16.27
2 ½ same 7.2 7.69 6.69
3 same 2.5 2.56 2.28
4 same 0.52 0.65 0.6
Average deviations for using galvanized steel and carbon steel are 0% and -11%, respectively. Chapter 2 /1/ states that the module’s formulae are more accurate than the chart.

Module 'Psychrometrics'

ParameterTest sourceUnitsActualPredictedDeviation
Atmospheric pressure Chapter 6 /1/ In. Me 29.921 29.921 0%
Dry-bulb temperature same oF 100 100 0%
Wet-bulb temperature same oF 65 65 0%
Humidity ratio same lb/lb 0.0052 0.0053 -2%
Enthalpy same Btu/hlb 29.8 29.8 0%
Relative humidity same % 13 13 0%
Specific volume same ft3/lb 14.22 14.25 0%
Dew-point temperature same oF 40 40.3 -1%

Module 'Thermal Comfort'

ParameterTest sourceUnitsTest #1Test #2Test #3Test #4
Metabolic heat production Appendix D /4/ met 1.1 1.1 1.1 1.1
Insulation of clothing same clo 1.0 1.0 1.0 1.0
Indoor air temperature same oC 19.6 23.9 25.7 21.2
Indoor air temperature same % 86.0 66.0 15.0 20.0
Mean radiant temperature same oC 19.6 23.9 25.7 21.2
Air velocity same m/s 0.1 0.1 0.1 0.1
Actual PMV same -0.5 0.5 0.5 -0.5
PMV by module -0.47 0.49 0.54 -0.45
Actual PPD same 10% 10% 10% 10%
PPD by module 10% 10% 11% 9%
Metabolic heat production Appendix D /4/ met 1.1 1.1 1.1 1.1
Insulation of clothing same clo 0.5 0.5 0.5 0.5
Indoor air temperature same oC 23.6 26.8 27.9 24.7
Indoor air temperature same % 67.0 56.0 13.0 16.0
Mean radiant temperature same oC 23.6 26.8 27.9 24.7
Air velocity same m/s 0.1 0.1 0.1 0.1
Actual PMV same -0.5 0.5 0.5 -0.5
PMV by module -0.46 0.55 0.52 -0.46
Actual PPD same 10% 10% 10% 10%
PPD by module 9% 11% 11% 9%

Module 'Air Flow'

Duct diameter, in.Test sourceUnitsActualBy moduleDeviation
26 Chapter 35 /1/ Inch w.c./100ft 0.08 0.08 0%
22 same same 0.195 0.190 3%
18 same same 0.50 0.52 -4%
14 same same 1.99 1.85 7%
Average deviation is 1.5%.