Testing Report
Team 10: Design of Sexton Library HVAC System
Jason Chin
Ashley Harding
Geoff Hibbard
April 9, 2008
As this was a no-build project, no physical tests could be carried out by the team. Instead, we performed
manual calculations to validate computer simulations of the library’s thermal behavior. Energy
consumption was also modeled for different system designs. These results could not be validated
through manual calculation due to the incredibly large amount of data and calculation required. The
results could, however, be compared to one another, as the relative efficiency of each system was
known.
Design Load Verification
Manual Calculations were performed to find the design heating and cooling loads for the library. The
loads found were the worst case scenario loading cases that would be used for sizing equipment and
defining power consumption in the space. Calculations were performed according to methods
presented in the text: Heating, Ventilation and Air Conditioning Analysis and Design (McQuiston et. al,
2005) which makes extensive reference to ASHRAE methods.
Design simulations were performed using Carrier’s Hourly Analysis Program (HAP) (Carrier, 2007). The
program cross referenced system characteristics with internal loads (occupants, equipment, lighting)
and weather data from Shearwater (the nearest weather station to Halifax) and determined worst case
scenario system loads. These loads were compared with the manual calculations described above.
Most of the simulation data agreed with the manual calculations. However, there were some
discrepancies between the cooling loads found for ventilation and infiltration. The source of this
discrepancy was investigated in depth, but could not be found. The effect of theses discrepancies on the
total load was small (<5%), so even though there were errors, the simulation was deemed valid by the
team. A comparison of the loads can be found in Table 1.
Energy Consumption Verification
Annual energy consumption simulations were performed using HAP. A total of 18 different systems
were modeled, not including iterative models of our final chosen Retrofit system. HAP simulated the
energy consumption of these models for each day of the year using average daily weather data form
Shearwater, the consumption was summed over the course of a year to yield annual energy
consumption. The relative efficiency of each type of system was known from theory, so the relative
energy consumption could also be determined. The performance of these systems was validated by
their agreement with each other’s relative energy consumption.
The relative consumption of each system was in accordance with the systems’ relative efficiency, so this
simulation was deemed valid by the team. The annual energy consumption of each system can be found
in Table 2.
Table 1: Heating and Cooling Load Comparison
Heating & Cooling Load Calculation Comparison
Heating Loads (kW)
Transmission
Cooling Loads (kW)
Manual Calculations
Sensible
Latent
Manual
Calculations
HAP
Calculations
HAP Calculations
Sensible
Latent
40.7
8.5
1.2
2.7
21.7
74.8
41.9
7.4
1.2
2.3
20.3
73.1
30.7
0.6
0.7
0.2
26.4
9.8
23.6
91.9
6.3
6.3
37.1
1.1
1.0
0.6
21.6
2.5
25.0
89.0
3.8
3.8
4.8
0.4
3.7
8.9
5.0
0.4
3.6
9.0
3.4
0.1
3.5
1.3
8.5
16.7
1.1
1.1
2.4
0.0
3.8
0.3
8.9
15.5
0.5
0.5
5.2
0.4
3.9
9.5
5.4
0.4
3.9
9.7
3.7
0.1
3.8
0.5
7.4
15.3
0.8
0.8
2.4
0.3
4.1
0.7
6.6
14.1
0.8
0.3
1.1
61.8
5.2
63.0
0.6
0.5
0.0
13.7
1.2
5.1
0.1
13.0
0.2
Stacks
Windows
North and West Wall
East Wall
South Wall
Roof
Occupants
Auxiliary
TOTAL
Foyer
Windows
North Wall
Roof
Occupants
Auxiliary
TOTAL
Offices
Windows
North Wall
Roof
Occupants
Auxiliary
TOTAL
Total Ventialtion
Total Infiltration
Table 2: System Energy Consumption
System Type
Econom izer
Reclaim er
Total
(MBTU)
Total
(MWh)
CAV Termial Reheat
N
N
1990
584
0
0
1914
75
CAV Termial Reheat
DB
N
1325
389
665
195
1250
75
CAV Termial Reheat
Enthalpy
N
1289
378
701
206
1213
75
CAV Termial Reheat
Non-int
N
1512
443
478
140
1436
75
CAV Termial Reheat
N
Y
1984
582
6
2
1908
75
CAV Termial Reheat
DB
Y
1319
387
670
197
1244
75
CAV Termial Reheat
Enthalpy
Y
1282
376
707
207
1207
75
CAV Termial Reheat
Non-int
Y
1506
442
484
142
1430
75
CAV 4 Pipe
N
N
1165
342
825
242
1151
15
CAV 4 Pipe
N
Y
1129
331
861
253
1114
15
VAV
N
N
1012
297
977
287
998
15
VAV
DB
N
698
205
1292
379
683
15
VAV
Enthalpy
N
676
198
1314
385
661
15
VAV
Non-int
N
844
247
1146
336
829
15
VAV
N
Y
980
287
1010
296
965
15
VAV
DB
Y
664
195
1326
389
649
15
VAV
Enthalpy
Y
642
188
1347
395
628
15
VAV
Non-int
Y
810
238
1180
346
795
15
N
Y
985
278
1005
295
942
43
RETROFIT
Energy
Energy Saved
Saved (MBTU)
(MWh)
Total Therm al
(MBTU)
Total Fan
(MBTU)
The team set out to achieve several goals based on comfort conditions inside the library. The conditions
in the library with the Retrofit system were simulated using HAP and maximum and minimum
temperatures were found. Equipment was also specified to meet our design goals. These goals and
results are summarized in Table 3.
Table 3: Design Goals
Requirement
Result
Goal Acheived?
20.4°C
Yes
25°C (decrea s es requi red cool i ng,
ASHRAE 55 s ti l l met)
25.1°C for 11 hours tota l
Yes
30% mi ni mum (energy s a vi ngs ,
expert reccomenda ti on)
30% mi ni mum
No - Energy
Savings
0.13m/s ma x
0.03m/s a t occupa nt l evel
Yes
Bel ow NC 35-40
Di ffus ers : NC 26
Fa n Coi l Boxes : NC 40
60-65% Effi ci ency fi l ters
i ncl uded wi th Fa n Coi l s
Yes
Minimum
Temperature
20°C
Maximum
Temperature
22°C
40-45%
Humidity
Air Flow in Space
Noise Level
Filtering Efficiency
35-60%
Design Changes
Yes
The Maximum temperature requirement was changed to decrease the energy consumption of the
system, and still fell within comfort ranges defined by ASHRAE. The humidity requirement was changed
to lower system energy consumption after a discussion with Don Baker, an HVAC expert (Discussion of
March 13, 2008).
References
Carrier Corporation. (2006). Hourly Analysis Program (HAP), 8760 Hour Load & Energy Analysis.
Retrieved from:
http://www.commercial.carrier.com/commercial/hvac/general/0,,CLI1_DIV12_ETI496_MID4355,00.html
McQuiston, F.C., Parker, J.D., Spitler, J.D. (2005). Heating, Ventilating, and Air Conditioning: Analysis and
Design, 6th Edition. John Wiley and Sons: USA.