Building Design and Construction Handbook - Merritt - Ventech!

13.66 SECTION THIRTEEN
Lights may be assumed to average 4 W/ft 2 . Assume 50 persons will be in the
store, 2 in the first-floor office, 10 in the second-floor office No. 1, and 5 in secondfloor
office No. 2.
Cooling Measured in Tons. Once we obtain the cooling load in Btu per hour, we
convert the load to tons of refrigeration by Eq. (13.15).
Cooling Requirements for First-Floor Store (Table 13.15a).
TABLE 13.15a First-Floor Store Load
86,951
Load in tons � � 7.25 tons
12,000
If supply air is provided at 18�F differential, with fresh air entering the unit
through an outside duct, the dehumidified air flow required for sensible heat is
[from Eq. (13.30)]:
Area, ft 2
U(T o � T i),
�F
Heat load,
Btu/hr
Heat gain through enclosures:
North wall 92 � 0.25 � 15 344
North door 28 � 0.46 � 15 193
South wall 412 � 0.25 � 15 1,540
South glass 154 � 1.04 � 15 2,405
East wall 480 � 0.25 � 15 1,800
West wall 228 � 0.25 � 15 854
Partition 263 � 0.39 � 10 1,025
Partition door 49 � 0.46 � 10 225
Floor 841 � 0.25 � 10 2,100
Ceiling 112 � 0.25 � 10 280
Load due to conduction 10,766
Sun load on south glass, 154 ft2 � 98 15,100
Occupants (sensible heat) from Table 13.9, 50 � 315 15,750
Lights [Eq. (13.29)] 841 ft2 � 4 W/ft2 � 3.42 11,500
53,116
Fan hp (4% of total) 2,125
Total internal sensible heat load
Fresh air (sensible heat) at 10 ft
55,241
3 /min per person [Eq. (13.30),*
500 ft3 /min � 1.08 � 15] 8,100
Total sensible load 63,341
Occupants (latent heat) from Table 13.9, 50 � 325 16,250
Fresh air (latent heat) Eq. (13.31), 500 � 0.67(99 � 77) 7,360
Total latent load 23,610
Total load 86,951
* Current criteria typically requires higher levels of ventilation air.