Heat Load Calculation
The highest potential heat load of any room or space that needs to be conditioned
is calculated in order to maintain a desired interior air temperature, assuming external
weather conditions. This will allow you to calculate the building's heat load by looking at
the heat generation source and heat balance. The sum of the sensible and latent heat
loads can be used to calculate the building's overall heat load.
All heat load calculations will be done using the indoor design temperature of 25°C
and the outdoor average temperature of 37°C. The exterior wall of the building is cream
with a K correction for wall color of 0.5.
HEAT LOAD COMPONENTS PER FLOOR
Transmission Heat Load
a. External Wall
Table 7
External Heat Wall for First Floor
Orientation
S
A
𝑼𝒘
19.8684 3.4482
TOTAL
𝑪𝑳𝑻𝑫𝒔𝒆𝒍
LM
K
𝑸𝒔
19
-3.33
0.5
940.325874
940.325874
Table 7 shows the values for each parameters needed to calculate the
external wall heat load of first floor for south portion of the building. The heat
transfer coefficient, Uw, can be obtained by getting the reciprocal of the thermal
resistance, R. Since the external wall is made of concrete block, sand, and
gravel aggregate, it has a thermal resistance of 0.29 m2 -K/W which results to
a heat transfer coefficient of 3.4482 W/ m2 -K. The table also displays the
computed sensible heat load for the external wall of first floor.
Table 8
External Heat Wall for Second Floor
Orientation
S
A
𝑼𝒘
𝑪𝑳𝑻𝑫𝒔𝒆𝒍
65.665096 3.4482
19
LM
K
-3.33 0.5
TOTAL
𝑸𝒔
3107.769925
3107.769925
Table 8 presents the results of the calculation for external wall heat load of
second floor which is the sensible heat load, for different orientation of the
building.
Table 9
External Heat Wall for Third Floor
Orientation
A
𝑼𝒘
𝑪𝑳𝑻𝑫𝒔𝒆𝒍
LM
K
𝑸𝒔
S
15.556
3.4482
19
-3.33
0.5
736.2256
TOTAL
736.2256
Table 9 displays the values of each parameter needed to calculate for the
heat load of the external wall of third floor.
Table 10
Summary of External Wall Heat Load
Floor
Sensible Heat Load (𝑸𝒔 )
First
940.325874
Second
3107.769925
Third
736.2256
TOTAL:
4784.32137
Table 10 shows the total external wall heat load for each floor of the building.
The preceding tables display the values per orientation of the building that are
needed to solve for the external wall heat load. Thus, the total external wall heat
load of the building is 4784.3217 W.
b. Roof Load
Table 11
Heat Load of Roof
Room
𝑼𝑹
A
Chem Lab 1-3 3.44827 210.93
𝑪𝑳𝑻𝑫𝒔𝒆𝒍
LM
K
f
𝑸𝒔
30
-0.55
1
1
27239.017
Chem Fac
3.44827
34.61
30
-0.55
1
1
4469.4562
Chem Stock
3.44827
22.48
30
-0.55
1
1
2903.0157
TOTAL:
34611.489
Table 11 presents the necessary values to solve for the roof load of the
building. The sensible heat load of the roof is 34,611.489 W as presented in the
table.
c. Glass Load
Table 12
Glass Load for First Floor
Orient. SHGF
S
115
SC
Ag
0.55 1.4375
CLF
0.81
𝑯𝒔𝒈
𝑯𝒕𝒉
8273.89 76.331
U
∆𝑻
𝑸𝒔
5.9
9
1349.81
Table 12 shows the necessary values for solar heat gain and thermal heat
gain to compute the total glass load of the first floor, as well as the results of the
calculation. By getting the summation of the calculated sensible heat load of solar
heat gain and thermal heat gain, the total glass load of the first floor is 75,151.99
W.
Table 13
Glass Load for Second Floor
Orient. SHGF
S
115
SC
Ag
0.55 1.4375
CLF
0.81
𝑯𝒔𝒈
𝑯𝒕𝒉
8273.89 76.331
U
∆𝑻
𝑸𝒔
5.9
9
1349.82
Table 13 presents the calculated solar heat gain and thermal heat gain of
the glass for second floor. The total glass load of second floor as displayed in the
table is 75,151.99 W which is the same with first floor glass load.
Table 14
Glass Load for Third Floor
Orient. SHGF
S
115
SC
Ag
0.55 1.4375
CLF
0.81
𝑯𝒔𝒈
𝑯𝒕𝒉
8273.89 76.331
U
∆𝑻
𝑸𝒔
5.9
9
1349.82
Table 14 displays the total glass load of the third floor which is the
summation of the calculated sensible heat load. This glass load is the same as on
the second floor which is 75,150.6 W.
Table 15
Summary of Glass Load
Floor
Sensible Heat Load (𝑸𝒔 )
First
1349.81
Second
1349.82
Third
1349.82
TOTAL:
4,049.86
Table 15 shows the total glass load of each floor. It was calculated by getting
the summation of solar heat gain and thermal heat gain of glass. The total glass
load of the whole building is 225,454.58 W.
d. Partition Load
Table 16
Partition Load Per Floor
Floor
First
Second
Third
Partitions
U (W/𝒎𝟐 . 𝑲)
Area
𝑻𝒊
𝑻𝒐
𝑸𝒔
Door
0.00603
20.79
25
37
1.12977
Wall
3.44827
189.0603
25
37
2663.39
Door
0.00603
15.12
25
37
0.82165578
Wall
3.44827
127.1493
25
37
3946.0138
Door
0.00603
17.01
25
37
0.924363
Wall
3.44827
179.990284
25
37
5585.905
TOTAL:
12,198.18459 W
Table 16 presents the different partitions with the necessary parameters and
values to evaluate the partition load of each floor. These include the area of each partition,
the heat transfer coefficient, and the temperature of the inside and outside space. The
partition load of each component per floor was also presented in table. The total partition
load of the whole building is 12,198.18459 W.
Infiltration Load
Table 17
Infiltration Load per Floor
No. of air
changes/
hr
0.46925
𝒕𝒊
𝒕𝒐
𝝎𝒊 (𝒌𝒈𝒗 /
𝒌𝒈𝒅𝒂 )
Amphitheater
Wind
Velocity
(m/s)
6.75
25
37
Offices/Dressing
6.75
0.46925
25
Nutrition Lab
6.75
0.46925
Skills Lab
6.75
0.46925
Rooms
Q (Li/s)
Sensible
Heat
Latent Heat
0.009883
𝝎𝒐
(𝒌𝒈𝒗 /
𝒌𝒈𝒅𝒂 )
0.02633
21.2466
313.5997
855.5810
37
0.009883
0.02633
6.9631
205.552
279.1246
25
37
0.009883
0.02633
13.9041
205.2250
559.906917
25
37
0.009883
0.02633
42.8339
632.0670
1724.8849
FIRST FLOOR:
1355.4437 3419.497417
Anatomy,
Biology and
Physics Lab
Faculty Office
6.75
0.46925
25
37
0.009883
0.02633
21.2622
941.491
2568.6324
6.75
0.46925
25
37
0.009883
0.02633
10.4668
154.4911
421.4917
Biology and
Physic Storage
Room
6.75
0.46925
25
37
0.009883
0.02633
10.3965
153.4522
418.6573
1249.4343
3408.7814
941.4918
2568.6327
SECOND FLOOR:
Chem Lab 1-3
6.75
0.46925
25
37
0.009883
0.02633
21.2622
Chem Faculty
6.75
0.46925
25
37
0.009883
0.02633
10.4669
154.4911
421.4917
Chem Stock
Room
6.75
0.46925
25
37
0.009883
0.02633
6.7976
100.3326
273.7334
THIRD FLOOR:
1196.3155
3263.8578
TOTAL INFILTRATION LOAD:
3801.1935
10092.1366
The values for the various parameters needed to calculate the infiltration heat load for each level are shown in Table
17. The sum of the sensible heat load and latent heat load determines the total infiltration heat load for each floor. The
ventilation heat load and infiltration load calculations will aid in choosing the type of air distribution system to be utilized
when designing the air conditioning system.
Ventilation Heat Load
Table 18
Ventilation Heat Load per Floor
Rooms
Occupancy
Category
Amphitheater
Educational
Facilities
Offices/Dressing
Office
Buildings
Nutrition Lab
Educational
Facilities
Skills Lab
Educational
Facilities
Anatomy,
Biology and
Physics Lab
Faculty Office
Biology and
Physic Storage
Room
Chem Lab 1-3
Chem Faculty
Educational
Facilities
Office
Buildings
Occupiable
Storage
Room
Educational
Facilities
Office
Buildings
No. of
occupant
𝒕𝒊
𝒕𝒐
𝝎𝒊 (𝒌𝒈𝒗 /
𝒌𝒈𝒅𝒂 )
Q (Li/s)
Sensible
Heat
Latent Heat
0.009883
𝝎𝒐
(𝒌𝒈𝒗 /
𝒌𝒈𝒅𝒂 )
0.02633
60
25
37
196.078
2894.1112
7895.8815
4
25
37
0.009883
0.02633
19.406
572.865
1562.9237
38
25
37
0.009883
0.02633
166.382
2455.7983
6700.0508
38
25
37
0.009883
0.02633
252.458
3726.2800 10,166.2525
26325.1085
7581.8229
FIRST FLOOR:
38
25 37
0.009883
0.02633
188.279
6249.0545
2778.9980
4
25
37
0.009883
0.02633
22.883
337.7530
921.4774
2
25
37
0.009883
0.02633
10.3965
452.6892
1235.0528
9738.3531
22745.4687
921.47746
SECOND FLOOR:
38
25 37
4
25
37
0.009883
0.02633
188.279
3569.4402
8336.994
0.009883
0.02633
22.883
337.7530
Chem Stock
Room
Occupiable
Storage
Room
2
25
37
0.009883
0.02633
THIRD FLOOR:
TOTAL VENTILATION LOAD:
6.744
99.5414
271.5740
8774.2884
18592.783
23938.4861
60001.947
The parameters required to assess the ventilation heat load of each floor are shown in Table 18. Additionally, it
shows the calculated sensible and latent heat loads, which when added together yield the total ventilation heat load. Total
sensible and latent heat loads determined by the calculation were 18592.783 W and 60001.947 W, respectively. The fact
that the total latent heat load is greater than the total sensible heat load shows that the total ventilation heat load of the
building is significantly impacted by the variation in air humidity ratio.
Occupant Load
Table 19
Ventilation Heat Load per Floor
Rooms
Activity
Amphitheater
Offices/Dressing
Nutrition Lab
and Skills Lab
Seated, quietly
Teaching
Office Work
Seated, quietly
Teaching
Anatomy,
Biology and
Physics Lab
Faculty Office
Biology and
Physic Storage
Room
Chem Lab 1-3
Chem Faculty
Chem Stock
Room
Seated, quietly
Teaching
Office Work
Standing
Heat
%SHG %LHG
No. of
Gain/person
Occupant
100
60
40
60
175
50
50
1
150
55
45
4
100
60
40
37
175
50
50
1
FIRST FLOOR:
100
60
40
37
175
50
50
1
150
150
SECOND FLOOR:
Seated, quietly
100
Teaching
175
Office Work
150
Standing
150
55
50
60
50
55
50
THIRD FLOOR:
TOTAL OCCUPANT LOAD:
45
50
40
50
45
50
4
2
37
1
4
2
CLF
Latent Heat
0.68
Sensible
Heat
2507.5
0.765
0.68
504.9
3138.2
413.18
2114.8
0.68
6150.6
4707.3
4219.48
3197.7
0.765
0.49
252.45
294
206.55
294
0.68
5253.75
4707.3
3698.25
3197.7
0.765
0.49
252.45
147
206.55
147
5106.75
16,511.05
3551.25
11,468.98
1691.5
The various parameters and their related values are shown in Table 19 in order to calculate the occupant heat load
for each floor of the building. To calculate the proportion of latent heat gain, subtract the percentage of perceptible heat gain
from 100%. According to the table, there are 16511.05 W of sensible heat load and 11468.98 W of latent heat load overall.
Lighting Load
Table 20
Lighting Load per Floor
𝑭𝒃
𝑭𝒖
CLF
Sensible Heat
54
Summation
of Lamp
Rating
2430
1.2
0.5556
0.90
1458 W
40
1800
1.2
0.5556
0.90
1080
40
1800
1.2
0.5556
0.90
1080
Floors
Description
Type
Quantity
First
Fluorescent
Light,
vented
Fluorescent
Light,
vented
Fluorescent
Light,
vented
Second
Third
TOTAL LIGHTING LOAD:
3618 W
Table 20 presents the values needed in the evaluation of the lighting load of the building. The light time is 5 hours
and the total operation hours per day is 9 hours. This result to a utilization factor of 0.556 for each type of lighting. The
cooling load factor depends on the type of lighting used and the total operation hours.
Equipment/Miscellaneous Load
Table 21
Equipment Load per Floor
`
First
Second
Third
Summation
𝑭𝒖
of Equipment
Rating
Ceiling Fans
6
420
0.556
Laptop
2
200
0.222
Oven
2
1200
0.222
Refrigerator
2
1500
0.556
Water Dispenser
1
100
1
Stand Fan
1
60
0.556
FIRST FLOOR:
Ceiling Fan
6
420
0.556
Biology Refrigerator
1
100
0.556
Laptop
4
400
0.222
SECOND FLOOR:
Ceiling Fans
11
770
0.556
Incubator
9
`1080
0.111
Equipment
Drying Oven
6
8700
0.111
Refrigerator
3
300
0.556
Fume Hood
3
45
0.111
Fuming Cabinet
3
150
0.111
Laptop
4
400
0.222
THIRD FLOOR:
TOTAL EQUIPMENT/MISCELLANEOUS LOAD:
Description Type
Quantity
CLF
Sensible Heat
0.90
0.90
0.81
0.90
0.96
0.90
210.168
39.96
215.784
750.6
96
30.024
1372.56
210.168
50.04
79.92
340.128
385.308
91.1088
0.90
0.90
0.90
0.90
0.76
0.76
0.90
0.76
0.76
0.90
733.932
150.12
3.7962
12.654
79.92
1456.839
3169.527 W
The parameters needed to determine the sensible heat load of the equipment employed for each floor are shown in
Table 21. The ratio of equipment time to the total number of operation hours per day was used to calculate the utilization
factor, or Fu. ASHRAE Table 4-6 was used to estimate the cooling load factor, or CLF, values, which were based on the
equipment's operational hours. The table displays the various load results by floor. The total miscellaneous load of the entire
structure, as can be observed, is 3169.527 W.
Summary of Heat Load per Floor
Table 22
Summary of Heat Load for Ground Floor
TRANSMISSION
Wall
Partition
Glass
VENTILATION
INFILTRATION
HEAT GENERATING
LOADS
Occupant
Lighting
Miscellaneous/Equipment
Load
TOTAL HEAT LOAD:
GROUND FLOOR
Sensible Heat
Latent Heat
940.325
2664.51977
75151.99
6249.0545
1355.4437 W
26325.1085
3419.497417
6150.6 W
1458 W
1372.56
4219.48
101342.49297
QT= 135.5595975
Table 22 presents the summary of heat load calculation for first floor of the building.
The sensible heat load and latent heat load per component was tabulated as shown.
Based on the table, the total heat load of first floor is 135.559575 kW.
Table 23
Summary of Heat Load for Second Floor
TRANSMISSION
Wall
Partition
Glass
VENTILATION
INFILTRATION
SECOND FLOOR
Sensible Heat
Latent Heat
3107.769925
3946.840358
75151.99
3569.4402
1249.4343
9738.3531
3408.7814
HEAT GENERATING
LOADS
Occupant
Lighting
Miscellaneous/Equipment
Load
TOTAL HEAT LOAD:
5253.75 W
1080 W
340.128
3698.25
94.0710244
QT= 125.8813909
Table 23 presents the summary of heat load calculation for second floor of the
building. The sensible heat load and latent heat load per component was tabulated as
shown. Based on the table, the total heat load of first floor is 125.8813909 kW.
Table 24
Summary of Heat Load for Third Floor
TRANSMISSION
Wall
Roof
Partition
Glass
VENTILATION
INFILTRATION
HEAT GENERATING
LOADS
Occupant
Lighting
Miscellaneous/Equipment
Load
TOTAL HEAT LOAD:
THIRD FLOOR
Sensible Heat
Latent Heat
736.2256
34611.489
5586.829363
75150.6
8774.2884
1196.3155
23938.4861
3263.8578
5106.75
1080 W
1456.839
3551.25
115,269.5395
QT= 145.9472637
Table 24 shows the summary of heat load calculation for third floor of the building.
The total heat load for third floor is 145.9472637 kW.