9.12

A zone of a commercial building in Miami is maintained at 24 C and 50% RH. It is occupied

by 12 people from 8 am to 5 pm, each with a computer (100 W), 4 printers (200 W) and a copier

(1000 W). The required ventilation flow rate is 7.5 l/s per person. The exterior walls are Wall

type 31 with 100 m² of west-facing wall area. The windows are double pane reflective coated

windows with 20 m² of area. The design day dry-bulb and wet-bulb temperatures and solar

radiation are given in the table below. Determine and plot the components of the total heat gain

for the zone. Determine the maximum heat gain, the SHR at this time, and the time it occurs.

Draw some conclusions from your analysis. Table 3 shows the hourly ambient dry-bulb and wet-

bulb temperature and solar radiation and Table 4 shows the material properties, thermal

resistance, UA-value, and capacitance for each wall layer. Please complete Table 4 in the by

inputting the correct thermal resistance, UA-value and capacitance of the gray boxes.

Table 3: Hour ambient data

Time T₁

1

2

3

4

5

6

7

8

9

10

11

12

F01 surface

M15 concrete

104 insulation

G01 Gypsum

board

27

26

26

26

26

26

26

27

28

29

30

31

L

E

k

Tub

24

24

24

23

23

23

24

24

24

24

25

25

W/m-

K

rho

G₁

W/m²

0

Kg/m³

0

0

0

0

12

83

139

184

219

243

262

23

24

Table 4: Wall Data

Time

kJ/kg-

K

13

14

15

16

17

18

19

20

21

22

Cp R (L/K)

m².

K/W

0.044

0.17 1.95

2242.58

0.92

0.07 0.05 19.22 0.96

0.01 0.16 800.92 1.09

T₂

(C)

32

32

32

32

32

31

30

29

29

28

27

27

R

m².

K/W

U

(1/R)

W/m².

K

Tub

25

25

25

25

25

25

25

24

24

24

24

24

Gt

W/m²

406

606

758

834

796

562

6

0

0

0

0

0

C (rho x Cp x

L)

kJ/m²-k

N/A