Homework 4:
Please complete one of the following problems. Follow all instructions.
9.10
Time T₁
1
2
دیا
A roof element is constructed as shown below. The steel members have an R-value of 0.12 m²-
C/W and occupy 3% of the cross-sectional area and the airspace has an R-value of 0.18 m²-
C/W. The remaining volume is filled with air.
10 mm built-up roofing Outdoors at 32 C
4
5
6
7
8
25.6
The hourly values of the temperature and solar radiation for summer conditions are given in the Table
2. The material properties, thermal resistance, UA value, and capacitance are provided for each layer
in Table 2.
Table 1: Hourly temperature and solar radiation for summer conditions
Gt
Time T₂
Gt
Time T₂
W/m²
W/m²
24.4
23.9
23.9
concrete
23.9
24.4
25.6
26.7
0
0
0
0
0
153
373
576
I
sonne
9
10
11
12
13
14
15
16
F
Room at 24 C
27.8
29.4
31.1
32.2
33.3
34.4
35.0
35.0
752
4 cm roofing
insulation (fiberboard)
10 cm Steel Joists
891
984
1026
20 mm plaster ceiling
17
18
19
20
1014 21
949
22
835
23
679
24
35.0
34.4
33.3
32.2
31.1
29.4
27.8
26.7
Gt
W/m²
490
279
59
0
0
0
0
0
Fig: 1
