From ASHRAE (1989), with permission
Conductances given in W/m2·°C)Values for still air
Position of surface |
Direction of heat flow |
Surface emittance |
|||||
Non-reflective |
Reflective |
||||||
e = 0.90 |
e = 0.20 |
e = 0.05 |
|||||
hi |
R |
hi |
R |
hi |
R |
||
Horizontal |
Upward |
9.3 |
0.11 |
5.17 |
0.19 |
4.32 |
0.23 |
Downward |
9.1 |
0.11 |
5.00 |
0.20 |
4.15 |
0.24 |
|
Sloping at 45° |
Upward |
8.3 |
0.12 |
4.20 |
0.24 |
3.35 |
0.30 |
Downward |
7.5 |
0.13 |
3.41 |
0.29 |
2.56 |
0.39 |
|
Vertical |
Horizontal |
6.1 |
0.16 |
2.10 |
0.48 |
1.25 |
0.80 |
Position of surface |
Direction of heat flow |
hi |
R |
24 km/h wind (for winter) |
Any |
34.1 |
0.030 |
12 km/h wind (for summer) |
Any |
22.7 |
0.044 |
Notes for both tables: