advanced building skins 14 | 15 June 2012 - lamp.tugraz.at - Graz ...

E [kWh/m²/ °
Advanced Building Skins
The maximum value for incident solar irradiation in winter is smaller than in summer for
south oriented vertical surfaces, but when taking into consideration that the total solar
transmittance is much greater for incident angles of 20° than for 70° (see. Figure 4), the
seasonal effect of the thermal impact on the building is only relatively weak.
January; 22nd Dec – 21st Jan (blue),
December; 22nd Nov – 21st Dec (red)
- 5 -
June (blue); 22nd May – 21st Jun,
July (red); 22nd Jun – 21st Jul, [3]
Figure 6: Angle-dependent distribution of total monthly irradiation incident on a south-oriented,
vertical surface in Freiburg for selected months
Even in months (Figure 7) that have their maximum of incident solar irradiation at an incident angle
for which the g-value is less than 5% inaccurate (see figure 4) more than 30% of the annual energy
impact occurs at incident angles for which the g- value is more than 15% inaccurate.
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
0 10 20 30 40 50 60 70 80 90
[°]
March; 22nd Feb – 21st Mar (purple),
October; 22nd Sept. – 21st Oct (light blue)
0
0 10 20 30 40 50 60 70 80 90
[°]
September (green); 22nd Jul – 21st Sep,
April (yellow); 22nd Mar – 21st Apr, [3]
Figure 7: Angle-dependent distribution of total monthly irradiation incident on a south-oriented,
vertical surface in Freiburg for selected months
E [kWh/m²/ °
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5