Facades and Summer Performance of Buildings - Low Energy Cooling for Sustainable Buildings - page 33

Figure 2.4 Distribution of irradiance from the solar simulator

Single Fa¸ade Energy Transmittance

The accuracy of the total energy transmission measurements was checked over a range
of single fa¸ade glazing with different U and g -values.
First a low-e coated double glazing (Isolar Neutralux premium) was measured and
compared with data from the manufacturer with U 1.4Wm − 2 K − 1 , g

= = 0 . 63 and

τ 0.52 for the optical transmission.

The experiment was carried out at boundary conditions of 475Wm − 2 external
irradiance, an external heat transfer coefficient of 25Wm − 2 K − 1 , an internal heat
transfer coefficient of 10Wm − 2 K − 1 , a room air temperature of 21.5 ◦ C and cooling
box temperature of 22.2 ◦ C. Measured, simulated and manufacturers g -values cor-
respond well ( g -value measured: 0.64; calculated: 0.63; manufacturers information:
0.63). The surface temperature level at the inside facing the room reached 27.6 ◦ C (see
Figure 2.5).

=

Figure 2.5 Temperature profile of double glazing without shading system