Facades and Summer Performance of Buildings - Low Energy Cooling for Sustainable Buildings - page 36

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

Figure 2.8 Summary of laboratory g -value measurements for double fa¸ades with varying blind po-
sition, changing air gap free cross-section and blind tilt angle. The last two bars show a single fa¸ade
without and with a blind

temperature levels increase with decreasing air flow rates, the measured influence on
the g -value is negligible.
Measurements were also taken on the double fa¸ade system where the sun shading
position was varied within the 0.5m air gap. The influence on g -value and temperature
levels was negligible. Within the measurement error of the calorimetric equipment,
neither blind position nor free cross-section of air entry have a significant influence
on the total energy transmittance (see Figure 2.8).
The measured energy reduction coefficients F c can now be compared with values
from the literature (Table 2.3).

2.2.2 Building Experiments

An experimental investigation of a double fa¸ade system similar to the labora-
tory set-up was carried out at the Zeppelin Carre business centre in Stuttgart (see
Figures 2.9 and 2.10). This partly historical building block was restored in 1996 and a

Table 2.3 Measured energy reduction coefficients of fa¸ades with sun shades compared with values
from the literature
Fa¸ade Sun shading Colour Energy Literature

system reduction coefficient values

Single External Grey 0.23 0.13-0.30

Double Gap integrated Grey 0.23