Conclusions - Low Energy Cooling for Sustainable Buildings - page 249

7
Conclusions
The energy consumption in buildings has been analysed with a special emphasis on
summer performance and low-energy cooling supply. This focus is supported by the
ongoing implementation process of the European Energy Performance Directive of
Buildings, which contributes to the development of unified and transparent calcula-
tion methods not only for heating energy, but also for cooling, lighting and electricity
demand. The main factors contributing to the summer performance and thermal com-
fort in residential and office buildings were studied using laboratory experiments and
monitoring results from buildings. In addition, passive and active cooling systems
were developed and analysed.
The thermal performance of glazed fa¸ades in various construction typologies
was characterized in detail, as they determine the external loads of a building. It
was shown that the total energy transmittance through single and double fa¸ades
can be low if sun protection devices are used effectively. Double fa¸ades with
varying blind locations achieve g -values measured under a laboratory solar simu-
lator of about 10%, that is lower than a single fa¸ade with closed blinds. Fa¸ades
implemented in a building have even lower measured g -values, as incidence angles
especially under summer conditions are high. Secondary gains only play a role in
fa¸ade systems with low-e coated glazing, if no shading is used. The shading element
reduces the room-side surface temperature by about 6 K at irradiance levels around
500Wm − 2 .
However, there are non-negligible ventilation gains if the ventilation air is taken
directly from the fa¸ade. Air gap temperature increases were between 2 and 6 K,
depending on the free cross-section of the air entry. The measured blind temperature