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Article August 31st, 2005
Dr. Norbert Wruk
Coated double glazing units are a very common and cost effective way to reduce the energy consumption of commercial and residential buildings. Gas filling additionally improves their thermal performance. However, it is often disregarded, especially in resi-dential applications, that the window is the only ele- ment in the building which is also able to gain en- ergy. Due to the high transmittance for solar radia- tion, a properly designed window is able to compen- sate for the heat losses. Even at high latitudes con- siderable energy gains can be made, at least for south facing windows. On the other hand, the total solar heat transmittance can be reduced to a com- fortable level, if required. Therefore, not the product exhibiting the lowest U-value or the lowest TSHT but the product offering the best balance between heat loss and solar energy gain for a given application is the most appropriate. In medium term, architecture will change in order to minimise the energy demand for heating and cool- ing of buildings by making optimum use of the solar energy, which is collected through the window free of charge.