Passive house windows - a dual function

Windows play an important role in passive houses in two ways; firstly, they can reduce heat loss despite their large areas of glazing and secondly, they allow the sunlight to produce additional heat through the glass.

With Internorm windows and heat-conserving glazing as installed in passive houses, it is possible to achieve Ug values of 0.58 W/m²K. These windows have two infra-red reflecting coatings and are filled with crypton or argon. This means that the surface temperature of the glass inside the room is comparable with the air temperature of the room itself. The amount of total energy-loss (g) with triple glazed Internorm windows is around 50%, depending on glazing and gas-filling. Where these window systems are installed in a south-facing position the heat gains even from December to February are higher than the heat losses.