windows and doors in a Passivhaus
There are many aesthetic options to choose from when selecting windows and doors for a passivhaus project, however they all have one thing in common: high performance.
There are 3 key areas of the window that have to be considered: the construction of the frame, the build up of the glazed unit, and the type of spacer that surrounds the glass in it's frame. All of these elements combine to create a window with optimum performance, which will have a real, perceptible effect on your passivhaus project.
Compatible window frames vary from cross-laminated timber with or without aluminium over-cladding to insulated aluminium or UPVC. The glazed units are typically be triple glazed with Low-E coatings, which help to retain solar radiation inside the building once it has passed through the glass, and filled with argon or krypton gas. The spacers must be 'warm edge' as this is one of the parts of the window where the most heat is lost.
Passivhaus compatible windows and glazed doors must have a much lower U-Value than an ordinary window that meets the current Technical Standards. In a typical central European climate the U-Value for all glazed units when uninstalled should be ≤ 0.8W/(m2K); windows when installed should have a U-Value ≤ 0.85W/(m2K), and total solar energy transmittance (or the g Value) should be > 50%.