A passive house consumes up to ten times less energy than a standard building. To achieve this, every component of the building envelope — including windows — must meet strict requirements. Here are the criteria to follow.
Thermal requirements: Uw ≤ 0.8 W/(m²·K)
The Minergie-P label (Switzerland's equivalent of the Passive House standard) requires an overall Uw ≤ 0.8 W/(m²·K). This systematically requires triple glazing and a thermally enhanced profile. The Kömmerling 88 MD (PVC) and Aluprof MB-104 Passive (aluminium) systems meet these requirements.
Triple glazing: the essential standard
Triple glazing (Ug ≈ 0.5 to 0.6) is essential to achieve passive house performance. It consists of three panes of glass with two argon- or krypton-filled cavities and at least two Low-E coatings. The solar factor (g-value) must balance useful solar gains against summer overheating.
Profile quality and airtightness
The frame accounts for 20–30% of a window's surface area. A Uf ≤ 1.0 is necessary to avoid undermining the overall Uw. Equally important is the installation itself. Airtightness (blower door test) depends directly on the quality of the perimeter sealing. BO Fenster uses certified sealing systems and airtight tapes.
Orientation and glazed areas
In a passive house, south-facing windows act as passive solar collectors. A south-facing triple-glazed window can generate more energy (solar gains) than it loses through conduction in winter. The architecture must balance south, north and summer shading surfaces (roof overhangs, external solar protection).
BO Fenster solutions for passive houses
BO Fenster offers the Kömmerling 88 MD (PVC, Uw down to 0.77) and Aluprof MB-86 SI (aluminium, Uw down to 0.79) systems for passive construction projects. Every project is analysed with a precise Uw calculation to EN ISO 10077. Contact us for a free technical consultation.
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