Passivhaus Pillar No. 2. High Performance Glazing
Windows can severely impact on the heating and cooling loads of a building.
Up to 40% of a home’s heating energy can be lost and up to 87% of its heat gained through windows.
There are many type of frames and glass to choose from when building or renovating a home. While this pillar of a passivhaus focuses on the glass, its also important (and it’s why you can’t just focus on one pillar at a time) to consider the frame that glass sits in.
The reason we choose to use uPVC frames on our builds is because it’s the most economical way to eliminate thermal bridging (another passivhaus pillar).
The bare minimum in passivhaus standard is double glazing.
If you’re looking at timber frames, they are very sustainable, and beautiful to look at when they’re finished, however one of the hardest things about wooden frames is that they move around seasonally because timber expands and contracts with changes in moisture.
This can make it difficult to maintain a good seal between the sash and frame, if the seals are able to become loose during summer then you’ll get greater air leakage and then the house won’t perform the way that it’s meant to.
The other thing is that timber costs more. If you want to more about building a passivhaus, download our guide to the five key skills of a passivhaus builder.