While almost all passive houses have advanced triple-glazed windows, many of those made in North America fall down in certain respects, particularly in the frames, which often seem like an afterthought, and have cold bridges allowing heat to escape and gaps where there should be insulation. But but for some reason, the manufacturers here just don’t seem to bother going all the way. This is certainly not true of windows made in Germany and Austria, whose manufacturers tend to have thought of everything. The downsides? Firstly, price. Such technically advanced windows can be very expensive. Secondly, weight. These highly engineered windows are often heavy and with the large spans of glass on our south wall, they will need a crane to be installed. However, if you cut corners on the windows and doors you undermine many of the insulation gains you make elsewhere. We also wanted wooden frames, not fibreglass, aluminium, or the most common but environmentally the worst solution of all, uPVC.
We have been lucky enough to find a solution. Again, through Malcolm Isaacs of the Canadian Passive House Institute, we were introduced to Optiwin, a co-operative of smaller window manufacturers in Germany, Austria and other Central European countries, and produces some of the best windows (and doors) in the world. However, they don’t have much of a presence in Ontario, or Canada more generally, yet. So we’re going to be one of the first customers for them, and as a result they are providing us with windows at a great introductory price, and will be sending over one of their installers to train our builder to install them. We’re using three of their products:
1. the new Resista aluminium-clad solid wood-framed, triple-glazed, inert gas-filled windows.
2. the new Motura lifting/sliding door, which is has the same window construction to the Resista windows and because of the ‘aircraft door’ type closing mechanism suffers from none of the poor insulation properties of standard French windows.
3. The Premium Frostkorken front door.
These are all certified at the highest performance level (A) by the German Passivhaus Institut. In fact, the front door may be the world’s only passive house certified door!