I was particularly looking for windows with wood frames for the aesthetics, exterior aluminum cladding for the low maintenance and a high visible transmittance. Visible transmittance (VT) is simply the amount of light the windows let through. Some of the high-efficiency windows I looked at had VT values below 0.5. In other words they let through less than half the light. I'm going to have a beautiful view - I want to see it. These windows have a VT of 0.71.
The windows that I found that fit the bill have to be imported from Europe. There are manufacturers of high-efficiency windows in North America but very few that offer wood frame windows. Luckily there's a distributor in Cambridge, Yaro Windows, that imports these windows.
The doors will be fully glazed as the triple-pane glass has a significantly higher R-value than solid panels would have. I will admit that I'm a bit concerned about privacy for the entry door but I figure I can always add a curtain on the interior if it turns out to be a problem.
Many of the windows, particularly the large windows facing the lake will be fixed rather than operable. The frames on the fixed windows are quite a bit narrower which not only allows for more glazing, and thus more light, but also makes the windows more energy efficient, as the R-value of the glass is about double that of the frame. And while the seals on the operable windows appear to be very well designed, nothing's going to beat a fixed window for tightness. Oh, and the fixed windows are significantly less expensive than the operable windows and these windows ain't cheap.
Here are the details on the windows:
|YARO Energy+ Aluclad Makrowin – MW88
with corresponding Uf-value of 0.185 Btu/(h·ft·°F) (R 5.4)
|Tripe Glazed Low E Insulated with Warm-Edge Spacer System
Ug-value of 0.088 Btu/(h·ft²·°F) (R 11.4)
SHGC of 0.50
VT of 0.71