When we were researching windows for our zero-energy house the reply to our questions about triple-pane windows was often “what do you want to do that for?” The common thinking is still that nobody really does it (not true, the Canadians and Europeans do it), and that it costs too much (although we actually make a choice between spending more on heating fuel versus insulation, windows and in turn less on oil or gas). Evaluating things strictly from that outdated ROI (return on investment) perspective is reductionist and simplistic in this day and age of climate change, need for sustainability, increasing energy costs and depletion of fossil fuels in the not so distant future.
Walls are of course by far the best insulators, but since we can’t live in the dark for the sake of our energy bill we need windows. Yet, there are windows and windows and windows. Typically, a house loses 20% of its heat through the windows, more if they are single-pane and old. That adds up to hundreds of dollars per year in utility costs that literally go out the window.
For over twenty years, while living in a 200-year-old house, we did just that, heat the outside. What kinds of windows you replace your old ones with, or buy for your new house, and where you place them (here in the northeast we lose the most heat in the north, and gain the most in the south) makes a big difference.
Besides the considerations of the frame material- aluminum (cold)/vinyl (better)/ wood (best insulator) -, frame type – casement or double-hung (casement closes much tighter and therefore prevents heat loss), frame hinging – swinging in or out (it is much easier to clean and doesn’t catch the wind on a breezy day), there is also the glazing consideration.
In colder climates, like here, where the heating season is longer than the cooling season, we profit from high heat gain glazing on the south side, which lets the heat from the winter sun penetrate the glass. In warm climates on the other hand, such as Florida, where the cooling season is longer than the heating season, a house profits from low heat gain glazing on the south side, because this glass deflects the sunlight.
Because of their colder climate, the Canadians have already jumped on the triple-pane bandwagon, albeit out-swinging windows with vinyl frames. They are better than the ones found south of the border (we don’t believe in them yet). The Europeans, however, make by far the best windows with far superior wood frames. Roughly, a European double-pane window compares to a Canadian triple-pane window in energy efficiency. In the European Union triple-pane windows will be the standard for new commercial construction beginning in 2019, and for new residential construction as of 2021.
Cost is of course always a consideration in any renovation or construction project, as are priorities. If neither your roof nor your walls are (well) insulated, forget about the triple-pane windows. If, however, you are building new or have improved all other aspects of your home, triple-pane windows are worthwhile looking into.
We love our European triple-pane windows. No drafts whatsoever; a heat gain of up to four degrees on a freezing cold sunny winter day in the room with the big southern windows; the entire panel (not just half, as in the double-hung kind) opens wide to the inside for easy cleaning and quick effective airing out; the frames close very tightly and lock in several places, which prevents air leaks and also makes them very secure; and lastly, they optionally tilt open at an upward angle to let air in without taking up window sill space or letting rain in on a wet day. www.susannemeyerfitzsimmons.com