Triple-glazed vs. double-glazed windows?
Building new house – are triple glaze windows worth the extra $15,000 compared to double glazed? Both triple and double are insulated fiberglass frames. Triple – warranty is 20 yrs on frames, 10 yrs on glass & 5 yrs on hardware. Double – warranty is lifetime on frames, glass and hardware. Triple u-value is 0.17. Double u-value is 0.24. Location southwest Ontario Canada, zone 5. Any concerns on the weight of a triple glazed window? Is that why warranties are so different between the two? Is triple glazed over kill for my location? My research shows it would take approx 18 yrs to recoup the extra $15,000 in energy savings. I guess that’s why I’m wondering about durability / weight of triple glaze windows. Thank you.
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Replies
Triple glazed are better for comfort. Weight of the window isn’t really a problem for the framing, just make sure the unit is properly installed and you’ll be fine.
The difference in warranties makes me think your particular manufacturer isn’t very confident in their ability to produce a triple pane window. Are they regular manufacturers of triple pane windows, or is your project a special run for them?
I’m in the northern part of climate zone 5, and I’m in something of a cold pocket here (it routinely gets colder at my house than the weather reports for the larger general area), and I’m putting in triple pane windows as part of my residing/reinsulating project. I have a large expanse of sliding windows where there is a BIG difference in heat loss. The other areas are more for comfort alone.
BTW, if those U values are center of glass values, good triple pane windows can do better. If you want the best U values, you need a 1-3/8” IGU. The thinner triple pane IGUs, especially the 7/8” size, aren’t nearly as good performers as the thicker IGUs.
Bill
I would take a look at the Efficient Window Collaborative window selection tool and use that to easily and quickly evaluate the performance difference (assuming that your window choices are in the tool, or, if not, pick windows in the tool that are as close as possible to yours and see what you find).
Energy payback analysis on windows never works. They can't "pay" for themselves based on operational savings. But that is crazy to begin with. If the windows are a long service life investment, you need to get your money back when you sell your home. If your home is worth more because it is better performing, and in some part based on better windows, you make the economic choice based on value transfer at sale, not just based on operational energy savings See this blog I wrote: https://www.buildinggreen.com/blog/capture-green-value-over-time-not-short-term-payback-analysis.
Peter