New-build vinyl windows – durable enough to justify triple-pane?
I’m building a new house in climate zone 4-marine and have bids back for regionally-manufactured vinyl windows, both double and triple pane. Depending on the brand, triple-pane is 10-25% more, or about $3-7 per rough square foot. U-value goes from 0.27 (code minimum is 0.30 here) to 0.20 with triple-pane. The sales guy cautioned me that vinyl windows are not multi-generation investments and may begin to fail before the extra layer of glass pays back. So should I just be happy with a great value on U=0.27 windows, or am I missing an opportunity to spend a little extra up front for better performance? And is it reasonable to assume that new vinyl windows will simply be replaced within 50 years by something better?
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Personally I don't see the need for triple pane in your environment, U.27 in a dual pane is more than adequate in zone 4.
Depending on location and orientation you might want to look at windows with a bit higher SHGC LowE coating that would offer better visible light transmission and solar gain numbers in a marine environment.
As to how long the windows will last, who is the manufacturer? There are really good and really average, and really bad vinyl windows on the market (same goes for wood windows), and the good ones are going to outlast the bad ones. Without context I'm not sure how to interpret the salesman's comment about multi-generational.
Can they last 50 years? I would expect higher quality vinyl windows to last well past 50 years, but some of the junk versions I would expect something more like 10 to 15 years. As you alluded to in your comment, and just like most technology-based products, there will certainly be better windows available well before 50 years, but that doesn't mean that current technology has failed, only superseded. Technological evolution at work.
I will probably order windows from Prime: https://primewindowsys.com/ I see a lot of their windows around here, but I don't know whether they would be considered "really good" or not.
In Zone 4, I would only spring for triple panes if I had condensation issues in the past that I was trying to avoid or if I had very large windows where the lower interior glass temperature could result in noticeable drafts.