We have a house from 1978 that still has the original single-pane windows. The contractor says that new windows with insulated glass would pay for themselves in 15 years, but I'm not sure if that's realistic. Does anyone here have concrete experience with how much heating costs actually drop?
The 15 years is honestly being optimistic - with single-pane windows from the '70s, new windows do save a decent amount, but how much really depends on your house, heating system, and how you use energy. Some people report 20 - 30% less in heating costs, others say more like 10 - 15%. The big catch: contractors often calculate based on current high energy prices, and if those drop at some point, the payback period obviously stretches out. Plus it matters how much heat loss is actually happening through the windows - if your walls and roof are poorly insulated, you'll notice the window effect less.
Realistically, probably 20 - 25 years for payback under average conditions, potentially longer if your house has other weak spots. But here's the thing: new windows also bring immediate comfort (no drafts, less condensation, better soundproofing) and boost your property value. If you need to replace the windows soon anyway because they're old or not working properly, upgrading to better glazing pretty much always makes sense. I'd rather ask for several quotes and see if you could also insulate walls or the roof while you're at it - the whole package is what counts 🪟
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