[Retric]

Assuming it is actually 60k, where in reality insulation is cheap. Having giant windows is useful for passive heat gain, but their mostly installed for aesthetics not practicality. Which means aesthetics are also increasing home values.

In terms of pure economics an extra 15k in insulation and 15k for a solar hot water system gets you further at much lower costs by actually providing hot water for showers not just lowering heating bills.

[jaclaz]

I think you are downsizing the project, from investing 60K to save 3K/year to investing 30K to save 1.5K/year.

[Retric]

No, I am saying you would save that much money more cheaply via other methods.

Sure, saving 3k/year on heating costs for a single family home is extremely high. An average 1,800sf house in Massachusetts on $1.87/therm natural gas is only projected at $1,243 / year in heating bills for 2021/2022. That said you can always build a larger house, so saving 3k/year isn’t impossible it’s just much easier when you include better methods to collect sunlight than covering a side of your house in giant windows which have low R factors because their giant windows.

PS: Insulation alone can only make so much difference. In other words you might save 1000$/year going from R10 to R20, but then going from R20 to R30 doesn’t also save you another 1,000$. Very quickly you’re better off collecting energy rather than reducing heat loss.