[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.