[tda]

Technically feasible sure, but I thibk I used 1100m3 gas last year (would have to look it up teo be sure). So to invest 30000 euro to save 50% of that makes no economical sense. Only when the windows need replacement anyway I'll upgrade to the latest and greatest. But for now I'm conetemplating investing in a moderate air/air heatpump (about 5000 euro, 5kw or something). I think that will also reduce my gas consumption considerably for all but the coldest days. Because labour is so expensive and replacing all windows is so wastefull (they are all oldish double layered windows) better insulation is not so appealing.

I must say though that a properly insulated house can have a better climate in winter as you can keep the humidity much higher.