What if you had your house insulated, and it actually worked!
At the end of August we had the entire first floor and beer hall roof insulated with Icynene spray foam. It costs more than fiberglass mats, but is a heck cheaper in the long run, easier to install, seals tighter, and has a lot more advantages.
Thing is, it really works, which in times can be annoying, particularly in the shoulder season (Übergangszeit von kaltem zu warmem Wetter oder umgekehrt), when you would like the place to pick up the outside temperature more quickly, in order to warm up the place without heating, or vice versa.
Here is a picture of the beer hall ceiling. Of course we still need to install wall and ceiling cover.
This picture shows to the right and bottom the spray foam in its raw installed form, after which it will be trimmed with a thin saw to fit the frame construction.