Probably due to differences in standards, like wall isolation (I don't know the english terms). My house has 25cm isolation in the walls and 40cm isolation unde

Probably due to differences in standards, like wall isolation (I don't know the english terms). My house has 25cm isolation in the walls and 40cm isolation under the roof. I also have 3-layer windows and a thick metal door. The ventilation system is isolated and the air heat is reused to save electricity. This is for a 260sqm house.