Rather little, and with district heating it's a non-issue. You can make it a "plus house", producing more energy than what it consumes using solar panels.
My point rather was that living in a really old badly insulated house or a place with horrendous building standards is a choice, and that has to cost something and not be what we aim for when alternatives are easily possible and has been for decades.
My point rather was that living in a really old badly insulated house or a place with horrendous building standards is a choice, and that has to cost something and not be what we aim for when alternatives are easily possible and has been for decades.