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.
The projected cost of ccs is much less than $4000/mo even for a oil heated home though.