Christian McArdle wrote:

I forget, but at building reg sort of U values, the vent loss is
getting close to dominating IIRC.


This can be easily sorted with heat recovery ventilation, though.


Capital cost is an issue.
Sometimes its easier to pay for the fuel.



Also, at least you gain something through ventilation losses, as you get
nice fresh air. Losing heat through the walls or roof gains you nothing
other than damp insulation if you don't have a vapour barrier.



No argument there.

However the point was, that beynd a certain point, insulation is
ineffective, unless you also deal with the ventilation issue as (e.g.)
you suggest.


Christian.