Terry wrote:

Another problem that can arise with very high levels of insulation and a
well sealed house, is large amounts of condensation.
In Scandinavian new builds I've seen this has been specially catered for.


Well, sort of. But ..............
Here in Canada with longer colder winters (and often heat leaching winds!)
higher values of the insulation reduce heat loss and therefore the cost of
heating ones home. Since the energy cost increases of the 1970/80s etc. much
thicker insulation has been the 'standard'. Most wood frame houses now have
6 inch wooden stud outer walls filled with insulation and/or sheeted with
foam boards, older homes 4 inch.
snip
Efficiencies of up to 80% heat recovery are claimed for the air/heat
exchangers but personally I doubt if that is true over a wide range of
temperatures. Not having an air exchanger in this older more 'leaky' and
less efficient house am not familiar with their operation in detail. They do
produce condensate which is drained away by a tube and do need cleaning of
the filters and heat exchanger core fairly often.. (How much water vapour
does a human breathes out during a typical night? A litre or two?

The air coming out of the lungs is at 37C, 100% humidity.
(the air coming out of the mouth may be a hair under this)
This works out at 40mmHg, or maybe 1/20th of the atmosphere coming
out.
At 15l/min, that's .8l/min of water vapour, or 384l/night.
As water, that's about 200ml or so.

However, it's only reasonable to insulate to the appropriate level.
Canada gets a mite chillier than the UK.
Insulating over what you need doesn't gain you anything, it just means
you have to do extra cooling.