In uk.d-i-y John Beardmore wrote:
In message , Ian
Stirling writes
In uk.d-i-y raden wrote:
In message , Eric Sears
writes

I think the usual assumption is that the building will have significant
thermal mass internally, in the form of an insulated concrete slab, or
something.



That's not a standard feature of the solar water heating systems we
install. You are getting into the realm of the Hockerton Housing
Project design strategy here, but this has been criticised because of
the environmental impact if making the concrete. Ultra low thermal
capacity buildings also have something to commend them as long as they
can dump heat when required.

I'm not convinced it has no place - you would admittedly need a very
large additional thermal mass - a ton or two of water probably, to keep
the heating on overnight, with a 10-20C drop.

This is not of itself very expensive, though the places it can be easily
installed are of course going to be very limited.