martinwinlow

(I should say I know very little about building swimming pools!) *Seriously*!! Are you saying heated swimming pools are not insulated (from the surrounding earth/whatever) at all?!! That sounds *UTTERLY BONKERS* to me? Why on Earth *wouldn't* you insulate the walls and floor? Having just got back from a rather nice stay at a spa up on the west coast of Scotland (where the outdoor temp was about 10C), sitting in their gorgeous outside 'infinity' pool overlooking Lock Fyne heated to 35C and wondering if one could use such a pool's heat to run underfloor heating in an adjacent house (so a bit off-topic but hope I'll be forgiven). The advantage would be that you could use the pool as a dump for excess renewable (we get *a lot* of wind up here in winter) and its capacity would be next to limitless so you would not have to export any electricity at all. Building the pool using insulated concrete formwork with an insulated base would be a doddle. You would have to come up with a way of keeping the heat in that did not involve using a conventional cover or it would look horrid (as ever). Maybe a retractable layer of twinwall polycarbonate or something sitting about a few inches below the surface... Anyway, just a thought...