jon lopgel wrote :
I have no damp in mine either and never get
any condensation on the single glazed windows
when cooking and don't use the exhaust fan when
cooking.

I find that difficult to believe, because I have double have good DG
and even so I can get a tiny amount at the lower edge of the panes if I
forget to turn the hob extract on, when doing serious cooking.

Before I sorted this place out with insulation and DG, it was single
glazed, very leaky, fixed vents and suffered lots of condensation. In
winter ice would sometimes appear on the inside of the glass when it
was really cold. Internal RH is always between 40 and 50%.