I find they do keep the heat out too, to a certain extent. Someone on the TV recommended that if the temps outside are warmer than inside then keep windows and curtains shut, so I tried it and it did help.Nope! Some buildings have it usually those open to the public like Supermarkets etc but not most homes. I think we are going to have to invest in it if our weather continues on a warmer trajectory.
I think our homes were built more with winter in mind, so double glazing is common loft insulation & cavity wall insulation, all to keep the heat in![]()