So before we had our new double glazed sash windows installed we had single glazed, not original. We were excited about the house being better insulated with double glazing but why did no one tell us - the new sash windows would now need to be open almost the entire day to ensure that the house remains smelling fresh and not like 3 day old sock clunge.
So basically the better insulation is completely redundant!
Before we had the new windows the house could breathe evenly without opening the windows and the air remained constantly fresh and not stuffy.
Now if we don't give the house a good airing every day the smell is just awful and stuffy and we are pretty clean people.
Anyway, this is just a word of warning to anyone thinking that double glazed windows are a saviour for insulation because if you like a fresh smelling house they will always be open, even in zero degrees!