Reading this article one thing shocked me: Do a lot of homes not have double glazing in the UK? I thought it was a standard, because it's so much more efficient at keeping cool/warmth inside/outside (depending on season)
I would say it would be unusual not to have double glazing these days. It has been a thing for decades and there are grants available to make your property more energy efficient.
That said there are a lot of a) old buildings that are protected and so can't have the windows replaced easily/in an economically viable way (e.g. each window needing to be hand-crafted in wood to non-standard sizes to look identical bto what was there before), b) a lot of just properties nrented out to single people who rent a single room etc and the landlord simply doesn't care/bother, c) houses that were lived in by someone for the last 30/40/50 years where basically no maintenance or decoration had been done - they've died and someone else had moved in.
My house in Surrey and several others around me were built in the Edwardian era 1900-1910 and they are all single glazed. The windows are made of timber with very attractive moulding around it. Most double glazed windows are made of PVC (plastics) and they look very plain. Double glazed timbers windows are extremely expensive.
All the previous homes I lived in had mould fungus growth on walls and behind wall papers. The double glazing ensured air-tight house but lack of air circulation. Single glazed windows seem to be really good at preventing mould growth, of course at the extra cost of heating bills.
I used to live in the UK 10 years ago and back then it seemed like double glazing was some sort of luxury while where I moved from it was the standard and people were converting old houses to it as well. Where I live now people use triple glazed windows...
