For listed buildings, you've got to get permission from the council. For most buildings they'll let you put in double-glazed windows if you can get them in a style that matches the existing windows.
One of the iconic features of many Art Deco buildings is curved windows [1], and the flat windows having very skinny frames. That means nonstandard "heritage" windows, which can be several times the price of normal, mass-produced windows.
Blocks of flats have the additional problem that it's unlikely every owner will have the cash to replace their windows at the same time. So it's tough to save money by getting them all done at once.
> For listed buildings, you've got to get permission
Sure - it's the same in our country, with the additional trouble that there is a special institution that has to approve any changes in protected buildings and they are pretty harsh. And even then lots of them get updated.
> Blocks of flats have the additional problem that it's unlikely every owner will have the cash to replace their windows at the same time.
We have that too and what usually happens with changes that apply to the whole building (like the whole facade) is that the community of the owners finances changes like that with a credit on the whole building, there are special laws for that. Happens less often with just the windows because they are so cheap most people can afford them on their own.
One of the iconic features of many Art Deco buildings is curved windows [1], and the flat windows having very skinny frames. That means nonstandard "heritage" windows, which can be several times the price of normal, mass-produced windows.
Blocks of flats have the additional problem that it's unlikely every owner will have the cash to replace their windows at the same time. So it's tough to save money by getting them all done at once.
[1] https://maps.app.goo.gl/uWUr5YyvJvRDPkH27