Thanks for your help. I did read a report of the decent homes standard. Here is my story incase you're interested, if you're not though feel free not to read
I live in a street of 20 flats some are owned by the housing association some have been bought.
There are 3 buildings that were built in 1928, 20 years ago these were renovated and central heating was put in. Roughly 22/23 years ago new windows were put in that are secondary glazing. They are now very draughty, we freeze in the winter with the draughts coming in, condensation is a nightmare in some properties and the window catches on most of them don't work properly so if you push the window the window catch, which is at the top, just gives way and the window swings open, very dangerous if you're in an upstairs flat with children.
There are also 2 other buildings that were built in 1976, these flats had single glazing until about 4 or 5 years ago when they were all replaced with double glazing.
I'm in one of the older flats and what myself and my neighbours can't understand is why the newer flats were given new windows but we weren't when ours are obviously in need of replacement as well. Someone had mentioned that they had to have DG but as you've pointed out this isn't true.
The Ha have said that windows have a life of 30 years but they replaced the newer flats windows after only 24/25 years. And they are lovely and have proper safety catches that children can't open so much safer than ours.
I guess it's back to the drawing board. We have a lot of issues with the HA as there are lots of things in the street that have been done to some properties and not to others etc and they're full of empty promises.
But thank you all for your help that clears up the question on the windows.