Monday 16th January 2017: 12.46am.
One of the really surprising things about cheap double glazing is that the glass typically loses far less heat that everything surrounding the glass which, because it's cheap, tends to be completely uninsulated because consumers don't realise until they find their double glazing install still leads to cold draughts coming down off them and condensation and mould forming all over them. Here is proof: this is our back door earlier tonight on our rental which is a former council house which was upgraded with cheap double glazing. The windows themselves aren't thermally too bad apart from the gaps in the seals letting cold air in when it's windy, but as you can see the door is truly awful, the frame is basically a hard cold thermal bridge to the outside and is unsurprisingly constantly wet from moisture, so it gets constant mould growth. This is despite the panes in the door being actually pretty insulated, but the frame lets the lot badly down.