The current awful trend would be hilarious if it wasn't actually dangerous. And by that I mean modern UK houses are very, very well insulated. And we recorded our first 40C temperature in England. There's a reason why houses in the Mediterranean are absolutely not grey, and are very definitely white. There have even been one or two TV programmes where they've measured these houses and apartments having indoor temperatures of high 20s low 30s C, long after the sun has set.
It could be. A well insulated home requires cooling of some sort to stay cool or it will heat up, as it contains heat sources and is well insulated. That gets harder as the outside temperature rises. This has nothing to do with the colour of the building, though. And it's not something you can ease by removing the insulation – that actually makes it worse as now the high outside temperature might just make the inside temperature even higher.
Insulation resists heat transfer in both directions. Extremely well insulated and air sealed homes resist heating up just as much as they resist cooling off.
Windows are a bit special in that you can get solar gain through them, but modern windows can have coatings that filter UV and IR from entering a building.
People and electronics are heat sources inside a home, but pretty minimal ones. Any reasonably speced ventilation system a modern home needs to exchange outside air will easily handle keeping a modern house cool.
Most UV and IR doesn't actually need any real coatings. Glass just isn't transparent to that light, completely by itself. It's actually specifically the imperfections in said glass which cut out the most dangerous part of UV radiation, and it's the inherent temperature which messes with IR.
"insulation - noun [ U ]
the act of covering something to stop heat, sound, or electricity from escaping or entering, or the fact that something is covered in this way"
In common language usage, UK houses are insulated to stop heat escaping in our mostly temperate climate for energy efficiency reasons, not to stop heat entering.
Everyone opens their doors and windows in the UK allowing the heat in. Aircon is rare, but increasing. So houses stay hot long after the afternoon peak.
This issue with hot houses would be solved with better insulation. Better insulation would also increase energy efficiency in both hot climates and cold.
I think you need to use a more precise term, maybe something like heat retention.
1970s-80s: stone cladding.
1980s-90s: cream brickwork, porticos
1990s-00s: boxes with white upvc windows, red tiles, garages
2020s: grey plague - grey windows, grey doors, grey plastic faux-wood cladding, grey roof tiles, car 'ports'.
The current awful trend would be hilarious if it wasn't actually dangerous. And by that I mean modern UK houses are very, very well insulated. And we recorded our first 40C temperature in England. There's a reason why houses in the Mediterranean are absolutely not grey, and are very definitely white. There have even been one or two TV programmes where they've measured these houses and apartments having indoor temperatures of high 20s low 30s C, long after the sun has set.