Will that radiator heat reflecting thermal silver stuff work on sunshine?

[Cotherstone]

You know the stuff that you put down the back of the radiator to make a room warmer - will that work to block sunshine through a window, like tin foil does, or will or just absorb the heat?

It should to an extent but it would have to be on the outside and it would probably be pretty awful for people walking past as a bit dazzling. Silver foil or white paper would work. Your making a sort of temporary shutter situation, like when you go to hot countries and they have the shutters shut when it’s very hot. It wouldn’t be as good as actual shutters obviously.

It reflects the radiation.

Well, I've just out my winter ones (which go on the outside of the car to stop the windscreen freezing) on the inside of the windscreen and it's made a difference.

I’ve gone for tin foil today as I can’t find an answer properly - I think it should just reflect heat but worried it’ll absorb some and make it worse!

The idea of it is to reflect heat back into your room from the radiator, so I would expect it to work. I’ve found some & will be using it (on the windows not facing the street as after might dazzle drivers)

Yes.

Yes, it will work a bit. It’s like the insulated, shiny accordions people put in front windshields when parking in Florida.

example: www.amazon.com/EcoNour-Accordion-Windshield-Automotive-Sunshades/dp/B08T743444/ref=mp_s_a_1_16?keywords=windshield+sun+shade&qid=1657979430&sr=8-16