I agree, @toodles, and I expect that's the scenario we're working on. However, if that were the case I'd've expected lots of reports from the French of cracked windows (which I haven't heard) so I'm yet to be convinced.

I do, of course, agree with @etchedpixels that shutters or blinds are a better solution but in my case it's a matter of finding a way to make those work on my windows.

Wrongly installed window films can crack double glazed units because you get trapped heat and very uneven heating if it's not done very well. No idea if simple whitening can have the same effect. Low E glass in particular is sensitive to it and most UK double glazing is low E (metal film).

Info from someone who sells the stuff as a kind of reference to back up the claim.

https://www.lustalux.co.uk/resources/does-window-film-damage-glass

You'll see other sources regard the risk higher but it's strangely enough people who sell film that think the risk is low and people who sell shading that think it's higher 8)

@majordennisbloodnok Oh Hello Mr. Bloodnock, this is your local garden centre here, may I interest you in a job lot of raring-to-go Leylandii trees? I might add that they are very quick growing and would produce shade wherever you might require it! Your Local Garden Centre.

Posted by: @etchedpixels

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You'll see other sources regard the risk higher but it's strangely enough people who sell film that think the risk is low and people who sell shading that think it's higher 8)

Yes, I did see that. One of the reasons I didn’t quote any sources I found suggesting the risk was negligible. Eventually I couldn’t find any opinions on either side that could be regarded as independent. Oh, the world in which we live….

Posted by: @toodles

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@majordennisbloodnok Oh Hello Mr. Bloodnock, this is your local garden centre here, may I interest you in a job lot of raring-to-go Leylandii trees? I might add that they are very quick growing and would produce shade wherever you might require it! Your Local Garden Centre.

I want shading, not firewood.

😉

@majordennisbloodnok Shade in the summer - warmth in the winter!

Posted by: @toodles

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@majordennisbloodnok Shade in the summer - warmth in the winter!

And carbon neutral. Pity about the particulates but otherwise good.

Generally speaking, we put the curtains over and close the windows where the direct sunlight is - oldest part of the house in the mornings, slightly less old part after lunch and in the early evenings. 

Up until the last hair dryer session, it never got hot enough in our house to be an issue. The oldest bit has massive thermal mass. The less old part, slightly better. The newest part is modern and we don't sleep in that anyway.

This time, even our bedroom got too hot at night - something like 26 degrees C. Trouble is, once hot, it doesn't shed the heat quickly.

So, we started leaving the tilt and turn doors in our bedroom open until .... the juvenile bats who live in the soffits seemed to lose their sat nav capability and started to get in through the tilt and turns! Luckily, only the odd one or two. We estimate about fifty bats share our home with us at this time of year and would prefer it if they stayed in their own bedroom and didn't come into ours.

Posted by: @etchedpixels

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Wrongly installed window films can crack double glazed units because you get trapped heat and very uneven heating if it's not done very well. No idea if simple whitening can have the same effect. Low E glass in particular is sensitive to it and most UK double glazing is low E (metal film).

Info from someone who sells the stuff as a kind of reference to back up the claim.

https://www.lustalux.co.uk/resources/does-window-film-damage-glass

You'll see other sources regard the risk higher but it's strangely enough people who sell film that think the risk is low and people who sell shading that think it's higher 8)

I've had a genuine velux roof window crack after fitting solar control film on the inside. That was several years ago and the first hot sunny day after installing it. Meanwhile three others with non velux double glazed units and also the replacement unit for the one which cracked were all filmed with the same film and no issues since.

As i work as window and door repairs, I know there's a recall notice for some velux units due to spontaneous cracking in cold conditions and there's plenty which aren't on the list that have also shattered for no apparent reason.If you have a velux with genuine glass, don't add a reflective film.

Since the film worked, but not enough for keeping the bedroom cool enough, I added one of the anti heat awning blinds and that's made a big difference.

https://www.veluxblindsdirect.co.uk/products/awning-blinds

@ian33a At 26 degrees and lower, a fan can be of help during the night.

@mk4 Too true, except the noise keeps me awake , and I sleep badly enough as it is !

@ian33a I am not easy with sleep either unfortunately….I have found the so called box fans to be acceptable though. They create a sort of low volume white noise that blends with the eerie noise (or lack there of) coming from the open windows (with screens to keep mosquitos out).

Trying to sleep when it is too hot is a torture. I ended up getting used to the box fan.