Kitchen foil on windows in full sun

[WindyMillerDrinksCider]

I've put kitchen foil on the inside of double glazed windows at the front of the house to keep the heat out. It's really effective because they get full sun. However, Google says it can crack the glass because of the heat so it should be put on the outside.
Does anyone have experience of this either way - cracking or no cracking?

Just use this stuff, it’s actually designed for the same thing and doesn’t come with the risk of cracking or the metal foil discolouring the glass- that happened to my daughter and her window looked horrific like it was marbled in different tones of brown. They had to replace the unit which was fun on the 4th floor .

https://amzn.eu/d/0fy21M1Q. This stuff has honestly coached my bedroom temperature for the best, I can sleep at night!

I have heard that reflective film and even blackout blinds can cause such high temperatures on the glass that the window can crack. I have film on one window in full sun and it’s been fine so far, but it’s tinted rather than fully reflective. I would be cautious with tin foil

Thanks both. I've taken it off - not worth the risk.

For now pin up a sheet on the outside of the window. That way the sun doesn't heat up the glass so much. Can make a good few degrees difference

I use the the silver side from rescue blankets indoors for years without issues.
(silver side looking out) https://www.amazon.co.uk/MIXIAO-Emergency-Survival-Blankets-Marathons/dp/B0CR651FQS/ref=sr_1_2_sspa?dib=eyJ2IjoiMSJ9.rc4deHBOSDaRRFsscUTtX9_IA5qqIlDewRK2AuCgGqga_6HF689C_6rQPWYuf9fcKtN0vKn5aJpDX4lW41P-VVlTaTxMNfmBsHNydlb4UXPQwTAijMnhpqubmkI0_Hyf8OXMLKXYYbd-t56NMGuJw6flyDCvnkTmGL2J3zD6mr3BY81CY4kImTxYZoUzLvs5FHjB6lEWCQJeeIeNla0xR1deH8CY-HzYtzMxsQ44kJK30OxIlS4PFr4EkNgZAwrKxT1X_b_jL_kX9mxlMgRzuTU7raZSm8tk7yb7f9VUwdo.2JoePW1GIa8gc9btwqznzKRuGLvzjmzrB5YhE2dTg7w&dib_tag=se&keywords=emergency%2Bblanket&qid=1782127432&sr=8-2-spons&aref=FkRrWrQPOk&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1

According to my double glazing firm …

We have to allow glass in double glazing to contract and expand as necessary.
Take care because it can crack or smash if we mess around with its natural capacity to do its job.
www.google.com/search?q=can+foil+on+windows+cause+it+to+smash+in&ie=UTF-8&oe=UTF-8&hl=en-us&client=safari#lfId=ChxjMe

We just keep the curtains closed on that side of the house until the sun moves round.

I’ve just ordered this. Thank you

I just close the curtains.
I have air con so im nice and cool right now indoors is 20.
Might have to turn the AC up as I have just put fish fingers in the oven.

Tinfoil though I dont think thats a good idea.

I did this it really cooled the room but buggered the window, it’s got a horrible stain on it.

lol - How comforting for the OP to know that your house is a little chilly.

Its comforting to me.
Its called planning, I didn't have any of it when we had 40 degrees years back so I made sure not to get caught out again.

We've used these on the outside of our Velux windows and it's made a huge difference.

Irrelevant to the thread, but yes I have friends i think we all do.

MIL’s window cracked due to one of those stick on blackout blinds on the inside , with direct sun on the window.

I’d put it outside or find a different solution

Nooooo. I did this and the glass cracked. It traps the heat between the layers of the double glazing.

😂

I bought a silver/grey version of the blackout blind for last year’s heatwave. It’s more like IKEA’s thermal curtain liners and it might help that it is pale, rather than black.

I have it hanging loose in between a blind and the windows on our very long landing window and a rather inelegant piece is held up with over the largest skylight in the kitchen. Ideally we’d have that on the outside of the window (which I might attempt if I can bribe a few of the Madcat household to get up some ladders to help manoeuvre it).

It’s not really about planning though. AC units are expensive and running them is expensive, if you are going to get a decent one, you need to put a hole in your wall for the exhaust pipe. For many people it’s an unjustifiable expense when we only get a month or so of unbearably hot weather.

I used to do it every heatwave and my windows never cracked. Both double glazing in the previous house and old fashioned wooden sash windows in an old flat were fine

Air con is totally worth it because you can use it for heating in winter as well! Last year I got two energy-efficient mitsubishi units for £3500 including labour and I haven’t regretted getting them a single time. Not expensive to run, can use for heating in winter, dry out moisture from the air, winner on all fronts

I have a beach towel thrown over top of back half glass door. It really helps.

There are some really good fans out there and portable AC units.
Just buy when pices are low good tip buy in winter time.
And it is about planning on somethings.

Well said.
I got mine after the huge heat wave a few years back.
No regrets.