Yes, aluminum foil can be used over windows to help keep homes cool

[SheltieLover]

https://www.localmemphis.com/article/news/verify/weather-verify/aluminum-foil-windows-cool-heat-wave/536-69a28e6f-0cef-4ae4-a730-fb29e42733a6

Emergency management agencies specifically recommend using aluminum foil-covered cardboard that goes between windows and drapes.

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People took to social media to share ways people in homes with no air conditioning or poor air conditioning could fight the heat and stay cool. One method in particular stood out because users claimed it was both cheap and effective: covering windows with aluminum foil to reflect sunlight and the heat back outside.

A TikTok video sharing the method got more than 100,000 likes and several tweets sharing the tactic received thousands of likes and retweets. All of the posts tell people to black out windows with aluminum foil.

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The Federal Emergency Management Agency (FEMA) published a June 29 blog post that included the aluminum foil tactic among six ways to combat extreme heat.

More at link.

Heat wave here in TN is brutal. 98-100F forecast for another 10 days, as far as my app projects. With near 100% humidity & a very high dew point every day, it is miserable outdoors.

For anyone interested, there is also attic foil. Various brands available. One friend paid ~$200 for a 1K sq ft. Roll (this friend is not a frugal shopper. I found a 1K sq ft roll for $93.) You staple the foil to roof rafters to reflect heat from roof away from house. The products I looked at have very good reviews & friend who installed it said it kept his upstairs a few degrees cooler.

Stay cool!

[4139]

1. B-)

[Pobeka]

2. We've used white posterboard for years to do nearly the same thing. nt

[ggma]

3. We kept a box fan in the front window.

At dawn, you pulled in cool air. Before noon, or the hottest part of the morning, you turn the fan around and it pulled the hot air out of the room. Better than no relief at all...

ggma

[multigraincracker]

4. I like cheap and simple.

Thanks for the tip.

[Old Crank]

5. The foil or other reflective device

works best when sun hits the windows.
Our previous house had windows facing north and south mostly. The west ones were shaded by trees.
At night when ever the sir temp was lower outside we opened the windows and sliding door and drew in cooler air with a box fan.
In the morning when the house was at its coolest and outside temps started to rise we closed all the drapes and windows to maintain the cool. Rinse lather and repeat.
You can dampen towels to put in the airflow from the fan to help drop temps if you are in a dry climate. Don't have the wet air drawn through the fan's motor.

[SheltieLover]

6. Yes, with the exception being attic foil (radiant heat barrier)

My roll arrived today (~$130/1,000 sq ft!) & is being installed as I write!

Holding hand over hot burner, then holding a piece of this foil above burner truly does eliminate nearly all heat! Claim is 97% heat blockage!

Genius!!!!!!

A great investment, imo. As more & more buy electric cars, rates will soar!

Stay cool!