Living in a suite with no air conditioning in Princeton this summer. The first week was disgustingly hot + humid, even with my fan going full blast. One of the negative features of the suite is that all of the afternoon sunlight beams directly through the huge glass windows in our common room (and bed rooms).

Fortunately it's a suite full of engineers, so we decided to turn our suite from a green house into a high-albedo nerd-cave.

Behold:







The effect was almost immediate, and right now there is a huge temperature gradient between our suite and the center stack of the dorm. The other cool feature of this project was that the air between the window and the aluminum foil was getting very hot (probably around 185F - 200F), as we were taping the sheets up, and they were inflating like balloons away from the wall.

Whoa, that's an awesome experiment! Now you need to figure out how to harness all that heat into an Einstein-Szilard refrigerator to cool the rooms down further. Or something; surely that degree of heat is useable.

About how hot was the room before and after the aluminum foil installation, and about how much time did it take for the temperature change? You could cook food with the heat...

Find a way to heat the small space between window and foil more and bake cookies.

I bet with some judicious curvature of the foil, you could concentrate enough heat on a single point to make that a reality. You could definitely at least make omelets with that heat.

The change was noticeable almost immediately. Yesterday it felt like mid/high 70s after we installed the foil, and mid/high 80s before. Today it's definitely cool in here, but the day is also much cooler than yesterday (overcast), but there's about 4 degree difference between here and the central stack. If it's sunny tomorrow I'll get a better feel for the real magnitude of the effect.

[edit]

The cooking would be interesting. It would be hard to put more space between the window and foil since we have shades pulled down over the top of it, to diffuse the beams that manage to reflect their way in between the sheets of foil when air pocket is inflated.

One thing that crosses my mind is a thermal electric chip for running some small fans or LED lighting or something.

Is the aluminum foil hot too?

yes, that's how we estimated the air temperature between it and the glass.

Did any of you accidentally touch the foil?

We had to pin it to the window to tape some of the bubbles down to keep light from coming through the larger cracks. So not accidentally, now.