Why do people put aluminum foil on windows?
aluhm > 02-23-2018, 06:05 AM
Mostly, it blocks out the light. It also blocks infrared radiation, so it keeps sunlight from heating the inside. And it blocks radio waves, so it makes it harder for your cellphone to get a signal, as well as makes it harder for your neighbors to hijack your WiFi.
But mostly it's to block out light, for people who are willing to be penny wise and pound foolish.