why put aluminum foil on windows
Report Abuse. Aluminum foil is a conductor and it keeps the heat in. It also helps to keep the heat out. People put it in their car windows during the summer to keep the excess heat coming in.I'm sure they're not growing anything, xP. heard that aluminum foil is the only way to keep people from stealing your thoughts. That is why you will often see people battling with schizophrenia with tin-foil helmets and hats and putting it on their windows. If you are not dealing with a mental disorder though... I'd say you are either cheap or have a grow-op.