According to PGE, 80 percent of residential customers have air conditioning of some kind, but while they keep your home cool, they cost money to run. So here are some tips to help you keep your home cool with or without air conditioning. Open windows when it’s cool outside (nights and early mornings) and close them when temperatures start to reach the mid 70’s. Close curtains on sun-facing windows and use white shades to reflect the heat. If you use an AC, close the house up for a central unit and if it’s just for a single room, close the windows and door to help it run more efficiently.