23. Keep certain things closed
You can save a lot of energy — and dollars — by keeping things closed. What things? Well, doors. Windows. Curtains. Fireplace dampers. If you leave your damper open, hot air can be escaping through your chimney, causing your heating system to work harder unnecessarily. If you’re enjoying some fresh air from a window without realizing that your heating system is running, you’re wasting energy. Curtains closed at night can keep more heat in your house, too, while opening them during the day will make your home bright while letting in more warm sunlight.