4. Energy-efficient lights
Regular lights are not energy efficient and radiate a lot of excess heat which can quickly warm up the house. Use energy-efficient lights like LEDs or CFLs in high-use areas. Turn off lights when not in use. Most electronics that use electricity emit heat even when they are not in use. Unplug electronic equipment when they are idle to reduce the amount of heat they generate. This can also help you to save light bills.