Many commercial buildings use air conditioning almost year-round.
For example, a restaurant produces so much heat that even when it is cold outside, the building may need cooling. An economizer uses the cool air outside to save cooling energy inside. An economizer control is a mechanical device that uses cool outside air to cool inside a building, thus reducing the need for electrical cooling. When it senses that outdoor conditions are correct, it shuts the air conditioner compressor off and opens the outside air damper. The fan then draws in outside air to provide cooling.