Economizers primarily save on cooling costs. It operates by shutting down the systems compressor and pulling cooler air from outside and reducing the load on the mechanical cooling system.
As part of the HVAC control system, an economizer is designed to save energy, typically reducing overall cooling energy consumption by twenty to thirty percent.
Here’s how an economizer works.
Using a collection of dampers, sensors, actuators, and logic devices, a economizer decides how much outside air can be brought into a building, allowing the load on the cooling system to be reduced.
Dampers regulate the amount of air introduced, recirculated, or exhausted from the building. Outdoor temperature sensors and logic controllers determine whether conditions are right for the economizer to operate, and govern the operation of the outside air damper. Actuators open or close dampers based on signals from the logic controllers.
When the logic controller decides the outside-air temperature is low enough to take some or all of the cooling load, the outside-air damper opens and the air conditioning compressors are turned off.
An exhaust fan always runs when the economizer operates, because for the economizer to work effectively, the same amount of air should be exhausted from the building as is taken in.
When the outdoor air temperature rises too high to provide useful cooling, the outside-air damper moves to a minimum position, maintaining minimum ventilation. Then the return opens and exhaust closes, and the compressors take over the cooling process.
When properly specified and installed, economizers provide significant cooling energy savings, but require regular maintenance and testing to ensure optimal performance.