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Simply put, economizers can be a way to cool a building without running the compressor. Therefore saving cost in energy spending. Oftentimes this is referred to as “free cooling” because it is taking advantage of the cooler outdoors rather than using the compressor.
An economizer is usually part of your RTU (roof top unit) and is an add on to the standard unit. The economizer also includes a variety of control and sensor options to evaluate outside air temperature and humidity levels. When appropriate, the economizer will help feed air into the return air, satisfying the thermostat without the need of the compressor.

  1. Improves energy efficiency, translation to energy cost savings. The less your compressor, which is typically the largest draw on energy, runs the lower your energy costs.
  2. Improve indoor air quality
  3. Prolong the life of your compressor since it is not running as frequent.
  4. Ease of installation – typically RTU’s come with an economizer option. You remove a panel, hook up the controls and you are ready to run.
  5. Increased comfort

Dry bulb – simplest type of economizer. Uses sensors to evaluate the difference between the interior temperature and outdoor air. Dry bulb economizers are most effective in the dry, arid climates.
Single enthalpy (Wet bulb) – a bit more complex of an economizer. Uses sensors to monitor humidity and temperature.
Differential enthalpy – the most advanced economizer of them all. Measures return air, outside air, and humidity in more complex applications.


Simply installing the economizer (usually like a jig saw kit) is not difficult. Ensuring the economizer is controlled, started-up, and operating correctly can be more technical. Refer to your local HVAC contractor for help.


Roof top unit (RTU)
Roof curbs