What is an HVAC Economizer?

If you are interested in generating energy savings in your building, an HVAC economizer may be the way to go. For most facility managers and building owners, saving energy is a necessity and upgrading your HVAC system is a great way to see a significant change in overall energy usage. Read on to learn more about the benefits of an HVAC economizer, as well as how it works and where it can be installed.

How Does it Work?HVAC Economizer 1

An HVAC economizer works by drawing in the outdoor air. That is if the air is below the temperature setting and the humidity in the building is lower than the percentage set. This operation reduces the time frame in which your air conditioning unit is in operation. Additionally, it will lower the energy consumption of your unit, thus lowering utility bills.

Dampers within the economizer control the amount of air that is pulled in, as well as how much is recirculated and exhausted from the building. The system also includes logic controllers and sensors for outdoor temperature control. These functions will decide if the weather conditions denote the use of the economizer.

Within the system are actuators that open and shut the dampers of the system. Once the outside air meets the temperature and humidity levels set, the damper will open, and the compressors of the AC unit will turn off.

If the outdoor temperature is hot and is unable to provide cooling, the damper will close, thus reducing ventilation. The return then opens while the exhaust fan closes. Finally, the compressors of the unit then restart to begin the mechanical cooling process.


An HVAC Economizer is often an addition to a rooftop HVAC system. If a system does not have an economizer attached, one can be easily installed. Also, a retrofit can be provided to add the economizer, and with moderate sizing, it won’t take up much space alongside an existing unit. Overall, cooler, drier climates benefit from an HVAC Economizer as they function when temperatures are hot in the daytime and cool at night.

HVAC Economizers offer energy savings as they pull colder air from the outdoors and circulate it throughout the building. This is considered a free cooling technique as the building doesn’t rely on the HVAC equipment to provide cool temperatures.

Types of HVAC Economizers

There are three main types of HVAC Economizers: Dry Bulb, Single Enthalpy (Wet Bulb), and Differential Enthalpy. The Dry Bulb option senses the temperature of the air only and does not consider humidity. This option has a lower installation and maintenance cost. The Wet Bulb type measures energy content in the air, heat and humidity included. With the Differential Enthalpy option, two sensors are used. One measures the outdoor enthalpy while the other measures return air enthalpy.

An HVAC Economizer provides a facility with a quality option for comfort while lowering monthly energy usage. As a facility manager, considering such an installation can be cost-effective, lowering the amount spent each month on energy.

Consider reviewing your HVAC system to see how an HVAC Economizer could be beneficial. As always, The Severn Group can help if you have any questions about energy efficiency or anything HVAC related. Contact us today.