What is an Economizer in an HVAC system?

Exploring the Function and Benefits of an Economizer in an HVAC System

In the quest for energy efficiency and cost savings, building owners and facility managers are constantly seeking innovative solutions for their HVAC systems. One such technology that has gained significant attention is the economizer. An economizer is a vital component of modern heating, ventilation, and air conditioning (HVAC) systems that plays a crucial role in optimizing energy usage. In this article, we delve into the concept of an economizer, its functioning, and the benefits it offers.

Understanding the Economizer

An economizer is a device or mechanism integrated into an HVAC system designed to take advantage of favorable external environmental conditions to reduce the need for mechanical cooling or heating. Its primary purpose is to maximize energy efficiency by utilizing outside air for free cooling or preheating, thereby reducing the reliance on mechanical cooling or heating equipment.

Functioning of an Economizer

The economizer operates by monitoring and comparing the outdoor air conditions with the indoor air conditions. When the outdoor air is determined to be more favorable than the indoor air, the economizer allows the introduction of fresh outdoor air into the building, reducing the need for mechanical cooling or heating.

There are two main types of economizers commonly used:

  1. Dry-Bulb Economizers: These economizers measure the temperature and humidity of the outdoor air. If the outdoor air temperature falls below the setpoint temperature for cooling, and the humidity is within acceptable limits, the economizer opens dampers to bring in the fresh outdoor air, bypassing the cooling coils. This process provides free cooling to the indoor space, reducing the load on the mechanical cooling system.
  2. Enthalpy Economizers: Enthalpy economizers not only consider the outdoor air temperature but also take into account the humidity levels. They measure the total heat content of the outdoor air, considering both sensible and latent heat. If the enthalpy of the outdoor air is lower than that of the indoor air, the economizer opens to provide free cooling or preheating, depending on the temperature differential.

Benefits of an Economizer

  1. Energy Efficiency: By utilizing free cooling or preheating provided by the outdoor air, an economizer significantly reduces the reliance on mechanical cooling or heating systems. This leads to substantial energy savings and lower utility bills.
  2. Improved Indoor Air Quality (IAQ): Bringing in fresh outdoor air through the economizer helps enhance the IAQ within a building by diluting indoor pollutants and replenishing oxygen levels. This contributes to a healthier and more comfortable indoor environment for occupants.
  3. Environmental Sustainability: With reduced energy consumption, an economizer reduces the carbon footprint of HVAC systems. By promoting the use of free cooling or heating, it aligns with sustainable practices and reduces reliance on fossil fuel-powered equipment.
  4. Extended Equipment Lifespan: By minimizing the operation of mechanical cooling or heating systems, an economizer helps reduce wear and tear on the equipment, ultimately extending its lifespan and reducing maintenance costs.
  5. Regulatory Compliance: Many building codes and energy efficiency standards mandate the use of economizers in HVAC systems. Implementing an economizer ensures compliance with these regulations, avoiding potential penalties or restrictions.


An economizer is a valuable component of an HVAC system that harnesses the natural advantages of outdoor air conditions to optimize energy efficiency and reduce operating costs. By providing free cooling or preheating when the outdoor air is favorable, an economizer enhances both environmental sustainability and indoor comfort. The implementation of an economizer offers numerous benefits, including reduced energy consumption, improved indoor air quality, extended equipment lifespan, and regulatory compliance. As the emphasis on energy efficiency continues to grow, integrating an economizer into HVAC systems becomes an increasingly viable and beneficial solution for commercial and residential buildings alike.