When was the last time that you changed the air filter in your heating, ventilation and cooling (HVAC) system? All ducted HVAC systems have an air filter. It’s a mesh screen consisting of fiberglass, polyester or organic fibers. The air filter is typically found between the return duct and the air handler where it catches and removes airborne debris.

Air filters aren’t designed to last forever, though. According to the U.S. Department of Energy (DOE), they should be replaced every one to three months. Even if your HVAC system seems to work fine with a dirty air filter, changing it is important for several reasons.

Improved Heating and Cooling

With a new air filter, your HVAC system’s performance will improve. HVAC systems require airflow for both heating and cooling purposes. A dirty filter will restrict airflow and, therefore, hinder your HVAC system’s performance.

After being conditioned, air must travel through the filter before entering the supply ducts where it’s expelled into your home’s living spaces. A dirty filter will slow down the conditioned air, meaning less cool or warm air will enter your home. At the same time, it may cause certain air conditioning components, such as the evaporator coil, to freeze up.

Cleaner Air

Changing your HVAC system’s air filter promotes cleaner air. The U.S. Environmental Protection Agency (EPA) states that the air inside most homes and indoor residences is two to five times more polluted than the outdoor air. Whether you realize it not, there’s probably airborne pollutants floating around inside your home.

An air filter is your first line of defense against airborne pollutants. Assuming it’s not clogged, it will catch airborne pollutants while still allowing air to travel through it.

Lower Energy Usage

For an energy-efficient HVAC system, you can’t ignore the air filter. Since the air filter affects heating and cooling performance, it can affect your HVAC system’s energy usage.

Your HVAC system will consume more energy to warm or cool your home if the air filter is dirty. It may, in fact, fail to achieve the temperature set on the thermostat. As your HVAC system continues to run, it will consume energy. You can make your HVAC system more energy efficient by regularly changing the air filter.

Protection From Premature Damage

Your HVAC system will be better protected against premature damage if you regularly change the air filter. A dirty air filter can harm your HVAC system’s components. It will cause warm air to build inside of the furnace and cool air to build up inside of the air conditioner. Over time, this additional stress can cause certain components to fail prematurely.