Key Factors that Influence Indoor Cooling Performance and Efficiency

Factors that influence AC performance

If you drive your car up hill, both ways, on tires with low air pressure, would you get the same miles-per-gallon (MPG) as you would if you were driving on a straight road, at a constant speed, with perfectly inflated wheels?  Probably not. Why? Because a vehicle’s fuel economy is measured under controlled conditions in the EPA's National Vehicle and Fuel Emissions Laboratory.1 Actual MPG may vary depending on driving conditions and other performance factors.

The Seasonal Energy Efficiency Ratio (SEER) stated on the system components can be compared to the MPG of an automobile. If the installation or usage varies from the standard test conditions, the performance and efficiency of an air conditioner or heat pump may be impacted.

The Match Game


Air conditioners and heat pumps, like automobiles, are tested within set laboratory conditions with properly matched system components. Manufacturers identify a unit’s SEER value through standardized testing and algorithms prescribed by the Department of Energy.2 In order to function at the certified SEER level in your home, the separate components of your cooling system must be compatible and in proper working condition.

Each cooling component plays a vital role in making sure that you enjoy a comfortable indoor environment in your home. A complete cooling system may be composed of:

  • Outdoor air conditioner and indoor air handler
  • Outdoor air conditioner and indoor gas furnace
  • Outdoor heat pump and indoor air handler
  • Outdoor heat pump and indoor gas furnace


According to the Air Conditioning, Heating and Refrigeration Institute (AHRI), “Improperly matched indoor and outdoor units can create undue stress on a cooling system, dramatically reducing efficiency.”3 AHRI suggests that mismatched systems are at least 30 percent less efficient than matched systems.”4


A licensed or professional contractor should be able to verify properly matched systems and SEER rating by providing you with a Certified Reference Number or a Certificate of Certified Product Performance. The AHRI’s free Directory of Certified Product Performance provides public information regarding certified reference numbers, SEER ratings and compatible equipment. If you are considering replacing just the outdoor portion of your cooling system, be sure to discuss compatibility and efficiency with your licensed or professional HVAC dealer.

The Energy-Savings Puzzle Pieces


Even if your HVAC components are compatible, a high SEER air conditioner or heat pump is only one piece of the energy-efficiency puzzle. Standards dictate that higher SEER heat pumps and air conditioning units are more energy-efficient than lower SEER units. Yet, when your cooling system is not being maintained as recommended or simple home energy-efficient solutions are ignored, your energy bills may still be higher than you would like.

To keep your central cooling system at peak performance, a licensed professional HVAC dealer should perform routine maintenance services. During an inspection, your dealer may identify any airflow problems, system leaks, coil issues or potential concerns that could impact your system from operating at peak performance.  Typical professional maintenance services that may keep your cooling system at peak performance may include the following actions:

  • Check for adequate air flow
  • Look over outdoor condenser coil  and indoor evaporator coils
  • Check outside and inside refrigerant lines and inspect for leaks
  • Clear indoor drain lines and pans
  • Check external and internal electrical connections
  • Check operation of indoor blower components
  • Lubricate internal and external motors, bearings and other moving parts
  • Inspect Exterior Fan


Homeowners should also keep in mind additional conditions that may impact energy costs. These factors can influence the ability of your cooling system to perform at its designed efficiency level. Some conditions include, but are not limited to:

  • Improper system installation
  • Thermostat or control system location or settings
  • Undersized or leaking ductwork
  • Inadequate level of insulation and non-insulated construction methods
  • Leaking or drafty windows and doors
  • Dirty or improperly installed air filters

Forward Thinking


In 2015, the U.S. Department of Energy changed from a national minimum SEER standard to regional standards. Currently, the minimum SEER values for air conditioners depends on location and ranges from 13 or 14 SEER. Heat pumps have a minimum SEER of 14 SEER.

Cooling system manufacturers continue to pursue individual technologies that collectively may improve overall HVAC system efficiency. Advancements, including refrigerant, variable-speed drives, advanced controls, and additional mechanics that simplify installation, will continue to impact the energy costs associated with cool, indoor comfort. To discover current HVAC technologies available that may improve the energy efficiency of your home, discuss the various options and potential cost saving with your licensed professional HVAC dealer.




1 Environment Protections Agency. Vehicle and Field Emissions Testing. n.d. 18 April 2017.

2 Department of Energy. Appliance and Equipment Standards Rulemakings and Notices. n.d. 18 April 2017.

3,4 AHRI. HVACR Replacement Guidance. 15 January 2013. 12 April 2017.