All air conditioning units have a SEER rating. That stands for Seasonal Energy Efficiency Ratio. This number represents the ratio of the cooling output over the season divided by the energy consumed in watt hours. It is a measure of air conditioner and heat pump cooling efficiency. The measurement is taken over the course of a typical cooling season. The higher the number, the more efficient the unit.
The minimum standard for a SEER rating is 14. A maximum rating can range between 21 and 25. Most newer air conditioning units will fall somewhere in this range. The SEER rating is a maximum rating but doesn’t mean the unit always performs at that level. Older air units may only have a SEER rating around 8 or 9. This means those units are not very energy efficient. The SEER rating is labeled on the yellow “Energy Guide” sticker found on the air conditioning unit.
When replacing an old AC unit, you’ll want to choose one that has a SEER rating of 13 or higher. That upgrade will significantly reduce the cooling costs for the homeowner. Today’s air conditioning units are 20-40% more efficient than models that are 10 years old.
AC units with a low SEER rating usually run on one speed. These older units turn off and on more frequently. They also tend to cool unevenly, leaving hot and cold spots in the house. Units with a higher SEER rating generally have a variable speed compressor. They provide greater indoor comfort and remove more humidity (moisture) from the air.
When getting ready to purchase a new unit, how high a SEER rating is high enough? The answer varies and will depend on several factors including:
- How many hours on average will the system run each day?
- At what temperature will the thermostat be set?
- How much insulation does the home have?
- Are the windows good quality, or do they leak?
- How often will the filters be changed?
- How regularly will the system receive routine maintenance?
The Energy Star website has an energy savings calculator that can help homeowners decide what SEER rating to consider for their new unit. Your HVAC contractor should also provide clear information and work with you to determine what best meets your needs.