COP, EER, SEER — A/C Efficiency Ratings Every Homeowner Should Understand

A/C efficiency ratings

When it comes to your home’s air conditioning, you probably just want to know what’s going to keep you cool through the summer heat. But if you’re paying attention to your whole home’s energy efficiency, there’s more you need to know. Being familiar with standards for A/C efficiency ratings can help you make the best choices at cutting costs and staying cool.

Understandably, if you’re not in the industry, A/C specs can sometimes just look like alphabet soup. But three of those troublesome acronyms (COP, EER and SEER) can give you a lot of insight into your A/C system. Here’s what each one means:

  • COP: No, it doesn’t have anything to do with the police. The Coefficient of Performance (COP) is the ratio of the power that comes out of your system compared to the power that goes in. With an electric heater, for example, pretty much all the energy that goes in comes out as heat, for a 1/1 ratio, or a COP of one. A heat pump, by contrast, doesn’t create heat, it just moves from one place to another, which doesn’t take much energy. So for every unit of energy that goes in, more heat than that comes out. (Air conditioners work this way, too.) Heat pumps (and air conditioners) can get COPs of two to four, and when it comes to COP ratings, higher is better.
  • EER: The Energy Efficiency Ratio. Another “energy out compared to energy in” rating (these all are), but this one looks at thermal energy (in BTUs, or British Thermal Units) out to kilowatt hours in. It’s determined by measuring the amount of energy an A/C uses to cool a house on a 95-degree day, as opposed to seasonably (as in the next example).
  • SEER: The Seasonal EER. This takes into account average use patterns of the unit (for example, if it’s not always running at capacity, or doesn’t run around-the-clock). That gives you the best idea of how the unit will work in your home, not a lab.

So how does this help you when you’re shopping for an air conditioner? You can use these terms to compare and contract models, and get a feel for how efficiently they’ll perform. For example, for a heat pump or A/C, you’ll probably want a model with a SEER of at least 16. The minimum required right now is 13.

To learn more about A/C efficiency ratings, contact us at Scott’s Heating & Air Conditioning!

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