If most consumers want to know the efficiency of their central air conditioner, they simply look to the SEER rating. The Seasonal Energy Efficiency Ratio (SEER) is a metric used to measure how much cooling a system puts out for each unit of energy it consumes. In theory, the higher the SEER rating, the more efficiently the air conditioner operates.

The problem with the SEER rating is that it doesn’t give consumers an accurate picture of energy efficiency. As a baseline, the SEER measures an air conditioner’s performance at 82 degrees. Most air conditioners don’t need a lot of power to cool down a space at that temp. However, raise the temperature to 90 or 95 degrees—which is a much more likely summer temperature for most U.S. cities—and you lose an entire ton equivalent of air conditioning. By increasing the temp just 10 degrees, the cooling capacity of the unit goes down while the energy consumption goes way up. So, when you’re using a conventional central air conditioner at peak load, you may think you’re getting by with an energy efficient rating of SEER 13, but the fact is, it’s much less. So, why do we use such an inaccurate measure of efficiency? It’s important to note that SEER is a marketing term used by the air conditioning industry. It was developed by the manufacturers who make traditional, compressor-based products to help make their air conditioners appear more efficient than they actually are.

Because our air conditioners don’t have a compressor, we don’t have a SEER rating. A much more accurate way to determine energy efficiency is using the EER rating—or Energy Efficiency Ratio. Like the SEER, the EER is calculated by taking the total BTU (British Thermal Unit) of heat rejected, or actual cooling per hour and dividing it by the watts of electricity used to reject the heat. But, the difference is that the EER is calculated for a controlled environment, whereas the SEER value takes into account seasonal variations. That means the value varies depending on the temperature and humidity of where the air conditioner is located.

Most unbiased experts agree that EER is a much more accurate way to rate energy efficiency. In fact, some utilities have voiced concerns with the SEER and have asked for discussions about transitioning to the EER. But, it’s sure to be a long, hard fight because traditional air conditioning manufacturers don’t want the standards changed. Until that happens, the best way for consumers to measure energy efficiency is by simply looking at their cooling bill. Coolerado customers use up to 90% less in cooling consumption. That’s a rating you can believe in.