What Is a SEER Rating?

Get to know SEER

If you’re looking to buy a new heat pump or air conditioner, you’ll likely see different SEER ratings for each model. What’s a good SEER number? What’s the typical range? How much more should I pay for one SEER rating over another? And, most importantly, what does it all mean? Let’s figure it out.

What does SEER mean?

The Seasonal Energy Efficiency Ratio (SEER) is how the HVAC industry often measures the efficiency of air conditioners and heat pumps in terms of cooling. 

Without getting into the math of it, SEER tells you how much cooling a unit puts out during a typical warm period, divided by the energy needed for that unit to produce that cooling.

SEER ratings help us estimate how much electricity and money is required to cool a home each year.

What SEER rating should I look for?

It’s better to buy a higher SEER-rated cooling system. But once you consider the upfront cost of a unit, the amount of space you’re cooling, the length and temperature of your summers, and lots more, your decision may not be so simple.

In general you should consider upgrading to a higher SEER if you live in a very hot climate and/or if you have a large home.

The best way to see how much a higher SEER unit can save you is by checking an online SEER calculator. Be sure to double check your electricity costs, the tonnage size of your unit, and other factors.

What to consider when shopping for cooling

Knowing a machine’s SEER is a helpful starting point when comparing different heat pumps and air conditioners but it isn’t the only thing to consider. Here are some other things to know about SEER ratings.

The difference between SEER and EER

The “S” stands for “seasonal,” and that’s the big difference. EER or Energy Efficiency Ratio also measures how much power it takes to produce a certain amount of cooling, but it’s not scaled to the real costs of a typical season.

EER’s baseline model is a unit running when it’s 95 °F (35 °C) outside and 80 °F (27 °C) inside, at about 50 percent relative humidity inside. The SEER model takes into account a range of temperatures from 65 °F (18 °C) to 104 °F (40 °C).

In other words, SEER tries to account for the fact that temperatures outside change, and with them the efficiency of cooling units do too. EER, by comparison, measures efficiency in a fixed environment. 

The SEER range

Most air conditioners and heat pumps in the U.S. have a SEER rating from the current legal minimum of 13 up to around 20-25, depending on the region of the U.S. That’s progress. In 1992, the minimum legal amount was 10. The current minimum of 14 or 15 depending on the region and unit means at least a 20 percent energy savings for most of the country.

There are some remarkably high-SEER units around, especially with a mini-split configuration. 

Is a heat pump with a higher SEER also more efficient at heating?

Generally, yes. Because a heat pump essentially works like an air conditioner in reverse to provide heat, a unit that can use less power to compress and expand refrigerants to move heat around in the summer can do the same in winter.

Your heat pump should also have an HSPF or Heating Seasonal Performance Factor rating, and this is a better measure of its heating performance in your home. 

Do mini-splits have higher SEER ratings?

Generally, yes, ductless “mini-split” systems, whether heat pump or traditional A/C, are more efficient and have higher SEER ratings than traditional “split” systems. This is for two reasons.

One reason is that mini-split systems allow for individual rooms, or zones in a home, to be set to different temperatures, depending on need. A standard forced-air system pushes air to the entire house, doing so whenever a main thermostat tells it. You can somewhat control this with vent shutters, but distributed units will always be more effective.

The other reason is that forced air systems lose efficiency in their ducts. Mini-split systems run refrigerant to and from a main outdoor unit, a more efficient heat transfer system.

Do dual-stage and variable-speed cooling systems get higher SEER ratings?

Yes, dual-stage and variable-speed cooling systems are almost always more efficient than their single-stage counterparts.

Cooling and heating systems are sized for a home based on the coolest or hottest day of the year. A single-stage system is always drawing the same power to run, whether it’s a slightly warm day or a swampy scorcher. Dual-stage and variable-speed systems can work at lower energy levels when needed.

Because they’re running more often, dual-stage and variable-speed systems also do a better job of constantly moving air and keeping a home dehumidified. This in turn keeps temperatures down, and makes people feel cooler.