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What Makes An AC Unit High Efficiency?

How Air Conditioners Are Rated What makes an AC unit high efficiency

No one ever goes to a store and asks for a low-efficiency product. We live in a world where high efficiency is king. We want better products, more production, and lower energy use and fuel costs. The same logic applies when shopping for a new air conditioning unit, and then some. Here’s what goes into making an AC unit high efficiency.

What’s the rating?

The first step in knowing if an AC unit is energy efficient is to look at its SEER rating. The SEER – or Seasonal Energy Efficiency Ratio – is how the Air Conditioning, Heating, and Refrigeration Institute (AHRI) rates the energy efficiency of the system. It calculates this rating by looking at the amount of cooling produced – or heat energy moved from inside to the outdoors (BTUs) – divided by the amount of electricity used (watts). Products with higher SEER ratings are more efficient.

Since 2006, the U.S. government has required that all new air conditioning systems have a minimum SEER rating of 13. Before then, you may see older models with SEER ratings 10 or below. For comparison, today’s systems with the highest efficiency have SEER ratings in the 20s.

How do they improve the rating?

“The manufacturers improve on this number by using larger heat transfer surfaces (condenser coils and evaporators), and by using more electrically efficient motors to move the air and in the compressor – which has the largest motor and is the heart of the air conditioner,” says Keith Hill, manager, technical support, for Minnesota Air.

Keith says that although those features make the AC systems larger in physical size, and makes them more expensive up front, the wattage needed to power them has gone way down. This means lower long-term energy costs.

Why do I need energy efficiency?

We pay a price to stay comfortable inside on a humid day, but with an energy efficient AC it’s not nearly as much as in the past. With all the ups and downs of Minnesota weather, buying a high efficiency product can help you stay prepared for whatever comes your way, and at a much lower cost.

According to the Department of Energy, “today's best air conditioners use 30% to 50% less energy to produce the same amount of cooling as air conditioners made in the mid 1970s. Even if your air conditioner is only 10 years old, you may save 20% to 40% of your cooling energy costs by replacing it with a newer, more efficient model.”

Another way of looking at it: models with the current minimum SEER of 13 are 30% more efficient than the previous minimum SEER of 10. Plus, when you talk to a professional to get the proper size, installation, and location for your high efficiency unit, your AC will be the unstoppable – and affordable - little engine that could!


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