The Truth Behind Those Efficiency Ratings

How Much Efficiency Is Enough? Depends on How Fast You Want Your System to Pay for Itself

12 SEER, 14 SEER, 80% AFUE, 90% AFUE – don’t get too confused by trying to figure out where all the numbers come from. All you really need to know is that these are relative measures of fuel economy — SEER (Seasonal Energy Efficiency Ratio) numbers for air conditioners, or AFUE (Annual Fuel Utilization Efficiency) for gas furnaces.

In simplest terms, the higher the number, the more heating or cooling you’ll get for your energy dollar.

As you shop around, use the numbers, not vague terms like “high efficiency” or “super high efficiency,” to really compare systems. Any air conditioner or furnace on the market today can be called “high efficiency” compared to the equipment of just a few years ago. What was called high efficiency then – say 9 SEER for an air conditioner or 70% for a gas furnace – wouldn’t even be permitted on the market today!

Air Conditioners

  • 10 SEER – The minimum efficiency allowed by law for new central air conditioning systems
  • 12 or 13 SEER – Trade up to this level from your old system and you’ll probably be delighted at how much lower your electric bills are
  • 14 SEER plus – Pushing the upper limits of what’s possible with today’s technology

Gas Furnaces

  • 78% – The legal minimum for new furnaces on the market today
  • 80% – Another once-impossible degree of efficiency that means drastically lower gas bills than you probably have with an old furnace
  • 90-plus % – Currently the highest efficiency you’ll find (but we’re working on it!)