Understanding AFUE Ratings

According to the U.S. Department of Energyhad a furnace with a 50% AFUE rating and
(DOE), heating and cooling the average home inreplaced it with one that has an 80% AFUE rating,
the U.S. accounts for about 56% of home energyyou can expect to save about 37% on your
use, making it the largest energy expense forhome heating bill over the course of a year.
most households. It is important then to have aThe U.S. government may have set minimum
way to know just how energy efficient homestandards, but to promote greater energy
heating and cooling appliances are when purchasingefficiency the DOE and the U.S. Environmental
them for your home. To give consumers anProtection Agency (EPA) have developed the
objective measure of how efficient fuel firedENERGY STAR program. For an equipment
heating systems are, the AFUE rating wasmanufacturer to earn the ENERGY STAR seal,
established.they have to comply with the standards that
AFUE stands for "Annual Fuel Utilization Efficiency"ENERGY STAR has established for energy
and is expressed as a percentage. It is not anefficiency.
absolute rating of the energy efficiency of a pieceThe current standard is ENERGY STAR 2.0 as of
of equipment per se, but it is intended to indicateOctober 27, 2006, which is higher than the U.S.
what the overall efficiency would be in a typicalgovernment's established minimum standard. For a
application over the course of a year. This is whatfurnace manufacturer to meet the ENERGY
people really want to know when they purchaseSTAR 2.0 standard, a gas-fired furnace would
heating equipment, so they can get an idea ofhave to have an AFUE of at least 90%, and an
what it is going to cost to operate compared tooil-fired furnace would have to deliver an AFUE
what they have now.rating of 83%. For instance, if you had a furnace
For instance, if a furnace has an AFUE rating ofwith an AFUE of 80% and you replaced it with a
50%, what that means is that for the energyENERGY STAR Furnace with and AFUE of at
value of the fuel to operate that furnace overleast 90%, you could expect to save 11% on
the course of a typical year, only 50% of theyour home heating bill over the course of a typical
energy went to heat the home. That soundsyear.
really dismal, but up until minimums wereCheck to see if your home heating and air
established for home heating systems, that'sconditioning dealer will offer ENERGY STAR
what you might have been stuck with. Now theequipment. They will be able to help you
minimum AFUE rating for a furnace is 78% asunderstand what the energy ratings of the
established by the U.S. government. There mayequipment mean, and work with you to
still be some of those old systems out theredetermine if it makes sense to upgrade the
presently in use, but any new furnaces installedheating and cooling equipment for your home.
have to meet the minimum AFUE rating. If you