Comparing energy efficiency of different brands of heating and cooling equipment is relatively easy. Although the rating systems are standardized, allowing you to make a fair comparison, there are three different rating systems used. Each rating is used for a specific type of product(in other words, all furnaces use the same system, heat pumps use a different system, an so on). They are:
- AFUE (gas heating)
- SEER (cooling)
- HSPF (heat pump heating)
AFUE (gas heating). The efficiency of a furnace is measured in a rating known as AFUE (Annual Fuel Utilization Efficiency). A lot like your cars miles per gallon rating, AFUE tells you how efficiently the furnace converts fuel (gas or oil) into heat. An AFUE of 80% means that 80% of the fuel is used to heat your home, while the other 20% basically goes up the chimney.
The government mandated a minimum AFUE rating for furnaces installed in new homes is 78%. (In contrast, many furnaces manufactured before 1992 had AFUE ratings as low as 60% so nearly half the fuel was being wasted.) Furnaces with AFUE ratings of 78% to 80% are considered “mid-efficiency”; those with ratings of 90% or higher are known as “high efficiency.” The maximum furnace efficiency available is around 96.6%.
In general, a higher efficiency furnace usually means two things:
- higher price
- lower monthly operating cost
If you have an older furnace (with an AFUE of about 60%), you could save up to 40% on your heating bills by replacing it with a new high-efficiency furnace. So the cost to replace your old, inefficient furnace is paid back through lower utility bills.
Payback. If you live in a cold climate, you could see a payback in a few short years. If you live in a moderate climate, it might make more sense to purchase a mid-efficiency furnace. Your dealer can use heating data from your area to help you determine about how long it would take you to recover the additional cost of a high-efficiency model in energy savings. (Of course, after the payback, you continue to save on your energy bills for the life of the system.)