It makes sense to want to save on heating and cooling costs, which are among the highest home maintenance expenses. One great way to do that is to install a high-efficiency furnace to replace an older, less efficient model. But how much would you really save? The honest answer is, it depends on a number of factors, including:
- The Size of Your Home. Of course, the size of your home is a big factor in how much fuel you use and the size of your heating bills. To standardize comparisons between furnaces, the industry uses the AFUE, or Annual Fuel Utilization Efficiency rating. This rating, which is similar to MPG for cars, is an average efficiency value for furnaces and boilers that is established by an independent third party (the Air Conditioning Heating Refrigeration Institute). By using the AFUE, you can get an idea of the comparative savings of one furnace over another.
- The AFUE Gain of a New Furnace. Today’s high-efficiency furnaces are typically AFUE rated at 94-97%. So, depending on how old your current furnace is, the efficiency gain you get can vary quite a bit. For example, if you have a furnace that pre-dates the ‘90s, it can rate as low as 65% efficiency. That means you could potentially increase efficiency by 30% or more with a new furnace! If your furnace is a little newer, say 10-20 years old, it could range up to 80% efficiency (although it could be less, as well). Your gain there is less, but still significant.
- Your Temperature Settings. Your usage of heating and cooling also has a huge impact on the potential savings you get with a furnace replacement. For a combination of top efficiency and comfort, recommendations are to set your heat at 68° or lower and your cooling at 78° or higher.
- The Energy Efficiency of Your Home. The amount of heat that your home retains is also a big factor in any savings you’ll see with a new furnace. So, along with that investment, you may want to ensure that your attic is well insulated and that windows and doors have adequate weather stripping. If your doors and windows are especially old and drafty, you may want to consider replacing them for added savings.
- The Weather. The weather isn’t something we can control, but it certainly plays a factor in energy usage. For example, a November that’s colder this year than last will cause more home heat loss and require more heat energy. Use “degree days” (usually listed on your utility bill or online at various weather sites) to gauge one month against another.
A Ballpark Estimate of Savings
In general, 80-100% of a home’s gas consumption is used for heating. With that in mind, here’s a ballpark calculation you can run to get an idea of your potential fuel savings with a new furnace.
- Estimate just the heating portion of your bill (take a look at your summertime fuel bill to get an idea of your water heater and dryer gas consumption).
- Calculate the estimated AFUE gain between your old unit and the new one. For example, if you’re going from 80% to 95% efficiency, that’s a 15% gain.
- Reduce your estimate from step 1 by that percentage to get a ballpark estimate of your expected savings.