Homes & Energy Efficiency

How much more efficient is a new furnace (or, heat pump) over the existing? Is it moreso that there are significant efficiency losses with older HVACs? When reading my question, consider the devil’s advocate here: First, I would argue that new equipment and technology can only be making minute, incremental advances in efficiency. We’ve come a long way, baby, but we’ve got to be way out on the flat part of the curve now. The squeeze in ain’t worth the juice out! Surely, it is asymptotically approaching some value beyond which no HVAC equipment will ever reach. (For one, we all know it is not approaching 100% efficiency!)

Now, at the other end of the scale, consider aging HVAC equipment. A high-efficiency heat pump from the late 1980’s (once everyone was energy conscious) with its tip-top CEER value…will it degrade to some lousy efficiency? If so, where are these losses? Is it a lack of fresh lubrication on the fan motor’s ball bearings? Dust reducing max heat transfer on the surface of the evaporative coil? What?

Or, could it be more that the industry WANTS us to upgrade for their economical benefit vs. significant gains in efficiency?

This is not a simple question to answer. I just replaced my ancient ( >15 years) heat pump with a new SEER 15 (EER 10.5) model. I have no data yet to compare its energy usage with the old one, but I can tell you that it’s heating ability is significantly improved. If the old unit had a SEER rating of 10 (likely, and possibly even less), than the new unit should save 33%. So, if you have a SEER 15 unit currently, it makes no sense to replace it with a SEER 16 unit (but a SEER 30, if it existed, might make sense.)

It’s also worth looking at replacing a 90% efficient gas furnace with a heat pump that can have a Coefficient of Performance of as much as 4x (you get 4x the heat for each unit of energy consumed). Of course, your location plays an important role in determining whether this makes sense for you - heat pumps don’t perform well in very cold winter areas.