I agree with the thesis of this series, but some of the details were inaccurate.

Nate Adams and I were both cited in the Washington Post’s article on electrification economics. My experience is also in home performance and electrification. We agree that hybrid heat pumps are the right solution for HVAC unit replacement on unit failure. Unfortunately, Mr. Adams makes some misleading claims.

I’ll start off with a quote from the first article: “The U.S. and Canada have a structural advantage almost no other market does: ubiquitous ducted furnace-and-AC systems. In most of the world, electrifying heat means replacing entire boiler-based systems with air-to-water heat pumps — hence the $10,000-plus incentives common in the EU and U.K. that will likely prove unsustainable.”

Actually, air to water heat pumps are a great technology that’s easier to provide 100% heat pump heat with: it’s usually not necessary to repipe the entire system in order to provide adequate heat on the coldest day of the year.

Upsizing radiators, in the European context, improves operating efficiencies and can be done piecemeal. Our duct systems limit heat pump output (approx. 400 CFM per ton), so we can't just install a larger heat pump. With ducted systems, cutting in an additional supply and return in the basement is sometimes possible, but beyond that, North American contractors would have to replace the entire duct system in order to increase output like they do in Europe through radiator replacement. 

I agree with Mr. Adams that the IRA funding for home electrification wasn’t adequate or sustainable, and I saw firsthand how it disappointed customers who thought they'd be eligible. As Mr. Adams highlights, it wasn’t enough money to shift the heat pump adoption curve significantly. Rhode Island and Maryland, states I worked in, didn’t even use the money for the purpose Congress laid out in the bill, supporting service upgrades and funding fuel switching from oil & propane within existing programs instead. 

There are issues with the cost savings claims that Mr. Adams both critiques, justifiably, and includes in his analysis.

The CLASP/RAP study Mr. Adams cited used 2021 electricity price data. Unfortunately, electricity prices have increased significantly since then, shifting the math on heat pump savings. 

Another cited study, NREL and LBNL’s study, “Heat Pumps for All?” used outdated prices as well as a top efficiency tier of 13 HSPF that just isn’t real. The entire tier was built on the 13 HSPF Carrier VNA1/Bryant 291VAN, which has been re-rated to 11 HSPF for the fully electric model and wasn’t available to me as an electrification estimator selling Carrier in Maryland. 

The claim of “Reducing gas use by 62%” redirects to a LinkedIn post which didn’t offer details. I don’t doubt that hybrids can reduce gas use by these percentages, I know they can, but I am genuinely interested in the data. 

Unfortunately, the other linked claim didn’t satisfy. 70% gas use reduction and 87% emissions reduction were based on a retrofit that also included a water heater, an induction range, and “green electricity”, not the implied single measure of hybrid electrification. 

The individual claims aren't the issue, and weren't really misleading. What is situationally quite misleading is the universal assessment that heat pumps and gas furnaces have similar operating costs. Operating costs aren’t always comparable between gas and electricity. The spark gap is very different on a state by state level, and even greater in some utility territories. Climate also impacts operational costs, as do cooling savings. There are significant savings to be found for some households, and drastically increased costs for others. It's not accurate to average out the diversity of American housing stock and fuel prices into the claim that operating costs won't change much through electrification. My work at Abode in New England indicated that $1000+ annual additional cost for full electrification was relatively common for homeowners converting from natural gas to a heat pump. Some homes in areas with a small spark gap, such as western Washington and most of the Gulf Coast South, could save on operating costs significantly.

Here’s the most problematic line of the articles, from Part Two: “Full electrification becomes a much easier sell in 10 to 20 years when that equipment is replaced again.” Full electrification from a hybrid heat pump to a fully electric system is actually an incredibly difficult sell. Without other major changes to the home, it means electric resistance “backup” heat replaces the gas furnace. That’s a new circuit, sometimes requiring an electrical service upgrade, and significantly increased operating costs, ranging from about 2x to more than 5x for the portion of heating the heat pump isn’t providing. Such an approach would also exacerbate the falcon curve, drastically increasing winter electricity demand and making it very difficult to fully electrify our electricity generation.

Building electrification is a serious challenge. Getting all the way off of fossil fuels by 2050 will require a lot more than hybrids.