California Air Resources Board

I appreciate the leadership that the State of California provides to help address the impacts of climate change and other important environmental issues. I also support CARB's efforts to help reduce emissions from buildings and are pleased to see that CARB has recognized that electrifying buildings can be an extremely difficult and costly effort in some situations.

The original concept with a blanket requirement for zero-emission heating equipment would have been very challenging for many buildings. In the new construction of residential and commercial buildings, it is technically feasible to electrify space and water heating equipment though it can often lead to significantly higher first costs as well as higher operating costs compared to alternative gas-fired equipment. That is a significant burden to place on the people and businesses of California. Arguably, however, the bigger barrier is applicability to new equipment that is needed to replace end-of-life equipment in existing buildings. In many of these cases, there are also costly electrical and structural upgrades required. In some cases, particularly large commercial buildings, there may physically be insufficient space for heat pumps and incompatibilities with existing HVAC distribution systems. A blanket zero-emissions requirement may be practically impossible to comply with in these cases.

Please also consider that electrifying heating equipment in a building may reduce/eliminate emissions at the site, but does not necessarily result in overall greenhouse gas emissions. It is not sufficient for policymaking to focus only on Scope 1 emissions, without consideration of the Scope 2 and 3 impacts. Climate change is a global issue, not a building-, city-, or even state-level problem. Policymaking needs to keep this perspective in mind. In particular, efforts to shift heating loads to electric equipment in order to reduce greenhouse gas emissions should also recognize that the electrical grid in California today relies on a range of power generation types, and that grid emissions factors can vary significantly by season and time of day. Though the overall grid may be getting cleaner on average, during winter nights and early morning conditions (i.e., when we need the most heating in buildings), the sun is still down and marginal power generation sources supplying the California grid are generally simple cycle gas power plants, which operate with thermal efficiencies around 30-40%.

Similarly for NOx generation, electric heating equipment can potentially result in higher net NOx emissions when effective heating COPs are lower and when the grid's marginal generation sources are fossil fuels. The biggest difference then is that the NOx emissions are concentrated around gas-fired power plants, which tend to be located in disadvantaged communities.

Consider a heat pump operating with a COP of 2.5 operating during a winter morning when the grid marginal emissions are ~1200 lbs/MWh (a PG&E study evaluating heat pump system performance measured the operating heating COP at one building to average 1.85). When including emissions from the power generation, the overall marginal emissions rate of that system at that condition would be roughly equivalent to a gas-fired system with 80% efficiency. Electric resistance heaters (COP=1) would have even higher marginal emissions than the gas-fired equipment. This is a simplified representation where there are lots of additional factors to potentially consider (T&D losses, refrigerant leaks, natural gas distribution leaks, variable efficiencies, batteries, seasonal performance, etc.) but the point is that effective decarbonization is more complex than simply electrification at the building. Many argue that we should electrify buildings now and expect that the grid will get cleaner, but it is not clear that clean power generation will keep up with the explosive growth in AI data centers, plus EVs and heat pumps. It is not clear whether California will meet its goal of a 100% clean grid by 2045 or find a way to provide clean power during periods of high heating demand. Even if California meets its 2045 goal, that is 20 years away, where typical HVAC equipment lifespans are less than 20 years. Though typical heat pump equipment for residential and small commercial are mature and cost competitive, equipment for large commercial buildings are still rapidly evolving and industry is still learning how to apply and install these correctly. The HVAC industry does not adapt well to change quickly! It needs more time to learn difficult lessons from early applications to avoid an entire generation of failed installations. We obviously need both heat pumps and clean generation sources to reduce emissions from the building sector but policymaking should ramp these up at a measured pace as we have appropriate solutions available.

Climate-change policymaking should focus on efforts that can reduce carbon emissions now based on robust solutions and the lowest cost per ton of avoided emissions, not based on immature solutions, narrowly-focused emissions accounting, or overly optimistic forecasts of the grid 20 years from now.

The revised CARB proposal uses gradually declining emissive sales limits which provides residential and commercial building owners with necessary flexibility to select appropriate options for a very wide range of potential conditions, whether new or retrofit, single family residential or high-rise, rural or urban. This places the burden on manufacturers to develop, market, and sell equipment to meet these targets, or use credits to make up the difference but I trust that industry will be able to adapt if the rules are clear, well-thought-out, and finalized well enough in advance. As an engineer with 20 years of practicing experience in the California nonresidential HVAC market, I think that the current CARB concept strikes an appropriate balance that will help the State achieve its goals while also considering cost and practical barriers on a site by site basis. I applaud CARB staff for recognizing the challenges faced with the original proposal and for putting forth a new concept that provide more flexibility. I look forward to hearing more about this approach in the future.