Cold Climate Air Source Heat Pump Building Electrification Study
Cadmus, with funding partners E4TheFuture, the Massachusetts Clean Energy Center, the New York State Energy Research and Development Authority, and the Department of Energy’s Building Technologies Office, recently completed an in-depth study into residential cold climate air source heat pump (ccASHP) operation in the Northeast. The goal of this study was to inform policymakers and program administrators on customer experience with—and in-field performance of—ccASHPs designed for whole-home heating and cooling.
The Challenge: Carbon reduction targets in the Northeast require transformation of the built environment. Massachusetts is seeking 50% GHG reductions by 2030 and 85% by 2050, and New York is aiming for a 40% reduction by 2030 and an 85% reduction by 2050. Achieving these targets will require widespread electrification of thermal loads, improved thermal performance of building envelope, the ability to store or shift energy use using grid integration, and suppling energy loads from zero emissions resources. However, across the Northeast, most building thermal loads are served by fossil fuels (oil, gas, propane, or wood). While the use of ASHPs for heating is increasing, they are still primarily being used as supplemental heating sources. Greater adoption of whole-home heat pumps, or heat pumps serving as the primary heating source, will be necessary to decarbonize building stock.
Our Solution: To address these concerns, and drive forward action on building decarbonization, Cadmus took a deep dive into the performance of ccASHP systems in over 40 homes across Massachusetts and New York that use their ccASHP systems as the primary heating source. We conducted in-field metered data collection for almost a full year (Fall 2020 through Fall 2021), assessing customer satisfaction, system utilization, heating load, and performance during a typical Northeast winter. About half of the homes that were metered maintained a back-up fossil fuel heating system, while the half were truly whole-home heat pump systems with no back-up except integrated electric resistance in some cases.
Key Findings: While the study sample size is insufficient to draw statistically significant conclusions, we identified the following key findings:
- Customers were highly satisfied with ccASHP performance. Comfort differences between primary with backup and whole-home system were minimal.
- Most participants reported having energy audits and home weatherization upgrades performed prior to, coincident with, or soon after their ccASHP system was installed.
- Contractors reported installation costs, aesthetics, customer misconceptions, and building logistics as the top cited barriers to wide-scale ccASHP deployment.
- A customer’s existing fuel type is an important factor to cost effectiveness. Based on current prices, natural gas customers will likely see overall utility bills increase by switching to electric ccASHP systems for heating due to the high cost of electricity relative to natural gas in the Northeast. However, customers who use delivered fuels such as propane and oil will likely see overall bill savings.
- On average, whole-home versus primary with backup applications had similar seasonal heating efficiencies, but site-level performance varied significantly due to many factors, including system type, size, and utilization.
- On average, measured heating performance during ‘cold snap’ periods for whole-home systems was above 2.0 COP (more than twice as efficient as electric resistance heat). The average seasonal heating performance for all measured systems was 2.34 sCOP.
- During the winter, utility grid impacts of wide-scale ccASHP adoption will likely occur during early morning hours, and whole-home applications with electric resistance elements will have the greatest electric grid impact during extreme cold periods.
What’s Next: The 2020/2021 winter was warmer than average and did not reflect periods of prolonged extreme cold that could have greater impacts on customer comfort and grid demand. Further study with a larger sample during an extreme cold weather event may be considered to provide more definitive conclusions on comfort, performance, and grid impact issues that could influence policymakers and program administrators.