Research Publications

Air-source heat pumps (ASHPs) provide high-efficiency electric space heating and play an important role in residential decarbonization. In cold climates, low outdoor temperatures reduce ASHP efficiency, while frost formation necessitates periodic defrosting, which lowers indoor temperatures and is typically offset by energy-intensive auxiliary electric resistance heating. Antifrost coatings offer a pathway to suppress frost formation and mitigate these comfort and energy penalties, but their system-level implications for residential ASHP applications have not been quantified. Here, we simulate ASHP operation in ∼7900 single-family homes across 25 U.S. cold-climate cities, comparing current practice, i.e., defrosting with auxiliary electric resistance heating, to defrosting operation without auxiliary heating, and to antifrost coatings assumed to suppress frost formation and thereby avoid defrost operations. Our calculations show that relative to current practice, antifrost coatings can reduce median winter emissions by ∼40% (assuming defrost is triggered after each hour of frosting conditions and lasts 15 min). Disabling electric resistance heating yields the largest emissions reductions but causes 1–5 °C indoor cooling during defrost, while a +2 °C increase in temperature set point halves under-heating. At scale, widespread adoption of antifrost coatings could yield winter emissions reductions of up to 30% of U.S. commercial aviation emissions in 2022, while eliminating defrost-related thermal discomfort.