Anti-Frost Coatings Reduce Winter Emissions from Heat Pumps Without Compromising Comfort

Area of Science:

• Building science
• HVAC technology
• Climate change mitigation

Background:

• Air-source heat pumps (ASHPs) are crucial for efficient electric heating and residential decarbonization.
• Cold climates reduce ASHP efficiency and necessitate defrosting, often requiring auxiliary electric resistance heating, which increases energy use and lowers indoor temperatures.
• Antifrost coatings can suppress frost formation, potentially mitigating these issues, but their system-level impact needs quantification.

Purpose of the Study:

• To simulate and quantify the system-level implications of antifrost coatings on residential air-source heat pump operation in cold climates.
• To compare the performance of antifrost coatings against current defrosting practices with and without auxiliary electric resistance heating.

Main Methods:

• Simulated ASHP operation across approximately 7900 single-family homes in 25 U.S. cold-climate cities.
• Evaluated three scenarios: current practice (defrost with auxiliary electric resistance heating), defrost without auxiliary heating, and antifrost coatings eliminating defrost operations.
• Quantified winter emissions reductions and indoor temperature impacts.

Main Results:

• Antifrost coatings can reduce median winter emissions by approximately 40% compared to current practices.
• Disabling electric resistance heating during defrost yields the largest emissions reductions but causes significant indoor cooling (1-5 °C).
• Adjusting the temperature set point by +2 °C can halve under-heating issues.

Conclusions:

• Antifrost coatings offer a viable strategy to reduce winter emissions and thermal discomfort associated with ASHPs in cold climates.
• Widespread adoption could lead to substantial reductions in residential heating emissions, contributing significantly to decarbonization goals.
• Further research could optimize set point adjustments to maximize benefits and user comfort.