Affordable Near- and Medium-Term Solutions for Integration of Low GWP Heat Pumps in Residential Buildings

Develop and Demonstrate next generation heat pumps utilizing low global warming potential refrigerant, achieve high efficiency, and achieve cost savings.

The Regents of the University of California on behalf of the Davis Campus



Recipient Location


Senate District


Assembly District



Amount Spent



Project Status

Project Update

The project is in the process of retrofitting the ten demonstration sites with the near-term heat pump solution using a lower-cost compressor drive coupled with the low-GWP refrigerant R-454B. The existing systems were monitored for one year to establish a baseline energy usage for each home. The medium-term solution is focused on improving the performance of air-to-water heat pumps with the potential to safely incorporating ultra-low, natural refrigerants. This project is evaluating advanced microchannel polymer heat exchanger designs to improve heat exchanger performance relative to typical fin-tube type heat exchangers used in hydronic systems. The project team is evaluating manufacturing methods for developing the polymer heat exchanger such as injection molding and 3D printing. A small scale heat exchanger has been completed with both manufacturing methods and currently being tested for mechanical and thermal performance. This heat exchanger will be coupled with an air-to-water heat pump and tested in a laboratory setting.

The Issue

Next generation heat pump technologies have the potential to significantly reduce greenhouse gas emissions from buildings in California but have had some challenges penetrating the California marketplace, largely due to high initial costs. In order to meet California's aggressive energy and carbon goals it will be necessary to find low-cost solutions for switching the primary fuel for heating buildings from natural gas to electricity while also improving the heating and cooling efficiency of heat pumps.

Project Innovation

This project develops and demonstrates affordable near-term (TRL 4- high 7) and medium-term (TRL 4- low 7) solutions for integration of lower cost, low- and ultra-low global warming potential (GWP) heat pumps. The combination of addressing both near-term (GWP < 750) and medium-term (ultra-low GWP <10) needs is necessary to meet California's carbon reduction goals. The near-term solution focuses on a closer-to-market emerging technology that uses a proprietary, a lower cost compressor drive. This technology will be demonstrated for cost and energy savings at 10 pilot sites. The goal is to provide a market-ready product that is more efficient and 10% lower cost. The medium-term solution incorporates an innovative heat exchanger in the secondary loop to improve its efficiency, enabling use of hermetically-sealed ultra-low GWP flammable refrigerants in heat pumps. This technology will be tested at a laboratory scale.

Project Goals

Develop, test, and demonstrate a 10 percent lower cost high-efficiency heat pump with low-GWP refrigerant.
Develop and test a high-efficiency microchannel heat exchanger with 15 to 20 percent higher effectiveness of performance.

Project Benefits

This project advances high-efficiency heat pump equipment at a lower installed cost compared to current competing heat pump technology, improving the appeal and affordability of heat pumps. Heat pumps are vitally important in the effort to meet California's carbon reduction goals through building electrification, but until now their cost has hindered widespread adoption.

Consumer Appeal

Consumer Appeal

Reducing the cost of heat pumps will make them more attractive to customers who have so far largely ignored them due to high upfront costs relative to alternatives.

Lower Costs


The proposed research will lead to lower costs for heat pumps in the near- and medium-term. This is necessary for greater market uptake.

Environmental & Public Health

Environmental Sustainability

A total of 9.2 Million therms of natural gas could be offset through increased use of electric heat pumps, and while this would increase the electric demand statewide by 63.7 GWh, the greenhouse gas emissions in California relate.

Key Project Members

Vinod Narayanan

Vinod Narayanan

Principal Investigator
UC Davis
Curtis Harrington

Curtiis Harrington

Senior Engineer
UC Davis
Felix Villanueva

Felix Villanueva

Commission Agreement Manager/Utility Engineer
California Energy Commission



TRC Engineers, Inc.




Eden Housing


Merced County Community Action Agency


Match Partners


Southern California Edison


Regents of the University of California, Davis




Dr. Prath Vaishnav


Contact the Team