Phase Change Material-Enhanced Insulation for Residential Exterior Wall Retrofits

Enhancing conventional low cost blown-in insulation with phase change material (PCM) and aerosealing of the wall cavities

Regents of the University of California, Davis


Davis, CA

Recipient Location


Senate District


Assembly District



Amount Spent



Project Status

Project Update

Project is on track. The Market Characterization of Advanced Insulation Products for Single- and Multi-family Residences report was completed on August 2021. Monitoring equipment was installed in the demonstration sites and project team has started collecting baseline energy use data. Project team is conducting small-scale laboratory tests of the aerosol wall cavity sealing apparatus and phase-change material.

The Issue

Single family homes built before the 1978 building codes have uninsulated exterior wall cavities that contribute to unwanted thermal losses/gains and air leakage, wasting energy and introducing outdoor air pollutants. This results in excessive natural gas consumption for heating and high utility bills. Existing insulation solutions are either expensive (spray foam) or do not address leakage (blown-in insulation). The cost effective retrofit wall insulation strategies can only achieve limited improvements in thermal comfort and limited reductions in heating natural gas consumption and utility bills.

Project Innovation

This project develops and tests a PCM-enhanced insulation solution for existing homes that have little or no wall insulation, with the goal of showing sufficient cost savings and other benefits to recover the cost within 10 years when compared to existing uninsulated walls. Through modeling and selected laboratory testing, the most cost-effective applications of PCMs for wall retrofit-wall assembly in a range of California climate zones will be identified. This will include analyzing PCMs melting point, amount, and installation location (mixed blown-in insulation or applied to the interior wall surface. The project also tests and evaluates the process for aerosol sealing wall cavities in retrofit applications prior to installing cellulose or fiberglass insulation. Finally, the project will evaluate an optimized PCM-enhanced insulation solution for homes in three climate zones (Bay Area coastal (CZ3), Central Valley (CZ12), and Southern California coastal (CZ9)).

Project Benefits

PCMs are designed to store and release thermal energy at specific temperatures by melting and freezing. Adding PCM has the potential to reduce total heating energy requirements at reasonable cost if designed with the correct melt point, amount, and location in the wall. Aerosealing of wall cavities, prior to blowing in insulation, can greatly reduce wall air leakage and enhance the performance of lower cost cellulose and fiberglass insulation. It is estimated that the PCM-enhanced insulation could reduce emission by 30 million metric tons of CO2eq emissions and reduce criteria pollutant emissions by reducing natural gas and electricity usage for heating and cooling. The cost effectiveness of PCM-enhanced insulation will drive adoption of the retrofit due to improved economic perform

Lower Costs


It is estimated that the PCM-enhanced insulation could save 5.0 billion therms of natural gas over the next 30 years due to reduce heating loads.This will reduce utility bills for ratepayers while also improving thermal comfort in their home. The timeframe of 30 years for energy saving was determined by the expected durability of the PCM insulation system. PCM is expected to have a lifetime similar to, or longer, than blown-in fiberglass or cellulose ins

Environmental & Public Health

Environmental Sustainability

It is estimated that the PCM-enhanced insulation could reduce emission by 30 million metric tons of CO2eq emissions as well as reduce criteria pollutant emissions through reduction in natural gas and electricity usage for heating and cooling over the next 30 years.

Key Project Members

Project Member

Theresa Pistochini

Engineering Manager



TRC Engineers, Inc.


Match Partners


Western Cooling Efficiency Center - UC Davis


Department of Mechanical and Aerospace Engineering - UC Davis


Senseware Inc.


Hearth Labs


Contact the Team