The US Department of Energy has issued a report in December 2017 (https://www.energy.gov/sites/prod/files/2017/12/f46/bto-DOE-Comm-HVAC-Report-12-21-17.pdf) entitled ENERGY SAVINGS POTENTIAL AND RD&D OPPORTUNITIES FOR COMMERCIAL BUILDING HVAC SYSTEMS. Amongst the high priority technology options listed are phase change materials. The report describes the potential as follows:
B.10 Phase Change Materials
Phase change materials (PCMs) provide passive cooling by storing and releasing thermal energy as latent heat. PCMs are substances such as
paraffin or salts that undergo a phase change (from solid to liquid and back) near the desired building temperature. Deploying these materials in buildings
can help maintain a consistent indoor temperature, as excess heat is absorbed by the PCM during daytime and released at nighttime. A 2013 NREL
study looking at PCMs in residential building envelopes estimated 15-20% cooling energy savings. Researchers are studying how to encapsulate PCMs and apply them to interior building surfaces, either as finished panels or as a thin coating materials integrated into wall paint or drywall.