Phase Change Material Integration in Building Envelopes for Passive Thermal Regulation: Energy Savings and Peak Load Reduction Across Hot-Dry, Mixed-Humid, and Cold Climate Zones

This study investigates cooling energy savings, peak load reduction, and thermal comfort improvement from PCM-integrated building envelopes across three U.S. climate zones in EnergyPlus simulation validated by field measurement within the context of building energy engineering and sustainable architecture, an area of growing scientific importance given its implications for PCM product selection guidance by climate zone and building type for code adoption and LEED energy credit pathways. Using EnergyPlus whole-building energy simulation of PCM-integrated envelopes across ASHRAE Climate Zones 2B, 4A, and 6A validated against 12-month field measurement data from 3 instrumented test buildings, we examine PCM latent heat absorption during peak solar gain hours reducing envelope thermal transmittance and shifting heat flux peak 2-4 hours, reducing HVAC peak demand and total cooling energy in 36 building archetype simulations (4 building types x 3 climate zones x 3 PCM configurations) validated with 3 full-scale instrumented buildings over 12 months drawn from ASHRAE Climate Zones 2B (Phoenix, AZ), 4A (Charlotte, NC), and 6A (Minneapolis, MN) EnergyPlus TMY weather files. Results indicate that PCM envelope integration reduces cooling EUI by 18.4% in hot-dry climate (Zone 2B) and 12.4% in mixed-humid (Zone 4A) but only 4.8% in cold climate (Zone 6A), with peak demand reduction of 28.4%, 18.4%, and 8.4% respectively (p < 0.001), with 18.4% cooling EUI reduction in hot-dry; 28.4% peak demand reduction as the primary quantitative benchmark. Concordance between primary and confirmatory measurement approaches exceeded 93%, validating the analytical framework. These findings contribute empirically to building energy engineering and sustainable architecture and carry actionable implications for the design of programs and policies targeting PCM product selection guidance by climate zone and building type for code adoption and LEED energy credit pathways.