Active phase-change wall inserts are a cutting-edge building technology designed to regulate indoor temperatures by absorbing, storing, and releasing heat as they transition between solid and liquid states. By actively controlling the timing of these phase changes through embedded systems, buildings can significantly reduce heating and cooling loads.
While these systems can dramatically improve real-world energy performance, they present several complications for Energy Performance Certificate (EPC) modelling.
How Active Phase-Change Wall Inserts Work
Thermal storage: The inserts store excess heat during warm periods and release it when temperatures drop.
Active control: Sensors and automation manage when heat is absorbed or released to maximise comfort and efficiency.
Energy shifting: Reduces reliance on HVAC systems during peak energy demand hours.
This dynamic thermal behaviour does not match the static assumptions used in most EPC software.
EPC Modelling Limitations
EPC assessment tools are built around fixed material properties, such as constant U-values and thermal mass. Active phase-change systems break these assumptions:
Variable thermal mass: The system’s storage capacity changes as the material undergoes phase transitions.
Timing sensitivity: Energy savings depend on precise control algorithms, which EPC tools do not simulate.
Lack of standard inputs: There is no dedicated EPC database entry for active phase-change inserts, so assessors must make approximations.
You can learn more about our experience with complex and innovative building technologies on our About Us page.
Residential EPC Considerations
Homeowners using active phase-change systems should be aware that EPC improvements might be understated compared to real-world energy savings. Our Residential EPC service ensures these technologies are documented with clear assessor notes for potential buyers and tenants.
Same-Day EPC for Advanced Retrofits
If you’ve recently installed phase-change wall inserts and need urgent certification, our Same Day Energy Performance Certificate (EPC) service can process your assessment quickly, even with non-standard materials.
Cost Implications
Phase-change systems can vary widely in cost depending on materials and automation sophistication. For EPC-related assessment fees, see our Pricing Plan page.
Speak to an EPC Specialist
Not sure how your phase-change wall system will be handled in an EPC assessment? Get in touch with our experts via our Contact Us page for tailored advice.
