Energy Performance Certificates (EPCs) are designed to evaluate a building’s energy efficiency and provide guidance on reducing energy consumption. However, buildings equipped with Combined Heat and Power (CHP) systems present unique challenges for EPC assessments. CHP systems, also known as cogeneration, simultaneously produce electricity and useful heat, which complicates the calculation of energy performance.
Understanding Combined Heat and Power (CHP) Systems
CHP systems generate electricity on-site while capturing and utilizing the waste heat for heating or hot water. Key features include:
High energy efficiency – typically 60–80%, compared to separate production of electricity and heat.
Reduced carbon emissions – by maximizing fuel use and reducing grid dependence.
Flexible operation – can be scaled to building demand, which varies over time.
While CHP systems offer substantial energy benefits, these advantages are not always fully captured in EPC calculations.
Why EPC Assessments Are Challenging for CHP Systems
Complex Energy Flows – EPC models must account for both electricity and heat produced on-site, which standard EPC methodologies may not handle accurately.
Variable Operation Patterns – CHP systems often operate according to building demand, time-of-day usage, and seasonal variations, making static modeling insufficient.
Grid Interaction – The interaction between CHP generation and imported/exported electricity complicates energy consumption calculations.
Data Availability – Accurate EPC assessment requires detailed operational data, which may not always be available.
These factors can result in EPC ratings that underestimate or overestimate the building’s true energy performance.
Strategies to Improve EPC Accuracy for CHP Buildings
Detailed Data Collection – Include hourly energy output, heat distribution, and fuel consumption.
Advanced Simulation Tools – Use dynamic modeling that accounts for variable operation.
Integration with Other Energy Measures – Consider insulation, renewable energy sources, and smart controls in the assessment.
Professional EPC Assessors – Employ experts familiar with CHP systems to ensure accurate ratings.
For professional assessment, you can check our EPC Assessors in London page.
Benefits of Accurate EPC Assessment for CHP Buildings
Provides a true reflection of energy performance.
Helps identify energy-saving opportunities.
Ensures compliance with regulations and improves sustainability credentials.
Supports decision-making for building upgrades or retrofits.
Conclusion
Buildings with CHP systems present unique EPC assessment challenges due to their complex energy flows and variable operation. Accurate assessments require detailed data, dynamic modeling, and expertise to ensure EPC ratings reflect actual energy performance. Properly evaluating CHP-equipped buildings helps maximize energy efficiency, reduce carbon emissions, and support sustainable building operations.
