As homeowners and landlords look for more sustainable ways to manage energy use, Micro-CHP (Combined Heat and Power) systems are gaining attention. Unlike traditional boilers, CHP units generate both heat and electricity at the same time, offering improved efficiency. But how does this technology affect your Energy Performance Certificate (EPC) rating?

1. What is Micro-CHP?

Micro-CHP is a system that:

  • Produces electricity on-site while heating the property.

  • Captures wasted heat from electricity generation to warm rooms and water.

  • Uses fuels such as mains gas, LPG, or biomass depending on the system design.

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2. How Micro-CHP Influences EPC Ratings

EPC calculations are based on the Standard Assessment Procedure (SAP), which considers energy efficiency and carbon output. Micro-CHP can impact scores by:

  • Improving energy efficiency – less wasted energy compared to separate heating and electricity.

  • Reducing carbon emissions – particularly if renewable or low-carbon fuels are used.

  • Lowering energy demand – self-generated electricity reduces reliance on the grid.

3. Challenges in EPC Assessment for Micro-CHP

While Micro-CHP is efficient, it presents some challenges for assessors:

  • System type variation – gas-powered CHP offers lower carbon benefits compared to biomass-fuelled versions.

  • Modelling complexity – SAP may not fully reflect real-world performance in smaller properties.

  • Upfront costs – although beneficial for EPC ratings, installations are expensive and may not be cost-effective for smaller homes.

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4. Best Situations for Micro-CHP

Micro-CHP systems are most effective when:

  • Installed in larger homes or multi-residential properties with high, consistent heat demand.

  • Combined with smart controls for heat and power distribution.

  • Supported by feed-in tariffs or energy export schemes (where available).

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5. Professional EPC Guidance

When assessing properties with Micro-CHP, a qualified EPC assessor will:

  • Examine system efficiency ratings and carbon factors.

  • Evaluate how the CHP interacts with insulation, glazing, and other building features.

  • Provide recommendations for further improvements alongside CHP benefits.

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Conclusion

Micro-CHP systems can improve EPC ratings by delivering efficient heating and electricity generation in one system. However, their effectiveness depends on property size, system type, and usage patterns. While not always suitable for every home, CHP can be a valuable solution for energy-conscious property owners aiming to boost EPC performance and reduce running costs.