Your heating system plays a decisive role in determining your Energy Performance Certificate (EPC) score. In most UK homes, space heating accounts for the largest share of energy consumption, which is why EPC assessments place significant weight on how heat is generated, distributed, and controlled.

Homeowners are often surprised to discover that even a warm, comfortable home can still receive a low EPC rating if the heating system is inefficient or poorly controlled. Our experienced EPC Assessors in London see this scenario daily and help property owners understand what truly affects EPC performance:
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1. How EPC Assessments Evaluate Heating Systems

EPCs don’t just ask “Do you have heating?” They analyse how efficiently your system operates by assessing:

  • Type of heating system (gas boiler, heat pump, electric, oil, etc.)

  • Seasonal efficiency of the system

  • Heat distribution method (radiators, underfloor heating)

  • Heating controls (thermostats, TRVs, zoning)

  • Fuel type and carbon impact

Because heating dominates energy demand, even small inefficiencies can significantly reduce your EPC score.

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2. Boiler Efficiency and EPC Scores

Boilers remain the most common heating system in UK homes.

Modern Condensing Boilers

  • High seasonal efficiency

  • Lower fuel consumption

  • Strong EPC performance when paired with good controls

Older Non-Condensing Boilers

  • Significant heat loss

  • Higher fuel consumption

  • Heavily penalised in EPC calculations

Replacing an aging boiler can deliver substantial EPC gains, particularly in properties sitting close to the next EPC band.

3. Heat Pumps and EPC Ratings

Heat pumps are increasingly popular due to their high efficiency and low carbon impact.

Air Source and Ground Source Heat Pumps

  • Very high EPC efficiency scores

  • Best performance in well-insulated properties

  • Strong contribution to Band A–B ratings

However, heat pumps installed in poorly insulated homes may underperform, limiting EPC benefits.

4. Electric Heating Systems

Electric heating systems vary widely in EPC impact.

  • Modern electric storage heaters with smart controls can perform reasonably well

  • Older electric heaters are inefficient and heavily penalised

  • Lack of insulation significantly worsens EPC outcomes

Upgrading electric heating often requires a combined approach involving insulation and controls.

5. The Role of Heating Controls

Even the most efficient heating system can score poorly if controls are lacking.

EPC-valued controls include:

  • Programmable room thermostats

  • Thermostatic Radiator Valves (TRVs)

  • Time and temperature zoning

  • Smart heating systems (when correctly configured)

Heating controls often provide some of the cheapest EPC points available.

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6. Fuel Type and Carbon Emissions

EPC methodology considers the carbon intensity of the fuel used.

  • Gas generally performs better than oil or solid fuel

  • Renewable electricity improves EPC scores

  • Hybrid systems can offer balanced performance

This means switching fuel types—where practical—can significantly affect EPC outcomes.

7. Common Heating-Related EPC Mistakes

Assessors frequently encounter issues that reduce EPC scores:

  • Modern boilers with no TRVs or thermostats

  • Smart controls that aren’t integrated into the system

  • Heating upgrades without supporting insulation

  • Missing documentation for recent installations

Even high-quality systems may score poorly if they cannot be fully verified.

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8. Heating Systems and Landlord Compliance

Heating efficiency is critical for landlords due to minimum EPC standards.

A poorly performing heating system can:

  • Keep a property below required EPC bands

  • Trigger costly upgrades later

  • Restrict rental eligibility

Targeted heating improvements are often the fastest route to compliance.

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9. Strategic Heating Upgrades for EPC Improvement

For maximum EPC impact, upgrades should be planned, not reactive:

  1. Assess insulation and building fabric first

  2. Upgrade heating systems only where efficiency gains are meaningful

  3. Add or upgrade heating controls

  4. Gather full documentation

  5. Schedule re-assessment at the right time

This approach avoids wasted investment and maximises EPC results.

Conclusion

Heating systems have one of the largest influences on EPC scores—often more than homeowners expect. Efficiency, controls, fuel type, and integration with insulation all determine how well your system performs in an EPC assessment.

Key Takeaways

  • Heating dominates EPC calculations

  • Efficient boilers and heat pumps score highly

  • Controls are as important as the heating system itself

  • Poor insulation limits heating system EPC benefits

  • Evidence and timing matter for accurate scoring

By understanding how heating systems impact EPC ratings, homeowners and landlords can make smarter, more cost-effective upgrade decisions.