EPC Frequently Asked Questions

An Energy Performance Certificate (EPC) is a legal requirement for properties in the UK that are sold or rented. Introduced in 2008, EPCs provide a standardised assessment of a property's energy efficiency.

Each EPC is conducted by a government-accredited Domestic Energy Assessor (DEA) who evaluates the property's construction, insulation, heating systems, and other energy-related features. The certificate is valid for 10 years and becomes part of the public record, available through government registers.

EPCs use a simple color-coded scale from A to G, where A is the most energy-efficient and G is the least efficient. Each letter grade is also accompanied by a numerical score between 0 and 100+.

Each EPC shows two ratings:

• Current rating: The property's energy efficiency as it is now
• Potential rating: What the property could achieve if all recommended improvements were made

The rating is affected by factors including insulation quality, heating system efficiency, window glazing, building age, and renewable energy installations like solar panels.

An EPC provides valuable information about a property's energy performance:

• ✓Current energy efficiency rating on the A-G scale with a numerical score
• ✓Estimated annual energy costs for lighting, heating, and hot water based on standardised assumptions
• ✓Potential improvements and their estimated impact on efficiency and costs
• ✓Individual efficiency ratings for major components (walls, roof, windows, heating, hot water, lighting)
• ✓Details about installed systems including heating type, fuel source, and controls
• ✓Renewable energy installations such as solar panels or solar water heating
• ✓CO₂ emissions estimate for the property (current and potential)

It's important to understand the limitations of EPC data. An EPC does not tell you:

• ✗Your actual energy bills - EPCs use standardised assumptions about occupancy and usage patterns, not your real-world consumption. Actual bills vary based on how you use the property.
• ✗Current energy prices - Cost estimates are based on standardised fuel prices at the time of assessment, which may differ significantly from current market rates.
• ✗Property-specific renewable energy potential - EPCs don't analyze whether solar panels or other renewable installations would be cost-effective for your specific location.
• ✗Carbon intensity of your local electricity grid - EPCs use national averages for emissions calculations.
• ✗Air quality in your area - This is tracked separately and is not part of energy performance assessments.
• ✗Real-world performance - The rating is a theoretical assessment. How efficiently the property performs in practice depends heavily on occupant behavior, maintenance, and actual weather conditions.

While EPC data is comprehensive, there are some coverage gaps to be aware of:

• Post-2008 only: EPCs became mandatory in 2008, so properties that haven't been sold or rented since then may not have a certificate.
• 10-year validity: Certificates are valid for 10 years but the data may become outdated, especially if improvements have been made since the assessment.
• Not universal coverage: Not every property in a postcode will have an EPC certificate. Some areas may have limited data.
• Northern Ireland: EPC data for Northern Ireland is not currently available through public APIs. Postcode Energy only covers England, Wales, and Scotland.
• standardised fuel prices: Cost calculations use standard assumptions for fuel prices that may not reflect current market conditions or your specific tariff.
• Property modifications: If significant changes have been made since the EPC was issued (new heating system, insulation upgrades, etc.), the certificate may not reflect the current state.

Postcode Energy integrates EPC data with other energy insights to give you a complete picture of your location's energy landscape:

Area-Level Statistics

We show the average EPC rating across all properties in your postcode, giving you a sense of the typical energy efficiency in your area. This includes average costs, potential savings, and property type distribution.

Individual Property Certificates

Where available, you can view individual EPC certificates for specific properties in your postcode, including detailed breakdowns of heating systems, insulation, and recommended improvements.

Combined with Other Data Sources

EPC data is just one piece of the puzzle. We combine it with:

• Solar and wind potential: Separate analysis using location, roof orientation, and weather data
• Real-time grid data: Live carbon intensity and generation mix
• Air quality monitoring: Current pollution levels in your area
• Energy pricing: Current tariff information and market rates

Clear Labeling

We clearly label EPC costs as "modeled estimates" and provide context about what the numbers mean. We also recommend consulting with MCS-certified installers for property-specific renewable energy assessments.

You should consider getting a new Energy Performance Certificate in these situations:

• Before selling or renting: It's a legal requirement to have a valid EPC when marketing a property.
• After major improvements: If you've installed new insulation, upgraded your heating system, or added solar panels, a new EPC will reflect these improvements.
• Certificate expired: If your existing EPC is over 10 years old, you'll need a new one for any sale or rental transaction.
• To establish a baseline: Even if not required, an EPC can help you understand your property's current efficiency and identify cost-effective improvements.

To arrange an EPC assessment, contact a qualified Domestic Energy Assessor through the government's register at gov.uk/find-energy-certificate.