An inaccurate Energy Performance Certificate (EPC) doesn’t just misrepresent your home’s energy efficiency—it can directly impact your property’s sale price, rental value, and buyer interest. Small mistakes or overlooked details during an EPC assessment can have a big financial consequence.
In this article, we’ll explore the common EPC mistakes that can lower your property value, why they happen, and how to ensure your EPC is accurate and protects your property’s market potential.
The Link Between EPC Ratings and Property Value
With rising energy costs and stricter regulations, buyers and tenants are increasingly influenced by EPC ratings. Properties with higher EPC bands (A-C) are:
More attractive in listings
Can command higher sale prices
Often qualify for better mortgage rates
Conversely, a low EPC rating (D-E-F) can:
Decrease market value by 5-10%
Limit interest from energy-conscious buyers
Create obstacles for renting or selling due to legal compliance
EPC Mistakes That Could Lower Your Property’s Value
1. Incorrect Use of Assumed Values (‘Unknown’ Defaults)
If an assessor marks key details (e.g., insulation, heating system efficiency) as ‘Unknown’, the software assigns worst-case default values. This can unfairly downgrade your EPC rating.
🔴 Impact: Your property may show as Band D/E instead of Band C, directly affecting sale and rental value.
➡️ Learn how EPC defaults silently damage ratings.
2. Missed Heating Controls & Thermostat Verification
Failing to identify programmable thermostats or zone heating controls removes efficiency credits in the EPC calculation.
🔴 Impact: Potential loss of up to 5-10 EPC points, which could drop you a full band.
3. Overlooking Insulation Upgrades Due to Lack of Documentation
Even if your walls, loft, or floors are insulated, missing installation certificates may lead the assessor to apply uninsulated defaults.
🔴 Impact: Increased heat loss assumptions, lowering the EPC rating and reducing perceived property efficiency.
4. Non-Accessed Areas Penalising Air Leakage Scores
If lofts, underfloor voids, or mechanical ventilation systems are inaccessible, the EPC defaults to poor air tightness assumptions.
🔴 Impact: The property is rated as draftier and less energy-efficient than it actually is.
5. Software Data Entry Errors by Inexperienced Assessors
Simple mistakes like selecting the wrong wall type, glazing spec, or floor area measurement can significantly skew results.
🔴 Impact: EPC bands can drop unnecessarily, hurting your property’s appraisal and negotiation power.
How EPC Mistakes Affect Property Price in the Market
| EPC Band | Market Perception | Estimated Impact on Price |
|---|---|---|
| A-B | Highly Efficient – Premium Appeal | 5-10% Price Increase |
| C | Modern Efficiency Standard | Neutral to Slightly Positive |
| D-E | Outdated Efficiency – Lower Demand | 5-10% Price Drop |
| F-G | Non-Compliant (Rental Restrictions) | Severe Sale/Rental Limitations |
Real Estate Agents Know: EPC Impacts Negotiations
A poor EPC can:
Become a bargaining tool for buyers to negotiate a lower price
Reduce mortgage lender appetite for the property
Trigger additional retrofit demands before sale closure
How to Avoid EPC Mistakes That Lower Your Property Value
1. Prepare Evidence of Upgrades
Ensure you have:
Cavity wall insulation certificates
Boiler efficiency labels
Glazing specifications
Ventilation system reports
2. Choose Experienced EPC Assessors
At EPCrate, our assessors:
Thoroughly inspect properties to avoid ‘Unknown’ defaults
Ensure every verifiable energy feature is recorded
Deliver EPCs that accurately reflect your property’s true value
➡️ Book a precision EPC assessment with EPCrate.
Transparent Pricing & Service Coverage
We offer:
Competitive EPC pricing
Specialist EPC assessments across London
Detailed documentation reviews to avoid rating mistakes
Conclusion: Don’t Let EPC Errors Devalue Your Property
EPC mistakes—whether through missing documentation, incorrect defaults, or assessor oversights—can unfairly lower your property’s rating and shave thousands off its market value.
By preparing documentation and hiring skilled assessors like EPCrate, you can ensure your EPC reflects reality, safeguarding your property’s price and buyer appeal.
