Many homeowners assume an Energy Performance Certificate (EPC) is a straightforward formality when selling a property. However, a significant number of sellers are caught off guard when their EPC assessment delivers a lower rating than expected—or highlights issues that delay marketing altogether.
Understanding why EPC assessments “fail” (or underperform) allows sellers to prepare properly, avoid last-minute stress, and protect property value. Our experienced EPC Assessors in London regularly see the same mistakes repeated across properties of all ages:
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1. What Does “Failing” an EPC Really Mean?
Technically, EPCs don’t have a pass or fail result for sales. However, sellers often consider an EPC a failure when:
The rating is much lower than expected
The property falls into Band E, F, or G
The EPC raises red flags for buyers
Recommended upgrades appear costly or disruptive
The property becomes harder to market competitively
A poor EPC result can reduce buyer confidence, slow down the sale, or trigger price negotiations.
2. Sellers Overestimate Their Home’s Energy Performance
One of the most common reasons EPC assessments disappoint sellers is overconfidence.
Typical assumptions include:
“The house feels warm, so it must be efficient”
“We replaced the boiler years ago”
“Double glazing alone guarantees a good EPC”
EPCs are based on measured data and standardised assumptions, not comfort or appearance. Without evidence of insulation, controls, or efficiency upgrades, assessors must score conservatively.
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3. Missing or Inadequate Insulation
Insulation is one of the highest-impact EPC factors, yet it’s often incomplete or undocumented.
Common problems:
Loft insulation below recommended depth
Missing cavity wall insulation
No insulation in floors, pipes, or hot water cylinders
Insulation installed but not visible or provable
If insulation can’t be verified during the assessment, it cannot be fully credited, even if it exists.
4. Outdated or Poorly Controlled Heating Systems
Heating systems heavily influence EPC scores. Sellers are often caught out by:
Old non-condensing boilers
Lack of thermostatic radiator valves (TRVs)
No programmer or smart thermostat
Inefficient electric heating systems
Even a functioning boiler can score poorly if it lacks modern controls. Simple upgrades here often deliver significant EPC improvements.
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5. Inefficient Windows and Draught Issues
Windows and doors play a major role in heat retention. EPC issues commonly arise from:
Single-glazed windows
Early double glazing with poor performance
Draughty doors or frames
Lack of secondary glazing where replacement isn’t possible
While full replacement isn’t always necessary, draught-proofing and glazing upgrades can prevent EPC underperformance.
6. Poor Lighting Scores
Lighting is a small but often overlooked EPC component. Sellers are frequently surprised when:
Halogen or incandescent bulbs remain installed
Only partial LED coverage exists
External or fixed lighting isn’t energy efficient
Switching to 100% LED lighting is one of the cheapest EPC upgrades and can prevent unnecessary score loss.
7. No Evidence of Energy Improvements
EPC assessments rely on visible proof and documentation. Sellers often forget that:
Improvements made years ago may not be obvious
Receipts or certificates may be missing
Loft insulation may be hidden or compressed
Boiler upgrades may lack efficiency labels
Without evidence, assessors must assume default performance values, which often results in lower EPC ratings.
8. Older Properties and Construction Limitations
Period homes and older builds frequently struggle with EPCs due to:
Solid walls without insulation
Original construction materials
Limited scope for modern upgrades
Restrictions on alterations
While older homes aren’t expected to match new builds, targeted improvements can still move them up one or two EPC bands—often enough to satisfy buyers.
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9. Sellers Don’t Prepare Before the Assessment
A major reason EPCs disappoint is lack of preparation. Many sellers book assessments after listing, leaving no time to improve results.
Common preparation mistakes:
Booking EPCs at the last minute
Ignoring assessor recommendations
Failing to do low-cost improvements first
Assuming upgrades won’t affect the score
A short preparation window—sometimes just a weekend—can significantly improve outcomes.
10. How to Avoid EPC Assessment Failures
To avoid EPC surprises, sellers should:
Upgrade lighting to 100% LED
Top up loft insulation to recommended depth
Install heating controls and TRVs
Draught-proof doors and windows
Gather documentation for upgrades
Book an EPC before marketing begins
Professional assessors can also advise on high-impact, low-cost improvements tailored to your property.
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Conclusion
EPC assessments don’t fail randomly—they underperform due to predictable, preventable issues. Sellers who understand how EPCs are calculated and prepare accordingly can avoid unpleasant surprises and protect their sale price.
Key takeaways:
EPCs reward measurable efficiency, not comfort
Missing insulation and outdated heating systems are the biggest culprits
Evidence and preparation matter
Small, affordable upgrades can deliver big EPC gains
Early assessment gives sellers control, not stress
By addressing common EPC pitfalls before assessment, sellers can market with confidence, attract energy-aware buyers, and avoid unnecessary price reductions.
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Phone:020 34884142
