An EPC assessor can identify energy inefficiencies within seconds of entering your property. These “red flags” directly influence your EPC score, so understanding them helps you prepare properly before your inspection. Fixing even a few of these issues can improve your rating and reduce long-term energy costs.

If you’re preparing your home for an assessment, you can also learn more about our certified assessors on the About Us – EPC Company in London page.

1. Missing or Insufficient Loft Insulation

Poor loft insulation is one of the first—and biggest—red flags.

Assessors check for:

  • Insulation below 270mm

  • Inconsistent or patchy layers

  • Damp insulation that reduces performance

Upgrading loft insulation often delivers immediate improvements. For professional guidance, explore our EPC Assessors Services in London.

2. Old or Inefficient Boilers

A boiler that’s outdated or non-condensing is one of the clearest energy-efficiency concerns.

Assessors also look for:

  • Lack of heating controls

  • Poor maintenance signs

  • No installation records

If you’re unsure about your boiler’s impact on your EPC, our team can help during your EPC Booking.

3. Single Glazing or Damaged Windows

Inefficient glazing results in heat loss and reduced comfort.

Red flags include:

  • Single-glazed windows

  • Failed double-glazing seals

  • Condensation between panes

If you’ve installed new windows recently, ensure you have proof ready before the assessment.

4. Uninsulated or Poorly Insulated Walls

Wall insulation contributes massively to your EPC score.

Assessors will flag:

  • Cavity walls without insulation

  • Solid walls with no upgrades

  • Damp or cold patches indicating heat loss

If you want an accurate evaluation of wall performance, check our EPC Services Page.

5. Visible Draughts and Air Leaks

Even minor gaps can significantly reduce energy efficiency.

Assessors look for:

  • Gaps around external doors

  • Leaks near window frames

  • Missing weather-proofing

Before your assessment, sealing these gaps can boost your score with minimal cost.

6. Inefficient Lighting Systems

While lighting has a smaller EPC impact, outdated bulbs still lower your rating.

Assessors flag:

  • Halogen or incandescent bulbs

  • Older spotlight systems

  • Lack of LED upgrades

Replacing bulbs is a very simple EPC improvement.

7. Signs of Damp or Poor Ventilation

Moisture problems often indicate insulation or airflow issues.

Assessors will note:

  • Mould patches

  • Persistent condensation

  • Areas lacking extractor fans

These issues suggest deeper inefficiencies that affect your EPC result.

8. Inefficient Hot Water Systems

Hot-water systems are a major component of your property’s energy performance.

Red flags include:

  • Uninsulated hot-water cylinders

  • Old immersion heaters

  • Unlagged hot-water pipes

Adding insulation jackets or pipe lagging can improve performance quickly.

9. Missing Heating Controls

A home without proper heating controls is automatically less efficient.

Assessors look for:

  • Programmable thermostats

  • TRVs (Thermostatic Radiator Valves)

  • Room thermostats

Heating controls are inexpensive yet powerful EPC boosters.

10. Missing Documentation

This is one of the most common—and most costly—EPC red flags.

Without proof of:

  • Loft or wall insulation

  • Boiler upgrades

  • Double glazing

  • Renovation work

… the assessor must assume the lowest efficiency scenario.

To avoid this, prepare your evidence before your appointment. If you haven’t booked yet, visit the EPC Booking Page.

Get Ready for Your EPC With EPCrate

Avoiding these red flags helps ensure a better EPC rating and reduces surprises during the inspection. Whether you’re a landlord, seller, or homeowner, our team is here to help.

Email :info@epcrate.co.uk

Phone:020 34884142