When an Energy Performance Certificate (EPC) assessment is booked, many homeowners and landlords wonder: What exactly does the assessor look at? The process can seem mysterious, but it’s highly structured and surprisingly thorough.
In this guide, we walk you through a room-by-room breakdown of what EPC assessors check — so you can prepare your property, avoid common pitfalls, and ensure your rating reflects its true energy performance.
🔍 What Is the EPC Assessment Process?
An EPC assessment is a non-invasive, visual inspection conducted by an accredited Domestic Energy Assessor (DEA). They gather data that feeds into government-approved software (RdSAP or SAP), which generates your EPC rating and recommendation report.
📏 Duration: 30 to 90 minutes, depending on property size
🧰 Tools: Tape measure, tablet/laptop, thermometer, laser measurer, possibly a camera
🏠 Room-by-Room Checklist: What the Assessor Actually Looks At
🛋️ Living Room (and all main living spaces)
Heating source: Radiators, underfloor heating, or wall-mounted units?
Fuel type: Gas, electric, oil, or renewables?
Heating controls: Thermostats, TRVs, programmers
Insulation clues: Draught proofing, thermal bridging indicators
Windows: Double/triple glazing? U-values? Air leakage evidence?
🔎 Pro tip: Clean, accessible radiators and visible thermostats help show off your heating efficiency.
🛏️ Bedrooms
Same checks as living spaces
Room orientation and glazing type
Signs of roof insulation access (especially if loft is above)
📸 Any hard-to-access areas (e.g., boarded lofts) can be documented with photos or previous receipts.
🍽️ Kitchen
Boiler or hot water cylinder location and make/model
Heating pipework visibility and insulation
Lighting type: CFLs, halogens, or LEDs?
Any mechanical ventilation or extractors?
⚠️ EPC software applies defaults when info is missing — often penalising your score. Be ready with documentation!
🛁 Bathrooms
Number and size (affects hot water demand)
Type of water heating system (combi boiler vs tank)
Presence of extractor fans or trickle vents
Insulation of hot water tank and pipes
🪜 Hallways, Stairwells & Landings
Floor construction type (solid vs suspended)
Visibility of insulation underneath (in suspended floors)
Glazing and wall type in stairwells
Access to loft — often located here
🏗️ Other Key Areas
🔲 Loft or Roof Space
Loft insulation: Depth, coverage, and type
Is it over or under 270mm (the benchmark)?
Converted lofts are inspected as part of habitable space
Flat roofs: May require assumption unless insulation is visible/documented
🧱 Walls (All Rooms)
Assessor checks wall thickness at windows/doors to determine:
Solid brick
Cavity wall (insulated or not)
Timber frame or other types
Cavity wall insulation: Visible signs or documentary proof
🪟 Windows & Doors
Number, size, and glazing type (single, double, triple)
Presence of low-E coatings, gas fill, and frame material
Draught-proofing checks
💡 Lighting Assessment (All Rooms)
Number of fixed light fittings
Count of low-energy (LED/CFL) bulbs
This percentage influences your EPC rating
💡 100% low-energy lighting won’t save your score alone, but it helps!
🔍 External Features
Construction type: Brick, block, timber, etc.
Roof type: Pitched or flat; insulation assumptions depend on visibility
Extensions and conservatories: Assessed for insulation, glazing, and heating
Solar panels: If installed, assessors check size, orientation, and inverter placement
📂 What Documentation Can Help?
EPC assessors rely primarily on what they can see — unless you provide proof.
✅ Helpful documents to prepare:
Building Control sign-offs
Certificates for loft/wall insulation
Boiler installation docs
Solar panel spec sheets
Floor plans (for complex layouts)
Receipts for new windows or insulation
📸 No receipts? Take photos during installation or request copies from installers.
⚠️ Common Mistakes That Lower Your EPC Score
Loft hatches blocked or painted shut (no insulation proof = default penalty)
Boiler in a cupboard without access
Assessor not shown heating controls or hot water tank
Low-energy lighting in sockets, not fixed fittings
No access to extensions or conservatories
🧠 Final Thoughts: Be Prepared, Be Transparent
EPC assessments aren’t intrusive, but they are technical. The more information you can provide and access you give, the more accurate — and potentially higher — your EPC rating will be.
🔧 Need an Accurate EPC in London?
EPCrate.co.uk offers:
✅ Same-day EPCs across Greater London
📋 Trained assessors who understand how to boost your score
🧾 Guidance on which documents will help your property perform better
💬 After-assessment advice on smart, affordable upgrades
Your EPC result is only as good as the data entered. Let your home speak for itself — fully and fairly.
