What Happens During an EPC Assessment? A Homeowner’s Guide

If you are planning to sell or rent out your property, you’ve likely heard that you need an Energy Performance Certificate (EPC). While the term is common, many homeowners and landlords are unsure of what actually happens once the assessor knocks on the door.

Is it invasive? Do they look under the floorboards? How long does it take?

In this guide, we’ll walk you through exactly what to expect during an EPC assessment so you can feel prepared and potentially even improve your property's rating.

What is an EPC Assessment?

An EPC assessment is a visual inspection carried out by an accredited Domestic Energy Assessor (DEA). The goal is to determine how energy-efficient your home is and provide a rating from A (most efficient) to G (least efficient).

The certificate is legally required in the UK for any property being sold or let, and it remains valid for 10 years.

The Assessment Process: Step-by-Step

The actual site visit usually takes between 30 and 60 minutes, depending on the size and complexity of your home. Here is what the assessor will look at:

1. External Measurements and Construction

The assessor begins by measuring the external dimensions of the property. They are looking at the "heat loss perimeter"—essentially how much of your home is exposed to the outside air. They will also identify the construction type (e.g., cavity wall, solid brick, or timber frame) to understand how well the structure retains heat.

2. Insulation Inspection

Insulation is one of the biggest factors in your EPC score. The assessor will:

• Check the Loft: They will need to look into your loft space to measure the thickness of the insulation.

• Wall Insulation: They will look for evidence of cavity wall insulation (often identified by small drill holes in the mortar) or internal/external wall insulation.

3. Heating and Controls

The assessor will examine your primary heating source (usually the boiler). They will record the make and model to determine its efficiency rating from a national database. They also check for:

• Heating Controls: Do you have a programmer, room thermostats, and Thermostatic Radiator Valves (TRVs)?

• Hot Water: How is your water heated, and is the cylinder insulated?

4. Windows and Doors

The assessor will check if your windows are single, double, or triple-glazed. If you have recently installed new windows but the date isn’t visible on the glass, having your FENSA certification handy can be very helpful.

5. Lighting

The assessor will count the number of fixed light fittings in the property and identify how many of them use low-energy bulbs (like LEDs). This is one of the easiest ways to boost your score!

6. Renewable Energy

If you have solar panels (PV), wind turbines, or a ground-source heat pump, the assessor will record these. These features significantly boost your energy rating.

How to Prepare for Your Assessment

To ensure the process goes smoothly and you get the most accurate rating, follow these tips:

• Clear Access: Ensure the assessor can get into the loft, the boiler cupboard, and all rooms.

• Gather Paperwork: If you’ve had underfloor insulation or cavity wall insulation that isn’t visible, have the certificates ready.

• Replace Bulbs: Switch any old halogen or incandescent bulbs to LEDs before the assessor arrives.

What Happens After the Visit?

Once the assessor has gathered the data, they input it into government-approved software (RdSAP). This calculates your current rating and generates a list of recommendations to improve your score.

You will typically receive your digital certificate within 24 to 48 hours of the assessment, and it will be uploaded to the official EPC Register.

Need an EPC for your property?

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