What Does an EPC Assessment Check? A Room-by-Room Guide for London Homeowners
If you are selling or renting out a property in London, you will probably need an Energy Performance Certificate (EPC) before the property is marketed.
But what actually happens during an EPC assessment?
Many homeowners assume an EPC assessor simply checks the boiler and gives the property an energy rating. In reality, an assessment looks at a range of features that affect the property’s energy performance, including its construction, insulation, windows, heating, hot water, lighting, floors and overall size.
Understanding what an EPC assessor checks can help you prepare your property properly and make the appointment as straightforward as possible.
According to GOV.UK’s guidance on Energy Performance Certificates, an EPC provides an energy efficiency rating from A to G and is generally valid for 10 years.
What Is an EPC Assessment?
An EPC assessment is an inspection of a property’s energy-related characteristics.
The assessor collects information about the building and its services and uses that information to produce an Energy Performance Certificate.
The assessment can take into account:
Walls and construction
Roof and loft insulation
Floor construction
Windows and glazing
Main heating system
Heating controls
Hot water system
Fixed lighting
Renewable technologies
Property dimensions and layout
The official GOV.UK guide to EPCs for homes explains that the energy performance of a property is assessed using information about the building fabric and services such as heating, insulation, ventilation and fuels.
The assessment is therefore about the property itself rather than simply looking at how much energy you personally use.
What Does an EPC Assessor Check?
The exact inspection depends on the property, but there are several important areas an assessor will normally need to inspect.
1. Walls and Property Construction
The construction of your walls can have an important effect on energy performance.
An assessor may need information about:
Wall construction
The age of the property
Brick or stone construction
Cavity walls
Wall insulation
Internal or external insulation
For example, a property with cavity wall insulation may perform differently from a similar property without insulation.
However, not every insulation measure can be confirmed simply by looking at the wall.
If you have documentation showing that insulation has been installed, it can therefore be useful to have this available.
The official EPC assessment guidance explains how supporting evidence can be relevant when certain building features cannot be visually confirmed.
2. Windows and Glazing
Windows are another feature considered during an EPC assessment.
The assessor may look at whether the property has:
Single glazing
Double glazing
Triple glazing
Different types of windows throughout the property
If you have recently replaced your windows, it is worth keeping any available certificates or documentation.
This can be particularly helpful if the age or specification of the windows cannot otherwise be established during the assessment.
3. Loft and Roof Insulation
A significant amount of heat can be lost through the roof, which makes loft insulation an important part of a home’s energy performance.
Where safe access is available, the assessor may inspect the loft area and look for evidence of insulation.
You should therefore make sure that loft access is available if your property has an accessible loft.
You do not normally need to remove insulation or make alterations to the property simply for the EPC assessment.
If you have paperwork confirming when insulation was installed or the type of insulation used, keep it available for the assessor.
4. Heating System
Your heating system is one of the key areas considered during an EPC assessment.
Depending on the property, the assessor may record information about:
Boiler type
Boiler fuel
Main heating system
Radiators
Heating controls
Thermostats
Timers
Secondary heating
The GOV.UK EPC guidance identifies heating systems, insulation, ventilation and fuels among the factors used when assessing a property’s energy performance.
If you have documentation relating to your boiler or heating system, keep it somewhere accessible.
5. Hot Water System
The assessor may also need information about how hot water is produced and stored.
This can include:
Hot water cylinders
Boiler-based hot water systems
Cylinder insulation
Heating controls
The type of hot water system
If you have recently replaced your boiler, hot water cylinder or related equipment, any installation paperwork may be useful.
6. Lighting
Fixed lighting can also form part of the EPC assessment.
The assessor may record information about the type of fixed lighting installed throughout the property.
Energy-efficient lighting can contribute to the overall energy performance of a property.
This is another reason why access to the different rooms in the property is important during the assessment.
7. Floors
The construction of the property’s floors may also be considered.
Depending on the building, floors can be:
Solid
Suspended
Insulated
Uninsulated
Some floor construction details may not be visible during a normal inspection.
If you have information about floor insulation or construction, you can provide it to the assessor.
The more reliable information available about the property, the easier it is for the assessor to record the relevant characteristics.
8. Property Size and Layout
An EPC assessment also requires information about the size and layout of the property.
The assessor may need to establish:
Number of floors
Floor area
Room layout
Extensions
Habitable rooms
Areas within the roof
Relevant dimensions
This is why an EPC assessment cannot normally be completed accurately simply by using the property’s address.
The assessor needs to collect information about the actual building.
Does the EPC Assessor Need Access to Every Room?
This is one of the most common questions homeowners ask before an EPC appointment.
The official GOV.UK EPC guidance states that assessors need access to rooms, the boiler and the loft where safe access is available.
Before the appointment, make sure the assessor can access:
Bedrooms
Living rooms
Kitchen
Bathrooms
Boiler
Heating controls
Meter areas
Loft access where applicable
You do not need to completely empty your home.
The important thing is simply to make the relevant areas accessible.
What Should You Prepare Before an EPC Assessment?
Preparing your property does not need to be complicated.
A few simple steps can make the appointment easier.
Keep Property Documents Available
If you have documents relating to:
Boiler installation
Double glazing
Loft insulation
Cavity wall insulation
Heating systems
Renewable energy systems
keep them available.
This can be particularly useful for improvements that cannot easily be confirmed during a visual inspection.
Make the Property Accessible
Before the assessor arrives, check that they can access:
All rooms
The boiler
Heating controls
Meter areas
Loft access
Relevant utility areas
There is no need to carry out renovations just because you are having an EPC assessment.
How Long Does an EPC Assessment Take?
The time required can vary depending on the size and complexity of the property.
A small flat will generally be different from a large house with several floors, extensions or unusual construction.
The assessor needs enough time to collect the information required for an accurate EPC.
Once the relevant information has been collected, it is used to produce the certificate.
If you are unsure about the process, our Step-by-Step Guide to Getting an EPC in London provides additional information about arranging an EPC.
What Happens After the EPC Assessment?
After the inspection, the information collected by the assessor is used to produce your Energy Performance Certificate.
An EPC provides information including:
Energy efficiency rating
Typical energy-use information
Energy performance details
Recommendations for improving energy efficiency
The rating runs from A to G, with A representing the highest energy efficiency and G the lowest.
If you want to understand what those grades mean in more detail, read our guide Understanding EPC Ratings: What Your Grade Means.
The official GOV.UK Energy Performance Certificate guidance confirms that an EPC is generally valid for 10 years.
Do You Need an EPC Before Selling or Renting?
For most homes in England and Wales, an EPC is required when a property is sold or rented.
More importantly, the EPC needs to be ordered before the property is marketed for sale or rent.
The current GOV.UK guidance on selling a home and EPCs states that sellers and landlords must order an EPC before marketing a property.
If your property already has an EPC, you can also use the official GOV.UK Find an Energy Certificate service to check whether a certificate is available.
This is worth doing before paying for a new assessment, as your existing EPC may still be valid.
What If You Need an EPC Quickly?
Sometimes a property needs to go on the market quickly and there is no valid EPC available.
In that situation, arranging an assessment as soon as possible can help prevent unnecessary delays.
Urgent EPC provides Residential EPC services in London for homeowners, landlords and property professionals.
If you need an EPC urgently, you can also explore our Same Day EPC service, subject to availability.
Our pricing page also includes options for standard domestic EPCs, priority services and combined EPC and floor-plan services. You can see the current options on our EPC Pricing Plans page.
EPC, Floor Plans and Photography: Preparing Your Property for the Market
An EPC is an important part of preparing a property for sale or rent, but it is not the only thing buyers and tenants look for.
A complete property listing can also benefit from:
Professional property photography
A clear floor plan
Accurate property information
A valid EPC
A floor plan helps potential buyers understand the property’s layout before arranging a viewing.
Our article How Floor Plans Help Buyers Make Faster Property Decisions explains why accurate layouts can make property listings easier to understand.
Professional photography serves a different purpose. While the floor plan explains the layout, photography creates the visual first impression.
Combining these materials can help create a more complete property listing.
If you are preparing a property for sale, you can also read our Preparing Your Property for Sale: EPC, Photography and Floor Plans Checklist for more property marketing guidance.
Can You Book EPC and Other Property Services Together?
If you are preparing a property for the market, arranging everything together can save time.
Urgent EPC provides services for:
Energy Performance Certificates
Floor Plans
Property Photography
You can view the available services on our Our Services page or use the Book Services page to request an appointment.
For homeowners who are working to a tight deadline, combining services can be a convenient way to get the property ready for marketing.
Frequently Asked Questions About EPC Assessments
What does an EPC assessor check?
An EPC assessor checks the energy-related characteristics of a property, including its construction, insulation, windows, heating, hot water, lighting, floors and dimensions.
The exact information required depends on the property.
Does an EPC assessor check every room?
The assessor needs access to the rooms and relevant areas of the property so that the required information can be collected. The official GOV.UK EPC guidance explains the access requirements.
Do I need to clean my property before an EPC assessment?
There is no need for a special deep clean.
The important thing is to make the relevant rooms, boiler and other accessible areas available to the assessor.
Can I provide evidence of insulation?
Yes. If you have documentation relating to insulation or other energy-efficiency improvements, keep it available.
This may be useful where a feature cannot be confirmed visually.
How long is an EPC valid?
An EPC is generally valid for 10 years, unless a newer EPC has been produced for the property. You can check the current position through GOV.UK’s Energy Performance Certificate service.
Do I need an EPC to sell my property?
Most properties being sold require an EPC, and the certificate needs to be ordered before the property is marketed.
For the latest requirements and exemptions, always check the official GOV.UK EPC guidance.
Final Thoughts
An EPC assessment is more than a quick check of your boiler.
The assessor may need to consider the property’s walls, insulation, windows, heating, hot water, lighting, floors, dimensions and other energy-related features.
Preparing in advance is simple. Make sure the relevant rooms and equipment are accessible, and keep any useful documents about insulation, glazing, heating or other improvements available.
If you are selling or renting a London property, it is also worth checking whether you already have a valid EPC before arranging a new one.
If you need a new assessment, you can book an EPC with Urgent EPC and arrange the service around your property requirements.
For properties that also need marketing materials, Urgent EPC can help with Residential EPC services, Same Day EPC and other property preparation services.
