Check your EPC 'Features' Table

At the time of writing this page, the methodology for EPC assessments of existing dwellings is RDSAP 10. A significant methodology overhaul from RDSAP to the Home Energy Model (HEM) is proposed for 2026 and government consultations indicate proposed changes to the format of EPCs and minimum rating levels required for private rental properties. Methods for improving EPC ratings will therefore change in the future.

A good place to start is to check if your property already has an EPC, either one that's currently still valid (they last for 10 years), or even perhaps one that has expired.

If you have an existing or previous EPC, locate and review the contents of the Features table. This can provide some useful headline information to work from.

Here is the Feature table from an old EPC for the house that I live in. This is a 1950s terraced house, and the EPC is rather out of date:

What you can do is check each of the features, consider whether they seem correct to you, and consider whether you might be able to improve the energy performance of that property feature.

You can also compare with the information on the EPCs of your neighbouring properties.

Before proceeding with any works however, always consult a local Domestic Energy Assessor and confirm what EPC rating could be achieved by the works you have in mind.

The Features table on an EPC is just a summary.

There is a significant amount of information that a Domestic Energy Assesor records during an assessment that is not indicated on the Features table.

The Features table should therefore be considered with this in mind.

EPCs from the early days from 2007 or so have very limited information in their Features table.

Those EPCs will have expired some considerable time ago now, as 10 years will have passed from when they were issued.

With an old, expired EPC, it's worth comissioning a new one so that you have up to date information. The methodology does get updated from time to time, so the rating can change from one assessment to the next.

Here is an example of the Featurs table from such an early EPC:

EPCs produced initially for new-build properties are slightly different to those produced for 'existing dwellings'.

An EPC for a new build property, or a conversion through a 'material change of use', is frequently called a SAP EPC (SAP is an acronym for Standard Assessment Procedure). Accurate engineering information about materials used to build the property are used in the calculation of the rating.

An EPC for an existing dwelling uses RDSAP (Reduced Dataset Standard Assessment Procedure), which uses assumed performance information based on the age of the building and building regulations or common construction practices at the time.

If your EPC is a SAP EPC it may appear something like this:

Notice that for Walls, Roof and Floor there is no description of the type of construction, but instead U values are directly specified instead.

This is the quickest way to spot a full SAP EPC.

Notice also that there is an Air tightness result as well, which has been supported by SAP for some time.

Since the 15th June 2025, the updated version of RDSAP (Version 10) can now accept air tightness test results in new EPCS for existing dwellings.

For the remainder of this page, we'll consider only the Features table from an RDSAP EPC - ie one for an 'existing dwelling'.

In the table above from my EPC, each Feature is listed once. For some properties however, some of the Feaures might be listed multiple times.

This can occur if you have an original building which has then had extensions built at different later dates. It might be possible for the Walls and Roofs features to be listed twice or even three times, with different wall types and roof types declared for the different building parts.

Perhaps there might be a Sandstone wall for the original building, a solid brick wall for the first extension and a cavity wall for the second extension.

This can also happen if a building part is declared as having a section of 'Alternative Wall' where a mix of construction types have been used in one building part.

This section decribes the type of external wall of your property.

Part of the information expressed here will be manually declared by an energy assessor during an assessment, and part might have been automatically determined by the EPC methdology (RDSAP) based on the date of construction.

A measurement will also have been made of the thickness of the wall. Some of this information can be determined from how the Features Table describes your wall.

With my house, the wall type has been manually declared as a Cavity Wall, which is correct. This will be determined partly by the brick bond of the wall, the thickness of the wall as measured in an opening such as a door or a window, and also with visual confirmation looking at a party or end-gable wall in the loft.

With my wall, the assessor could not locate any visual evidence of retrofitted Cavity Wall Insulation (CWI) so has correctly described the insulation status of the wall in the assessment as 'As Built' (ie still in the state that it was at the time of original construction).

The EPC methodology then refers to a table of U values for cavity walls to choose the thermal performance of this wall that it will use in the rating ccation. These U values are based on typical construction practices at the time, or the minimum perfromance required by building regulations (following their introduction in the mid 1960s).

In my case it's a 1950s house, built before national building regulations were introduced in the 1960s, and the U value chosen for this 'As Built' cavity wall is 1.6.

Because CWI was not in common use at the time, the description indicates: 'no insulation (assumed)'. This is correct for my external walls - there is no cavity wall insulation present.

For a cavity wall to be described as 'insulated', without the word assumed, it is important to understand that this is only for walls with retrofitted cavity wall insulation - ie where cavity wall insulation has been installed after the property was originally constructed.

With your property, does the entry for Wall appear to match your expectation of the wall type present in your property?

Could the wrong dateband have been applied to a building part resulting in your wall having assumed insulation when in fact it doesn't, or vice versa?

If the insulation is not assumed, and it was manually selected by the assessor, does it match your expectation of whether retrofitted insulation is present or not?

Could your property be a conversion, following a material change of use?

Is there a way you could improve the energy performance of your wall(s)?

With a standard pitched roof, with access through a hatch, you'd expect to see a level of measured loft insulation present - 50mm in my case

(although there was actually much more than this in the loft, and the assessor had clearly made a mistake here looking at the date of the loft insulation certificate stapled to the cross beams).

There's no mention of 'assumed' in brackets on my EPC here because access was available to the roof space for the assessor to check, and they manually declared a level of insulation that they had 'measured'.

If access was not available to a pitched roof, perhaps in the case of the loft hatch being locked in place, then you might see: 'Pitched, no insulation (assumed)'.

This can also be the case if the area of loft was boarded over and the owner was not available to, or not prepared to lift the boards due to insurance/health and safety reasons.

In the case of sloping ceilings and vaulted ceilings then access is normally not available 'assumed' will appear, with the insulation status depending on the construction date of that building part, unless documentary evidence was provided to prove otherwise.

A 'Room In Roof' (where rooms are present within the area of pitched roof space) is similar in that access is often not available to check the presence of insulation, although the flat ceiling part can sometimes be accessed and measured.

Does the description on your EPC for Roofs match your expectation of what it should be?

Could you improve the energy performance of your roof?

Do not under any circumstances however install spray foam insulation between the rafters.

Check with your local Domestic Energy Assessor.

For me it's 'Fully Double Glazed', which matches what I have present in the building. Double Glazing is categorsied by age in an assessment, but this level of detail is not shown in the Features Table.

Broadly speaking, glazing can be Single, Secondary, Double, Triple.

Does the description match what you have at the property?

Can you improve the energy performance of your Windows? Is it worth the expense doing so?

See our page about Glazing. Good improvements can be made moving away from Single Glazing but it might not be worth your while improving existing double glazing.

As per our note at the end of this page, always check with an energy assessor about your specific property before making decisions.

This describes the heating system used to keep the living areas of the property warm. This is often referred to as 'Space Heating'.

This is an important section, and it has a big effect on the EPC rating of a property. It needs to be considered in conjunction with the section for 'Hot Water Heating' and 'Secondary Heating' and 'Main Heating Control'.

Typical factors to consider include the fuel type used, and particularly the cost per kWh of that fuel because the headline EPC rating on domestic EPCs is a cost based metric.

Large gains could be made from moving from a more expensive fuel to a cheaper one - eg Electric Panel Heaters or Storage Heaters to a gas boiler (not that that would be taking us towards net zero however).

With standard heating controls for a boiler, you'd want to have Programmer, Thermostat and TRVs. If you are missing any of those, could you get them added?.

Could you also improve your heating controls to qualify as Time & Tempeature Zone Control (TTZC)?

Does the description of your heating system seem correct on the EPC?

As a chid I remember tungsten filament bulbs and how hot they ran. We'd have to unscrew a blown bulb with a double-folded tea towel before fitting a new bulb, and the light fittings would brown over time becase of the long-term exposure to high levels of heat. Light fittings would be rated by to the maximum power of bulb they would accomodate, and some domestic bulbs were even rated at 150W. Imagine how much power would be drawn if you had 10 of them powered up at the same time.

Things have changed since then, and the sale of filament bulbs is now prevented by legislation. Even fluorescent tubes in the UK are on their way out. The move for some time has been towards what is called 'Low Energy Lighting', with LED of particular interest.

We have a page just about lighting, and it's worth reading to ensure you understand what counts as 'Low Energy Lighting' from an EPC perspective. Moving to 100% Low Energy Lighting doesn't make much of a difference to the EPC rating, perhaps 2 points for a typical house when moving from none to 100% but it all helps.

Does the percentage displayed on this Feature seem about right to you for your property? Usually, with an EPC that has just expired (they last 10 years), the percentage will now already be much greater that that indicated.

Could you increase the percentage of Low Energy Lighting in your property up to 100% if it's not already?

Here, there will be an indication of the type(s) of ground floor present in your property.

Common types might include Solid floor or Suspended Timber, or if it is a flat it might indicate 'Another property below'.

Does the floor type indicated here seem right for your property?

Would it be possible to add insulation to the floor to improve the EPC rating?

Would it be worth doing so? Probably not in most cases because the cost is high and the gain in EPC rating is usually small.

This is one of those less interesting looking items that I would often lump together in my mind along with Floor type and Heating Controls before I became an Energy Assessor.

Nowadays I know better, and it is really important to look at this particular Feature in the table.

The example of my EPC is particularly important, and I want you to check if you have this entry on your EPC Features table or not. On my EPC it says:

'Portable electric heaters (assumed)'

Normally, Secondary Heating is any form of additional fixed heating source such as a gas fire or log burner or electric heater etc that might be in the property in addition to the main heating system, assuming you have one.

In my property the main heating system declared at the time was storage heaters.

However, and this is the important part: during the assessment of this property, the energy assessor recorded that one or more habitable rooms was not heated by the main heating source (Storage heaters in this case).

The EPC methodology therefore assumes that, in the case where no other source of Secondary Heating was declared in the property, in order to fulfil the shortfall in heating required to maintain the internal temperature due to the un-heated habitable rooms to that required by the model, that portable electric heaters will be used by the occupants.

In my case where storage heaters are the main heating system, this doesn't matter due to how the methodology works, but if your main heating system was for example a gas boiler, the presence of Secondary heating running on a more expensive fuel, particularly electric, can reduce the EPC rating considerably.

A similar degradation of EPC rating can also occur if you do indeed have one of more fixed peak rate electric heaters in the property, and a main heating system that operates on a cheaper fuel such as gas (or that uses electricity efficiently such as a Heat Pump).

See our Heating Systems page for more details. See also our Conservatories page if you have a conservatory, because that can be considered an un-heated habitable room in particular situations.

One useful approach is to compare the Features Table of your EPC against that of your neighbours properties.

Compare with properties of the same age and type. In particular, if the property is semi-detached or a terraced house you can compare with your directly attached neighbours.

There may be some differences with insulation added after original construction, but you might be able see what is achievable for your type of property.

It might be possible to spot mistakes in EPCs by comparing in this way, however you need to be careful about assuming any particular EPC is right or wrong.

Always check with a Domestic Energy Assessor before deciding what changes to make to a property in order to improve your EPC rating.

Without doing this, you will just be making changes to your property from a position of uncertainty. When you instruct an asssessor to produce a new EPC you would not know whether the changes you have implemented were the best ones, whether they will have made a difference, or what magnitude of difference, until you get that new EPC, and you may be disappointed with the result, and have spent money unecessarily.

By instructing an Energy Assessor from the outset, and asking them specifically what you can do to improve your EPC rating, you will be working from a position of certainty, and be able to target the most cost effective changes for your property.

So, get an energy assessor to assess your property first and make some recomendations to you (this is better than just relying on recomendations listed on the EPC), and then get that same energy assessor back to assess the property again once you've completed any works.

This will clearly cost slightly more, but it's likely to save you money by avoiding 'improvements' that would not make a useful difference.

Click here to return to our 'Improve Your EPC' main page, and see if there is another way you could improve your EPC rating.