EPC Rating B

EPC Rating B

What it takes to achieve an EPC rating B

If you are aiming to get your property to an EPC rating B, then you will be entering the realms of the best of the best in terms of energy efficiency and a low environmental impact.

According to the Department for Levelling Up, Housing and Communities, only 11% of UK homes have an EPC rating of B. This is based on the number of EPCs lodged on the Energy Performance of Buildings Register.

The benefits of having a property with a good epc rating is that it will be more comfortable to live in and have lower energy bills. You will also be eligible to access lenders that offer Green Mortages that have preferential interest rates.

There are 2 main components to a B rated property. The first is that all the following elements must have insulation to the current building regulations.

  • Walls
  • Floors
  • Lofts
  • Flat or Sloping Roofs
  • Full double glazing
  • 100% low energy lighting

If even one of the elements above are sub standard, then it may end up being an EPC rating C property. However, there is a secret sauce that can be added if you find yourself short in any one department which I will come to later.

The second element is that the property must be using a cheap source of fuel to heat the property such as gas and also have no secondary heating, such as gas fires, electric heaters, wood burners etc. Also it will also have a full set of main heating controls such as programmer, room thermostat and TRVs. If the property is over 120m2 it should preferably have time and temperature zone controls.

However, if the property doesn’t have much heat loss perimeter and a low heat demand, then it may get away with using a more expensive form of fuel such as electric.

An example of this would be a flat where it only has one heat loss wall at the front, a sheltered corridor, another flat below and above it and a flat either side of it. In this kind of scenario, the cost of the fuel plays a less significant part.

How The Age Of A Property Impacts The EPC Rating

When conducting an EPC survey, the Assessor has to determine the age of different sections of the property. The software will then use the thermal values for elements that can’t be seen based on the building regulations for that age.

Most properties built after 2012 are likely to be a B rating or better. This is because they would have had all the elements previously mentioned built in from new.

The further your property is away from 2012, the more improvements you’re likely to have to make.

How The Energy Performance Certificate Rates A Property

The final rating on the EPC certificate is determined by the primary energy use for the property in kilowatt hours per square metre (kWh/m2). The lower that value, the higher the rating.

Primary energy use is a measure of the energy required for lighting, heating and hot water in a property. The calculation includes:

  • the efficiency of the property’s heating system

  • the energy used to produce the fuel and deliver it to the property

  • power station efficiency for electricity

An Energy Performance Certificate (EPC) shows the energy current and potential energy rating of a property, known as a ‘SAP rating’. A ‘SAP’ rating stands for S tandard A ssessment P rocedure and is the governments recommended system for producing a home energy rating.

Boost Your Property’s Energy Efficiency Rating With Solar Panels

This single energy improvement is what we call the secret sauce. Because the epc rating is based on the running cost, installing solar panels can reduce energy consumption by over £350 a year.

This has a massive impact on the rating and can increase a property’s energy efficiency rating by as much as 10 sap points. So for example it can take a C71 property to a B81 rating in one single step.

When trying to improve your home’s energy efficiency, a fabric first approach should be taken in addressing the walls, floors, roof, windows. However, if you’re looking for a quick win in the ratings department, then solar certainly fits the bill.

Get The Rating You Deserve- The Importance Of U-values

When trying to get to a EPC rating of a B, you may have to use actual calculated u-values, instead of software assumed u-values.

A u-value is the rate that heat is lost through an element. The lower the u-value, the better an element is at reducing heat loss. So for example an un-insulated cavity wall will have a u-value of 1.50 and an insulated cavity wall a u-value of 0.55.

The methodology that the software uses to produce your energy performance certificate rating is call rdSAP which stands for reduced data Standard Assessment Procedure.

Typically in an existing home the actually make up of an element ie a wall, roof, floor, wouldn’t be known. Therefore the software assumes the u-value based on the building regs for the year that element was constructed.

In these situations, a worse case scenario u-value would be used which may not actually reflect what is really there and may have an impact on your epc rating. Also the exact thermal value of the insulation product you fitted may not be exactly represented.

Here’s a real world example

You’ve refurbished a solid wall property and fitted 72.5mm PIR insulated plasterboard to the internal walls.

In rdSAP you have only a limited amount of insulation thicknesses to select from in the software. So in the example above, if the thickness actually fitted is not in the software, you have to select the next thickness down. So in the example above, 50mm would be selected. Also the worst case u-value of a 50mm insulation product would be used and the software will calculate the walls with a u-value of 0.55.

In reality the product of 72.5mm insulated plasterboard with a thermal conductivity of 0.022 would acheive an actual u-value of 0.31 and have a better rating on the EPC over the assumed u-value of 0.55.

The Solution

To get the most from major thermal improvements you have made, make sure you have documented evidence of the products and thickness you have fitted. This could be a receipt or specification of works, or plans from the contractor.

Get calculated u-values if required. A normal epc assessor can change the default u-values in the software but the calculations have to be carried out by either an On Construction Domestic Energy Assessor (OCDEA) or a Non Domestic Energy Assessor (NDEA), or alternatively by a qualified person that has suitable expertise and experience which can be demonstrated by having membership of a recognised U-value calculation competency scheme or any other process recognised by Accreditation Schemes/Approved Organisations and Government.

If a major refurb has been undertaken and there are numerous different themal elements to the different parts of the walls, floors, roof and windows, then significant variations can’t be modeled properly in rdSAP, then a different methodology may have to be used such as SAP.

SAP stands for Standard Assessment Performance and is the UK governments methodology for measuring energy efficiency in homes. All elements (if known) can then be more precisely calculated and may produce a better EPC rating.

Because an EPC produced using full SAP is more detailed and time consuming then this is likely to cost you more to get the EPC done.


So to summarise:

Stop guessing EPC rating

•Only 11% of UK homes have an EPC rating of B.

• The benefits of having a good EPC rating include a more comfortable home and lower energy bills.

• To achieve a B rating, all the following elements must be insulated to current building regulations: walls, floors, lofts, flat or sloping roofs, windows (double glazed).

• The property must also be using a cheap source of fuel to heat the property.

• Solar panels can increase a property’s energy efficiency rating by as much as 10 sap points.

I will later be showing a case study of a 1900 victorian mid terrace Islington town house, how it increased the EPC rating from a D60 to a B81. So watch this space.


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Rickie Dickson

Written by Rickie Dickson

Rickie Dickson is an experienced and qualified domestic and non domestic energy assessor. He helps homeowners and businesses in all matters relating to energy efficiency, from meeting building regulations compliance to improving a property’s energy rating score.