Certification | Air Tightness | Thermography





SBEM Calculations 



SBEM Calculations are a requirement of non-domestic properties in the UK. They are required for new build properties as well as when substantially renovating a property and when converting a property (i.e. flats into offices). 

The calculation takes into account all of the building elements which affect the thermal performance of the property such as the wall, roof and floor build-ups, insulation levels, window U-Values, and HVAC details as well as the activities each building zone is to be used for. These details are then used to model the building and calculate its energy efficiency. The outputs from these calculations are the Energy Performance Certificate (EPC) and a set of Building Regulation Compliance Reports.  

 01  Do I need a SBEM Calculation?

99% of the time the answer is YES. All new build non-domestic properties require one as do all conversions and anything that constitutes a 'material change of use' (such as flats being turned into offices). Major renovations will also require one.



 02  When should I get my SBEM Calculation?


​The sooner the better. If we are given drawings and a building specification at the end of the build, there is very little we can do to change the specification if it is not achieving compliance. We advise arranging your calculations before you start the build so they can be done in two stages: Design-Stage and As-Built. 




 03  What is Design Stage and As-Built Stage?

Before building commences we will review your architects' drawings and planned specification. From these details, we will model a 'Design-Stage SBEM'. This allows us to calculate the energy performance of the property and ensure that all areas of the calculation are achieving Building Regulations compliance. At this stage, we will issue the Design-Stage Compliance Reports, a specification document and a Predicted EPC. This stage will also let you know the air tightness test target that you need to aim for. You can contact us at any time throughout the build for advice on how to achieve this target. See our air tightness page for more information.


At completion, you will be asked to confirm that you have built the property to the same specification as the Design-Stage SBEM. Once this is complete we can issue you the As-Built Compliance Reports and the final EPC for the property. 




 04  How do I pass my SBEM Calculation?

To achieve compliance under Part L2A (New Build) the DER of the property much outperform the TER:


The Dwelling Emissions Rating (DER)

This has to outperform the Target Emissions Rating (TER). The TER is set by reference to a notional dwelling (see below) within the SBEM Calculation. This notional dwelling is of the same orientation, size, shape and zoning arrangements however uses a set of baseline values and a maximum level of glazing.

Dwelling Fabric Energy Efficiency (DFEE)

Again this figure needs to outperform the Target Fabric Energy Efficiency (TFEE). This is measured in energy demand i.e. how well a home retains its heat. This will also have a knock on effect on the DER.


The Notional Dwelling

The figures below are those used in the notional dwelling within the SBEM Calculation. These are much better figures than the minimum U-Value standards within Approved Document Part L.

Windows & Doors:                   The same as the actual dwelling up to 25% of the total floor area

External Walls:                         0.26 W/m2K

Roof:                                        0.18 W/m2K

Exposed & Ground Floors:      0.22 W/m2K

Glazing:                                   1.60 W/m2K (whole window U-Value)


Roof Lights:                             1.80 W/m2K (whole window U-Value)


Vehicle or Large Doors:           1.50 W/m2K

Pedestrian/High Use Doors:    2.20 W/m2K

Air Tightness:                           5.00 m3/h/m2

Lighting:                                   55 luminares lumens per circuit - watt

There is flexibility to change these in your specification i.e. you can use a specification for the walls that has a U-Value of 0.28 W/m2K (for example) but the specification will need to be improved upon elsewhere i.e the floor or roof insulation. 


 05  What happens if my current building specification fails?

We won't leave you with a fail. Our fee includes a recommended specification from us if you end up in this situation. It also covers any changes to your specification throughout the build i.e if you're struggling to get a certain make of blockwork or a specific boiler is out of stock with the suppliers. A full design change (new drawings etc) with significant level of remodelling will incur a fee from us but we've never had to do that yet. We like to work with our clients and not against them. It's why our regular clients keep coming back to us.

 06  How much do SBEM Calculations cost?

This depends on the size and complexity fo the property. It all comes down to the time it will take us to model the property. We are highly competitive and think our repeat clients would agree. The feedback we generally receive is how helpful we have been throughout the build as well as at the key SBEM stages. 

To get a quote for a specific property or development please get in touch with us. 

Tips to Pass

  • Start your SBEM calculations before you start to build

          Don't end up fighting for a pass at completion, know from the start that you're going to pass.

  • Fabric first... save energy before creating more

          Compliance can be achieved without the need for renewable technology to be installed. ​Focus on insulating the dwelling when            designing your specification and then you won't need to create the extra energy at all.

  • Air tightness is key... from the start!

          Heat loss through air leakage is huge and the SBEM calculation knows it. Minimum standards in Part L for air leakage is 10​.00              m3/h/m2, however, the leakier your peroperty is, the more money you will have to spend on insulation to improve the SBEM                    Calculation. We generally aim for 5.00 m3/h/m2 - if you are confident and want to take on the challenge then we recommend                going down to 4.00 m3/h/m2. Ask us throughout the build and we can help with air tightness tips and advice.


  • Thermal bridging can turn a good property into a bad one

          Using the government's Approved Construction Details package (ACDs) will allow us to avoid using default figures and will                  make a significant different to the calculation.

  • Even better use bespoke PSI values

          When building a larger development or using a repeated specification it may be more economical to calculate PSI values                      instead of using the accredited values - this will save you spending money elsewhere in the building specification. See our                    thermal modelling page for more information​.


Commercial EPCs



SBEM Calculations are also used to produce commercial EPCs for existing non-domestic buildings. These are valid for 10 years and involve a site visit in order to measure the building dimensions and gather evidence on constructions, insulation levels and the HVAC specification.

For these visits, the more information you can have available the better i.e. O&M manuals, HVAC manuals and access arranged to locked areas.

Minimum Energy Efficiency Standards (MEES) now make it a legal requirement for all non-domestic properties to achieve an EPC rating of an E or better if they are to be rented out on a new tenancy agreement.


From 1st April 2023 landlords must not continue to let any buildings which have an EPC rating of less than an E, even if it is continuing on an existing rnetal agreement.

There are the following exemptions to MEES compliance:

  • buildings which are not legally required to have an EPC i.e. industrial sites, agricultural buildings with low energy demand, certain listed buildings, temporary buildings and holidays lets;

  • Short lettings (6 months or less);

  • Lettings over 99 years.

Should you require further MEES advice or wish to book an initial survey please contact us. If your property does not achieve an E rating we can advise on ways in which to improve it and, after works are complete, provide a follow-up EPC with your new rating.