Learn how to assess a building for 2021 Building Regulations compliance and energy certification. An energy performance certificate (EPC) is required when non-domestic buildings are built, sold, or rented, and are valid for up to 10 years. To produce an EPC you must be a qualified Energy Assessor.

The application you will use is called the UK Building Regulations 2021 Studio. The 2013 and 2010 applications are still available through the Tas Manager in the TasUtilities folder. This guide assumes you’ve already set up source T3D and TBD files and the input data and assumptions are known.

How you zone the source building will affect the results and therefore the predictions of energy performance. Zoning rules are explained in paragraphs 200 and 201 of the NCM modelling guide (2021). The notional and reference buildings will have the same zoning arrangement as the actual building.

The UK Building Regulations 2021 Studio can be used for projects using English (2021), Scottish (2022), or Welsh (2022) regulations. The process of setting up and running a studio project is the same for each country. You should read the NCM modelling guide for the relevant nation and be familiar with it.

The latest NCM Constructions database (TCD) is version 6.1.e (the 6.1.b TCD should no longer be used)

The latest NCM Activities database (TIC) is version 6.1.b (NB there were no activity changes between 6.1.b and 6.1.e)


You should read the NCM modelling guide for the relevant nation and be familiar with it.


The NCM Activities database must always be used for compliance checking and energy certification. Details of occupancy, temperature set-points, fresh air rates, and heat gain profiles must not be changed regardless of how they may be in practice. This allows buildings to be compared on their intrinsic potential performance.


Standard weather sets are available and should always be used. The choice of available weather sites depends on which country’s regulations are being used for the project.

For Scotland, Glasgow weather data must be used (despite the fact that Edinburgh weather data also exists, Glasgow weather data must always be used, even for buildings in Edinburgh itself).

For Wales, Cardiff weather data must be used.

For England, there are 14 weather data files available to choose from. Select a file based on the distance to the site of the proposed building. Refer to paragraph 199 of the NCM modelling guide (2021) for more information.

In the example in this guide, the CIBSE Test Reference Year weather data for London was used to simulate demand, consumption, and CO2 emissions for every hour of the year for both the Part L2 analysis and EPC calculation.