UK's National
Method for Non Domestic Buildings

Latest News   

25th October 2021: Release of cSBEM_v6.0.d to accompany Wales' 2021 Part L consultation

18th August 2021: Release of cSBEM_v6.0.c to accompany Scotland's 2021 Section 6 consultation

19th January 2021: Release of cSBEM_v6.0.b to accompany England's 2021 Part L consultation

18th September 2020: Release of iSBEM_v5.6.b and iSBEM_v4.1.h

21st August 2020: Release of patch 4 for iSBEM_v5.6.a and patch 3 for iSBEM_v4.1.g

22nd May 2019: Release of patch 3 for iSBEM_v5.6.a

13th November 2018: Release of patch 2 for iSBEM_v5.6.a

12th October 2018: Release of patch 1 for iSBEM_v5.6.a

3rd October 2018: Release of iSBEM_v5.6.a

31st July 2018: Release of patch02 for iSBEM_v4.1.g

6th April 2018: Release of iSBEM_v5.4.b

6th February 2018: Release of patch 1 for iSBEM_v5.4.a

20th November 2017: Release of iSBEM_v5.4.a

17th March 2017: Release of patch 4 for iSBEM_v5.3.a

1st March 2017: Release of optional 64-bit version of iSBEM_v5.3.a

22nd February 2017: Release of patch 3 for iSBEM_v5.3.a

7th December 2016: Release of patch 2 for iSBEM_v5.3.a

22nd November 2016: Release of patches for iSBEM_v5.3.a and iSBM_v4.1.g

21st November 2016: Release of iSBEM_v5.3.a and iSBEM_v4.1.g

18th November 2016: Release of patches for iSBEM 4.1.e and iSBEM 5.2.d


Introduction to NCM

The National Calculation Methodology (NCM) for the EPBD (Energy Performance of Buildings Directive) is defined by the Ministry for Housing, Communities, and Local Government (MHCLG) in consultation with the Devolved Administrations (DAs) . The procedure for demonstrating compliance with the Building Regulations for buildings other than dwellings is by calculating the annual energy use for a proposed building and comparing it with the energy use of a comparable 'notional' building. Both calculations make use of standard sets of data for different activity areas and call on common databases of construction and service elements. A similar process is used to produce a 'asset rating' in accordance with the EPBD. The NCM therefore comprises the underlying method plus the standard data sets.

The NCM allows the actual calculation to be carried out either by an approved simulation software or by a simplified tool based on a set of CEN standards. That tool has been developed for MHCLG by BRE and is called SBEM - Simplified Building Energy Model. It is accompanied by a basic user interface - iSBEM.

Introduction to SBEM

SBEM is a computer program that provides an analysis of a building's energy consumption. SBEM calculates monthly energy use and carbon dioxide emissions of a building given a description of the building geometry, construction, use and HVAC and lighting equipment. It was originally based on the Dutch methodology NEN 2916:1998 (Energy Performance of Non-Residential Buildings) and has since been modified to comply with current CEN Standards. Details of the calculation method, the algorithms used and the assumptions made are provided in the SBEM Technical Manual, available from the Download page.

SBEM makes use of standard data contained in associated databases and available with other software.

The purpose of SBEM and its interface iSBEM is to produce consistent and reliable evaluations of energy use in non-domestic buildings for Building Regulations Compliance and for Building Energy Performance Certification purposes. Although it may assist the design process, it is not primarily a design tool. It does not calculate internal temperatures, for example.

As SBEM is a compliance procedure and not a design tool, if the performance of a particular feature is critical to the design, even if it can be represented in SBEM, it is prudent to use the most appropriate modelling tool for design purposes. In any case, SBEM should not be used for system sizing.

In line with revisions to Approved Document ADL2A and equivalent documents in the DAs, SBEM and iSBEM have been revised and updated a number of times to include additional functionality. The current version of the software can be used for demonstrating compliance with Part L2A in England and the equivalent regulations in other parts of the UK, and for generating Energy Performance Certificates. See the Download pages for more details on applicability and approved versions for use in different parts of the UK and the Republic of Ireland. All relevant versions of the tool, along with user guides, can be downloaded free of charge from the Download pages.

SAP for dwellings

The calculation method for dwellings is a new version of SAP - the Standard Assessment Procedure for the Energy Rating of Dwellings. This is specified in documents available at and is implemented through a number of commercially available software tools.

ORCalc Methodology (for Display Energy Certificates)

The purpose of Display Energy Certificates (DECs) is to raise public awareness of energy use and to inform visitors to public buildings about the energy use of a building. DECs provide an energy rating of the building from A to G, where A is very efficient and G is the least efficient, based on the actual amount of metered energy used by the building over a 12 month period.

For further information regarding DECs and the ORCalc please visit