Latest News
24th July 2026: Release of cSBEM_v7.0.e to accompany Scotland's 2026 Section 6 consultation
26th August 2025: Release of cSBEM_v7.0.d to accompany Wales's 2025 Part L consultation
30th May 2024: Release of Patch04 to iSBEM_v6.1.e for Scotland's Section 63 Action Plan
28th February 2024: Release of Patch03 to iSBEM_v6.1.e (E&W) and Patch01 to cSBEM_v7.0.c (E)
13th December 2023: Release of cSBEM_v7.0.c to accompany England's 2025 Part L consultation
9th February 2023: Release of Patch01 to iSBEM_v6.1.e for England's 2021 Part L amendments
19th December 2022: Release of iSBEM_v6.1.e for Wales's 2022 NCM and 2022 Part L
Introduction to NCM
The National Calculation Methodology (NCM) is defined by the Health and Safety Executive (HSE) 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 glazing. A similar process is used to produce an 'Asset rating' for Energy Performance Certificates (EPCs). The NCM, therefore, comprises the underlying method plus the standard databases.
The NCM allows the actual calculation to be carried out either by an approved dynamic simulation model (DSM) or by a simplified tool based on a set of ISO standards. That tool has been developed for HSE 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 which provides an analysis of a building's energy consumption, under standardised operating conditions. SBEM estimates the monthly energy use and carbon dioxide emissions of a building when given a description of the building's geometry, construction, and its building services equipment. It was originally based on the Dutch methodology NEN 2916:1998, Energy Performance of Non-Residential Buildings. SBEM has since evolved and been further developed to comply with ISO/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 the associated databases and available with other approved 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 assessments and for Energy Performance Certification purposes. Although it may assist the design process, SBEM is primarily a compliance and energy certification 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 England's Approved Document Part L, Volume 2, and the equivalent documents in the DAs, SBEM and iSBEM have been revised and updated a number of times to include additional functionality and accommodate revised compliance targets. The current version of the software can be used for demonstrating compliance with the ADL2 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 the approved versions for use in different parts of the UK and the Republic of Ireland. All relevant versions of the tool, along with corresponding user guides, can be downloaded free of charge from the Download pages.
SAP for dwellings
The calculation method for dwellings is SAP - the Standard Assessment Procedure for the Energy Rating of Dwellings. This is specified in documents available from the SAP website 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: https://www.gov.uk/government/publications/display-energy-certificates-and-advisory-reports-for-public-buildings
