UK's National
Calculation
Method for Non Domestic Buildings

Latest News   

15th July 2022: Release of iSBEM_v6.1.c for England's 2021 NCM and 2021 Part L

29th April 2022: Release of iSBEM_v6.1.b for England's 2021 NCM and 2021 Part L

15th December 2021: Release of iSBEM_v6.1.a for England's 2021 NCM and 2021 Part L

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) is defined by the Department for Levelling Up, Housing, and Communities (DLUHC) 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 DLUHC 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, it is not primarily a design tool. It does not calculate internal temperatures, for example.

SBEM is 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 the Approved Document Part L, 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 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