Latest News
- 11 April 2008 - iSBEM_v3.1.a Patch Release
- 1 Apr 2008: New release of iSBEM_v3.1.a for EPCs
- 12 Feb 2008: New release of iSBEM_v3.0.b for EPCs
- 11th December 2007: SBEM Technical Manual
National Calculation Method
Introduction to NCM
The National Calculation Method for the EPBD (Energy Performance of Buildings Directive) is defined by the department for Communities and Local Government (CLG). 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 (click here for details), or by a new simplified tool based on a set of CEN standards. That tool has been developed for CLG 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 the emerging CEN Standards.
SBEM makes use of standard data contained on 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 eventually for Building 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 iSBEM 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.