SBEM Calculations

An SBEM Calculation is a detailed calculation report submitted with Planning Application that shows a Non-Domestic development will achive the local authority’s emissions target.

SBEM stands for Simplified Building Energy Model. It is a computer program that provides an analysis of a building’s energy consumption. It calculates monthly energy use and carbon dioxide emissions of non-domestic buildings. It takes into account the building’s geometry, construction, use, and HVAC and lighting equipment.

Sustain Quality provide assessments to ensure new commercial buildings are:

• Well insulated
• Well ventilated
• Efficiently heated, cooled and lit
• Sustainable

The National Calculation Method (NCM) describes the procedure, for buildings other than dwellings, for demonstrating compliance with the carbon emission requirements of regulation 17 C of the Building Regulations and calculating ‘operational ratings’ and ‘asset ratings’ in the production of Energy Performance Certificates (EPC’s).

The NCM provides the underlying method and the standard data sets necessary to calculate the annual energy use of a proposed building and comparing it with the energy use of a ‘notional’ building of a similar type, under similar circumstances. This is done by calculating the Target Emission Rate (TER – the CO2 emission rate for the notional building) and comparing this with the Building Emission Rate (BER) for the proposed building. The BER must not be higher than the TER.

The calculations can be performed using approved simulation software (Approved Dynamic Simulation Models (DSMs)) or by using the Simplified Building Energy Model (SBEM), a computer programme developed by BRE and available to download from the NCM website. Unlike some of the DSM’s, SBEM is a ‘simplified’ compliance tool, rather than a design tool.

The Simplified Building Energy Model was originally based on the Dutch ‘Energy Performance of Non-Residential Buildings’ (NEN 2916:1998). It has been available to demonstrate compliance with Part L of the Building Regulations since 2006, and for Energy Performance Certificates since 2008.

It calculates monthly energy use and carbon dioxide emissions, given a description of the building which is entered through its user interface iSBEM, based on:

• Building type.
• Building geometry.
• Construction.
• Use.
• Heating, ventilation and air-conditioning (HVAC).
• Lighting equipment.

A design stage SBEM assessment should be completed before the construction starts, and then an as-built SBEM when construction is completed, which includes the results of an air permeability tests and demonstrates the building has been constructed in accordance with the design. This is referred to as a Building Regulation UK Part L report (BRUKL).New houses or apartments blocks will each need a Standard Assessment Procedure (SAP) calculation completed. Any building, which is not a dwelling, will require an Simplified Building Energy Model (SBEM) calculation. These calculations should ideally happen as early as possible in the design stage. They lead to the Energy Performance Certificate (EPC) respectively.

There are two stages to the construction process; ‘as design’ and ‘as built’, and an SBEM calculation is required for both stages. ‘As design’ refers to the initial design process. This SBEM calculation will be carried out prior to construction work beginning.

Once the work has been completed, another SBEM calculation is required. This is known as the ‘As built’ stage.

The SBEM calculation carried out during the ‘as design’ stage should be detailed and comprehensive so that it is reflective of the final, ‘as built’ SBEM calculation. This ensures that Building Control can sign it off in a smooth and efficient manner.

We recommend that you get your SBEM completed as early as possible. We would suggest that you involve your assessor as part of the Design team in order to identify any shortfalls before they become a problem.

There has been much focus recently on the gap between the predicted energy usage of dwellings and the actual energy usage: this performance gap is often sizeable. The Zero Carbon Hub has conducted a research program to identify the causes of the gap and has issued several reports with recommendations. Many of those recommendations are likely to be accepted by Government and introduced into the regulatory system in the next round of revisions.