Recent research carried out by Elmhurst Accreditation Body has found that the latest version of SBEM (Simplified Building Energy Model) for England, version 6.1 will significantly affect the EPC ratings of existing non-domestic buildings. These much-anticipated changes have been a long time coming but will be in place by mid-June and will provide a much more accurate estimate of actual carbon emissions. Here are the details.
EPC software explained At the heart of EPC software is the Simplified Building Energy Model, SBEM, which is a government-approved software tool that analyses a building's energy consumption, including the energy needed to cool, heat, ventilate and light a commercial (non-dwelling) building over 12 months of normal use. It also computes the carbon dioxide emissions of the building.
We use it to demonstrate that a building complies with Part L of the Building Regulations in a Building Regulation UK Part L Report (BRUKL) and produce the building's Energy Performance Certificate (EPC).
The latest version of the SBEM has been released and takes effect on 15th June 2022. This version includes an updated model for carbon emissions, and a significant impact of the update is its effect on the EPCs of existing buildings.
Decarbonisation of the electricity grid Back in 2013, when the SBEM was previously updated, most of the grid derived its power from fossil fuels. This was reflected in how the SBEM converted energy consumption into carbon emissions using carbon factors related to the then-current technology. Since that time, there has been rapid decarbonisation of the grid. Today over half (53%) of electricity is generated using renewable or low carbon energy sources. As a result, the old carbon factors used in the model no longer provide a realistic estimate of actual carbon emissions.
The 2022 update has eliminated those problems. The revised version uses different carbon factors that alter the calculated emissions, lowering the estimate by 73% compared with the old version. Nevertheless, it is clear that regular model updates are required to keep it in line with ongoing grid decarbonisation.
The effect of the revised SBEM on EPCs Elmhurst has carried out several case studies in which they compared the old SBEM (version 5.6) with the latest SBEM (version 6.1) using identical inputs. Of the 14 case studies:
Nine were heated by electricity, and five by natural gas.
All those heated by natural gas showed higher carbon emissions (got worse), with three increasing by one EPC band.
All those heated by electricity received an improved rating – e.g. one went from an F to a D rating and one from an E to a D rating
All C ratings improved to a B rating or remained at a C rating
Poor ratings showed the most significant improvements
The overall trend is clear – electrically heated buildings that received the poorest EPC ratings under the old SBEM demonstrated the most significant improvements when analysed with SBEM version 6.1. The big step-change results from failing to update the model for almost a decade. Ten years ago, electricity was worse than gas in terms of carbon emissions, but it is now significantly better.
Going forward
Before implementing SBEM 6.1, EPC ratings wrongly promoted the use of gas over electricity, with electricity being aroundwice as bad as gas; after the revision, it is now overall slightly better than gas. In addition, the revised version is now in line with government policy, while previously, it was opposed to government policy. Furthermore, some buildings that previously failed to meet the minimum energy efficiency standard would now exceed it by reworking the original data in SBEM 6.1.
This change is hugely significant for all stakeholders involved with non-domestic building regulations. Currently, the new SBEM applies to England only, though it is expected that Scotland and Wales will follow suit over the following months. However, Northern Ireland is unlikely to change from its current SBEM until at least 2026/27.
