Part L Building Regulations: What exactly is a SAP/SBEM calculation?
Put simply, SAP or Standard Assessment Procedure, is for domestic dwellings, SBEM, Simplified Building Energy Model, is for non domestic buildings – most essential for energy and sustainability statements for planning submissions. Both must be produced for the building control officer with on-construction EPC at practical completion. An SBEM calculation is often referred to as a BRUKL report.
The triggers for SAP/SBEM calculations are:
- A new build
- An extension where 25% or more of the total area of the extension is to be glazed
- An extension that is greater than 25% of the total floor area of the existing building
- Change of use
A SAP/SBEM calculation is a heat loss calculation that considers the type of structure, size of the building, the build-ups of the ground floor, exterior walls and roof/s together with the heating type, glazing and renewable technology.
New build project SAP/SBEM calculations and SAP/SBEM calculations for anything else such as change of use, extension or refurbishment are treated differently in terms of Part L compliance. There is a pass or fail benchmark for new buildings and a demonstration of improvements in accordance with building regulations for existing building with extensions, change of use or certain major refurbishments where heating and glazing are changing.
There are two types of SAPs/SBEM, As Design and As Built.
As Design SAP/SBEM calculations, at the early stages of a project, does what it says on the tin. It will produce the proposed carbon footprint of the building for planning permission or Part L Building Regulations compliance highlighting any design issues for the architect. A typical example of this is where a client has chosen a traditional heating system for their new build project not realising that nowadays virtually all new build houses have to incorporate renewable technologies in order to meet the percentage carbon emissions reduction stipulated in the local planning core strategy or planning decision notice. If photovoltaic panels are the only way forward further planning permission may be required. Also, the As Design SAP calculations can serve as a useful guide to costing and installing the correct insulation, heating, glazing and renewable technology for the project.
As Built SAPs/SBEM and on-construction EPCs are generated when the building is completed. Evidence has to be provided from site with U-value calculations and possibly thermal bridging calculations so that the As Built SAPs can be generated and the EPC can be lodged with Landmark the government Energy Performance Certificate database. Evidence for projects that do not fall into the new build category compliance is less onerous and generally neither renewable technology or thermal bridging calculations are required.
Once the project is completed the BCO will want to see the As Built SAPs/SBEM calculations together with the EPC.
