SBEM

SBEM Calculations

Part L Building Regulations

What are SBEM calculations?

SBEM calculations are the approved calculation method for demonstrating compliance with Part L of the Building Regulations. SBEM stands for simplified building energy model. The calculations are desk based and carried out using architectural drawings and a detailed building performance specification.

The alternative to SBEM is DSM. This is dynamic simulation modelling and must be used for a complex building that qualifies for a level 5 non-domestic EPC.

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Our top tips for SBEM calculations

  • Come to us at an early stage to ensure the design is going to meet the requirements of Part L.
  • Insulate the building as well as possible with consideration for air tightness.
  • Get a detailed lighting design, go for high efficiency LED fittings and use daylight sensors in naturally lit rooms.
  • If the building has shower facilities, hot water generation can play a big role so consider how this is heated.
  • SBEM focuses on CO2 emissions so the space heating fuel (or water, as above) is important. Oil and LPG are generally poor options; biomass and electricity give good results.
  • Electric panel heaters are a ‘clean’ option, but they are about three times less efficient than a heat pump, so you will need a very high specification in other aspects, in order to use these for space heating, quite possibly requiring solar panels.
  • Full and Detailed Lighting Design – in offices and retail projects this can be one of the most important factors in the SBEM calculations. Our advice; Go for the most efficient high lux and low W/m2 design possible within your budget.
  • Heating system – whether the building is heated via a conventional gas boiler, biomass district heating, ground source heat pump or any myriad of systems go for the highest efficiency possible. Anything listed on the Energy Technology Product List (ETL) is usually a pretty good bet, and has the advantage of being able to claim 100% of its capital allowance in its first year.
  • Hot water – sometimes overlooked, but can be of key importance in buildings with showers and baths. SBEM calculations for Care Homes or Hotels should be replete with hot water cylinders using low standing losses.
  • Mechanical Ventilation – high efficiency heat recovery will assist with compliance and a low Specific Fan Power (W/l/s) is vital.
  • Insulation – Part L2A and L2B provide minimum requirements for U-values. The reality is that we must go above and beyond. Look at U-values of below 0.16 where possible, but don’t focus all of the attention here as there is a law of diminishing returns. Glazing U-values are of equal importance but the G-value (thermal transmittance of the sun’s rays) can make a difference too depending on if the building is cooled and its orientation.

Frequently Asked Questions

When are SBEM Calculations needed?

The calculations are needed for all, new non-domestic buildings, that are standalone and over 50m2. SBEM can also be used to demonstrate compliance with Part L when a commercial building is extended, extensively refurbished, or has a change of use.

What do SBEM calculations involve?

We use advanced 3D modelling software to undertake the calculations. We construct a 3D computer model from the drawings supplied and then populate all the rooms with various data, including the following:

  • Building fabric
  • Lighting
  • Heating
  • Cooling
  • Ventilation
  • Hot water
  • Renewable energy

The calculation methodology then analyses the building as a whole to produce a document known as a BRUKL (Building Regulations UK Part L), which shows the predicted building emissions and energy rates. These are compared to targets, which the building has to meet.

There are minimum standards required for all of the above listed aspects (except renewable energy, which is optional, but sometimes necessary) but passing Part L is the sum of all parts and minimum standards must be surpassed to ensure compliance.

How can Up Energy help?

We have experienced, non-domestic energy assessors qualified to carry out SBEM calculations, or DSM calculations, on buildings of all complexities (level 4 and level 5).

We carry out all assessments in house, nothing is sub-contracted, and with over 15 years’ experience working in the sector, we are well placed to advise on your proposed design and help suggest the best options to achieve compliance.

We highly recommend you contact us at design stage, to ensure that the proposals you have are going to meet Part L of the Building Regulations. However, if you have already reached the ‘as built’ stage, we can still do the calculations for you and give guidance wherever possible.

What does SBEM stand for?

Simplified Building Energy Model.

When is an SBEM calculation required?

Similar to SAP calculations for new build residential properties, SBEM calculations are for non-domestic buildings and are required at planning stage. The ‘As Designed’ SBEM calculation is submitted to show that the building meets the Target Emission Rate for energy efficiency. The ‘As Built’ SBEM calculation is then submitted at the end of the build when all works have been completed and building control can sign the project off. To have SBEM explained further read on.

Do I need ‘As Designed’ calculations?

It is important to undertake the SBEM calculations early on in the build cycle to ensure it will pass Part L of the Building Regulations without having to add costly retrospective measures later on.

What is the difference between SBEM and an EPC?

The calculations that go into an EPC for a new building should be the same as those for the SBEM calculations. The EPC is the formalised certificate that allows the building to be sold or let. To avoid confusion, and duplicating costs, the EPC should be produced by the same assessor who undertook the initial calculations.

Do SBEM calculations involve a site visit?

No, an SBEM calculation can be purely a desk based exercise.

What details are required to run SBEM calculations?

Full scaled plans, sections and elevations of the final or intended layout, together with specifications for heating, cooling, ventilation, hot water and lighting. Details of the building fabric, in the form of U-value calculations for all the thermal elements together with information and certificates on air tightness and thermal bridging. If any renewable systems are to be installed then detailed specifications of these will also be required and certification at completion stage.

Who can undertake SBEM calculations?

Valid SBEM calculations should only be undertaken and submitted to building control by a qualified Level 4 or 5 Energy Assessor. It’s important to also ensure that the same assessor can complete and lodge the EPC at the end of the project so that the building can be sold or let. To have the process of SBEM explained to you or your design team get in touch.

How much do SBEM calculations cost?

The cost is really determined by the size and complexity of the building.

For more information, please get in touch with Up Energy.

Tim Smith BSc (Hons) MRICS | Commercial Property Manager | FWS Carter & Sons Ltd

“Alistair and Simon of Up Energy have provided us with professional and pragmatic advice in relation to Energy Performance Certificates across our property portfolio. Their ability to deal with a variety of different property types from proposed new builds through to existing buildings both new and old has been invaluable to us.”

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