SBEM Calculations vs. DSM & Thermal Modelling: Similarities and differences between the services

  • 30th March 2021|
  • News
  • |C80 Solutions

Here at C80 Solutions we offer a variety of services that ensure your construction project complies with the building regulations in a straightforward and hassle-free way. Both SBEM Calculations and Dynamic Simulation Modelling (DSM) can be used to demonstrate compliance with Part L2 of the Building Regulations (energy efficiency requirements for non-residential buildings) – so how do the two services differ from each other?

Each of the Simulation programs are used to produce a 3D model of the building using actual solar and weather data for the building’s specific location. Both SBEM and DSM can use other important details, such as building fabric, mechanical and electrical services and zonal activities, whilst DSM can also use occupancy periods and HVAC schedules. These details are then inputted into the software to produce year-long simulations on a room-by-room basis, creating a detailed picture of the building’s performance.

SBEM Calculations

SBEM, which stands for Simplified Building Energy Model, calculates the monthly energy use and carbon dioxide emissions of a building based on the building’s geometry, construction, HVAC, and lighting. SBEM can highlight solar gain exceedance on a basic level. The calculations should be carried out before the building is constructed based on the proposed plans and again once it has been built.

SBEM Calculations play an important part in protecting the environment. The calculations demonstrate the estimated kilograms of carbon emissions from the building each year and seeing the number like this can put things into perspective for many people. They can also highlight the efficiencies of heating/cooling, ventilation and lighting systems as proposed and demonstrate where these things fall below the required standards.

SBEM will not necessarily comply if the building is simply insulated to the minimum standards. The calculations ensure a building’s thermal performance is looked at and holds developers accountable for insulating buildings to a good standard. This has benefits for both the environment and those who end up occupying the building.

DSM & Thermal Modelling

Dynamic Simulation Modelling (DSM) uses whole building simulation programs which can then be used to undertake the calculations for Part L compliance.

Where DSM looks to provide an output, which looks the same as SBEM, DSM goes beyond SBEM in that it uses hourly weather data with time stop control and can model geometry for better results. Building orientation and inclination is modelled at 1-degree increments and there is inclusion of internal openings. DSM also gives more control over modelling of thermal bridging and improved modelling of glazing, daylight and solar shading and reflection, as well inter-zone heat transfer and better modelling of thermal mass.

DSM can also be used for other purposes; Thermal Modelling and daylight calculations are among a few, with these two simulation types frequently used for BREEAM Assessments. At C80 Solutions, we offer different types of this service, including but not limited to, CIBSE TM59: Residential Thermal Modelling and CIBSE TM52: Commercial Thermal Modelling.

CIBSE TM59 looks at overheating in dwellings. In a world where the climate is only getting warmer, the objective of this is to maintain thermal comfort in housing. This type of Thermal Modelling seeks to address the issue of homes that become uncomfortably hot in the summertime.

Meanwhile, CIBSE TM52 is for commercial buildings that are not mechanically cooled. The idea behind it is the same as TM59: to reduce overheating and increase thermal comfort, but for commercial buildings rather than residential dwellings.

What projects require SBEM Calculations, DSM and Thermal Modelling?

SBEM Calculations are a mandatory requirement for the majority of new build commercial buildings exceeding a total floor area of 50m2. Some commercial extension and conversion projects will also require an SBEM Calculation. DSM is used on more complicated and complex buildings where they cannot be modelled accurately enough within SBEM, for example, buildings with an atrium. SBEM and DSM, where used to show compliance with Part L2, Section 6 or other country appropriate standards, are used for commercial developments; the residential equivalent is SAP Calculations.

Thermal Modelling might be required for different reasons. For example, a BREEAM Assessment is taking place, the local authority has requested it, it may be a Building Control requirement, or it may be required in order to comply with any relevant government guidelines and standards. Thermal Modelling is not specific to commercial buildings and can also be used on residential buildings.

Learn more: C80 Solutions SBEM Calculations Service

Learn more: C80 Solutions Thermal Modelling Service

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