Methodical steps to SBEM compliance
Achieving SBEM compliance for a commercial building doesn’t have to be a nightmare if a methodical approach is followed — as Marcus Eves of Darren Evans Assessments explains.
SBEM (Simplified Building Energy Model) is the current method of assessment to demonstrate compliance with Part L2 of the building regulations. It takes into account the amount of energy used by a building to condition the internal environment. Heating, cooling, hot water, lighting and ventilation all play their part in contributing to the amount of CO2 the building emits.
To reduce emissions, Part L2 sets heat-loss targets for the fabric, as well efficiency targets for the building services. Part L2A says an SBEM assessment is compulsory for all new-build non-residential buildings with a floor area greater than 50 m2. There are key areas which can improve results and are common across most building types.
Achieving a well-built, thermally efficient and airtight building gives greater flexibility for the specification of the building services. Buildings under 500 m² are exempt from an air-permeability test. However, an air test on a smaller building can be a very cost-effective way to hit the emission targets.
Selecting a heating system compatible with the operation of the building will ensure the route to compliance is straightforward. Sticking to centralised systems is most effective; unless there is no other option, avoid localised electric heating. If the building does not have mains gas, opt for heating served by a ground-source or air-source heat pump.
If space permits, consider biomass or CHP to produce heat and electricity. CHP is proven where the building has high heat and hot-water demands such as a hotel or student accommodation.
In warehouses and spaces with high ceilings, consider radiant heating, as it warms people and objects, rather than increase air temperatures. If traditional hot-air systems are installed, you can install de-stratification fans to ensure an even temperature balance across all levels.
Ventilation and cooling
Mechanical plant increases electricity consumption and emissions. Maximise passive strategies — focusing on utilising thermal mass, heat-gain control and heat dissipation along with natural ventilation. For installed mechanical plant, ensure that the system is appropriate for the size of the space to maximise effectiveness. Choose air-conditioning systems with high heating and cooling efficiencies.
LEDs should be the first choice for lighting. They are highly efficient and now, relatively inexpensive. A controls strategy utilising passive infra-red or photo-electrics will minimise wasted energy when lighting is not required.
Bolt-on renewables should be the last resort. The fabric-first approach is proven to be successful, as demonstrated by Passivhaus design.
Implement a renewable strategy if there is adequate south-facing roof space for photovoltaic panels or open space for wind turbines etc, but don’t rely on these technologies to get you over the line.
The above is just a selection to consider. It’s certainly not an exhaustive list, as there are so many other factors to consider —including how they all fit together. Don’t be constrained by simple compliance. Look to a bigger picture: taking an holistic view on energy saving and sustainability will guarantee success at every stage.
Marcus Eves is technical lead at Darren Evans Assessments.