Energy

All new buildings or those undergoing major refurbishment must meet minimum standards for carbon emissions and primary energy as laid out in Approved Document Part L: Conservation of Fuel and Power.

Energy modelling is an increasingly important part of the design process and if carried out early can help to inform good building design rather than just being a compliance exercise.

Part L Non-domestic

How are we different to other energy assessors?

We don't operate on a 'check and forget' basis. This approach can often lead to poorer performance outcomes and worse still, completed buildings that are no longer compliant when it comes to producing the As Built energy model.

We take ownership of the energy performance of your building, acting as an additional project team member, regularly checking in and attending design meetings to ensure no design changes made during construction are missed.

This leaves the rest of the project team to do what they do best, freeing up resource.

We also offer full project management for Part L compliance

Find out more

DSM or SBEM?

SBEM stands for Simplified Building Energy Model and is synonymous with Part L calculations. As its name implies it is a simple approach to energy modelling based on a steady state calculation using monthly, average weather data. it is adequate for buildings with very simple heating and ventilation systems which do not need to take into consideration the impact of factors such as solar shading.

DSM stands for Dynamic Simulation Model which is a more accurate approach using hourly weather data and taking into account solar shading and bulk airflow to calculate a building's thermal performance.

How does it work?

There are two distinct stages to carrying out a Part L calculation; the DESIGN stage and the AS BUILT stage.

The early design calculations may be carried out during the planning phase and utilising DSM, the energy calculations can be run in conjunction with with other thermal modelling assessments such as overheating, daylighting etc offering time and cost savings. It is important to note though that any early design modelling carried out up to RIBA stage 3 will be based on high level data and assumptions and should always be carried out again prior to construction.

Detailed design calculations can then be carried out at RIBA stage 4 and can be checked and updated throughout the construction should any design changes be made or value engineering be carried out.

Once construction has been completed and air testing carried out, the as built version of the model can be created to create the BRUKL document and Energy Performance Certificate (EPC).

SAP (Standard Assessment Procedure) calculations are the domestic equivalent used to assess the energy performance of dwellings.

The process is similar to that carried out for SBEM and will ultimately produce the EPC on completion.

Part L - Dwellings

CIBSE steady state heating and cooling load calculations.

Heating loads are calculated using a steady state calculation as described in CIBSE Guide A. This will provides a peak load for each zone of the building taking into account the fabric losses + gains and infiltration.

Cooling loads are calculated using the CIBSE admittance method (also described in CIBSE Guide A), which will take into consideration all internal and solar gains applicable to the space as well as any shading.

CIBSE heating + cooling loads

Modelling undertaken for the purposes of Part L is carried out for compliance purposes only. It does not (and was never intended to) predict actual energy use. In order to do predict the potential operational energy use a much more in depth analysis is required taking into account unregulated energy uses such as appliances, external lighting and lifts and how the building will be occupied and used.

Using a baseline model as a starting point a number of sensitivity analyses are then run to take into account potential differences in areas such as occupation patterns, building management and weather events. Running these scenarios gives a range of potential energy usage for the building and is a much more accurate prediction of running costs. For buildings over 1,000m2 which are subject to The London Plan this is now a requirement of planning.

Operational Energy - CIBSE TM54

Request a quote for Part L

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