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Significant changes have been made to the way in which energy performance is assessed under the BREEAM UK New Construction 2018 scheme within Ene01 – Reduction of energy use and carbon emission.

In order to address the energy performance gap, new criteria rewarding more detailed energy modelling, encompassing regulated and unregulated energy uses has been introduced.

Four Credits are now available for the setting of operational energy performance targets, with two exemplary credits for making commitments to undertake a post occupancy assessment, to measure and monitor the extent to which the performance target is achieved. The methodology for targeting the energy performance credits and post occupancy assessment is described in a new BREEAM Guidance Note GN32.

To reflect this change in emphasis, the number of credits awarded based on compliance modelling has been reduced from 12 to 9, with up to three additional credits for buildings that go beyond zero net regulated carbon.

Although the minimum energy performance standards for Building Regulations in each country has remained unchanged the methodology for awarding credits using compliance modelling has been updated to reflect observed improvements in the energy efficiency of buildings and the availability of more energy efficient building components.

We have therefore updated the translator curves used to determine the Energy Performance Ratios (EPRs) for each of the three energy metrics; energy demand, primary energy consumption and carbon emissions.

For England, the translator curve is now based on a sample of buildings that were assessed under BREEAM UK New Construction 2014. This translator curve is set so that a building that achieves a performance equal to the average for the BREEAM sample will achieve 50% of the available credits. This means that credits awarded directly reflect performance relative to (BREEAM) peers.

For Scotland, Wales and Northern Ireland there was insufficient sample data to allow this approach to be adopted. Here the set of “hypothetical high performance” buildings used to determine the translator curves previously, were updated to reflect improvements in the energy efficiency of building components.

Further improvements have also been applied to the calculation methodology. An equal weighting factor is now applied to all three energy performance metrics to directly reflect the equal importance that BREEAM puts on these three interrelated environmental performance parameters (energy demand, consumption and carbon emissions).  Therefore where the ‘Actual’ value is worse than the ‘Notional’ for any of the three energy performance parameters the calculation now recognises negative EPRs to ensure that poor performance is penalised to the same extent as good performance is rewarded. This ensures that only buildings that achieve good performance across all three parameters achieve a high number of credits in BREEAM. (Previously the calculation assigned a zero EPR where A/N was greater than 1.0 which effectively ignored poorly performing parameters).

The calculation procedure continues to assign zero credits where the carbon emissions for the actual building exceed that of the notional as it would not comply with building regulations.

For multi residential buildings assessed using both SAP and SBEM the number of credits awarded are now calculated based on the floor area weighted average of the EPRs, rather than on an average of the credits as previously, so as to more accurately reflect the overall performance of the building.

More details of the revised methodology for calculating Ene 01 energy performance credits is provided in a new BREEAM Guidance Note GN 39.

About the Author
Christine Pout (BSc, DPhil) is a principle consultant at BRE and has been working in the area of energy efficiency and low carbon technologies in non-domestic buildings for over 25 years. She led the team that developed a model of energy use in the UK non-domestic building stock which was extensively to provide strategic advice to Government and other mainly public sector organisation to inform energy efficiency and climate change policy for many years. She now works within the BREEAM team where she is responsible for developing energy performance assessment methods used across all BREEAM assessment schemes, both in the UK and internationally.

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