Predicted energy consumption in BREEAM

BREEAM 2018 and in-use energy performance

BREEAM New Construction 2018 was released earlier this year, and we have been busy reviewing the impact on new projects for our clients, prospective developers and planning authorities.

There have been substantial changes in most parts of the new technical standard, including a positive small increase in the importance given to energy performance in use, and in particular the new credits available for carrying out predicted in-use operational energy calculations. This provides a double advantage for clients; earn a few BREEAM credits, and more importantly get a more reliable estimate for future running costs, energy consumption and carbon emissions.

Prediction of operational energy consumption – closing the performance gap

BREEAM has been rightly criticised for not being a good indicator of energy performance and operational cost, there is virtually no correlation between BREEAM rating and energy consumption[1]. The new scheme will hopefully begin to improve this.

The predicted operational energy calculation adds some additional work, with several scenarios being set up to show the possible range in costs depending on changes in annual weather, and how different use patterns affect energy consumption. It also means your design team are more informed on the likely higher uses and can act to reduce them during design, helping to reduce operational costs.

The most welcome part is that the results for all scenarios must be quoted in kWh and broken down between use types. Finally we have modelling output required by BREEAM that we can compare with the meter readings! This could eventually introduce some much needed feedback into energy modelling assumptions.

New post occupancy monitoring stage

BREEAM 2018 also includes a new, optional, post-occupancy stage of assessment. The assessment provides validation for the process of monitoring, reviewing and reporting on the performance of the building once occupied. It is carried out a minimum of 12 months after occupation and would normally be before a period of two years has lapsed from the date of ‘full’ occupation.

This is an attempt to standardise and encourage best practice project commissioning, handover and post-occupation support. It aims to help the Design Team, Facilities Manager and building owner understand the actual performance of the building and optimise this in line with design expectations.

Allowing credits to be awarded for genuine low carbon energy strategies is a great opportunity, and rewards clients for wanting to understand how much energy their building is likely use alongside quantifying savings in running costs. Get in touch with us if you would like to find out more.

[1] From Etude analysis based on Carbonbuzz database, also see work of Robert Cohen.