Energy performance: Postulation or practice?

It is increasingly acknowledged that we build non-domestic properties without any real measure of their in-use energy efficiency. Indeed, the CIBSE TM54, which I have touched upon briefly before, highlights that the performance of new low energy building designs can be up to three times greater in use than the Part L energy model used for statutory compliance.

They are also often little better and sometimes even worse than that of the much older buildings they have replaced, due to the complexity of technology and the need to conform to institutional standards such as the BCO specification for offices.

The difference between the Part L design model and actual in use performance is because the current methods of calculating energy use in a building do not take into account all forms of output. For example lifts, escalators, catering facilities, plug socket uses and even server rooms are not included, all of which might only comprise a very small percentage of a building’s internal floor area but also, in some cases, be the largest single energy output. It is also about ensuring that the building delivered and occupied matches the way in which it was designed to be built and operated, which so rarely is the case.

Since government’s U-turn on mandating Display Energy Certificates to the wider commercial sector, we have continued to witness a lot of postulating as to the correct way to go and methods to use

So how do we examine the real in-use energy performance of our buildings once they are occupied? Since government’s U-turn on mandating Display Energy Certificates (DECs) to the wider commercial sector, we have continued to witness a lot of postulating as to the correct way to go and methods to use.

The Better Building Partnership has been undertaking a three year study to develop Landlords Energy Ratings to label the energy efficiency of the landlord’s energy consumption. At present this has morphed into a “Rolls Royce” style investment grade audit, which will work for large, landmark assets but not for a fund with over 1,000 assets. There has also been much talk from the GLA, UKGBC and other consultants in the field about universal IT databases, which will develop industry benchmarks automatically with minimal cost and data analysis, but there is nothing tangible yet and I have to admit to being somewhat sceptical as to how this will work out.

While the property sector argues the best path to follow, Legal & General has been working with our managing agents JLL, the National Energy Foundation (NEF) and Phil Jones of Building Energy Solutions, also chair of the CIBSE Energy Performance Group and a member of CIBSE’s benchmarking committee, to develop an improved version of DECs that can be voluntarily implemented by property owners - VolDECs. The aim of the project is to establish a methodology for producing separate owner and tenant DECs, based on the existing DEC methodology, while producing an analysis system that is both cost effective and easy to implement on a regular basis.

To date the project has been piloted on multi-let offices and has produced a credible “range” of ratings, which match what we currently know about the efficiency of each property. In order to compensate for the fact that large air conditioned offices are much more energy intensive than the non-air-conditioned, open-plan, government regional offices, used as the existing benchmark, we have extended the A to G scale to include G1 to G4 categories, along with an U (Ungraded) category, encouraging improvement at every level.

The second phase of this project should see it opened out to the wider industry and extended to other asset classes. Once this has happened and there is an effective industry standard in place for assessing real energy in-use split by landlord and tenant use, might we start to see better understanding of a building’s true output from design stage through to end user? Indeed, could the industry start to predict a split between landlord and occupier energy performance at the design stage so that it can put its money where its mouth is and underwrite real energy performance deliverables from the outset?

Debbie Hobbs, is head of sustainability at Legal & General Property