What is the ‘Performance Gap?’
The ‘Performance Gap’ is the term used to describe the difference between theoretical energy use in a building’s design and operational energy use post construction. The last decade has produced irrefutable research Zero Carbon Hub: Closing the Gap between Design & As -Built performance proving that the gap exists. Today it is now widely accepted amongst building professionals that this problem will impact continued development in the built environment whereby compliance is achieved at the design stage without taking into account operational considerations usually resulting an under-estimation of the energy consumption. Once a building is being used, it often results in higher energy consumption, increased bills and higher emissions than are accounted for in the design model. All of which begs the question, now we know it’s there, how do we solve it?
A new stream of dialogue
Regional discussions are taking place, throughout the UK, amongst professionals from the built environment sector to review what tools we have in our kit to address this issue. Hosted by Integrated Environmental Solutions (IES), as part of their series of faculty events, we participated in the Bristol session in forward thinking discussions to ‘close the gap’, sharing our experience of delivering projects for clients and our knowledge of retrofitting practicalities and understanding about the carbon performance of old and new buildings.
The consensus from experts in the region is that the ‘Performance Gap’ is having an increasing impact on our standards, in general for quality in design and future proofing, and the ambition of achieving truly sustainable buildings which looks further away than before. An underestimation of energy use at the design phase makes it easier for buildings to reach compliance, whilst energy use in operation soars way beyond initial regulations. This could ultimately lead to larger energy bills, increased risk around fuel prices and difficulty in meeting carbon reduction targets. Clearly an energy and carbon reality check is needed early at the concept and design stage.
Never mind the new, what about the old?
Sustain recognises that this gap also exists for our existing build stock. There is an ever growing need for building owners, managers and tenants to understand what their building is using and why. It is often the case that actual energy bills climb greater than any of the standard energy analytics would suggest. Without a robust understanding of operational energy use it is impossible to make informed investment decisions regarding building improvements.
Embodied carbon is inherently related to the ‘Performance Gap’ and is, as yet, a little under recognised as an issue and opportunity. Steve Allen, one of our Associates, blogged about embodied carbon earlier this year and Kevin Boniface raised the issue of zero carbon for existing building stock in May. With advances in measurement tools and audits for the built environment combined with our continued work for clients on their properties and buildings, our focus is sharpened to this issue. We base our projects on actual energy billing and usage data to model any given buildings energy envelope and provide recommendations. Working on Cobra projects for residential buildings and the Carbon Trust with SMEs showcases our range but also the commonalities when challenged with the carbon performance of old and new buildings, residential and commercial properties, embodied and new carbon.
It might not be a new concept but it is a new edition to the conversation around low carbon buildings. Welcome to the start of The Performance Gap story – what’s your part?