Energy Performance of Non-Domestic Buildings: Closing the Credibility Gap

Recital 16 of the Energy Performance of Buildings Directive (EPBD) requires the energy certificate to describe a building’s actual energy-performance situation to the extent possible. If we wish to achieve the rapid reductions in energy use and CO2 emissions that the EPBD anticipates, it is vital that this clause is taken seriously. It provides a fantastic opportunity to report actual energy use clearly, to grade it against a clear description of the building in use, and to relate it transparently to expectations at the design stage. This will at last begin to close the feedback loop, reduce the credibility gaps that so often occur between design expectations of energy efficiency and actual fuel consumption outcomes, and consequently lead to more rapid improvements in building energy performance. Credibility gaps arise not so much because predictive techniques are “wrong”, but because the assumptions often used are not well enough informed by what really happens in practice, because few people who design buildings go on to monitor their performance. While some differences are legitimate (e.g. the building is used more, or has more things in it), surveys nearly always reveal avoidable waste- which can arise from poor briefing, design, construction and commissioning, and not just bad training, bad maintenance and bad management. A widespread problem is control systems which just do not work, or have poor management and user interfaces, resulting in equipment defaulting to ON unnecessarily. To achieve genuine step-change improvements, procuring clients, design and building teams, users and managers will all need to engage much more closely with achieved performance. Better transparency between intentions and outcomes will release drivers towards better assumptions, better predictions, better design, better implementation, and better management of both the procurement and the product. We discuss how certification might be developed to help identify and close the credibility gaps, and present an idea for an energy certificate which takes these issues into account