‘Mind the gap’: The difference, in performance, between design and the building ‘in-use’

The non-domestic building stock is inefficient with respect to energy and the reasons given are devoid of substantive evidence to back them up. Buildings rarely perform as well as their designers predicted, and energy consumption and costs are, on average, double what was expected. This difference has become known as the performance gap. To address this problem, operators of commercial and public buildings need clear and realistic guidance on targeting energy running costs and on the potential savings available. To truly understand how a building uses energy, it is necessary to know about the building itself and about how it is used. However, what is missing are ‘real-life’ exemplars to investigate the actual causes of the performance gap and propose practical solutions. Liaising with the industry, a number of possible causes have been proposed: (a) lack of maintenance due to resource and skills shortage; (b) limited data; (c) modelling tools limited to asset data that don’t take into account operational parameters; and (d) lack of practical solutions and their costs. All of these may or may not be valid, and there is a need to join asset with operation data with targeting auditing of both the building and its operation to investigate the causes of poor performance.