Deep retrofit approaches: Managing risks to minimise the energy performance gap

Energy use in buildings remains a significant part of overall energy demand. Deep renovation projects, delivered at scale, remain a challenging task to achieve a lower carbon building stock. The complexity of building renovation is related to inherent characteristics of buildings which require distinct project management techniques. While there are now more projects focusing on achieving operational performance, there is still very little research on the management of the renovation and retrofit process itself – this paper aims to contribute to that literature. First, the policy context for renovation is briefly set out. Then five different approaches to building renovation are distinguished: whole house; fabric first; room-by-room, step-by-step, measure-by-measure. These categories provide the basis for analysis of the risk of there being a gap between designed and actual energy performance. In addition, ten stages of retrofit are set out, and three different types of risk at each stage distinguished: assessment, sequence, and communication. Combining this typology of risks with the work stages and types of retrofit, the risks associated with renovation processes and technologies were estimated using evidence from cases studies of deep retrofits across the UK and EU. Risks are not restricted to just one retrofit type, nor are they found solely or predominantly in a small number of work stages. Risk management needs to be integrated into retrofit works, whichever approach is taken, at all stages and across the assessment, sequencing and communication aspects of the retrofit. Getting retrofit right will involve sophisticated strategies, and will require multiple innovations, which could include new management systems, new documents (e.g. Building Passports) and new professional practices, with implications for education and training. Minimising the energy performance gap will only be achieved with increased focus on this hitherto neglected aspect of deep retrofit.