CPD PROGRAMME Continuing professional development (CPD) is the regular maintenance, improvement and broadening of your knowledge and skills, to maintain professional competence. It is a requirement of CIBSE and other professional bodies. This Journal CPD programme can be used to meet your CPD requirements. Study the module and answer the questions on the final page. Each successfully completed module is equivalent to 1.5 hours of CPD. Modules are also available at www.cibsejournal.com/cpd Towards the closing of the building performance gap This module considers some of the key areas covered by CIBSE TM61: Operational performance of buildings The recently published CIBSE TM61: Operational performance of buildings aims to provide insights into the problem of the performance gap (as illustrated in Figure 1) by following an integrated approach to the assessment and delivery of robust designs that perform in terms of both energy and indoor environmental quality. This article will explore some of the key areas considered in TM61. CIBSE TM61 and its companions TM62, TM63 and TM64 aim to provide detailed insights into operational building performance for those who influence design, construction, and facilities management outcomes. The technical memorandum (TM) explores contributors to the energy performance gap and aspects that affect the coincident internal environmental quality in non-domestic buildings and large apartment blocks, by providing an overview of key parameters at design, construction, commissioning and handover, as well as the operational stage. TM61 also recognises the potential unintended consequences of undue focus on particular sets of performance objectives. The uncertainties of energy modelling are discussed in terms of the vagaries introduced during the building specification; the development of the model; the robustness of the underlying algorithm; the setting and simplification of the modelled scenarios; and, finally, issues that result from human-introduced errors in the form of modellers bias or mistakes. It notes how the variability in different tools, developed to meet the needs of different global regions, can deliver significant differences in predicted energy consumptions for similar buildings. The lack of a certified audit trail to confirm that buildings have been built to meet the performance desired by the specifications is identified as a significant failing in the construction process. This allows deficiencies potentially caused by inappropriate site practices and misguided interpretation of design documents, as well as those introduced by post-design, onsite variations to corrupt the design intent. This might, of course, be identified by a robust, and possibly continuous, commissioning process that reaches across the whole building process into post-occupation that as suggested in the TM could be facilitated through a Soft Landings Framework.1 Once occupied, a buildings performance will be highly dependent not only on the operating practices of the building systems and equipment, but also on the conduct of the building occupants. The TM notes that the degree of engagement and behaviour of a buildings users and the systems has been shown to potentially impact on the overall energy consumption of a building by between -50% and +90%. Throughout the operational life of a building, the TM highlights that performance will typically deteriorate. The ready availability of data from the control systems are, in themselves, not a panacea for operational inefficiencies, as the TM points out that large amounts of data can potentially result in more confusion and operational problems. The section on indoor environmental quality (IEQ) performance explores performance evaluation approaches for lighting, acoustics, thermal comfort and indoor air quality (IAQ) in buildings. This relatively brief section provides a summative overview, giving useful references to and 46 February 2021 www.cibsejournal.com CIBSE Feb21 pp46-49 CPD 175 v2.indd 46 22/01/2021 15:51