Abstract
To manage the concerns regarding the energy performance gap in buildings, a structured and longitudinal performance assessment of buildings, covering design through to operation, is necessary. Modelling can form an integral part of this process by ensuring that a good practice design stage modelling is followed by an ongoing evaluation of operational stage performance using a robust calibration protocol. In this paper, we demonstrate, via a case study of an office building, how a good practice design stage model can be fine-tuned for operational stage using a new framework that helps validate the causes for deviations of actual performance from design intents. This paper maps the modelling based process of tracking building performance from design to operation, identifying the various types of performance gaps. Further, during the operational stage, the framework provides a systematic way to separate the effect of (i) operating conditions that are driven by the building’s actual function and occupancy as compared with the design assumptions, and (ii) the effect of potential technical issues that cause underperformance. As the identification of issues is based on energy modelling, the process requires use of advanced and well-documented simulation tools. The paper concludes with providing an outline of the software platform requirements needed to generate robust design models and their calibration for operational performance assessments. Practical application The paper’s findings are a useful guide for building industry professionals to manage the performance gap with appropriate accuracy through a robust methodology in an easy to use workflow. The methodological framework to analyse building energy performance in-use links best practice design stage modelling guidance with a robust operational stage investigation. It helps designers, contractors, building managers and other stakeholders with an understanding of procedures to follow to undertake an effective measurement and verification exercise.
Highlights
The ‘performance gap’ is a commonly used terminology in the context of building energy consumption and is described as the difference between the Institute for Environmental Design and Engineering, University College London, London, UKJournal of Building Services Engineering Research and Technology 0(0)actual energy use of a building and the energy use envisaged at the design stage.[1,2] Depending on the baseline selected, the magnitude of the gap varies considerably
The aim of this paper is to show a process of using modelling, from design stage to operational stage, as a tool to accurately determine the energy performance gap in the context of measurement and verification (M&V) and to demonstrate a robust M&V protocol to effectively identify root causes of a building’s performance gap using calibrated energy simulation method
To achieve the carbon emissions targets in the UK,[12] various schemes have been implemented in the building sector that focus on improving energy efficiency and quantification of performance at the design stage.UK building regulations (Part L) and asset ratings energy performance certificates (EPCs) focus on design stage quantification of energy performance
Summary
To address the issue of misinterpretation of compliance calculation results as predicted performance, an industry guidance document was created in the UK, CIBSE TM54.15 CIBSE TM54 sets out a framework, using dynamic simulation models, to provide estimates of the likely operational energy performance of buildings at the design stage. The outcome of this simulation can be used as a more appropriate baseline for estimating the magnitude of the energy performance gap; in contrast with ‘compliance modelling’ this approach is termed as ‘performance modelling’.3. The resultant potential gap between the performance modelling results and the actual energy use is a more appropriate quantification of the performance gap
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