Towards energy performance evaluation in early stage building design: a simplification methodology for commercial building models

The paper analyses the benefits of the application of energy analysis in the early-stage building design, in particular for large commercial buildings. The research highlights the barriers that prevent this early integration and finally proposes the development of a methodology tailored around the optimization of energy efficiency during early-stage design. In general, the research aims to identify (a) the accuracy obtainable through progressive simplifications of the building model, (b) the most significant building parameters with respect to the model result accuracy and (c) the maximum number of simplifications able to ensure the respect of time requirements dictated by early-stage building design and to maintain an acceptable level of correctness. Here, as detailed example of simplification process, a case study of a large multi-storey office building is modelled starting with a previous detailed simulation performed through EnergyPlus and Openstudio software. The detailed model is then analyzed and progressively simplified. At each progressive simplification step, a comparison with the detailed results is given in terms of building energy needs and power curves of the system. The analysis is performed based on three different system hypotheses: a single-zone system and a variable air volume system with and without humidity control. The quantitative differences between detailed and simplified model are analyzed to determine the quality of the results of the simplified model.