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 earlyintegration and finally proposes the development of a methodology tailored around the optimizationof energy efficiency during early-stage design. In general, the research aims to identify (a) the accuracyobtainable through progressive simplifications of the building model, (b) the most significant buildingparameters with respect to the model result accuracy and (c) the maximum number of simplificationsable to ensure the respect of time requirements dictated by early-stage building design and to maintainan acceptable level of correctness. Here, as detailed example of simplification process, a case study ofa large multi-storey office building is modelled starting with a previous detailed simulation performedthrough EnergyPlus and Openstudio software. The detailed model is then analyzed and progressivelysimplified. At each progressive simplification step, a comparison with the detailed results is given interms of building energy needs and power curves of the system. The analysis is performed based on threedifferent system hypotheses: a single-zone system and a variable air volume system with and withouthumidity control. The quantitative differences between detailed and simplified model are analyzed todetermine the quality of the results of the simplified model.