Abstract

Energy reduction standards have been adopted in legislation by many US states, such as ASHRAE 90.1. Aspects of 90.1 have also been adopted within many country’s national mandated building regulations. The development of Building Energy Performance Simulation (BEPS) models is one of the principal methods used to show compliance with these mandated building codes. In order to achieve the higher levels of certification of LEEDTM, a design stage model is virtually a requirement. Researchers and practitioners are indicating a growing concern with the perceived inaccuracies of BEPS models when compared to an occupied building’s energy usage. While the standard’s authors state that compliance models should not be used to compare to the actual building’s energy use, the developers funding the creation of such models, may not be aligned with this view.
This study has been undertaken in order to assess the accuracy of BEPS models developed to show code compliance and where these models fit on the spectrum of design stage models. A methodology has been developed to examine these model’s accuracy at different points through the building design process, from early stage conceptual design to finished construction, but pre-occupation. Four different building types have been examined to determine the relative complexity and accuracy of five typical pre-occupation model stages. The study assesses the accuracy of each of the five model types when compared to the actual energy usage figures for each building and discusses the industry expectations of a particular model type.

Keywords: Building energy performance simulation; Building energy model; ASHRAE 90.1; Code compliance; Energy model sensitivity analysis; Performance Gap