PNNL

Abstract

In software tools such as COMcheck, use of the EnergyPlus simulation engine for performance-based code compliance raises a concern about simulation runtime which impacts the dynamic feedback of compliance results to the user. EnergyPlus annual simulations for proposed and code base line building models, and the mechanical equipment sizing runs together increase the annual simulation runtime beyond unacceptable duration, for example, to 5 minutes for a typical small commercial building. This report presents a study undertaken to compare the results of a shortened simulation time period, using 4 weeks of weather data to do a simulation of a full 52 weeks of data. Three representative building types and three climate zones were used for determining the validity of using shortened simulation run period. Further sensitivity analysis and run time comparisons were made to evaluate the robustness and run time savings of using this approach. The results of this analysis show that the shortened simulation run period provides compliance index calculations within 1% of that predicted using annual simulation results, and typically saves about 75% of simulation runtime.