Sensitivity of Energy Simulation Models to Occupancy Related Parameters in Commercial Buildings

Commercial buildings are responsible for 19 percent of the total energy consumption in the United States (US) and are projected to expand their share of energy use at increasing rates. Saving energy in the commercial building sector has therefore become the focus of many governmental initiatives. The first step towards more energy efficient buildings is improving design. Optimizing the sizing of mechanical and electrical systems is particularly important as it highly affects the buildings' life-cycle energy use. Consequently, designers and engineers are using energy modeling and simulation to compare different systems and predict building performance. Large discrepancies are however being observed between predicted and actual building performances. In order to improve these predictions, the sensitivity of energy models to different input parameters needs to be evaluated. Although proven to significantly affect energy use, occupancy related parameters have rarely been evaluated. This paper presents a sensitivity analysis study performed on the occupancy parameters of the most typical commercial building type encountered in the United States (US). Results indicate that occupancy chosen building temperature set points have the highest impact on energy use, while the influence of building schedule and after-hours equipment/lighting use is also significant, particularly in hot weather climates.