PNNL

Abstract

Recent research studies, including field testing and simulations, have demonstrated the energy-saving potential of occupancy-based heating, ventilation, and air conditioning (HVAC) controls in commercial buildings. However, building energy code development has not fully adopted this technological progress compared to the multitude of academic research. The objective of this study is to evaluate the economic and sustainability advantages of HVAC controls based on occupancy, with the aim of offering guidance for the integration of occupancy sensors into the development of building energy codes. To this end, a parametric simulation using EnergyPlus is carried out to evaluate the energy savings potential of different occupancy-based HVAC controls across three building types in 40 representative cities. Data from several sources, including the U.S. Energy Information Administration (EIA), Bureau of Labor Statistics (BLS), and Environmental Protection Agency (EPA), are collected and analyzed to compute the net savings (NS), discounted payback period (DPB), and CO2 emissions reduction of occupancy-based controls under various scenarios. The findings reveal that although occupancy-based HVAC controls can lead to significant net savings and a short DPB in hotel buildings, they may not be cost-effective in office and school buildings due to the current high cost of occupancy sensors. However, incorporating the societal cost of carbon factor in future energy and environmental policy could greatly enhance the cost-effectiveness of occupancy-based controls. Besides, a reduction in the cost of occupancy sensors to approximately 60% of the current price level could also greatly shorten the DPB. Despite the limited cost-effectiveness, occupancy-based controls remain an excellent option for building decarbonization, with potential CO2 emissions savings of more than 5.56 million metric tons across the three building types and 40 selected cities. Finally, policy implications are provided to guide the incorporation of occupancy-based HVAC controls in future energy codes.