Towards cost-effective energy savings: Learnings from non-invasive occupant-centric control implementation in an office building

Occupant-centric control (OCC) has been a popular topic in building energy research and is a viable strategy for reducing operational energy use in buildings. Yet, the implementation of this control strategy often involves sophisticated technology that is expensive to acquire, install, and maintain, weakening the economic argument for implementing these controls. An approach that tailors OCC solutions to buildings with minimal or outdated occupant sensing technology could increase the likelihood that operators of existing buildings adopt OCC to reduce energy use and improve thermal comfort. This study implemented OCC in an 80-person office suite only through existing hardware to investigate how energy savings can be achieved in buildings by working with legacy control systems. Over the course of two summer months, energy use in the office suite was reduced by 53%. The bulk of the savings come from a reduction in occupied hours, achieved by shortening daily occupancy schedules in common spaces and determining occupancy through manual overrides in single-occupancy spaces. The results of the study confirm that, under a schedule where the office is only partially occupied during the working week, significant energy savings can be achieved in offices through non-invasive methods that make use of existing infrastructure and thoughtfully selected system parameters. However, the lack of flexibility in legacy systems means that energy consumption during occupied hours remains highly contingent on individual occupant behavior, limiting potential energy savings. Thus, occupant engagement and education should be considered crucial to OCC implementation in legacy building control systems and surveys should be emphasized as a necessary procedure for understanding occupant behavior and preference. The widespread implementation of non-invasive, computationally efficient OCCs in legacy systems could effectively reduce energy use in existing buildings where a substantial retrofit is not financially viable.