Simulating energy savings potential with high-resolution daylight and occupancy sensing in open-plan offices

Office lighting installations often inefficiently expend energy illuminating space that is unoccupied and/or already receiving adequate daylight. Illuminance and occupancy sensors can enable substantial energy savings by deploying electric lighting only in proximity to occupants, and at levels required to supplement available daylight. Savings vary based on sensor granularity, daylight availability, facade geometry and occupancy. In the current study, an open-plan office is simulated for 1 year to estimate energy savings relative to a conventional configuration. Available daylight is modelled using DAYSIM and occupancy is stochastically modelled in accordance with a standard schedule. Forty-eight combinations of simulation parameters are compared. Savings exceed 60% with high-resolution control. Greater savings are observed where daylight is available and occupancy is low. Estimated savings decrease to less than 35% with coarser lighting zones. The proposed workflow can assess the energy savings of occupancy- and/or daylight-based controls for open-plan offices of any common configuration.