Energy savings potential of occupancy-based HVAC control in laboratory buildings

Abstract

Laboratory buildings are one of the most energy intensive commercial building types. High requirements on indoor air quality combined with safety regulations result in high air change rates for ventilation. Air handling units are the main energy consumers in laboratory buildings and are therefore predestinated for energy efficiency measures. In this work the holistic integration of passive infrared (PIR) motion detectors for controlling variable air volume systems in a laboratory (R&D) building is presented. In total, 72 laboratories were equipped with PIR motion detectors. Their operation and activity have been monitored for several months. Average occupancy/Degree of Capacity Utilization (DCU) in big labs was found to be at maximum 90% during a normal working day whereas in small labs, this number decreases to approximately 70%. On weekends occupancy/DCU was higher than expected, reaching values between 10% and 20%. Compared to a typical fixed time program or Time Control Program (TCP), PIR-triggered occupancy-based air control yields savings of up to 18 % in electricity consumption for the scientifically evaluated time period 11.2020 – 09.2021. The economic evaluation for the investigated energy-efficiency measure stated a payback period of less than three years.