Energy-saving strategies for luminaire-level lighting controls

Abstract

Luminaire-level lighting controls (LLLCs), also called luminaire-integrated controls, have the potential to reduce energy use, compared with traditional zone controls, when used in an open office setting. Additionally, LLLCs can be installed without incurring the additional costs associated with the installation of connected lighting. Due to this potential for both cost and energy savings, the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute conducted a study to determine how various parameters affect the energy savings of LLLCs. The investigated parameters were: field of view of the built-in motion sensor, delay time between when the last occupancy is detected and when the luminaire is turned off or dimmed, number of luminaires that turn on and off together in groups, and if the luminaires dim to a low level or turn off completely when no motion is detected. This study measured the occupancy pattern of an open office and then used that data in a computer simulation to determine energy use. The results show that LLLCs have significant energy savings potential in open offices with a 43% average energy reduction compared with the calculated manual-control base case. Results also show that choices made during LLLC selection (e.g., sensor field of view) and commissioning (e.g., delay time, grouping, dimming vs. turning off during vacancy) significantly impact potential energy savings. However, selecting LLLC products and settings for maximum energy savings can adversely impact occupant satisfaction. Lighting designers and specifiers should balance energy targets with the needs of occupants, including safety, comfort, health, visibility and wellbeing.