Field data and simulations to estimate the role of standby energy use of lighting control systems in individual offices

This paper investigates the effectiveness of lighting control systems (LCSs) in 57 individual office rooms of an educational building located in Lund, Sweden. The study uses simulations based on actual occupancy data. The simulations, performed with Daysim via the Honeybee interface, focus on the portion of standby energy use on total lighting energy use considering different combinations of LCSs and lighting power density (LPD). The results show that standby energy use accounts for about 30% of the total lighting energy use, but it can raise up to 55% in extreme cases. The portion of standby energy use increases with lower occupancy rates and lower LPD. As a conclusion, a complete switch-off of systems during unoccupied hours is fundamental to preserve savings from LCSs. In addition, the article argues that, when standby energy use cannot be minimized or eliminated, daylight design and very efficient light sources may reduce the need for complex LCSs in individual office rooms or the like.