Assessment and measurement of energy demand and efficiency in public lighting networks

Due to technological developments in the last decades and to a long lifetime of installations, public lighting is recognized as one of the fields in lighting with significantly high energy saving potential. Side by side there exist obsolete systems older than 40 years and new modern high-performance systems with discharge lamps and powerful luminaire optics as well as promising LED technologies and sophisticated lighting control systems. To promote energy efficient solutions and to support or speed-up re-constructions of old systems, it is desirable to create tools for decision makers and municipal authorities helping them to distinguish between good and better. Linking thoughts to other lighting fields like EPBD, a numerical indicator expressing the energy efficiency level is to be set up. Works on this task currently run in CEN as a European normalization body as well as world widely recognized CIE. This paper focuses on analysis of different approaches that are actually discussed. A leading role is played by SLEEC (Lighting Energy Efficiency Criterion), a working name for a new lighting energy indicator proposed for public lighting systems. It is based on effective system comprising of the effective power of lamps, gears and other devices like control units, directly associated to the lighting of the area to be lit. Switching profiles, lighting control and operator’s behavior or preferences should be considered as well. Depending on the main user and respective lighting class, different versions of SLEEC are proposed. The paper attempts to generalize the leading approach, branching into different variants and discussing their pros and cons. Methods and schemes for measurement of SLEEC are also proposed.