Energy performance of buildings: An useful procedure to estimate the impact of the lighting control systems

The amount of the electrical energy used for in interior lighting of medium and large buildings is generally considerable. The European Standard EN15193 was devised to establish conventions and procedures for the estimation of energy requirements of lighting in buildings, and to give a methodology for a numeric indicator of energy performance of buildings. The methodology of energy estimation is based on statistical data and default values and adopts a general approach that requires few parameters. It assumes reference average values for all the Europe regions, while they can vary substantially according to the national laws and uses, it does not consider the actual layout of the control system that contributes to additional energy savings. The paper suggests an improvement of the procedure for the estimation of the lighting energy in the cases that it is possible to know or define the prospected operation time, and three derating factors: daylight, constant illuminance and occupancy. The factors are evaluated considering the actual type of control like the number of control groups, the technique of modulation (dimming or switching), the delay in turning off. The suggested procedure is compared with the Standard one to highlight the improvements.