Building automation and control systems: A case study to evaluate the energy and environmental performances of a lighting control system in offices

Building automation and control systems (BACs) allow plants in buildings to be controlled and managed, thus increasing the users' comfort and reducing the operation and maintenance costs. As far as the lighting services are concerned, control systems offer an important opportunity of managing lighting systems and reducing energy consumption, due to the use of integration strategies between daylight and electric lighting and strategies based on the occupancy of spaces. The results of an experimental case study of ten offices in Torino (Italy), in which a custom-design building automation and control system has been designed to control both the lighting plants and the air conditioning system, are presented in this paper. The study was carried out in order to evaluate the energy efficiency of the lighting control system and to analyse the environmental luminous conditions obtained through the application of this technology to a real case. The environmental and energy performances, together with the degree of users' satisfaction and acceptance of this control system, were analysed after a year of activity to verify the potentiality and operation of this lighting control system. The obtained results regarding the potential energy savings (from 17% to 32%) were evaluated taking into account both the monitored annual electric energy consumption (for operation) and the parasitic energy consumption due to the installed devices (luminaire ballasts, sensors and controllers), and were compared with the estimated energy consumption calculated applying the method proposed in the European standard EN 15193:2007