ENERGY SAVING AND ENVIRONMENTAL COMPATIBILITY IN ROAD LIGHTING

This research was carried out with the cooperation and the financial support of ENEA, the Italian Agency for Energy of the Ministry for the Economic Development. The paper analyses the conditions for assuring the compatibility of external lighting with the environment and particularly with consumption of energy on one side and the interference with astronomical observations on the other. The effects of different types of luminaires are described relative to the road illuminated according to illuminance and luminance criteria. The paper demonstrates that illuminated towns seen from far distances, i.e. the main source of disturbance for astronomic observations, behave like single diffusing sources, since the luminaires are hidden in urban "cavities" bordered by buildings. A model is presented for the analysis of territory around a site, aimed at identifying the possibilities to improve the environmental compatibility of outdoor lighting installations and the possibility of local modification to improve the situation.