The impact of room and luminaire characteristics on general lighting in interiors

General lighting is the most common way of illuminating interiors and the source of electricity consumption in buildings. This fact forces the search for lighting solutions effective both for people and the environment. In this study the impact of room and luminaire characteristics on general lighting conditions and energy efficiency in interiors is considered. In rooms of different sizes and reflectances, seventeen luminaire types with various light distributions were arranged in uniform layouts. The levels of average illuminance, uniformity and normalised power density related to two horizontal working planes were calculated. The impact of working plane reduction, room index and reflectances, lighting class and luminous intensity distribution of luminaire on the considered parameters was investigated. The use of the reduced working plane resulted in the increase in the average illuminance (7.7% on average), uniformity (33% on average) and normalised power density (23% on average). The impact of the room index and lighting class on the average illuminance and normalised power density was significant while the impact of the luminaire luminous intensity distribution and room reflectances was low. The normalised power density levels of the general electric lighting in interiors, with luminaire luminous efficacy of 100 lm/W, are in the following range: 1.08‒3.42 W/m2 per 100 lx. Based on these results a normalised power density level of 2 W/m2 per 100 lx is recommended for designing and assessing the new general electric lighting systems in buildings.