Equilibrium User Centred Lighting Design Towards the development of a lighting design that is individually psychologically, physiologically and visually supportive

Doctoral thesis, 2012

Why and in what way should daylight and artificial light be designed for the indoor environment in order to fulfil goals about visual comfort and light-related health? When the outdoor and indoor interactions of man, light, colour and space (MLCS) are compared to one other, the spectral component plays the decisive role (Hollwich 1979, p. 90). Through empirical studies and theoretical surveys the knowledge about the interaction of MLCS in the indoor and outdoor environment is investigated. Patterns in responses and preferences of room and light settings are studied. The process of lighting design is investigated and the process that gives a psychological, physiological and visual (PPV) support from light for the individual user is described. Lighting design for the indoor environment should give the same input to melanopsin and ipRGC as can be seen in daylight outdoors, to be physiologically supportive. The pattern that can be seen in the studies performed in the Thesis, in responses and preferences to light in the indoor environment, concerns differences between individuals and changes during the day. Laws, recommendations and methods for lighting design are developed for a general visual support from a static artificial light. The use of EN12464-1:2011 do not fulfill goals of visual comfort set out in the standard or light-related parts of goals of health in EC Treaty 137 or WHO target 9 and 13-17. It is argued in the Thesis that the findings of melanopsin and ipRGC demonstrate the need to develop laws, recommendations and methods for lighting design in a way that gives an individual support for visual comfort and light-related health. The computer calculated lighting design process (CCLDP) used in a majority of the lighting applications performed today is not done in contact with daylight, the user or the space, and by that it is not possible to support the individual user PPV by the use of the CCLDP. The user centred lighting design process (UCLDP), on the contrary, is done in contact with daylight, the user and the space and has by that the possibility to support the individual user PPV. Lighting quality (LQ) seen from the individual user’s perspective is a well functioning PPV support from daylight and a daylight mimicking artificial light. When LQ is defined seen from the contractors or the clients perspective it is a general and theoretical approach, not related to the individual user’s senses. Research in lighting design can be positioned around the lighting design process (LDP). This points out the cluster of topics that are related to lighting design, and their role is described in the research. The field of lighting science and design is theoretically delayed and a rapid development in the topic is valuable for the individual and for the society as well.