Perceptual Metric for Lighting Design

The project aims at developing a tool to communicate perceived light quality.

There is a need for tools and methods that can define light quality on the basis of visual and emotional aspects and that can identify individual preferences. This project aims to develop definitions and a set of concepts for perceived light quality that can be used as a basis for a communication tool for perceived light quality.

Light radiation can be measured physically. But light in the sense of the experience created when the light ray hits the retina is something more complex. Visual experience occurs on a basic sensory level as well as on an emotional level. This process cannot be translated into physical terms only. So far the tools available have been the lighting standards, for example the European (EN 12464-1), which is based on photometric measurements. Photometry is based on physical measurements of light related to the eye's ability to detect the radiation. It thus describes only a very limited part of the light experience. The lighting standards are therefore insufficient as tools for creating good lighting environments. Also, the purpose of the standards has never been to provide the best possible light environment, but to guarantee a minimum level of visual comfort.

The lack of measures for the perceived values of light combined with the limitations of the norms and a general lack of knowledge of light among various stakeholders in the construction process results in a large proportion of lighting installations having inferior visual qualities which affect well-being and comfort. In addition, perfunctory interpretations of the norms tend to result in oversized installations, which in turn means inefficient use of energy.

The project is a collaboration between Konstfack, RISE (Research Institutes of Sweden), LTH (Lund University), HKR (Kristiandstad University) and companies in the lighting industry.

A pilot study for the project was funded by ARQ 2019-20. From 2020 the project is funded by Energimyndigheten.

Project leader: Johanna Enger, senior lecturer and researcher in light design
Funded by Energimyndigheten
Project period: 2020-2023