Evaluating an integrative lighting design for elderly homes – a mixed methods approach

Abstract The experience of light in a space and the physiological effect of light combined is complex to study. Methods which combine parameters from the fields of the biological, visual and atmospheric effects of light through a combination of both qualitative and quantitative data collection on site, seem more important than ever to validate the potentials of integrative lighting. A case study, conducted in two elderly homes in Copenhagen and Aarhus, in Denmark, is used to evaluate a mixed methods approach, assessing an integrative lighting design solution. Luminaires with circadian settings are implemented as a supplementary lighting with the aim of supporting various objectives, including biological stimulation and a homely atmosphere in the elderly homes. To evaluate the implementation of the lighting, a convergent mixed methods approach is used, collecting quantitative and qualitative data. In parallel to collecting quantitative measurements, such as melanopic equivalent daylight illuminance (mEDI) and photopic lux, semi-structured interviews based on questionnaires and card-sorting, on the same subjects, are carried out. To evaluate the approach for evaluating the implementation of this integrative lighting design, three criteria are introduced: a) integration, b) flexibility and c) validity. The integration of results enabled to compare the different methods and findings to identify and study correlations, differences or contradictions. That was conducted across the three topics: biological, visual, and atmospheric effects of the integrative lighting design solution. A framework for a holistic approach for evaluating lighting in elderly homes was defined, with an indication of the need for further development in an iterative process.