Expert consensus on integrative lighting descriptors and indicators for green building rating systems: A Delphi study

The study on integrative lighting (IL) focuses on its impact on the visual system and various non-visual physiological processes. Its goal is to optimize light exposure to positively influence multiple light-affected functions. Despite advancements in understanding and measuring IL, field measurement methodologies need refinement. The research aims to define descriptors and indicators for evaluating IL in workplace environments through a Delphi study with 32 experts. The study had three stages: (I) consensus on descriptors, (II) agreement on indicators and (III) weighting of descriptors and indicators. In stage I, candidate descriptors from the Ergonomic Lighting Indicator (ELI) dimensions, including Visual performance, Vista, Visual comfort, Vitality and Control, were presented. Experts agreed when at least 75% rated descriptors as 'important' or 'very important'. The study emphasized comprehensive assessments of these dimensions and the importance of indicators that are simple, valid, reliable and non-intrusive, categorized into visual/photometric and temporal/human factors. The study proposed a weighting procedure for ELI dimensions in educational, administrative, commercial, industrial and healthcare contexts, using a multiple-criteria decision-making framework. This facilitated identifying descriptors and indicators through expert consensus, enabling comprehensive evaluation, accreditation or certification of indoor spaces.