Analysis of integrative lighting through field measurements and annual daylight simulations in offices

The paper presents results from a study on integrative lighting carried out for existing offices and considering the contribution of both daylighting and electric lighting. The research addressed two objectives: (i) to verify if the lighting conditions could meet the recommendations proposed in recent literature (by the CIE or in the WELL protocol) concerning light exposure for appropriate non-visual responses; (ii) to assess the influence on integrative lighting played by daylighting as a function of different room depth and orientation, by electric lighting as a function of different lighting systems and by the combination of both. Electric lighting was assessed through field measurements, while daylighting through annual simulations using Lark v2. Concerning results for non-visual effects, the study showed that the position of the desk played a key role under daylighting conditions: only the desks within 2 m from the window were able to meet the circadian recommendations. Furthermore, in the spaces analysed, where different lighting systems are installed, the supplementary electric lighting did not always provide a sufficient contribution to meet the circadian recommendations on an annual basis across the full area. One office only, which underwent a retrofitting with LED luminaires, showed mel-EDI values consistent with requirements, but photopic illuminance on desk Ewp > 700 lx.