From Barcelona to Sicily: an investigation on the relationship between composition and daylight in squares

The perception and liveability of an urban space can greatly depend on the correct management of solar radiation. The practice of using daylight as a design tool to evaluate the environmental comfort is not very widespread for outdoors: however, the light analyses in the exterior places can allow an ideal reading of the architectural scenario in formal and functional terms. This research seeks affinities between the composition of public spaces and their illumination during the day, in order to understand which parameters, influence the visual and thermal comfort for the users. In this essay it is evaluated the distribution and trend of daylight physical data in the squares of Mediterranean cities. The survey focuses specifically on two rectangular squares (one Sicilian and one Catalan) with similar spatial characteristics, which were chosen for a comparative study. The four urban scenes of each square were photographed in three different time intervals: these images were processed by an experimental software that provided data on the perceived daylight in terms of luminance, standard deviation, and spatial contrast. The technical assessment of light in different times of the day, together with the morphological analyses of the places, provides a series of information on the environment that can be used for urban redevelopment works or as a support for the architectural composition of new spaces. This study therefore researches how spatial and lighting characteristics influence the level of habitability of square areas, the time spent there and how these indicators can be improved.