Integrating urban context in daylighting simulation

Abstract

The Netherlands is facing a housing demand of 1 million homes before 2030. Most of these residences are planned to be built in and around existing cities, causing an increase in urban densities with sub-optimal indoor daylighting conditions as a result. Simultaneously, the daylight assessment methodology for buildings in the Netherlands is set to change from the Dutch NEN 2057 to the European EN 17037. The European norm uses more accurate metrics to express daylighting performance but does not consider urban context (i.e. external buildings) in the simulation models. As a result, a concern is that indoor daylighting in dense urban areas is inadequately protected. Moreover, it is unknown to what extent the urban context affects the well-being of humans, regarding visual and non-visual levels of daylight.

A multitude of daylight simulations is run and analysed in the thesis to better understand the impact of the urban context on indoor daylighting performance. Visual daylighting is assessed following the EN 17037 methodology with urban context integrated. Non-visual daylight performance is assessed using two novel metrics: melanopic autonomy and melanopic isotropy. The results have revealed that the discrepancy between simulations with and without the integration of urban context is up to 90% for realistic residences throughout the Netherlands, depending on urban characteristics and density. On average, indoor daylighting is decreased by 36% when the urban context is integrated with the EN 17037. The non-visual stimulus was found to be sufficient in residences that are compliant with EUmin levels but insufficient for residences that only comply with the Dutch building code. Sky view factor (SVF) and Building Floor were found to be useful indicators of daylighting performance in early design stages. Urban density indicators such as the FSI and OSR seem to be negatively correlated with daylighting performance.

The thesis concludes with the advice to include urban context in daylighting simulations so that bad daylighting can be properly mitigated. Effective mitigation strategies are increasing glass transmission values, interior reflectance values, and exterior building reflectance values. Another effective strategy is to avoid bad daylighting conditions in the first place by not positioning residences on the first 5 building floors in high-density urban areas. The results from this thesis can be used by daylighting designers and architects who are interested in ensuring adequate and healthy daylighting conditions in the residences they design: not only in digital environments but in the real world.