Proposal for revised criteria for daylight provision for the European Daylight Standard EN 17037:2018+A1

Sammanfattning: The European daylight standard EN 17037 was first introduced in 2018 with the aim of encouraging building designers to evaluate and ensure adequate daylight provision in buildings. However, experience has shown that the standard’s criteria are generally perceived to be too challenging to achieve. Therefore, to suggest a more balanced threshold, this master’s thesis aims to investigate compliance rate of existing buildings in Sweden for daylight provision criteria. In this study, 30 residential buildings in Sweden with a total of 3,570 rooms were selected based on Swedish building typical building forms and evaluated through Radiance-based daylight simulations using three different approaches: (1) Daylight Factor-based methods, (2) LM-83-12 method, and (3) a modified EN 17037 calculation method using illuminance level which is largely based on spatial Daylight Autonomy (sDA). In relation to the latter, compliance was checked for different combinations of illuminance thresholds and targeted area fractions. Then these compliance rates and the different combinations of the illuminance threshold as well as the targeted area fraction were compared to existing standards. Finally, a new criterion with three level of recommendations were proposed based on the new method. Results revealed that a large proportion of the examined individual rooms were able to meet various criteria for daylight provision. However, when looking at the buildings as a whole, only a few of them were able to fully meet these criteria. This is because a large proportion of the buildings have critical rooms that have limited access to the daylight, which makes it difficult to achieve the desired level of daylight provision at the building level. Furthermore, the finding of the study indicates that employing an illuminance threshold of 300 lux may not be beneficial in the context of the new criteria. Rather, a lower threshold coupled with a higher targeted area fraction would increase compliance and could be proposed as an alternative, but it needs to be backed up by further research.