Daylight compliance of Swedish residential blocks according to past and current performance criteria

The importance of daylight to occupants’ health and wellbeing has been extensively documented, as well as its role in reducing electric lighting use. As a result, most countries have today some form of regulatory framework, specifying minimum daylight requirements for built spaces. The present Swedish building code (BBR – BFS 2011:6) includes general recommendations for daylight provision of residential spaces, which stipulate a minimum window area relevant to the floor area or a minimum point daylight factor within rooms “inhabited more than temporarily”. Currently, policy makers in Sweden are considering the possibility of updating the current regulation, in light of the new European Daylight Standard (EN-17037), recently adopted by the Swedish Standards Institute. The challenges for policy makers include the extensive ongoing development of housing projects and the resulting impact of urban densification on daylight levels. Given this context, this paper investigates the compliance of residential developments, located primarily in Stockholm, for different daylight performance criteria. A sample of 10.888 rooms belonging to 3.151 apartments in 25 multi-family urban blocks was selected to represent different construction eras and major architectural typologies in Swedish urban planning history. All rooms were assessed by Radiance simulations according to the current Swedish regulation, the EN-17037 standard and other, commonly used, international compliance criteria. Results indicate that the implementation of different daylight criteria deem different building typologies better or worse performing, depending mainly on urban density and building height. A consistent finding is that all evaluated developments achieve lower compliance rates when standard 17037 is applied. Finally, policy implications on design and compliance are discussed, along with the necessary future investigations.