Many residential buildings in Germany are inadequately provided with daylight. This is the result of a study commissioned by the Initiative GutesWohnen [“Good Living Institute”]. It shows that the legal requirements for the provision of daylight in buildings lags far behind what is advised by the experts. As a result, residents run the risk of damaging their health.
“Daylight is essential for humans’ well-being and health,” explained Till Reine, from the Initiative GutesWohnen. The most recent medical findings show the high influence of daylight on our biological clock and therefore on our health. As people spend up to 90% of their time in enclosed spaces, houses and flats need to have enough daylight available.
“Unfortunately, the political system has been extremely neglectful on this subject in the past. Having sufficient daylight must play a significantly greater role in the future planning and refurbishment of residential buildings. The statutory minimum requirements are no longer up-to-date and must be amended as a matter of urgency,” said Reine.
A study by the consultancy firm Ecofys looked into whether the current daylight requirements from the “Building Code” correspond to the current state of the art. The Code stipulates that the windows of a room must always be of at least one eighth of the room's surface area. The findings of the study are sobering: In a typical inner-city non-detached property, this leads to no more than a third of the daylight recommended by experts. Following a typical energy-oriented renovation, the value is almost 30% worse. Therefore, when faced with pending renovations, building owners should definitely be made aware of the lack of daylight. In addition, suitable optional measures should be flagged up to improve daylight provision. Otherwise, in the face of the German Federal Government’s climate protection goal of renovating virtually the entire building stock up by 2050, there is the risk of the further and widespread deterioration to the current situation.
The authors of the study also suggest doubling the current prescribed window surface area for new-builds, up to one quarter of the floor area. This represents the minimum required to achieve the daylight levels deemed according to scientific standards. A glance at other European countries shows that these higher requirements are achievable. According to a survey by the Buildings Performance Institute Europe (BPIE) the daylight requirements in many European countries are indeed higher, with Germany in the group bringing up the rear.