Light exposure and insulatioin

In the course of thermal renovations in existing residential buildings main emphasis is laid on the insulation of the building‘s surface in order to minimize thermal losses. Consequences of these renovations are changes in the dimensions of the soffits or window frames which result in a reduction of day light within the building. The quantification of daylight indoor is generally done in accordance with DIN 5034 – daylight in interiors – by calculating the daylight ratio under a uniformly overcast sky, i.e. diffuse light. Location and orientation of the building as well as direct light are not taken into account in this calculation. When taking a more holistic approach to renovation-related changes of light conditions in living spaces it is essential to consider the direct light gains related to the orientation of the building and the passive solar gains too.