Winter Sun

So how much sunlight should a building receive in the winter? According to BS 8206-2, the British Standard on Lighting for Buildings, interiors in which occupants have a reasonable expectation of sunlight should receive a minimum of 5% of probable sunlight hours in the winter. That is, between the 23rd of September and the 21st of March.

BS 8206-2 points out that the controlled entry of sunlight is especially valued where occupants have little direct contact with the outside world. Provision should be made for it in rooms occupied for long periods during the day, such as those for the elderly. Unfortunately, there is no obligation on anyone to do so. The health benefits are largely ignored, especially in hospitals. However, if too much sunlight is let into wards there can be health risks. One recent example of a hospital designed for sunlight illustrates the point.
http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2006/07/21/nheat121