Where it's done:
According to ÖNORM O 1052, façade lighting is prohibited in legally defined areas as a nature protection measure. In the Tyrol, a permit under nature protection law is required for the installation of outdoor lighting systems.
The aim is to prevent lighting in exposed locations and on high buildings, as it can be fatal to migrating birds and bats. Migratory birds are on the move from mid-February to mid-May and from August to mid-November. Bats arrive in autumn (September) and move to their summer quarters in spring (March, April).
Buildings with bat roosts - at least the exits - are not to be illuminated during the breeding season from May to August. Bats are protected species and must not be disturbed or impaired by artificial light (TNSchG 2005 and TNSchVO 2006). This also applies within the built-up area.