A view of Freiburg’s Vauban neighborhood, known for its Plus Energy homes, with a decade-old tree on the right. When the neighborhood was developed in the 1990s, none of these historic trees was felled. In Germany, homeowners generally have to get permission from the city before cutting down a tree even in their yard – and the city can turn down the request if the reason is not good. Nonetheless, Germany is a leader in Passive House architecture and solar.