For many cities, the question of ecologizing infrastructure means tearing down the old and bringing in the new -- a costly and sometimes bewildering prospect. But after World War II, Freiburg was one of many German cities that were able to find the good in the aftermath of destruction. A community of educators and professionals, the post-war period found Freiburg and Munster competing to rebuild along the most sustainable principles.
Freiburg continues to rank as a green city, with a particularly German flair for engineering and planning, social cooperation and profit. From cycling incentives to solar paneling (on as many as 50 percent of the roofs in some districts), the city has continually rebuilt itself as greenly as possible. Plans to build a nuclear plant in the nearby countryside were derailed by protests in the mid-1970s, and the city promotes alternatives to classic transportation, like trams and pedestrian walkways. In 1986, Freiburg was one of the first cities in Germany to adopt local energy production.
By creating a situation in which citizens are committed stakeholders -- as is the case with most of the cities on this list -- the green movement is a natural part of daily life. Some districts are created and supported by multiple-family flats, designed and built by the families that live there along environmental principles. The latest development is the "passive house," which uses ingenious ducting and insulation to remove the need for heating and air conditioning of any kind. Costing 10 percent more to build at the outset, the passive house construction reduces energy loss and bills by 90 percent [source: Purvis].