Freiburg: City of Vision
The City of Freiburg is often called Germany's "ecological capital" and has been recognized internationally as one of the world’s most livable, sustainable and child-friendly cities. In 1993, IMCL awarded the City of Freiburg the IMCL City of Vision Award. Since then, Freiburg has received numerous awards for its leadership in sustainable transportation planning, promotion of walking and biking, traffic calming mechanisms, human scale mixed-use development, renewable energy, protection of nature, and sustainability.
Today, we are proud to work with the City of Freiburg to further disseminate the innovations and improvements in livability and sustainability the City has achieved in recent years by organizing the 2013 City of Vision Study Tour. For more information, vist the Study Tour's page.
Not only retaining and enhancing the beauty, walkability, mixed use and vibrancy of its historic city, Freiburg planning over the last 40 years has emphasized biking, walking and public transit, traffic calming, and mixed-use human-scale development to create a “city of short distances”. Numerous sustainability measures such as regional heating, recycling, and low-energy buildings have been implemented. Regional planning has focused development within city boundaries, and thus prevented sprawl. Historic castles, villages and towns have been protected. A strong emphasis is placed by Germany, Switzerland and France on ensuring ecological standards and protecting the diversity of vineyards, orchards and farms that produce the region’s renowned specialty items.
Situated on the edge of the Black Forest close to Switzerland and France, Freiburg has a cheerful character. Blessed by a warm climate, a young population (it has a large university interwoven throughout the city), excellent wines, and a festive tradition, Freiburg is a delightful city to study for all those concerned with city livability. Cities around the world have much to learn from details such as Freiburg’s “city carpet” (paving throughout the pedestrian zone); bicycle network planning and bike services; public transit design and linking policies; principles for developing new urban neighborhoods; traffic calming details (Wohnstrasse, Verkehrsberuhigung), etc.
Freiburg[i] is a medieval university city with a population of 220,000 situated on the southwestern edge of the Black Forest. At the heart of the city is the magnificent red sandstone cathedral, completed in 1513, with a fine filigree stone spire. Among other medieval buildings that survive are the old town hall “Gerichtslaube” from 1303, and the painted red sandstone Historic Merchants’ Hall, “Historisches Kaufhaus” facing the cathedral.
Albert Ludwig University, with 24,000 students, is one of the oldest in Germany, having been founded in 1457. With many of the university buildings in the center of the city, university students and faculty play an important role in the everyday life of the city, and account, in part, for the city’s lively spirit.
Freiburg’s location at a major crossing point of north-south and east-west trading routes made the city an important market center in the middle ages. This accounted for the broad market street, Kaiser Johann Strasse, and several smaller market squares, such as the Potato Market, “Kartoffel Markt”.
In 1944 most of Freiburg was destroyed in an air raid. Only a few buildings remained. The cathedral, fortunately, was untouched, surrounded by rubble. After the war, the decision was made to rebuild the city on the medieval street plan, maintaining the irregular narrow streets, and to reconstruct buildings as far as possible to retain the medieval scale and feeling of the old city. In this way, Freiburg’s decision was atypical for European cities, most of which chose to follow modern planning concepts, widening and straightening streets to accommodate cars.
Only a few of the most significant historic buildings, such as the city hall (Rathaus) and grain storehouse were rebuilt as they had been before. All others were built on the original building lines and within the original building envelope, not as replicas, but as modern buildings in the spirit of the medieval city. Some buildings constructed in 1952 preserved the city’s historic character so well that they are already placed under preservation law.
The economic boom of the ‘60s, which changed the face of so many German cities with high-rise buildings, the attempts to preserve the historic feeling of the city gave way to an attitude of modernism. Some very inappropriate, glass and steel department stores, and parking garages were built at this time, with flat roofs and horizontal strip windows.
City regulations were able to prevent high-rise buildings in the old city, and to prevent the use of steel, glass and concrete facades for most large department stores. Gradually, the city was able to compromise with architects to obtain facades that reflected the historic structure of the city by breaking a large façade into smaller units, adding window apertures in the wall surface, and a pitched roof.
In the '70s design guidelines were drawn up. By and large, these were accepted. New designs were asked to conform to the traditional building type: the roof should be as steeply pitched as the original building on that site, with roof ridge parallel to the street; the eaves should be very clearly defined, as they were in the medieval buildings; windows should be apertures within the solid wall surface, and they should be openable. Dormer windows were permitted to utilize the considerable space beneath the roof. Greater flexibility was permitted in the design of rear facades, in order to permit balconies and roof terraces.
At the end of the '60s a major program was initiated to maintain and increase the residential population in the inner city. The area of Konviktstrasse is particularly interesting. The street has been largely rebuilt, but the scale and character of the medieval street still remains. A prototype of appropriate urban renewal was carried out. The city did not permit amalgamation of the small building lots, but bought the properties and sold each lot to a different individual, with the injunction that they must build and live in the buildings themselves, and that each owner must employ a different architect.
It was assumed that these houses would not be built exactly as before but that they should be clearly new buildings, varied in style, but following the principles of Freiburg's traditional architecture. The various architectural designs had to be considerate of their neighboring buildings. Each architect was required to submit drawings and a model, and these were compiled to see how the ensemble would look.
The street became such a popular place to live that by the end of the '70s architects were competing with each other to design a unique facade. Nevertheless, the designs balance each other, and the ensemble is very pleasing.
Parking was one of the chief problems for residents and business people. The area behind Konviktstrasse, which had previously been the site of the city wall and some additional housing, was therefore used to provide parking. The city constructed a three story garage with six hundred spaces. On top of the stepped roof of the garage the city identified twenty-two sites for townhouses, each with its own garden area. Each of these sites was also sold to different individuals, who were also required to hire different architects to design appropriate dwellings following the traditional principles. From Konviktstrasse, one would not guess that a parking garage exists; the houses appear to have been built on the slopes of the Schlossberg hill. Indeed, from these row houses one steps across a bridge and is directly on a trail that connects through the Schlossberg woods to the rest of the Black Forest.
Development of Pedestrian Zone
Freiburg was one of the first German cities to close the city center to traffic. As early as 1949 cars were banned from five small side streets off Kaiser Joseph Strasse, the main shopping street, but it was not until l971, after the construction of a ring road around the city center, that the city undertook a very careful evaluation of goals and priorities for the future of the city.
In Freiburg, as in many other cities in the '60s, families were moving out to the suburbs, shopping centers were being developed around the periphery, and traffic in the city center had become a major problem, threatening the quality of life for those living in, and visiting the city center.
It was decided that "the attempt should, and had to be made to put a stop to the impending depopulation of the city center". It was agreed that the city must be livable for the community. Residential accommodations, and workshops had to be increased. The historic and cultural significance of the city had to be restored. These goals included improvements in Freiburg's market function, and streetscape.
In order to make the city center the unquestionable focus of economic and business life in the region, and to improve the quality of life for everyone who lived, worked, visited or enjoyed themselves in the city, it was decided that the center should become a traffic free zone. The pedestrian zone, the Freiburgers decided, should encourage promenading and social life. It should provide for meetings, and exchanges of opinions and ideas. That is the life of the city; for that, the heart of the city must offer ideal settings.
This important definition of goals and priorities prepared the way for the City Council's decision in 1972 to close Kaiser Joseph Strasse to traffic. Until then, this street was used as the major north-south traffic route and carried 22,000 vehicles per day. Finally, in 1973, after much preparatory redesign and repaving, all the main streets and almost all the side streets in the city center were closed to traffic.
The pedestrianized city center was intended in 1972 to be an experiment. Most citizens were always in favor of the idea, but some business groups opposed it. It was not until 1986 that the "experiment" concluded, when a consensus in favor of the pedestrian zone had clearly emerged.
The streets were repaved, for the most part, with natural stone. Trees, fountains, seats, lamps and art objects were installed. Commercial elements, such as showcases and kiosks, which were common in pedestrian zones created in other cities during the '60s, were not wanted here.
The city paid very special attention to the repaving of the streets and squares. Kerbs and asphalt were removed from all streets, and natural stone paving - reddish quartzite, black basalt, granite, red porphyry, and pebbles from the river Rhein - were used almost without exception in the medieval city center.
Indeed, the floor of the city has been treated as the city's "carpet". It is a work of art, and exhibits fine craftsmanship. Geometric and flower designs, historic, cultural and business symbols, executed by traditional artisans working with the different colored stones, pebbles and mosaics emphasize the unique character of each street, stimulate a sense of history, and prompt fantasy and imagination.
On the square outside the town hall are pebble mosaics representing the emblems of Freiburg's sister cities, Besançon, France; Guildford, United Kingdom; Innsbruck, Austria; Padua, Italy; Madison, Wisconsin; Lwow, Ukraine; and Matsuyama, Japan. Institutions, commercial buildings and churches are invited to sponsor a pebble mosaic in the pavement at their entrance; a bakery may be identified by a pretzel, a pharmacy by a pestle and mortar, a cafe by a cup and saucer, a tailor by a pair of scissors. In this way, the business reaches out into the street and extends its jurisdiction into what, in other cities, is a no-man's land. The pavement becomes personalized.
These pavement designs demonstrate that the Freiburgers value artistic craftsmanship, and that imagination, patience, humor, and the ability to create something that will last for generations are qualities that are highly valued. The sense of civic pride and responsibility are very strong in Freiburg.
During the pedestrianization process, Freiburg took the opportunity to reopen the "Bächle", the little streams that run off the mountains through the streets of the old city. These streams had provided the drainage system dating from the fourteenth century, but had been covered up to make the streets accessible for vehicles.
On hot days these tiny rivulets are very refreshing: many people paddle to cool hot feet; and children find the swift flowing water irresistible for all kinds of games. The pedestrian zone has proved immensely popular, and economically very healthy. Indeed, the pedestrian streets are so successful that some shopkeepers and residents on streets with traffic also demand to become traffic free.
Closing the center of the city to private vehicles made public transportation by tramway and bus much more attractive. The tramway system runs through the main shopping streets and, without the delays caused by private vehicles, the trams are able to run much more efficiently. As a result of pedestrianization, therefore, more people began using public transportation because it could take them quickly and comfortably into, and across the city center. As a result of this increased use, it became possible to further improve the service and extend the routes.
In Freiburg, transportation planning aims to reduce motorized traffic by means of integrating urban development and transportation planning to achieve a “city of short distances”. The goal is to reduce automobile traffic by increasing use of the more healthy and sustainable modes of transportation, walking, biking and public transit. While it is recognized that use of the automobile is necessary in some circumstances, it is carefully regulated in an environmentally and urban-friendly manner.
Transportation planners make use of five mechanisms to encourage healthy and sustainable transportation modes: 1. Extension of the public transportation network; 2. Traffic restraint; 3. Channeling individual motorized vehicle traffic; 4. Parking space management; and 5. Promotion of cycling.
Early plans had proposed moving public transportation into tunnels beneath the pedestrian streets. These plans were abandoned for cost reasons, and it is now thought that the visibility of trams and busses on the main street also keeps public transportation more attractive. They are relatively noiseless, and limited to a maximum speed of 25 kilometers per hour.
In 1984 a new philosophy for local public transportation was developed. An "urban environmental protection ticket" was introduced. This was a monthly season ticket, usable on all busses and trams, and was offered at 25% discount to everyone. When the number of passengers rose it became possible for new streetcar lines to be opened and new equipment to be installed.
In 2012, the streetcar (Strassenbahn) extends 19 miles (30 km) from Kaiser Joseph Strasse at the heart of the pedestrian zone to eight different destinations in surrounding neighborhoods. They provide a regular service every 7.5 minutes at rush hours and carry 70% of public transit users. An additional four new lines are proposed to provide greater interconnectivity. The regional light rail service runs every 30 minutes from the city center to surrounding towns. This connects to the national train system and bus system at the main train station.
Freiburg's public transportation company joined with all the public transportation companies in the region to form a single transportation company. It is now possible to purchase a monthly ticket for unlimited use on all regional busses and trams, including trains and busses of the national system "Bundesbahn". This has made it as easy to travel by public transportation to the surrounding mountains and lakes of the Black Forest as it is to go shopping. Fifty-six bus routes and eight railway lines are included in the system. The ticket is transferable, and can be used by several passengers simultaneously. This ticket is called the "Regional environmental protection ticket" or the "Green ticket", and is intended to encourage as many people as possible to leave the car at home and travel by the much more ecological public transportation system.
It was decided in Freiburg that bicycles would be too disruptive to pedestrians within the main pedestrian areas. Riding bicycles, therefore, is not allowed on Kaiser Joseph Strasse, Münsterplatz, Augustinerplatz, or Rathausplatz. Bicyclists are permitted to ride on some pedestrian streets, but not others, and sometimes they are only permitted in one direction.
Within the pedestrian zone, there are 50 bike parking lots. Bicycle parking is provided at primary, elementary and high schools as well as at all university buildings. Safe bike parking places are provided in the surrounding neighborhoods at streetcar, local railway and bus stops, often with protective roofs. At the main railway station, a large three story bicycle station has been constructed, providing bike parking, maintenance and rental services. Throughout Freiburg, it was estimated in 2009 that 60,000 bike parking spaces were available.
An extensive network (450 kilometers) of bicycle paths has been created. At first, paths to surrounding villages were intended for both bicyclists and pedestrians. It became clear that the speed of bicycles made these paths unsafe for pedestrians, to now, wherever possible, separate paths have been created for both. These routes run along the banks of the river Dreisam, around fields, through woods, and beside roads. Within the city, separate bike paths are often created next to sidewalks, protected from traffic by planting strips where space allows.
Bicycle lanes have also been created on the road, clearly marked with solid white lines and bike symbols. At intersections, special care is taken to bring bicyclists to the front in “bike boxes”, permitting them to cross before motorized vehicles. Occasionally, in order to complete and connect the bicycle network, quiet streets have been designated as “Cycle Streets” the give priority to bicyclists.
Use of the automobile has been made less attractive by parking space management. Within the center city, parking garages cost almost $3 per hour (Euros 2.20). In immediately adjacent neighborhoods, parking costs $2 per house (Euros 1.60). Neighborhoods where residents are required to obtain parking permits are being extended.
Many streets have been traffic calmed by removing some parking areas to make way for trees and plants, seating areas, and outdoor restaurants. Throughout most of the city, a 30 kilometer per hour speed limit is in place, and many short streets and small neighborhoods have been designated as “Play Streets” or “Living Streets” (Wohnstrasse). In these streets, speed limit is reduced to walking speed, and only residents or delivery vehicles are permitted to park.
Freiburg has one of the most extensive and successful farmers' markets in Europe, which takes place on the large Münsterplatz that encircles the cathedral. At least half of the market, on the north side of the cathedral, consists of local farmers and gardeners selling their own produce.
While the market takes place every morning from 7:00 a.m. until 1:00 p.m., Saturday is the busiest day, when the square is filled to overflowing. Around the edge of the Münsterplatz are many outdoor cafes, inns and restaurants which, from mid-morning on, provide light refreshment and traditional fare. By noon during fine weather every table and chair is occupied. Many have been shopping, others come because this is the liveliest place to meet friends.
The market has a very festive spirit, with its colorful umbrellas and overflowing baskets of fruit, flowers and vegetables. For the Freiburg citizens, this is an important weekly social ritual, an opportunity not only to buy the best and freshest produce of the region, but more significantly, to meet friends and acquaintances. Many people, including city officials, business people, university professors and students can regularly be found at the Saturday market. This farmers' market plays a very important role in Freiburg's social life.
Festivals and Street Entertainers
Celebration and festivity are cherished in Freiburg. Hardly a week goes by without some festival in the center of town or in one of the neighborhoods. The annual carnival celebration, "Fasnet" revives a centuries old tradition of masked and costumed performances in the streets. Thirty-three fools' guilds take part in the celebrations, and there is a "Hemdglunker" procession, which leads to the storming of city hall.
Many new festivals were introduced during the '70s: in 1973 a Christmas market was inaugurated on the Rathausplatz in front of city hall; in 1970 the wine growers' cooperative societies began a festival called "Freiburg Wine Days" for the last weekend in June on the Münsterplatz; in mid-August there are nine days of Wine Tasting, "Weinkost" of all the wines grown within the boundaries of Freiburg. In addition there is an Old City Festival, a Beer Festival, the "Oberlinden Hock", and various neighborhood festivals.
Street entertainers are welcomed in Freiburg. Saturday afternoons are especially lively, when music of all kinds, from medieval and baroque music, classical Spanish guitar and Indian sitar music, to folk music from Ireland, America and Peru, jazz and rock music, as well as clowns, acrobats, and other performers fill the streets and squares of the old city.
Renewable energy, solar industry, photo-voltaics, and water quality
Spurred by research at the University, and a population eager to put into practice principles of ecology and sustainability, Freiburg has become a leader in innovative sustainable energy, with solar, wind and hydro-power industries, co-generation and district energy systems.
Water quality has long been a focus of planning, with extensive use of permeable ground surfaces (rather than asphalt), bioswales, and green roofs. To encourage permeable ground surfaces, property owners are charged a stormwater fee according to the percentage of their land that is permeable.
The two new urban neighborhoods, Rieselfeld and Vauban have been built using low energy construction and passive and active solar design methods, as well as a strong community participation process in the planning.
Design of a New Urban Neighborhood, 'Rieselfeld'
The population of Freiburg increased rapidly in the '90s, largely due to the migration from former East German States. Freiburg's response was to plan a complete new city quarter, called Rieselfeld, for a population of 12,000 on seventy-eight hectares at Freiburg's western edge. The city wanted to ensure that this new neighborhood would be designed on the most advanced ecological principles.
The land had originally been used as the municipal sewage farm, but was closed in 1980 when the sewage system was connected to a regional treatment system. At that time, the intention was to protect the landscape and ecology of the area. However, the need for housing was so great that the city decided to use one quarter of the area for the new neighborhood, and to maintain the rest as a nature conservancy area.
The city wanted to avoid the social problems often associated with large scale housing developments, and to ensure that they did not repeat the planning mistakes made in the adjacent district of Weingarten. Here, modern planning principles had been used in the construction of a predominantly social housing district of high-rise apartment blocks. The combination of poor planning principles, absence of urban texture, and ghettoization of lower income families had created a neighborhood with distinct social problems.
The city paid much attention to defining equitable and sustainable planning principles to form the basis for Rieselfeld. They invited experts in planning, social sciences, transportation, ecological planning, energy, housing, and other fields to advise them and to help shape the guidelines for the conceptual plan competition.
Seven principles were considered of prime importance:[ii]
Human Scale: In its architecture, and urban space design, the new neighborhood should be built to a human scale. There should be a clear differentiation between public, semi-public and private spaces. Public spaces should be defined by continuous urban fabric - shop/houses or terraced houses - along the street to a maximum of five or six stories.
Identity: Since the social stability of a district depends on residents identifying with their neighborhood, the neighborhood must have a good image, with its own unique and consistent character.
Social structure: From the beginning the neighborhood must have a balanced social structure. This means that while social housing is an important element, it must be balanced by market rate housing.
Infrastructure: For the neighborhood to have it's own identity it must contain all the essential infrastructure. Shops, schools, kindergarten, health care and senior services, work places, restaurants, churches, sports and other facilities must all be included.
Transportation: It is of the highest priority to encourage use of public transportation; the new district must be connected to the city center and other parts of Freiburg by tramway and bus.
Ecology: Ecological principles must influence architectural design and urban design. Buildings should make use of passive solar energy, solar collectors and photo-voltaics.
Community participation: It is important to develop a process of community participation in the planning and building designs for the new neighborhood.
In 1992 a competition for the conceptual plan was held. The first prize winner, a planning firm from Freiburg, worked with the City of Freiburg to further refine the plan to reflect as closely as possible the city's planning principles.
The street layout is roughly orthogonal with the main street carrying the Strassenbahn connection to the city center running down the middle of the site. The main street contains most of the commercial activities, with a large supermarket at either end, and a diversity of smaller shops, cafes and restaurants between them. It has wide sidewalks, separate bike lanes, vehicle lanes, and the Strassenbahn running down the middle along a green sward.
While the emphasis is placed on public transit, walking and biking, the automobile has not been banned from Rieselfeld. Almost all apartment buildings and condos have underground parking; row houses and townhouses have parking in adjacent alleys.
“Wohnstrasse” abound throughout the area. In these streets, traffic can go no faster than a pedestrian. There are no sidewalks because the whole width of the street must be shared by playing children, adults socializing, bikes and cars. This requires all users to be mindful of others in the space. In addition, there are numerous lanes, paths and trails that are for pedestrians and bikes only.
The urban fabric consists primarily of a classical block structure reminiscent of some of Freiburg’s best loved 19th century neighborhoods (though in a modern style of architecture), and two to four-story town houses. Rieselfeld was the first district in Germany to require stringent energy saving measures for housing construction in the entire district, and builders were encouraged to use passive solar design features. Across the whole neighborhood there is a minimum amount of sealed paving: rainwater seepage is facilitated through natural ground surfaces and a rainwater conservation system.
Much attention was paid to making the streets and outdoor natural areas safe for children to explore and range on their own, and hospitable for children’s play. Green streets, and green spaces within and between the blocks are filled with natural playgrounds, small streams, ponds, community gardens and wild areas. Nature reigns supreme.
The city established a municipal project management team, headed by Klaus Siegl, under the direction of the Erster Bürgermeister Dr. Sven von Ungern-Sternberg to manage the whole development. Since the city owned the land, they were able to sell small parcels to developers, building contractors and individual owners and thereby finance the provision of services.
Major housing construction was not undertaken until the necessary infrastructure was in place. This meant that the tramway was in place, a kindergarten and shops, including a grocery, were completed to coincide with when the first residents moved in. Major community resources at the center of the development now include a grammar school, a media center, and a multi-cultural church that provides many meeting rooms for diverse religious observances. The development broke ground in December 1994. The neighborhood was built in sections and finally completed in July 2010.
Redesign of the Military Barracks: Vauban
In 1992, the French Vauban military barracks were decommissioned. The city of Freiburg bought the land and decided to develop it as a high density neighborhood for a population of 5,000. The land was heavily wooded, and the idea developed to create a “green” neighborhood – a place where residents could live in a park, not in a parking lot.[iii] The barracks were less than 3 kilometers from the city center, with a good bus connection and easily accessible by bike. As with Rieselfeld, it was also decided to connect Vauban to the city center with a new tram line.
The Vauban lands offered several advantages for transformation into a new type of garden suburb, but at a higher density[iv]. It was adjacent to existing city services, and many offices and job locations were easily accessible on foot or by bike. On the south side, it was close to hills and woods attractive for recreation. It was therefore decided to build a new neighborhood at the greatest possible density compatible with ecological and social sustainability.
It was felt that a high standard of livability would only be achieved in such a dense neighborhood if the streets and public spaces were relieved of the burden of automobile traffic. An important criteria, therefore, was to remove the automobile from the neighborhood as much as possible.
Planning for pedestrians and bicyclists took first priority. This meant that shops, services and work places had to be located within walking or biking distance. Bus lines stopped at the entrance to Vauban, and a tramway was constructed along the neighborhood’s main street.
The comfort and safety of children, handicapped persons and elders was prioritized over the comfort of the car driver. Residents were protected from the noise and air pollution caused by cars by the provision of large parking structures at the entrances to Vauban. These ensure parking is available within 300 meters of every home. While there are a small number of parking spaces available throughout the neighborhood, it was emphasized that this neighborhood would be ideal for those who wished to live without a car, or who did not need to have their car parked inside, or in front of their home. In Freiburg, 35 – 40% of households do not own a car. Many of these have consciously chosen a car-free life style, so it was felt that the time was right to create a neighborhood that was, as far as possible, car-free. Delivery and emergency vehicles, of course, have access to every dwelling.
A car-free neighborhood was also considered to offer ecological and economic advantages: residents would walk on the streets more, thus get more exercise and be healthier; without cars, the air would be cleaner, and thus healthier; residents would be more likely to get to see each other, talk, and get to know each other in the public realm; they would develop a stronger connection to their neighborhood and to the community. It was considered especially important to ensure that the street adjacent to the elementary school and Kindergarten should have minimal car traffic. By not providing underground parking for every dwelling, construction costs would also be lower, reducing costs for owners and renters.
It was planned that east of the main street, Merzhauserstrasse, approximately 20% of residents would have parking available near their homes, either underground or in parking structures. West of Merzhauserstrasse, the area is divided into four quadrants, each of which would provide parking for approximately 25% of residents within the quadrant. Other residents would be able to park in the parking structures at the periphery of Vauban.
Since the neighborhood was constructed in phases, planners were able to test out their estimates as to the number of parking places desired near the homes, and adjust their planning as they progressed.
The land was divided into comparatively small parcels, enabling individuals to build for themselves and own their own home. This was a deliberate effort to encourage diversity of architectural forms that would reflect the diversity of the population.
On Merzhauserstrasse a mixed-use solar building was constructed, with shops at street level and south-facing low energy apartments above. Row houses behind this building are constructed on principles of passive solar design. Active solar panels on the roof allow these houses to produce more energy than they need, which is traded back to the energy company.
[i] This article incorporates sections from: Freiburg-im-Breisgau, Germany, in Livable Cities Observed (1995) by Suzanne H. Crowhurst Lennard and Henry L. Lennard
[ii] Sven von Ungern-Sternberg. Freiburg-Rieselfeld, in Making Cities Livable: Wege zur menschlichen Stadt. (1997) Suzanne H. Crowhurst Lennard, Sven von Ungern-Sternberg and Henry L. Lennard (Editors)
[iii] Sven von Ungern-Sternberg and Volker Jeschek, Von der Kaserne zur Gartenstadt Vauban. in Making Cities Livable: Wege zur menschlichen Stadt. (1997) Suzanne H. Crowhurst Lennard, Sven von Ungern-Sternberg and Henry L. Lennard (Editors)
[iv] Hans Billinger, Freiburg, Vauban-Geländer, in Making Cities Livable: Wege zur menschlichen Stadt. (1997) Suzanne H. Crowhurst Lennard, Sven von Ungern-Sternberg and Henry L. Lennard (Editors)