Bahnstadt - an impressive inner city development project
Heidelberg’s former goods station is the site of the world’s biggest passive house development, to be completed by 2022. The residential and energy-saving project is causing a sensation – in Germany and around the world.
Two kilometres separate tradition and modernity in Heidelberg. The past and future of the university town are marked by the “Altstadt” (old part of town) and the “Bahnstadt” (train station district). As a fashionable counterpart to the historic centre, the new Bahnstadt, to be completed by 2022, will relieve the situation in the housing market. With an area of 116 hectares, it is one of the biggest inner city development projects, after Hamburg’s HafenCity harbour district. The urban planning is provided by the architects and urban planners Trojan Trojan + Partner, as a result of an international architectural design competition in the year 2003. About 5,000 people will live here, and 7,000 will work here. There will be a close interrelationship of living, science and commerce in the future.
Proud interim balance
2,000 residents and hundreds of new workplaces – that is the current balance and the tendency is rising. The first construction stage was completed in the summer of 2014; since then, residents, companies and the first businesses have moved into their new accommodations. “It is nice to see how the new district is being accepted,” Dr. Eckart Würzner, Mayor of Heidelberg and the “face” of the Bahnstadt, is happy to report. Würzner is often asked, both at home and abroad, what is so special about this modern housing development. “Our Bahnstadt,” he then answers proudly, “will be the biggest passive house development in the world.” All of the buildings are designed so that they cause no emissions and the energy requirement is reduced by about 50 to 80 percent. A colourful mix of families, students and seniors live in the already completed rental flats and condominiums, as well as the university apartments. Special funding also allows the less well-to-do to enjoy the advantages of a passive house. Anyone who climbs to the highest point of the housing development can get a view of the energy technology of the past: “Back there you can see the cooling towers of the Philippsburg nuclear power plant,” visitors learn, “and over there you can see the chimneys of Mannheim’s coal-fired power plant.” For Bahnstadt residents those are the energy suppliers of yesterday – a CO2 neutral biomass wood-fired power plant generates the electricity and residual heat needed by the passive houses.
Passive House Award 2014
After completion of the first construction phase, the housing development in Heidelberg received the first Passive House Award in 2014, which is awarded by the Passive House Institute as part of the European project PassREg (Passive House Regions with Renewable Energies). “The Bahnstadt is gaining acceptance internationally and is rapidly becoming one of the most innovative urban development projects of our time,” explained Mayor Würzner at the official unveiling of the Passive House Award plaque. Prof. Dr. Wolfgang Feist, Director of the Passive House Institute, adds: “Maximum energy efficiency in construction is becoming widespread in more and more countries. But an entire district built according to passive house standards in this form is unprecedented. The city of Heidelberg is providing, so to speak, a blueprint for the future: the European Building Performance Directive requires that the nearly zero energy building become the rule by 2021 – and with the passive house standard, the Bahnstadt already fulfils this requirement today.”
Innovative lighthouse projects
Heidelberg’s mayor acts on conviction and is hardly willing to accept climate compromises. For example, he and his team insisted that the 12,000 square metres DIY store at the edge of the Bahnstadt also be built as a passive house. A special landmark of the new district is the Skylabs office and lab building – likewise according to the passive house standard, of course. The building from Fischer Architekten with its nine-storey tower will be the architectural highlight of the development. Technologically, however, it also fulfils the highest standards for energy efficiency, special focus having been placed on optimisation of the ventilation technology, which is especially important in laboratories. The building shell is characterised by bands of floor-to-ceiling windows, which also let in ample light during the winter. In the summer, on the other hand, folding shutters, characteristic of the appearance of the building, provide protection against the heat. Finely perforated, they also ensure that soft light can always shine through. Artificial illumination of the Skylabs is therefore significantly reduced. On a much smaller scale, but no less innovative, is the already completed daycare centre on the “Schwetzinger Terrasse”. The daycare centre and the adjacent public square were designed by the Behnisch architects and are especially striking due to their unusual forms.
Successful bridge solution
In the Bahnstadt, cars are banned; the traffic-calmed area is dominated by pedestrians and cyclists. They are also the ones who benefit from the latest innovation: LED streetlights provide light over a stretch of 3.5 kilometres. If no one is in sight, the lights automatically dim to about 30 percent of the luminous power. As soon as someone approaches, the lights again become brighter. When cyclists or pedestrians are out of range, the light power automatically switches back to energy-saving mode. No one needs fear that the lights will go out too early in the Bahnstadt. The demand for passive house residences is greater than the supply; the mix of living, leisure and work is very popular. “The concept of the Bahnstadt works,” Mayor Eckart Würzner is convinced. Even the separation of the town centre and the Bahnstadt has meanwhile been overcome – at least architecturally: a long bike and pedestrian bridge now unites the two dissimilar parts of town.
Networked living 2030
Vaillant is also working intensively on the issue of “living in the future”. The company is part of the innovation network Universal Home, an ideation platform on the issues of efficient use of energy, trade-spanning products and new technologies for demanding users. “In this cooperation we can develop products and services that cannot be achieved by a single manufacturer alone,” says Udo Ermert, Senior Design Manager at Vaillant and founding member of Universal Home. “At present, Vaillant is involved for example in a project for intelligent networking of a heating and storage system with heat/cold-generating appliances in a household of the future.”