Five years after its construction, we revisit a successful experiment in the optimization of energy at neighborhood level. Precise recommendations, efficient equipment and persuasive incentives made it one of the most ambitious programs of its kind in Europe.

The Hanover world's fair that took place in 2000 will leave at least one mark: the Kronsberg area, purpose-built and incorporating the best available technology in terms of sustainable development and energy optimization. But there is nothing spectacular in Kronsberg – just the demonstration that energy norms applied intelligently can generate significant savings.

A low-energy standard

The program as a whole is based on Hanover's energy plan of 1992, from which it draws the main goals: priority to energy savings, development of cogeneration systems allowing the use of primary energy sources, more extensive use of renewable energies. Precise recommendations were given. These go from a consumption limited to 50 kWh/m2 (4.6 kWh/ft2) per year for house heating (solely through the use of insulation) to buildings being systematically equipped with central heating or urban heating with heat recuperation. These recommendations may also cover such issues as the length of drainage pipes (as short as possible) or the banning of electrical heating. All residential buildings built are low energy, in accordance with the LEH (Low-Energy Houses) standard. Urban heating is produced by cogeneration units burning gas, supplemented at 40%, from spring to December, by thermal solar panels connected to a buried tank.

In terms of renewable energy, photovoltaic panels have been used on an ad hoc basis on public buildings such as the neighborhood house, school, and cogeneration center, with a total output of 45 kWh. Two wind turbines, 3.3 MWe in total, one of which is assigned to a local organic produce company, were also installed.

An incentive system that makes it worthwhile to play the game

But the innovation didn't stop there. Kronsberg cleverly put into place an effective system to encourage residents to "play the game" of saving electricity to the fullest extent. A mobile demonstration booth was used to introduce residents to low-consumption light bulbs and water-saving faucets that were then handed out free of charge, low-consumption domestic appliances were also subsidized and, finally, a campaign of phone advice was launched and information leaflets, "Living in a low-energy house", were distributed.

A model to follow

To date, 3,000 homes housing almost 6,300 people, and community facilities consisting of a community center and an art center have been built on the outskirts of the Lower Saxony capital on 70 hectares (173 acres) of former industrial land. The area is structured according to a grid system with housing in the neighborhood in a checkerboard layout grouping compact and dense buildings that combine a wide variety of structural shapes and architectural styles. A very high priority was given to green spaces with proportionally 5 to 10% more area than is found in conventional urban planning. Finally, transportation was an important component. Its environmental impact in terms of visual and noise pollution, traffic, and emissions was minimized as far as possible. A policy was implemented to limit local traffic to the strict minimum by building a network of pedestrian and bicycle paths, together with non-polluting public transportation connecting the neighborhood with the Hanover city center. Not only were the savings targets reached or even surpassed, but also Kronsberg is now considered to be a model project for many European cities.