Approximately 50% of the global population lives in cities. In 2020, this figure will be more than 60%. The success of climate protections is, therefore, dependent on energy consumption and pollutant emissions in our cities and conurbations. Local councils can specify important framework conditions for implementing energy efficiency measures. Examples of this include land-use plans and specifications for supply structures based on the local council's energy concept. As a shareholder in municipal utility companies and housing associations, cities influence the development of district heating, the use of renewable energy sources and the refurbishment of residential buildings.

And of course, they can act as role models when building or refurbishing their own properties. This requires action plans at city district or residential neighbourhood level. With these plans, measures can be specified and the competent parties can be appointed. Their interaction, based on defined aims and responsibilities, is the key to successful implementation.

The following model is being tested in Karlsruhe: An energy concept has been developed and implemented for a residential neighbourhood in the district of Rintheim. The aim of this concept is to achieve the best possible cost efficiencies and reduce primary energy use and CO2 emissions by more than 80%. In addition to establishing a local heating network, buildings constructed in the 1950s and 1960s are to be costeffectively modernised. Subsequent operation of the refurbished buildings connected to the district heating system is continuously monitored and optimised over three heating periods. Residents participate in the energy saving efforts. This research focuses on two residential buildings, in particular. They are being refurbished based on an ambitious energy concept and monitored through measurements in 2009-2010. In addition to innovations in building conceptual design, building services equipment, measurement and control technology and tenant communication, this is the first time a “low-exergy” (LowEx) approach is to be implemented for an entire residential neighbourhood. This is a pilot project of the EnEff:Stadt research initiative of the German Federal Ministry of Economics and Technology. Accompanying measures to improve local infrastructure and social integration are being promoted through the joint federal and state government programme, “Socially Integrative City”. Work on the residential neighbourhood concept began in 2009. It should be completed by around 2015.