How CO2 Emissions from 3,000 Apartments in Hannover Kronsberg in Germany Were Reduced by 74 Percent

Hans Hertle, Institute for Energy and Environmental Research

Keywords

Abstract

The City of Hannover developed the World EXPO pilot settlement of Kronsberg (2,890 apartments with a combined size of 213,000 m2) with the goal to reduce the energy consumption from heating by around 45% compared to conventional building methods regarding total domestic energy use (heating, hot water, electricity); thus avoiding at least 60% of the emissions carbon dioxide (CO2) that is affecting the climate. A target of 80% reduction was attempted by the installation of wind turbines.

This paper describes the audit of the measures consisting of a detailed evaluation of data of the monthly consumption in all apartments over three years. The average thermal energy demand of the buildings in 2001 was determined to be 56 kWh/(m2*yr), which is about 42% below what is expected for conventional buildings complying to the 1995 building insulation regulation. All buildings on Kronsberg draw their heat and hot water from gas-powered decentral Combined Heat and Power (CHP) plants via two district heating systems. The parallel generation of electricity and heat reduces the primary energy demand and associated CO2 emissions. An information and motivation campaign conducted in 2001 resulted in further reductions of electricity use of the households.

All measures combined resulted in a 56% reduction in CO2 emissions. In addition, three wind turbine generators with a total capacity of 3.6 MW were in operation on a nearby hill which account for a further reduction in CO2 emissions by 28%. In summary, the measures achieved a reduction of CO2 emissions per Kronsberg by 74%, from 1.7 to 0.4 tonnes per resident and year which is close to the target value of 80%.