More than 80 % of the electricity consumption and more than 50 % of the heat consumption of 650 flats is covered by the electricity and heat produced in CHP units installed inside the block of flats. Electricity from the CHP units is distributed directly to the consumers through a local grid and the missing electricity is bought from the regional distribution grid. The CHP output power is regulated according to the electricity consumption. The maximum power demand of the connected buildings is 360 kWel. The produced heat is used for the preparation of warm water. Additional heat for the heating of the building is bought from a district heating system.