The residents of the Olympic Park housing estate are also supplied with solar thermal heat for space and domestic water heating in winter. This is ensured by a seasonal hot water storage tank in combination with a heat pump. With a capacity of 5.7 million litres, the underground bunker is large enough to almost fill three average-sized public swimming pools. With their heating concept, the researchers at the Bavarian Centre for Applied Energy Research achieved a return temperature of just 30 °C in the local heating network.

The City of Munich selected a section of its new “Am Ackermannbogen” urban district to construct a local solar heating system. The residents live in either one of the four large apartment blocks or in one of the eight smaller townhouses. The buildings’ thermal insulation standards accord with the requirements of the currently applicable German Energy Saving Ordinance EnEV 2009. The local heating system supplies a total of 30,400 square metres of floor area with solar thermal heat, which is supplemented with district hot water heating from Munich’s municipal utility company, Stadtwerke München (SWM). The municipal utility company planned, constructed and operates the entire heat supply system on behalf of the City of Munich.

Solar heat is supplied by 2,761 square metres of aperture collector area. The buildings have roof substructures on which the collectors are mounted as an external roof envelope. This separation is required for legal reasons: the roof substructures belong to the respective buildings while the solar thermal systems are owned by Stadtwerke München. A mixture of water and glycol transports the energy through the solar collection network installed in the street into the heating centre. The liquid flows through a pipe system that, compared with standard pipes, is furnished with greater insulation in order to reduce heat losses. In the heating centre, the heat is transferred to the pressureless storage circuit. Since 2004, scientists from the Bavarian Centre for Applied Energy Research (ZAE Bayern) and the Solites Steinbeis Research Institute have been monitoring the project with simulation calculations, technical suitability tests and optimisations during the ongoing operation. Up to now a solar fraction of 45% has been achieved.