Prora was a 4.5 km long block building planned and erected between 1935 and 1939 on the island of Rügen in Germany. After the war the listed building was not in use and fell into decay. Now a 500 m long section of the building will be refurbished to become a pilot project concerning energy efficiency. It will be the biggest and most energy efficient youth hostel of Germany. Construction work started in July 2009.
The energy efficient retrofit concept is based on a reduction of the primary energy need to a third of the German requirements for new buildings and on the environmental friendly supply of the remaining need including the neutralisation of the CO2 emissions. The main goal is to have an CO2 emission neutral building. High performance windows, an integrated insulation system with good airtightness and nearly no thermal bridges, mechanical ventilation with high heat recovery rates, user-dependent lighting and heating are measures to reduce the needs. The CO2 emissions will be neutralised by biomass boilers and a photovoltaic system on the roof of the building.