The old courtyard building, situated in the centre of Linz and dating from the year 1950, had been empty for a couple of years and appeared to be going to wrack and ruin. The Linz city council planning department had already earmarked it for demolition; therefore, renovation was the only option. The crumbling plaster, the leaky roofing, and the fungus problem, etc., meant that comprehensive renovation was necessary. The fact that the building is situated in the interior courtyard and therefore inaccessible to building vehicles made a huge amount of manual work necessary. The renovation concept included a complete gutting down to the supporting structure of the building. Comprehensive thermal insulation measures, controlled living room ventilation and a gas-fired boiler combined with 16 m² solar panels made it possible to reduce the energy consumption from 295 kWh/m²a to 46 kWh/m²a. The solar panels are able to provide 70 % of the hot water and 30 % of the heating.