Bochum, Dusseldorf In a mouse-grey Bochum settlement, of all places, where apartment buildings are lined up like shoeboxes, Germany’s hope for renovation is said to be hiding. Even Thomas Gumm, project manager at the housing company VBW Bauen und Wohnen GmbH, didn’t want to believe at first “what you can conjure up out of such boxes”.

Gumm, gray sweater, shaved head, points to a house that stands out with its wooden exterior, modern and bright. “Air-to-water heat pumps are installed in all apartments,” says the 53-year-old as he guides us through the three-storey box-type building . A narrow metal staircase leads to the flat roof, Gumm climbs through the hatch and looks at the black solar panels at his feet.

The photovoltaic system supplies the house from the 1960s, which according to Gumm was previously “completely uninsulated”, with as much energy as it needs for heat and household electricity. In this way, VBW wants to save 92 tons of CO2 per year there.