The construction industry is booming. With over 114 billion in sales, it drives the economic forces in Germany and devours huge amounts of land and nature. The hunger for sand, gravel and cement is so great that in some places it is already difficult to produce concrete. Cement, with about eight percent CO2 emissions, is one of the major global climate polluters. Companies in Vienna, Hanover and Amsterdam are now showing that there are alternatives. Climate-friendly construction is possible because many raw materials are already in our cities. They are a huge camp created by us humans.

"It was an experiment," says Nils Nolting, architect of the Recyclinghouse Hannover: "Most comes from demolished houses, the windows, profiles and façade panels. At the beginning of the planning, we did not even know how much we could actually take from old buildings. " In the meantime, a new, bright, light-flooded single-family house has been built on the Kronsberg. The shell construction in solid wood has a CO2 - neutral effect; in addition, many materials, old bricks, industrial glass and used pavement slabs have begun a new life cycle.

Tom van Soest, founder of the Dutch company Stonecycling, began to experiment as a student. From demolition houses in Eindhoven, he fetched bricks, roof tiles, mortar remnants and tiles. He crushed and mixed with new clay. "It took a long time to get the recipe right," says the designer in retrospect. In the meantime, the Amsterdam-based company processes 1,000 tonnes of waste per year into new, colorful clinker, façade and building blocks. "I always wanted a colorful façade", Cecilia Petit enthuses one of the first customers on the terrace of her apartment in Amsterdam: "Now it is almost like a Hundertwasser house".

Brigitte Kranner also discovers her own beauty in demolition when it comes to old cables, sorted heaters or aluminum windows. Together with her husband, she manages the business of a large scrap metal trade in Vienna and is considered a recycling expert. Kranner knows that components are so rarely reused because they are contaminated with adhesives and binders. Their goal: varietal purity. "For example, like copper," she says, as the light pink metal peels off an old plastic cable: "It's 100 percent recycled, simply melted down, and restored to perfect copper wire." This principle could apply to many components, Kranner says: "We should reuse as much as possible and extract as little as possible from nature."