Construction is responsible for around 40 percent of all greenhouse gas emissions. That is why, before every construction project, questions arise such as: Do we really have to tear everything down and build anew? Or is it better to examine the existing building, renovate it and adapt it to our changing needs? Every building requires such analyses and decisions, which have a direct impact on the environment.

More than 500 million tonnes of mineral raw materials are used in construction in Germany every year. Every step towards documenting these materials, making them easier to separate and reuse, is a step in the right direction. We are guided by the concept of the ‘ecological backpack’, introduced by chemist Friedrich Schmidt-Bleek in 1992. It shows the sum of all material and energy flows necessary to produce goods and services. The figures are sobering: on average, every kilogram of ‘product’ carries almost 30 kilograms of nature. The more complex the products, the heavier the backpack. No wonder that the construction industry, with millions of tonnes of steel and concrete, bears a special responsibility for the environment. Old materials are therefore given a new lease of life. Wood, for example, is proving to be a super material for construction.

In 2012, the leitmotif of the German Pavilion at the Architecture Biennale in Venice was "Reduce, Reuse, Recycle". This heralded a new era. As architects, it is our task to promote the circular economy, even if this initially means more work: more information about the right materials and suitable structures, more about the location and its traditions, more about the people for whom we build. This is the building revolution: circular economy/C2C (cradle to cradle) in the service of people. After all, sustainability is only as good as the people, the structures and the materials we use.