On a site formerly used for experiments on solar energy, Stuttgart-based architectural practice Behnisch Architekten has completed Building 668 (KIT Energy Lab 2.0), a massive testing lab for new energy systems as part of a scheme to move Germany toward greater adoption of renewable energy. Located at the Karlsruhe Institute of Technology (KIT) campus near Stuttgart, the KIT Energy Lab 2.0 is also remarkable for its eye-catching design — the timber-framed structure is wrapped in translucent polycarbonate cladding and topped with a dramatic sawtooth roof as a nod to the industrial character of the neighboring buildings.