Harvard University's Grinham Research Group has developed cladding tiles made from waste wool that can be applied to the outside of existing buildings, avoiding the costly process of opening up walls for insulation upgrades. The tiles combine a low-density wool back panel for insulation with a denser outer layer for durability and weather resistance. No petrochemical resin is used; instead, an alkaline treatment and citric acid bind the wool fibers into a rigid composite. The group notes that roughly 1.95 billion kilograms of raw wool are produced annually, with about 60% going to clothing manufacturing. Much of the remainder is stockpiled, burned, or buried. By capturing this waste stream, the tiles store biogenic carbon that would otherwise be released and extend the useful life of buildings, supporting retrofit and reuse goals. The prototype was showcased at the 2026 Oslo Architecture Triennale, using preconsumer waste from the American Woolen Company in Connecticut.
