They Needed Something to Hold the Wool Together. They Used Wool.

The Grinham Research Group at Harvard University has developed an exterior cladding tile made from waste wool, presented at this year's Oslo Architecture Triennale and published by Dezeen on Sunday. The installation, called Upcycling Wool Ecologies, mounts the tiles on a timber frame inside Oslo's Sofienberg Church, where the triennale's main exhibition runs until 1 October.

The chemistry is the interesting part. Wool is treated with an alkaline solution that partially breaks down its keratin proteins, then worked mechanically until the material separates into a liquid. Citric acid goes in, and heating the acid together with the wool-derived keratin binds the residual and unprocessed fibres into a rigid composite. The binder is wool that has been taken apart, which is how the tile arrives without petrochemical resin in it. Felting does a coarser version of the same trick using barbs and moisture. The finished tile carries two layers, a low-density back panel that insulates and a denser outer panel that takes the weather, and it fixes to the outside of a wall that already exists, so upgrading the insulation stops meaning digging the wall open. The batch in Oslo used preconsumer waste from the American Woolen Company in Connecticut, naturally coloured fibres mixed with dyed ones, which is why the colours shift across the frame.

Founder Jonathan Grinham told Dezeen that wool “has lost its economic value, but not its material properties”. Around 1.95 billion kilograms of raw wool are produced each year and roughly 60 per cent of it goes into clothing manufacture; what is left over gets stockpiled, burned or buried, partly because synthetics undercut it and partly because of the way fleece is graded. Wool is insulative, fire-resistant and antibacterial, and the group points out that carbon captured by grass and sheep stays put once the stuff is bolted to a building. What if the most useful material in a retrofit turns out to be the one nobody could find a buyer for?