The construction of housing, commercial property, and infrastructure projects--roads, bridges, tunnels, railways, airports--for both the private and public sectors is one of the biggest industries in the world. It contributes around 10 per cent of world GDP, employs 7 per cent of the global workforce, and consumes around 20 per cent of the world's energy (and generates a third of the world's CO2 emissions). So important is the contruction industry...