ABSTRACT
Cities cover only 2 per cent of the world's land surface yet they consume over 75 per cent of the planet's material resources. 1 The ongoing improvement and expansion of our urban environment are making increasing demands for the creation of new, and the upgrading of existing, buildings, roads, and landscape (some 40 per cent of worldwide raw material flow is attributed to construction 2 ). In the UK, the production of construction materials contributes over 5 per cent of national CO2 emissions, 3 and a further 5 per cent is incurred in their transport. 4
