Sustainability is arguably the challenge of our time. There is growing recognition that our current development path is now threatening the natural systems upon which our civilisation ultimately depends. Sustainable urban development requires a new way of doing things – a way which reduces environmental impact while at the same time promoting widespread economic and social progress. The buildings and supporting infrastructure of our towns and cities contribute positively to people’s quality of life but often use materials, produce waste and release CO₂ significantly in excess of that which our land, water and climate can continue to accommodate. Many urban centres are still blighted by crime and poverty: poorly designed developments have negative effects on the health, welfare and economic prospects of communities.