Urban gardens

Green roofs and walls can reduce building energy bills and boost bio diversity while still aesthetically pleasing. Green roofs come in several shapes and forms. The simplest is an extensive mixed Sedum roof, planted with several species of tough, drought-resistant succulents that store water in their fleshy leaves and are highly attractive to bees. These require only 8 cm of rooting substrate for the shallow-rooted plants and minimal maintenance, though cannot be walked upon to any degree. Extensive roofs need no irrigation and are the lightest of all vegetated roofs. Structural engineer Dave Rayment of London-based Morph Structures says: "Extensive green roofs are relatively lightweight - similar to atraditional flat roof with gravel - and so don't have a big impact on the structural design of a building". The green roof allows the building to blend into the sensitive natural landscape of the South Downs.