Croydon's residents have perhaps been puzzled by their skyline's growing number of green roofs (see case studies overleaf). The causes of urban change can often be obscured as individual decisions get lost in shifts of taste or style. But the greening of Croydon's roofscape began as an idea over a decade ago and is now gathering momentum through the planning system.
In 1993, the Architecture Foundation organised the exhibition Croydon: the Future, which explored ways in which the area's latent potential could be utilised. For the exhibition, Branson Coates identified existing transport nodes as regeneration opportunities.
Its proposal 'reclothed' the uppermost level of seven car parks as programmed green spaces.
Vincent Lacovara, who occupies a unique position as both senior urban design officer at Croydon Council and a founder of AOC, was strongly inuenced by his schoolboy trip to the exhibition: 'People making proposals for the place where I grew up - which you think nobody really cares about - got me interested in making Croydon a better place.'
Lacovara views his twin roles not as a conict but as a convergence of interests. In 2003, the newly-formed AOC produced Roof Divercity for an exhibition called the Future of Croydon, organised by the council's director of planning.
'By that point I was already working at Croydon Council, ' says Lacovara, 'which had already begun conversations about green roofs - but the image started to have a direct inuence on the development of the unitary development plan (UDP).'
The Croydon Town Centre Area Action Plan currently being prepared by the planners will provide a spatial strategy for the city's roofscape that will consider how conceptual ambitions can be delivered.
Lacovara believes that the creation of aspiration is a key tool in implementing the vision: 'Because people like Nigel Coates have made proposals for the roofs there is already a culture which exists, so it won't be seen like too much of a radical proposition.'
At the moment the UDP only 'encourages' rather than requires the use of green and brown roofs. There are two types of green roof: extensive (which are lightweight, often proprietary systems) and intensive (which are inhabitable and therefore require a greater depth of soil and structure).
Brown roofs are created from rubble (perhaps sourced from the site) on which local pollens self-propagate.
The arguments for these roofs - that they look attractive from above, add insulation, cool the building down in summer, reduce rainwater runoff and improve local air quality - have been made successfully by the planners to a number of developers.
A nine-storey residential scheme with green sedum roofs was recently completed by KingsOak Homes, a company which has been taken over by Barratt Homes. Could it signify a sea-change that the nation's largest house-builder has actually embraced the green-roofing agenda?