Green space

The value of green spaces to people living and working in towns and cities has increasingly been recognised by Government. The work of the Urban Green Spaces Taskforce (Green Spaces, Better Places, 2002) demonstrated the various benefits that green space provide, such as ecological function, visually softening the built environment, supporting biodiversity, aiding people’s mental and physical health, and providing a communal focus and sense of place. Government has subsequently launched a raft of new policies, initiatives and funding to promote the good design and management of green spaces.

An early growth stage Green Roof still provides an escape

English Nature has published research that suggests that an accessible natural green space should be no more than 300 metres from where anyone lives in order to meet people’s needs for contact with nature. Evidence suggests that regular direct contact with natural green space (and elements of the natural world such as birdsong and seasonal colour change) is good for people’s health (see below).

There is a need for increased densities in urban residential development (>30 dwellings per hectare), which could result in terrestrial green space being reduced or lost. In the urban core the provision of green space is usually already severely limited, partly through historical circumstances, and more recently very high land values; this makes the creation of new green space both important and difficult. Given the nature and pressures of urban regeneration, the creation of new spaces has to meet a number of interests; these generally result in highly formal spaces with little ecological benefit. Creating low-maintenance, terrestrial, naturalistic green spaces in the urban core is not popular; green roofs may provide one solution.

Green roofs can provide both visually accessible and physically accessible green space. Roofs are largely visually ‘dead’ and unappealing and their appearance to those overlooking them can be softened by vegetation. There are instances where the sole justification of a green roof installation is for visual aesthetics. Areas of green roofs can also provide accessible space for people to enjoy, and some can be landscaped to extend existing green space, for example at Canary Wharf station on the Isle of Dogs, London.

Roof gardens and terraces are options for smaller buildings and have some historical ancestry. The Berlin roof gardens of the 19th century, have been adopted on similar housing blocks in Britain (for example, Peabody Trust’s Balderton Flats in Mayfair) and were one of the inspirations for the first modern green roof in the UK, at Derry & Toms, Kensington, 1938, which still serves as a garden, albeit with limited public access. Roof gardens are increasingly being proposed for new office and housing developments.

Large areas of accessible green roof space can be created if the building is large enough, for example above Cannon Street Station in the City of London [intensive], and at Chicago City Hall [extensive]. More ‘extreme’ examples include a golf course on a roof in the USA.

The key issues that need to be considered in providing accessible open space are health & safety (the need for a external rail or fence), over-looking neighbouring properties (a material planning consideration), access to and from the roof-space, load-bearing (if the proposed numbers of people are to be more than a few), and management. The existence of green roofs that provide this function suggest that these issues can usually be easily addressed.