Residents living in a social housing block in the heart of London's Soho District can now look down on two living green roofs.

Kemp House, a 1960s building, is owned and managed by CityWest Homes and sits beside the hustle and bustle of Berwick Street Market. It consists of two storey buildings with a large tower block perched in the middle, now dividing two biodiverse nature roof areas of 330m2.

Green roofs have a positive impact on water management and surface run off, the heating and cooling of buildings and in supporting biodiversity. Their deployment is increasing rapidly, however there are still only a few to be seen in most urban roofscapes. The value of living roofs both for the environment and the people who use the buildings are significant.

Designed for biodiversity the first phase of greening the flat roofs of Kemp House was completed in October 2010. This nature roof installation serve purposes such as cooling the office space below and storing rain water. However, the main reason for the green roof and how it has been designed is to meet the City of Westminster and London’s Biodiversity Action Plan targets, creating habitat for the rare Black Redstart and invertebrate species - three Redstarts were spotted the day after installation.

The green roof consists of a sedum blanket on top of a substrate layer in line with the recently developed Green Roof Code (GRO).

The designers, the Green Roof Consultancy (GRC), chose a number of native wildflower plugs, spring bulbs and other features such as logs to ensure that the roof was a diverse environment for both rare invertebrates and birds. Over time this roof should develop into an important patch of wildspace in the heart of the capital.

When planning green roofs for refurbished buildings such as Kemp House, unique design approaches have to be taken to follow weight constrictions.

‘It took a lot of work to reach the implementation of the project - checking with the planning department, raising funds, agreeing the specification and checking the load bearing capability of the roof,’ explained Liz Waine of CityWest Homes.

Due to insufficient financial resources, CityWest Homes’ plans to green the other side of the split roof on the council building had to be put on hold last year. After pushing for access to this larger part of the roof for many years, the Kemp House resident association was even more keen to put their vision into practice when the possibility of having access to a roof garden arose. Resident David Barrett and his neighbours where delighted when funding was granted by the Greater London Authority (GLA).

In 1992, the Government signed the Rio Convention and committed to halting biodiversity loss through the UK Biodiversity Action Plan. Matthew Thomas, part of the urban greening sector within the GLA, explained: ‘There are several reasons why the GLA are fully supportive of the Kemp House green roof project. Firstly, the GLA wants to reduce surface water flooding in London. The Drain London project, of which the GLA is a key partner, aims to better understand and then reduce the likelihood and severity of such flooding in London now and in the future. Green roofs will help to achieve this.

‘Secondly, the Mayor has a target to increase existing green cover in central London by at least 5% by 2030. In the most densely developed areas of London, it is likely that much of this target will be met through the installation of new and retrofitted green roofs.

‘We hope that the installation of such an exemplar green roof on Kemp House will help encourage other building owners to realise the multiple benefits of green roofs.’

With the support of the GLA the other side could eventually be greened this summer. For accessibility to the roof garden the perimeter railing now needs upgrading to ensure health and safety for the tenants of Kemp House.

Kemp House is just one example of how green roofs will improve urban environments not only with addressing stormwater, urban heat island effect and air pollution, but also making a very significant contribution to wildlife in the capital as well as serving as aesthetic component of sustainable building.

Miriam Zoller works for Optigreen, member of the Green Roof Organisation (GRO).