Wimbledon Grounds, Galliard Homes’ new residential development of 583 apartments is ground-breaking for its large-scale use of the triumvirate of sustainable roofing technologies, blue, green and solar.
- One of London’s largest blue roofing projects to date.
- Every roof in the development is blue and green (wildflower roofs)
- Half of the roofs are also solar
- This proves that blue roofing works at scale for residential developments
Video: Behind the scenes one of the London’s largest blue roofing projects.
- All 26 roofs and four landscaped podiums are blue roofs, or sustainable urban drainage systems (SuDS).
- With a total area of 14,000 square metres, this is one of the largest blue roofing projects ever seen in London.
- All 26 blue roofs are also green roofs have living roofs, installed above the blue roofs, which are seeded with a mix of native wildflowers, sedum and grasses.
- On 15 of these blue-green roofs, Galliard has installed farms of solar panels to generate electricity for the complex.
The Wimbledon Grounds development
Located off Plough Lane in Merton, Wimbledon Grounds is a 51,000 square metre mixed-use regeneration project which provides a new purpose-built stadium for AFC Wimbledon, leisure and retail facilities and 600 new homes offered for private sale by Galliard Homes, a leading London residential developer, and shared ownership housing, provided by Catalyst, one of London’s largest housing associations.
The first of the three apartment buildings, called Stadia Three, is now complete, with new residents currently moving into their homes. Stadia Two, also known as The SW17CH, and Stadia One will be completed and ready for residents to move in later in 2021.
Blue roofs at Wimbledon Grounds
Every roof and podium in Wimbledon Grounds residential complex is a ‘blue’ roof, which incorporates a sustainable drainage system [SuDS], to prevent flooding and pollution. The total area of blue roofing/podiums covers over 14,000 square metres, which makes it one of the largest if not the largest blue roofing projects, commercial or residential, ever seen in London.
There are four large blue podiums – a podium is a landscaped garden / outdoor community area situated above ground level, perhaps over a carpark or entrance hall.
There are 26 blue roofs. Each of the roofs has a green roof, installed above the blue roof. These are seeded with a biodiverse mix of native wildflowers, sedum and grasses. 15 of these blue-green roofs also house farms of solar panels to generate electricity for the complex.
The installation of the blue roofs and podiums at Plough lane started in April 2020. The completion of roofs and podiums in Stadia 1, the largest, is expected in late 2021.
- Pritchard & Pritchard – The installer of all the blue roof and green roof systems.
- Kingsley Roofing (London) Ltd – Lead roofing contractor, and installer of the waterproofing.
- ZinCo Green Roof Systems – Manufacturer/supplier of the blue and green roof technologies.
- Turkington Martin – Landscape architect and designer
How the blue roofs at Wimbledon Grounds work
The Blue roofs capture the storm water that falls on roofs and landscaping and hold it within a thin reservoir built on top of the roof or podium structure, then release it slowly into urban drainage systems to prevent flooding and pollution.
The Wimbledon Grounds blue roofing system works on a cascade system. According to details shared by ZinCo Green Roof Systems, each roof stores up to 55 litres/metre2 of storm water in a reservoir. This is gradually released by a flow controller over 12-24 hours to the larger reservoir in the 4 podiums, which holds 60l/m2 of storm water, from where it is slowly released into the urban drainage system.
This capacity at Wimbledon Grounds allows the blue roof reservoirs to store 40% more rain water than is calculated to fall in the ‘one in 100 year’ storm.
Why blue roofs are important
London’s Victorian sewers are regularly overwhelmed by storm water as it runs-off unchecked from roofs and paved areas, causing local flooding and pollution when sewage flows through combined sewer overflows into the Thames and its tributaries.
Developers must take action to reduce the rate that water drains from properties. Government guidance says that from 2015, local planning decisions for development of 10 dwellings or more must ensure that sustainable drainage systems for the management of run-off are put in place. The SuDS guidance for Merton, the London borough where Wimbledon Grounds is located, states that “discharge rates for new developments should be restricted to Greenfield runoff rates” (meaning the same run-off as if it was a field). Other London boroughs set similar expectations, see London Sustainable Drainage Proforma.
There are alternative sustainable drainage strategies (SuDS) such as subterranean attenuation tanks or ponds for storm water control, but with in-city developments, where space is at a premium and excavation can be costly and may not be permitted, thus making retaining storm water at roof level the preferable option.