GREEN & BLUE INFRASTRUCTURE
Geogreen ’ s work encompassed all aspects of the installation for the 11 separate ribbon areas and the judges recognised the contribution the roof design makes to enhancing the biodiversity of the site , providing a significant area of native grassland for local insect and bird species . The green roof also plays an important function as part of the development ’ s overall sustainable drainage strategy , absorbing rainwater and minimising surface water run-off , with as much as 95 % of rainfall naturally absorbed into the vegetated surface . The vegetation , growing media and filtration fabrics within the green roof construction also helps filter dust and pollution from the air and rainfall , thus reducing the amount of chemicals and pollutants that reach the surrounding river networks .
Incorporating a green roof also significantly reduces the carbon emissions from the amenity building by allowing the heat generated to be drawn into the cool roof construction and then dissipated more readily to the environment than with traditional roof constructions . In summer months this reduces the air conditioning requirement whilst providing a level of insulation against heat loss in winter . The green roof is also very good at reducing low frequency sounds from the nearby motorway , with the extensive build up insulating up to 40dB .
The green roof build-up The underlying structure for the extensive wildflower meadow roof is constructed from a series of interconnected glulam beams , manufactured by fixing timber boards together and forming them into the curved sections . The beams are then spanned using structural deck cassette panels of 20mm thick in 3 layers .
A Kemperol cold applied liquid membrane is applied to the timber panels to give a fully adhered , monolithic waterproofing to encapsulate the surface and preserve the deck from weathering . A 180 mm thick XPS insulation board plus a water control layer , is installed directly onto the waterproofing to complete the inverted warm roof build up .
For the base of the living roof structure , a combination of 20mm and 40mm deep Roofdrain geocomposite reservoir boards were used . The main core of the reservoir board features a grid of storage cups to attenuate rainwater and provide irrigation for planting during dry spells . Small holes in-between the cuspates allow excess rainwater to channel to the nearest drainage outlets , preventing the root growing media from becoming waterlogged and stopping water pressure buildup on the water control layer .
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