Eco Green Roofs worked alongside Sir Robert Mcalpine and Allard construction to create a biodiverse green roof habitat on 5 and 6 St James’ square, Piccadilly London.
Eco Green roofs were instructed after the design stages of the project, which meant that the design scheme for the required green roof had to be modified and enhanced in order to maintain the high BREEAM ratings needed for the building.
The green roof was specified by local ecologists to support 38 species of native wildflowers, offering a variety of ecological values. Even at ground level this amount of species is very difficult to maintain; due to competitiveness of certain plant species and due to the fact that many wildflowers are annuals, meaning that they would need to be reseeded every year. This, combined with the environmental conditions found at roof level, made the task of creating a roof with so many species a real challenge. Therefore we used our specialist scientific knowledge about green roof substrates to create a range of microhabitats, using different types of growing media and creating topography (undulations and mounds) using various substrate depths. This approach created shaded areas for particular wildflower species as well as areas that would hold more water on the living roof. Shallower and more nutrient-poor areas were also designed to support less vegetation and provide certain invertebrate species with bare ground, ideal for their ecological needs. The wildflowers were distributed randomly and planted at around 25 plug plants per meter square. Several substrate types were used across the roof where depth ranged from 80mm-150mm.
In addition, we added sand piles to the green roofs for burrowing bees, log piles for beetles and boulders for rare invertebrates including some spider species. We also erected bird boxes and provided a source of water for the green roof fauna (in particular for birds to drink and bath).
A carefully constructed green roof maintenance plan was set in place to ensure the level of biodiversity was sustained. Maintenance is a requirement on any living roof but the level will depend on the green roof type. In this project, the BREEAM rating was so high that a bespoke specification was created. It included the possibility of removing all dominating plant species (that may reduce overall biodiversity) to restore the desired plant species originally specified by the consultant ecologists.