HORIZON 2020: Soil moisture supply and green roof plant requirements incorporating drainage and energy functions

Green roofs can improve local biodiversity by bringing productive habitat into urban spaces. In temperate climates, such as the UK and Northern Spain, rainfall is distributed throughout the year, yet may still be insufficient to supply water for green roof plants all year round. Sub-base modifications can overcome this limitation by adding storage capacity and facilitating contact between reservoir and soil. To increase the attractiveness of GBGR (green and blue-green roofs), both in sustainability and cost, they should be deployed on the maximum number of sites as possible, including sloping roofs, using recycled components for sub-base and potentially using geothermal heat recovery at the base of these installations. We will therefore use the green roof lab (BLOCK, Scientific platform for urban runoff tests), at University of Coruña, Spain, to grow habitat enhancing plants in a proprietary green roof substrate, on a variety of roof slopes with subbase replacement voids, wicking materials and recycled content. Soil moisture values through roof profiles will be correlated with plant health, growth and diversity, to identify key
moisture values that promote a viable sward cover, flowering and seeding for long-term communities. Furthermore, the viability of installing ground source heat pump collection loops into roofs of different composition will be evaluated, including with slope, varying water depth and material for subbase. We aim to update the specification of green roof options with the planning and construction authorities, to open new opportunities for GBGR deployment, new markets and more urban green infrastructure.