This green screen trial forms the first experimental section of this CASE-funded PhD project and is part of a wider University of Glasgow initiative called the 'Smart Campus'. Air pollution and flooding are major global urban challenges. This trial, which is the first of its kind in Scotland, is designed to evaluate how well green screens compare to traditional construction hoarding to trap air pollutants and slow down rainfall runoff. It is funded by the Engineering and Physical Sciences Research Council with support from Arup, Mobilane and Multiplex.
Why do this? Why Glasgow?
A report by the Royal College of Physicians in 2017 found that 44 out of 51 UK cities were above WHO guidelines for particulate matter (PM). Glasgow registered as the highest in the UK for fine particulates (PM2.5). Recent studies have suggested that these particles not only do damage to the respiratory system, but every organ in the human body.
Meanwhile, changing weather patterns brought about by climate change and an increase in impervious surfaces caused by rapid urbanisation has increased the risk of both fluvial and surface water flooding. Surface flood risk maps produced by the Scottish Environment Protection Agency (SEPA) show that surface water flood risk is prevalent across the extent of Glasgow.
What are Green Screens?
Green screens are comprised of a planter and a mesh upon which climber vegetation grows, thus forming a screen which can be freestanding, attached to buildings or used in the place of traditional fencing or construction hoarding. The structure of green screens makes them easier to install and maintain than other urban green infrastructure solutions such as living walls and street trees, meaning they are relatively inexpensive in comparison. Along with policy, local-scale interventions such as this could be an effective tool in managing air quality and pluvial flood risk associated with climate change mitigation and adaptation.
Preliminary results have shown that PM counts are lower in front of green screens compared to the control screens (plywood construction hoardings). Whilst this effect varies, the largest reductions have been measured during monitoring periods with the highest particle counts and thus their effectiveness as buffers during high pollution events.
Similar results can be seen for rainfall runoff, with the highest reductions are posted during the highest rainfall events.
A further trial site has recently (July 2019) been set up at the Atlantic Square development site in Glasgow city centre. This trial, which is supported by Bam Construction, Arup and Mobilane, will use Scanning Electron Microscopy (SEM) in conjunction with real-time particle count data to assess the particle capture performance of green screens, each comprised of a different species of vegetation with different microcharacteristics: Helix hedera (Common Ivy), Euonymus fortunei (Dart’s Blanket) and Carpinus betulus (hornbeam). The characteristics of each species that contribute the most to particle capture will be assessed and a matrix of suitability built in order to aid in the selection of species for future projects.