The Maltese climate can extreme: debilitating heat in summer on one hand and localised flooding after mild rainfall in winter on the other. The LifeMedGreenRoof project, managed by Mr Antoine Gatt (Faculty for the Built Environment, University of Malta), investigated a possible solution to both problems.
Their research suggests that in summer, having a green roof can keep the roof slab’s temperature at a stable 27°C, as opposed to varying from 25°C to over 60°C over a daily cycle, keeping homes cooler and reducing maintenance costs in the long run. In winter, falling rain water is absorbed by the green roof, helping with flood mitigation provided nationwide implementation.
Green roof technology is already used successfully in northern Europe but there were doubts about whether it could be applied in Malta. These doubts are precisely what Gatt and his colleagues set out to dispel in a baseline study spanning four years. This meant finding viable growing medium materials as well as hardy plants that would withstand the harsh conditions of a Maltese roof.
For the plants, they took inspiration from garrigue habitats characterised by little shelter, intense sunlight, high temperatures, and lots of wind. They managed to successfully grow a number of local species, including some rare plants like the Maltese Pyramidal Orchid. Gatt and colleagues also identified the most effective growing medium to be a mixture of pumice, lapillus, coconut fibres and biochar.
At this point, a policy proposal has been submitted based on the findings of the project, outlining a set of incentives and regulations that are needed for effective implementation across the island. These include rebates for the building of green roofs, and taxation on soil sealing. Feedback from the the government, MEPA, and the ERA have been positive and we look forward to more developments.
For more read the in-depth feature in Think magazine: www.um.edu.mt/think/bloomin-roofs-go-green.