Finnish Museum of Natural History
Green Roof Seminar 12.10.2011 Helsinki
Background & Main questions
Green roofs could essentially improve the living environment in cities, as they can easily be anticipated to produce regulating, provisioning and cultural ecosystem services such as improvement of microclimate, balancing of hydrological cycle, CO2 sequestration, habitat provision, active cooling/insulation, dust filtering, opportunities for gardening and local food production in kitchen gardens, aesthetic improvement, additional green space and recreational services and educational services via e.g. nature paths on the roofs. The roof area increases dramatically with urban development.
We will study the quantity and quality of ecosystem services that could be provided by green roofs. We will focus on the regulating and cultural services at the first phase of our project, while provisioning services would be studied later.
We will study
Firstly, storm water retention is a possibly important part of balancing the hydrological cycle in cities where the great proportion of impermeable manmade surfaces allows for serious run-off incidents and flooding during heavy rain. This problem is pressing as it is broadcasted that due to climate change, heavy showers will become increasingly frequent. About half of the yearly rain water raining on roofs can be retained in green roofs if the roof's soil structure is about 50 mm thick (Veg Tech Ab). Internationally, one of the drivers of city planning at the moment is storm water management.
Secondly, habitat creation is another issue that is pressing during this era of global change. As certain kinds of habitats are disappearing due to land use and climate change, or their combined effects, new kinds of habitats have to be investigated in order to save species from extinction. One option would be the green roofs that could be taken as parallel situations to some natural habitats. This habitat approach has several benefits as compared to mass production of any species that could survive on the roofs. Green roofs could offer compensatory habitats for declining species and could be explicitly created to maintain desired services, for example pollination via supporting pollinators. Furthermore, mass production and use of unstudied species means a great risk of invasion (Heywood 2010), therefore it is imperative to carefully study the concepts, species and communities that will be used in the mass production of green roofs.
Thirdly, the aesthetic services provided by the green roofs may include several perspectives raising several benefits. This so called “top landscape” can be viewed from the distance from the airplane, the “fifth facade” from buildings, and oblique roofs also from the ground level. In order to improve sustainability, our cities should be attractive for both living and spending free time, to avoid suburban sprawl and excessive travelling during weekends and holidays away from the cities.
Fourthly, history of green roofs should be studied as it might provide unpredictable insight and perspective into the reasons, uses, benefits, functions, problems and structural solutions concerning them.
Finally, we will study the current attitudes and worries of planners and other authorities, decision makers and citizens in order to develop ways of solving mental obstacles that currently hinder the general use of green roofs in Finland. This will facilitate making green roofs a part of city planning and structure and a widely used solution.
Veg Tech Ab. Vegetationsteknik. Systemlösningar och produkter.