Green roofs are becoming increasingly popular in urban areas throughout the world. Many scientists have been speaking out about the benefits that green roofs have on the environment. Not only do green roofs recover lost green spaces, but they also provide ecological, environmental, and economic advantages. The truth is green roofs have been mitigating many of the problems that cities are facing due to urbanization.
According to a study of the mitigation of climate change through the implementation of green roofs conducted by the University of Technology in Malaysia, it is strongly believed that green roofs could be the answer to the ever-evolving problem of climate change. The study also stated that by the year 2050, the world’s population would see figures surpassing 9.6 billion. Perhaps most astonishingly, the research suggests that 66 percent of the world’s population is expected to be living in urban areas. These figures are significant as rapid urbanization is likely to exasperate the environmental issues the world is currently experiencing.
The reality is rapid urbanization has already begun and is likely to continue exponentially over the coming years as more of the global population moves away from rural areas and into the cities. As this phenomenon gains traction, cities are being met with a surge in environmental problems. However, there is a rising light at the end of the tunnel. Green roofs in urban areas have slowly begun to make a difference and have shown promising results from their long term application in many cities across the world.
Another study that focused on green roofs as urban ecosystems published in the bioscience journal highlighted three main areas that green roofs benefited in urban landscapes. Namely, the study specified how green roof ecosystems are providing solutions to stormwater management, the heat emitted from buildings, and urban heat islands.
Many urban areas have an incredibly high density of buildings with miles of nonporous surfaces that negatively contribute to heavy rainwater runoff. The runoff leads to city stormwater management facilities being unable to cope with the influx. When this happens, the sewerage overflow often finds its way into lakes and rivers and pollutes natural habitats and local wildlife. In addition to this, the urban runoff causes erosion, sedimentation, and in some cases, flooding.
Green roofs provide the ideal solution to this problem as they prevent urban runoff before it has a chance to leave the surfaces of the buildings. The implementation of green roofs building runoff in urban areas is reduced as the ecosystem stores water during rainfall events. They also allow the water to return precipitation to the atmosphere through the evapotranspiration process.
Besides stormwater management, green roofs are excellent for heat dissipation for buildings, particularly in the hot summer months. Green roofs lower the quantifiable amount of heat transferred through the top of a building during hot weather, which reduces the energy demands of the building’s cooling system. According to the bioscience article, research conducted in Japan demonstrated how green roofs reduced heat fluctuations in buildings by nearly 50 percent per year. Green roofs achieve this by lowering heat flux through building roofs by promoting evapotranspiration, providing insulation and thermal mass, and shading the roof with vegetation.
The research team involved in the article pointed out that one of the most significant ways green roofs are helping urban environments is through the mitigation of urban heat islands. These islands have become increasingly problematic in many cities throughout the world. The problem with urban environments is that the naturally occurring vegetation is often replaced with asphalt and dark nonporous surfaces that retain heat. By retaining heat, urban environments are much hotter than rural and suburban areas as the heat is trapped within a metropolitan area. Some of this phenomenon’s effects are mitigated through green roofs as the vegetation allows an urban area to cool and temperatures to lower.
Green roofs are quickly becoming a necessity, and the numerous studies and research analysis’ surrounding the positive effects they have on the environment. This demonstrates that the implementation of green roofs is mitigating urban environmental problems. However, further study is required to establish the economic and environmental costs and the other benefits green roofs could have on the environment.
WORDS: Jason Collins