Research and Describe Green Roof Benefits in Urban Areas (Research Paper Sample)

          Green Roof Benefits Name: Institution:   Introduction Green roofs feature vegetation on the rooftops of buildings, and they have become a primary element in most urban areas. The increase in the number of buildings in the majority of the large cities has altered the urban ecosystem, resulting in environmental problems. The construction of buildings also degrades the natural environment, and this changes the ecosystem of an area. However, green buildings are sustainable, and they have a variety of economic, environmental, and social benefits. This review will focus on the environmental aspect of green roofs’ sustainability, but it will also address some of the social and economic benefits of designing rooftops with vegetation cover. Most of the sources used in this review conclude that the technology employed in green roofs creates an ecosystem with properties that are similar to the vegetation at the ground level. Green roofs are common in many parts of the world, and their popularity is also increasing due to their environmental benefits. Berardi et al. (2014) evaluated different types of green roofs and their significance in environmental sustainability.  The construction of buildings and their maintenance consumes high amounts of energy, and a significant level of greenhouse gas emissions comes from the structures as seen in the study by Berardi et al. (2014). The manner in which buildings change the ecosystem of urban areas indicates that environmental issues are likely to arise due to the presence of many structures, and this illustrates the importance of green roofs. Although the design of green roofs is a modern concept, its variations have always been used by different societies for centuries, as Berardi et al. (2014) explain. For instance, roof gardens were a common feature of the Roman architecture, and Northern European nations used them to enhance a building’s thermal insulation. Most urbanized areas do not have green spaces, and green roofs offer a solution to such problems. Berardi et al. (2014) classify green roofs into two groups, where a significant amount of soil is necessary for an intensive green roof while less medium is required in an extensive living roof. Green roofs have various environmental benefits, and it is important to consider some of the ways in which urban greenery improves the ecosystem. Madumadhi, Radhakrishnan, and Shandhipriya assessed the indoor thermal performance of Indian residential structures that had green roofs, with the area of study having a warm and humid climate. When comparing white reflective and green roofs, Madhumadhi, Radhakrishnana, and Shandhipriya, (2016) found that the latter has various benefits such as insulation, shading, and evapotranspiration, and this improves a roofing system’s thermal performance. The vegetation on a green cover provides shade to the exposed surface, hence reducing its temperature. These environmental sustainability aspects evidently improve the comfort of the internal spaces in buildings located in areas with extreme temperatures.   Madhumadhi, Radhakrishnana, and Shandhipriya (2016) evaluated the energy efficiency and thermal performance of green roofs in India, and whether they have had an impact on the urban ecosystem. The design of a building’s roof determines the rate at which it absorbs sunlight. When a roof is flat and made up of concrete, it has the potential of taking in most of the incident sunlight, and this heat is transmitted to the building’s interior. Besides, roofs that are artificially designed to reflect sunlight lose their reflectivity with time due to their exposure to the elements, and this reduces a building’s energy efficiency. Getter and Rowe (2006) also suggested that the insulation that green roofs provide on the surface mitigates the urban heat island effect, which saves large amounts of power.  The vegetation on green roofs shades the surface exposed to the sun, hence lowering the temperature that the concrete absorbs. Liu and Baskaran (2003) also suggested that this is true. In the study where the two researchers observed an experimental Field Roof Facility, they found that the temperature fluctuations on the membrane reduced as a result of the presence of vegetation. Even if one artificially designs a building’s rooftop to reflect sunlight without the presence of vegetation, it might not be efficient. The study by Liu and Baskaran indicates that the surface temperature of an exposed membrane rises due to the absorbed radiation, and it significantly drops after re-radiation. With time, the efficiency of such a roof reduces because of the temperature fluctuations. Although the study conducted by Madumadhi, Radhakrishnan, and Shandhipriya suggested that a green roof lowers the temperature absorbed by a concrete rooftop, it would be important to understand how this occurs. After assessing the energy efficiency and thermal performance of green roofs in the experimental facility, Liu and Baskaran (2003) found that vegetation decreases heat flow through insulation, evaporative cooling, and insulation. The membrane of an exposed roof experiences positive heat flow due to the absorption of solar radiation and re-radiation during the day and night respectively. The green roof abates the movement of heat between a building and the environment, and this regulates the room temperature when it is hot. Oberndorfer et al. (2007) found that the longevity of the membrane in an exposed roof deteriorates because it becomes brittle due to its subjection to ultraviolet light. Urban environments have buildings and road surfaces that are impervious and dark, creating the heat island effect, as Oberndorfer et al. postulate. The conditions brought about by the lack of vegetation result in an increase in the temperatures, especially during the night. Getter and Rowe (2006) found that green roofs alleviate the effects of the urban heat island because of the shade and insulation that they provide. According to these researchers, the indoor temperatures of buildings that have green roofs are lower by 3^oC to 4^oC. Oberndorfer et al. (2007) theorize that green roofs alleviate the increase in temperatures at night as a result of the evapotranspiration from the vegetation cover. Most urban areas have surfaces that are impervious, and this increases water runoff as a consequence of the decreased infiltration. As a result, various environmental issues such as water pollution in the urban areas arise when the storm water runoff increases. Li and Yeung (2014) evaluated different types of green roofs to determine their performance in a maritime monsoon climate zone. The drainage layer of a green roof affects the runoff dynamics and water retention capacity. Li and Yeung found that the vegetated rooftops retain 40% to 60% of the rainwater, and when the rain was lower than 10mm, there was no runoff since the roof would keep all the water. However, the type of medium used in making the green roof determines the amount of water it retains. In the findings that Oberndorfer et al. (2007) present, green roofs whose substrate was more than 10 cm keep 66% to 69% of water.  Wachtel (2007) evaluated some of the characteristics of a green roof that enable it to retain water and reduce surface runoff. The study found that the feature that increases the effectiveness of green roofs in the management of stormwater is their ability to hold and release water at a particular rate. Besides, the medium used to make a green roof enables it to support vegetation cover, and the resulting surface does not leak as much as the conventional rooftops. Wachtel also suggests that the ability of a green roof to retain water during heavy rainfall modulates the intensity of runoff, and this conserves the water from precipitation. Gibbs et al. (2006) similarly argue that the absence of a green roof results in an increase in the quantity of water that enters storm drains, resulting in water pollution and a surge in the runoff. In their study evaluating the impact of different fertilizer treatments and growing mediums on the green roof systems, Gibbs et al. (2006) found that the planting the right species and dressing them with fertilizer results in an optimal reduction of storm water runoff from a building with a green roof. Whittinghill et al. (2015) postulate that factors such as microclimatic conditions and the plants’ water use efficiency influence the stormwater retention capacity. Stormwater management facilities in many urban areas might struggle to deal with the heavy runoff that results from the nonporous surfaces of buildings. However, Oberndorfer et al. (2007) present findings indicating that implementing the conventional techniques of managing storm water in dense urban areas is challenging. The high level of pollutants in urban areas also has a detrimental effect on the ecosystem, and Oberndorfer et al. theorize that this is another reason as to why green roofs are important. The retention of water by green roofs ensures that there is a delay in the runoff and that precipitation returns to the atmosphere through evapotranspiration. In the review where Getter and Rowe (2006) present the sustainability dimensions of green roofs, they found that runoff delays occur since the media does not become saturated immediately after it starts raining. The conservation of the biodiversity is another aspect that makes green roofs suitable especially in urban areas, as Williams, Lundholm, and McIvor (2014) theorize in their study. While assessing the biodiversity conservation benefits of green roofs from different projects, the three researchers found that vegetated rooftops provide habitats for various species of animals, and they help in the achievement of urban biodiversity conservation goals. However, while a high numb...