Introduction
The pollution in the highly urbanized areas allows the phenomenon called ‘greenhouse effect’ wherein the heat from the Sun is trapped on the land causing tremendous amounts of heat and leads to numerous issues such as the rise of temperature, drought, the melting of icebergs, and high evaporation of water. Unfortunately, the cities contribute to this effect, the use products containing CFC’s and the pollution of too much carbon dioxide in the atmosphere leads to the destruction of the ozone layers. With the destruction of the atmospheric barrier, the excessive radiation from the sun cannot be prevented. In this respect, numerous styles emerged in order to shift the trend of heat factor amongst urban areas. One of the innovations that emerged in commercial and residential buildings is the ‘green roof styles’ which uses live plants to regulate the flow of heat and increase the production of oxygen.
Goals and Objectives
The purpose of this paper is to provide an assessment regarding the use of green roofs in large scale building structure. In fact, the main goal of the construction of the green roof is to dissipate the heat and provide a cooler temperature in the suburbs and highly urbanized areas since these are the places with high concentration of heat allocation due to the pollution and the lack of greeneries in these areas. This study presents a critique; a pros and cons of constructing green roofs on the top of the buildings as an imitation of an actual forest. One of the largest realty development in California, the Proto Homes Company are known for their modern and minimalistic design combination, housing styles which can adapt to the high paced cosmopolitan living in the urban areas. In this respect, the Sunlight Residence with its innovative modern design will be assessed whether it can sustain having green roof style.
Background and Significance
Among the emerging styles in building construction is the ‘Green Roof” design wherein the building utilizes natural mediums in reducing heat, improve the air quality, create an artificial habitat for the animals such as birds, as well as the utilization of recycled materials for the construction of the mini gardens on top of the roof. Additionally, this method also contributes to the increase of oxygen, a gas essential for both humans and animals in order to live. Plants emit oxygen in a process called ‘Oxygen and Carbon Dioxide Cycle’ while the animals and humans exhale the needed carbon dioxide by the plants in order to make food. Furthermore, plants also utilize bacteria found on the soil during the photosynthesis period; thus, creating this mini rooftop gardens will contribute to the increase of beneficial bacteria for the plants. Based on the study of Gaffin et al. of the Columbia University, the green roofs are effective in reducing the heat index compared to the traditional roofs. For instance, a black roof is found to absorb all heat due to its color; black absorbs all colors in the surroundings, making it more hotter compared to the colors white which is found to absorb only quite a small fraction of heat while the green roof is found to have the lowest capacity of retaining heat. (8-10). Other independent scholastic studies also found out that green roofs in large scale building construction have a drastic effect in regulating the temperature in the areas where the buildings are located. (Mukherjee et al., “Thermal Performance of Green Roofs,” 1; Choi et al., 4, Mukherjee et al., “A Parametric Study of the Thermal Performance,” 1-2; Anwar et al., 127-128; Sproul et al., 20).
Methodologies
A review of published scientific literature provided ample information on why Proto Homes should also adopt the ‘green roof method’ in residential construction. Initially, the Proto Homes Sunlight Residential Series utilizes the exterior space outside the house in order to construct a garden (see figs. 1-3) that will regulate the amount of heat in the community in addition to providing aesthetic patch of lush greenery in the urbanized areas. However, this also means that there should be a wider space in order to build this garden, but one of the rising issues from the metropolis is the lack of space for housing construction. Therefore, suburbs and other places located near the urban areas are also prone to this problem. In this respect, one of the recommendations for effective heat dissipation is the construction of green roofs on top of the roof of each house to save the ground space.
Results and Discussions
Numerous studies from different scholars approved of the construction of green roofs (fig. 4) in lieu of the traditional roofs. The main differences of the green roofs versus the normal roof structures is the fact that since it is all covered with plants, the heat factor does not go beyond the scale, but rather the plants acts up like a shield that removes away the heat absorbed by the structure. In this case, the atmosphere near the area covered with green roof has a relatively colder temperature compared to the ones without any green roof structures. Meanwhile, during nighttime, the green roof is also essential in protecting from heat loss especially in winter seasons. The artificial land within the perimeter enclosure of the roof structure remains warm because some of the heat stored by the plants and the soil is still trapped within the boundaries; therefore, the structure with green roof has the ability to retain more heat compared to the ordinary roof designs. (Sailor, Elley, and Gibson, 19). Additionally, according to the Green Roofs for Healthy Cities, a non-profit organization, there are many benefits in constructing green roofs instead of the traditional one. First is the creation of green environment in cities, which is essential in reducing pollution. Second, green roofs also serve as environments that use recycled materials, which can contribute to the decrease in waste amongst cities. Third, these artificial green structures are also proven to have effective storm water management wherein the trees and plants retain the water from rainfall and can act as temperature moderator. “With green roofs, water is stored by the substrate and then taken up by the plants from where it is returned to the atmosphere through transpiration and evaporation.” (Green Roofs for Healthy Cities, “Green Roof Benefits”). Further reduction of carbon dioxide is one of the significant contributions of the green roofs to the cities since plants use these gases to manufacture their own food while the extreme sunlight is also beneficial in the photosynthesis phase. Lastly, the dependence on the landscaping design, these green roofs can be converted as money makers since these not only provide additional habitat for animals but also the spaces on them can be converted into living spaces where people can interact with each other especially on public buildings such as those people who crave to have a solitude with nature. The green roof structures are mostly suitable in areas such as those located near or in the regions of Inland Desert (Desert Arid), Central Region (Cold/Warm, Desert/Mediterranean Climate), and the North Central Region (Warm/Temperate Mediterranean Climate). According to the results obtained from the study, the choice of the roof largely depends on the energy budget and the urban climatic system. One of the main factors considered during the summer is that the conventional roof heats up significantly during the day, but at the same time cools down very quickly in the nighttime. The White roof on the contrary, does not heat up as much during the day, but still cools down in the nighttime. Considering this, the green roof seems to be the optimal choice with its ability not to heat up to mc during the day and best of all to maintain this temperature throughout the night. However, the various climatic conditions, energy budgets in different zones make it a hard race between the white roof and the green roof. Another factor that is considered is the depth of the soil on a green roof, as this factor greatly influences the energy efficiency of the building. The study has shown that a more energy efficient region is the North Eastern (New York) and North Western (Portland) part of the country. Whereas both Phoenix and Arizona, showed figures, significantly lower than others. More so, this allows us to make a conclusion that for the hot and humid south more preferable in terms of energy efficiency would be the white roof. Whereas the mid-country and the North can opt for a green roof. Considering California, a green roof is definitely a better option than a conventional roof. However, through some parameters, as in gas and electricity efficiency, the white roof surpasses the green roof. Green roof can sustain the needs of California community in pursuit of regulating the heat. The area belongs to the climate zone 8 characterized by cold winters and dry, semi-arid temperatures. Summers are also hot and in some cases, the heat level in California can be likened to the dry temperature of the desert with minimal rainfall. The rest of the Central Californian region has a temperature similar to the Mediterranean isles.
Leaf Area Index refers to the extent of plant growth on the green roof. The larger the leaf index, the better sustainability for regulating heat in the above climates. Meanwhile, to better mimic the actual forest, the depth of soil must be at least half of the height of the roof to provide more opportunity for plants to grow; materials to be used in these structures are insulators such as plastics, rubber, and fiberglass to remove excess heat. On traditional roofs, concrete and metal roofs are the ones commonly used and these contribute to high heat index. A green roof is much better compared to the white roof because it absorbs minimal energy from the environment while the conventional and white rood have a disadvantage because white also absorbs the warm colors from the surroundings whereas the traditional materials for roof are often conducting heat instead of dispersing it. The effect of green roofing n California zone 8 will have a drastic effect in reducing the heat that plagues the region by making it cooler and shadier.
Conclusion
Constructing green roofs are a challenge for modern day architects and engineers due to the immense planning in order to make the project work. The green roof differs due to the fact that it requires numerous layers of structural support, soil, and insulation materials so that it can function as a heat reducer. This study further encourages other researchers to work on sustainable design for green roofs in cities.
Future Work
We have studied only one climatic and time zone. In order to prove the general beneficial effect, it is necessary to expand the area of the research. The time allocated for the research is simply not enough as more time would be beneficial to the calculations required by the project. Instead of only the soil and the plants themselves, it is important to be sure in using re-cycled materials so as not to increase the carbon footprint, and keep the temperature within the approved limits.
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Works Cited
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