GREEN ROOF, ENVIRONMENTAL APPROACH TO ACHIEVE SUSTAINABLE DEVELOPMENT AND ITS IMPLEMENTATION SYSTEM IN DIFFERENT CLIMATES

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1 INTERNATIONAL JOURNAL OF MODERN MANAGEMENT & FORESIGHT JOURNAL HOMEPAGE: IJMMF.COM, ISSN: VOL.2. ISSUE 2, PUBLISHED ONLINE on June 2015, pp GREEN ROOF, ENVIRONMENTAL APPROACH TO ACHIEVE SUSTAINABLE DEVELOPMENT AND ITS IMPLEMENTATION SYSTEM IN DIFFERENT CLIMATES ABSTRACT SEDIGHEH MEIMANDI PARIZI Researcher, Faculty of Civil engineering, Sirjan University of Technology, Sirjan, Iran Green architecture or sustainable architecture is one of trends and new approaches of architecture which is taken in to consideration by many contemporary designers and architects in recent years. This architecture that is derived from the concepts of sustainable development, seeking compatibility and harmony with the environment is one of the basic human needs in today`s world. Green architecture and green roof system is also defined in line with the fundamental goals of sustainable development and while it includes the roots of sustainable development, it also follows its components. Green roof is one of the new approaches of architecture and urban planning and it is arose from the concept of sustainable development that it can be used to increase the per capita green space, improve the quality of the environment and sustainable urban development. In other words, green roofs of the city with improve air quality, reduce the volume of superficial waste, reduce the effects of urban heat islands, establish thermal balance of indoor and outdoor of the building, create natural habitats, biodiversity and increase longevity of operation of roof insulation, are a positive step towards improving the quality of urban environment and thus urban stability. The overall goal of this study is to evaluate green roof, its forms and required details in the design of the roofs, the advantages and disadvantages of each of demand finally evaluate the executable systems in different climates. In this study, the qualitative methods has been selected to achieve better results and during study, library researches including books, papers, articles and etc. has been used to provide proper solutions. Keywords: green roofs, sustainable development, different climates, the environment, green architecture 1. INTRODUCTION In the past few decades, spaces that have been perspectives for cities, have been reduced because of uncontrolled growth of roads and buildings. This leads to alarming effects in deterioration of air quality and an increase in the average temperature of the cities and the creation of heat island in the cities (Abdollahi far and Fatehi far and Vosugh Mahmudi, 2009). During the summer, along with the process of absorption of ultraviolet (UV) and the infrared emission, in each region, the roof of the buildings, streets and dark surfaces, attract the heat and end it into the air. Considering that nearly all the roofs in Tehran are dark, these dark surfaces that attract the heat emitted by the sun and hold it in themselves, are included about half of Tehran area. This phenomenon increases the temperature of the residential areas from 2 to 15 C and it is known as the urban heat island phenomenon (Sepehri and Zarei, 2007). In order to solve these problems, new technology introduces a phenomenon called green roof. Green roofs are part of efforts to make cities more sustainable and there are one of the modern solutions to solve urban problems and particularly increase urban green spaces per capita (Moradi and Mohammadi Ghaffari 2:2013). Green roof technology is a one of the fields of sustainable architecture that today, is used in many developed countries. In fact, with regard to cultural and environmental policies of these countries the position of technology has been identified and has been supported by all groups and necessary measures to support the initial construction costs have been considered by the government and also with regard to environmental problems, the culture of using of sustainable architecture tools have been perceived by the people of these countries and it has become like an executable instruction in construction (Nemati and Bemanian and Pourjafar, 2013). Page 94

2 This study focuses on green roof, its types, methods of its implementation and finally the system of its implementation in all types of weather so that we can help the sustainable development in cities across the country with climate variability. 2. GREEN BUILDING The building that has the least inconsistency and contradiction with the natural environment around it and in wider area, with the region and the world, is called sustainable or green building. The goal of green architecture is to reduce the harm on the environment and energy and natural resources. The main objectives of sustainable architecture is achieving high standards of quality, security and comfort that actually provides human health and reach to such a situation occurs with using an efficient management and latest technology. Quality is the basis of the green architecture design. Design buildings and cities and their relationship with nature in every corner of the world can damage or improve the environmental situation in the world and for this reason and with taking into consideration interactions, designing constructions that energy saving and also environmental protection are their feature, is one of the main tasks of architects. Sustainable or green building was an approach based on this claim that it can be the aim to achieve these goals that by definition, the green buildings also eliminate the spiritual needs of the people in addition to meet their physical needs and in fact they are systems that express sustainable development in the society based on human health, productivity and well-being (Aalamrasi, 2014). 3. THE DEFINITION OF GREEN ROOF Green roof is a roof that covered with soil and plants and its plants and vegetation are growing on a waterproof layer. Swimming pools on the roof are also a type of green roofs. Finally, all the roofs that use a kind of "green" technology such as solar panels are also green roofs (Mirkouhi, 2010). The green roofs are identified with titles such as gardening on rooftop or planting technology on the roof, live roofs and eco roof or roof garden. Actually the green roof is a live ecosystem that provides the ability to live well for urban environment and makes it more efficient and sustainable (Abdollahzadeh and Litkouhi, 3:2013). Figure 1 shows an example of a green roof. Figure 1. An example of a green roof (Shahroudi, 2013) Types of Green Roofs A- Wide system B- Centralized system C- Modular or plant box system D- Hybrid or synthetic system Figures 2, 3 and 4 respectively are examples of centralized, wide and plant box systems. Page 95

3 Figure 2. An example of a centralized system (Aalamrasi, 2014) Figure 3. An example of wide system Figure 4. An example of plant box system In table 1, we introduce two major systems of green roofs. Table 1. Introduction of two main roofs (Resource: Authors) Centralized system Wide system This type of roof has the ability to create more than The word green roof has been used for wide system 15cm thickness and depth. They are suitable for planting a variety of trees and This system is also called" low height section" or "run shrubs. thin". Despite the thick soil and plant height, more structural This type of roof includes just one or two types of weight is entered by these roofs. plants and shallow planting environment. These roofs need more maintenance, water This system Is usually used when the minimum weight maintenance and watering and feeding programs. to be considered. The cost of this type of roof is very high. Particularly, only maintenance personnel have access to this type of roof. Selected plants for this type of roofs are more willing In this system, plants usually used with the depth of 40 to meet the visual attractions. to 100 mm. The ultimate burden range approximately are in saturation between 50 to 100 kg per square meter. In most places, the sloping roofs is recommended 10 to 20 percent slope. For the maximum slope of 30% need to use drainage and tools like anti-erosion. It has superficial and shallow cultivation environment and usually a part of roof and a part of building structure is green. A wide green roof is generally available for people and it is not used for special functions. Page 96

4 Fig. 5. Details of the wide system performance (Aalamrasi, 2014) Fig. 6. Details of centralized system performance (Aalamrasi, 2014) Table 2. Comparison of disadvantages of two centralized and wide systems (resource: authors) Wide system Centralized system disadvantages Very limited selection of plants. It is usually inaccessible for recreation and other activities. It is usually not appealing to everyone, especially in the winter. Enters a very high weight to the roof. It needs irrigation and drainage systems and therefore needs more energy, water and other substances. It`s very expensive. Table 3. Comparison of the advantages of two centralized and wide systems (resource: authors) Wide system Centralized system Advantages Low weight Suitable for a wide range Requires low maintenance It is usually needs very few professional techniques Deep soil and irrigation system make favorable conditions for the most plants. A much wider range of plants and species. Excellent insulation characteristics. We can simulate a zoo in it. Page 97

5 It is cheap You can leave the plants to reach full growth It is usually available for users. It is accommodate a set of our activities in itself: recreation, public open space, restaurants Modular or plant box system: In this system, its plant and planting environment is maintained in special boxes that cover all or most of the green roof. In non-modular system, planting environment is a continuous layer on the green roof. In modular system this environment is discontinuous. Combination system Figures 7. Executive system of plant box system (Aalamrasi, 2014) This type of roof is a combination of both wide and centralized system and it has advantages of the roofs has been mentioned and while plants growth is done in wide lightweight panels but it has a higher load capacity. Anatomy of a Green Roof Classification of administrative components of roof gardens is very diverse and extensive. The cause of this subject is that any institution or commercial company provide some suggestions according to its approach to this issue. (Competition in the market is the most important reason of the complexity of these components. We show two examples of classified components in fig. 8). Figure 8. An example of a green roof components category (Aalamrasi, 2014) Page 98

6 Layers of the roof Vegetation layer Cultivation environment Drainage layer Protection layer Table 4. The main executive components of green roof (resource: authors) Virtually we can put any kind of plant in the roof. But this encounters with restrictions such as weather, structural design and maintenance costs and the imaginations of green roof designer. Since the green roofs are designed as light as possible, they often include a coverage that can grow in a little depth of the soil and with a little care or with no maintenance. Cultivation environment is the space where plants start to grow in it. Cultivation environment must have a low weight through certain structural requirements and that is why it is different from regular soil. We have to use a cultivation environment that have light weight as much as possible and its weight should be about 900kg per cubic meter in a wet state, a good mixture is consisting of 1.3 ordinary sand, 1.3 porous stones and 1.3 artificial plants (a combination of punk and vegetable fertilizer). Drainage layer is placed between cultivation environment and protection layer so the water can flow from anywhere in the green roof to drainage system of the building. Selection of the appropriate drainage layer is done based on the maximum water flow that is determined from rainfall data and since the drainage layer is protecting the cultivation environment and plant, the compressive strength must be appropriate. Some systems simply use a thick layer of expanded soil, but now many green roof companies is using a corrugated plastic drainage straw with the same structural pattern of an egg carton. The minimum thickness of the drainage layer is 20mm, but a thicker straw can provide an additional insulation. Drainage layer could be a complex set of other layers: This layer mostly includes layers that protect roof from leakage and water intrusion or protect the insulation system. These layers are: Water distribution layer: This layer can include a fabric texture. Modern systems are usually used one or two non-woven layers. This can even be layers of sand and soil and in this case it may combined with drainage layer. This layer is usually made of a polyethylene shell. This layer is used more in public projects such as squares that have high flow traffic and roof load and places where cultivated plants with deep and invasive roots. Root barrier layer: It is a layer that prevents well from root penetration and their harm to the insulation and roof membrane. This layer is usually used in centralized system and it is placed under the drain and immediately at the top of the final layer of sealing or thermal insulation. Drain board: It is a three-layer sheet that is doing the top layer of function and it takes excess water away from the roots. This layer also acts as a protective layer over the roots. Middle layer that is in the form of a coneshaped bowl, receive the excess water from the roots and holds it. This layer helps to reduce the speed of rain water and it also causes air circulation and prevents from sepsis of the environment. Roof membrane or moisture insulation layer: It protects the roof from leaking and dripping. Membrane is use in both forms, an integrated waterproof layer and interconnected sheets. Selecting a suitable membrane depends on conditions of the roof, cost and ease of implementation. Recently, some factories are produces a product that the root barrier layer and membrane are placed in one layer. Page 99

7 Resistant roof structures Protector screen: Protector screen is placed directly on membrane and protect it during operations and from failure. Depending on the design characteristics and the usage of green roof, Protective layer can be strips of light concrete, a screen of solid insulation, thick plastic sheet, copper sheet, or a combination of these. Some of the green roof systems does not necessarily require protector screen and root barrier layer may be used instead. Green roofs should generally endure a load between 122 to 488 kg per square meter (25 to 100 pounds per square foot) more than conventional roofs. New roofs made of wood, steel or concrete can be designed in such a way that with no additional costs, they can be able to tolerate the green roofs. The conversion of existing roofs to green roofs almost always requires structural consolidation with a huge cost. (Abdi and other one, 9:1393) The Benefits of Green Roof We bring some of the benefits of green roofs in table 5. Environment aesthetic benefits Psychological benefits Biological benefits Economic benefits Table 5. The benefits of green roofs (resource: authors) A- Creating open and leisure space. B- Improving the quality of mental image of the city by increasing the visual values in city regions with high density. C- Creating health and medical values (Nemati and others, 4:1392). A- The possibility of exchanging culture and information between residents of the building. B- Strengthening the social interaction. C- Reducing stress, aggression and invasion D- Increasing peace E- Treatment of mental illness. A- Protecting the environment and increasing the per capita green area. B- Reducing noise pollution by 40 db. C- Absorbing 75% of surface water during rain. D- Reducing air pollution. E- Protecting the building against fire. F- Reducing the effect of urban heat islands and power of cooling up to 7 C. G- Reducing energy in the summer up to 25%. H- Protecting urban ecosystems and development of habitat diversity (Singari, Badrinam, 4: 1391) A- Increasing thermal resistance of the walls and the ceiling of the building, and thus saving energy costs associated with heating and cooling. B- Protecting the roof and walls covering, especially in maintenance of materials of the larger openings in damage caused by extreme temperature fluctuations which reduces maintenance and replacing costs. C- Green roof and green walls protecting members from UV radiation. D- Reducing flow water of the rain in building and the need for water resources. E- Rising the value of the building (studies in America and Britain shows that the value of units with green spaces is 15% more than the others.) (Aybaghi Esfahani, 2011) Disadvantages of the Green Roof The need for strong structural system and high running costs are the major disadvantages of the project. But the cost of green roof performance should not be compared with the cost of a conventional roof, because in the meantime, the costs of air, water and environmental pollution, diseases and deaths caused by this pollutions and Page 100

8 personal and social damages caused by the lack of green spaces in the built environment should not be forgotten and the costs of threatens of running out fossil fuels, surface water controlling costs, the cost of insulation and multiple performing of the traditional black roofs must be added to these expenses. (Singari, Badribenam, 2012) Green roofs in different climates According to weather conditions, rainfall, humidity and mean temperature, any climate needs its own specific plants. Given that we may have semi-sunny, sunny and shade areas throughout the day, we should be considered that the plant achieves all its solar needs at the site. More specifically the plant that we use for green roof must have low water requirement, it should be four seasons as much as possible and its root must not be deep, but it must have wide root and the power of its root penetration must be low, so that it reduce maintenance with creating the conditions and easiest situation arise for people in this issue (Raisivanani, Mir Alai, 2011). We bring a number of standards for selecting plants for green roof. Species with long life Plants with low expectations (the more compatible with environment) Plants with low water needs Criteria for selecting plant species suitable for green roofs Species with less need to prune and shape Species with less secreted substances (such as gum) Species without creating allergies Figure 9. Criteria for the selecting species of green roof plants (source: authors) Page 101

9 The type of climate Cold and wet Cold and dry Warm temperate Table 6. The type of vegetation and its implementation system in different climates (source: authors) case Weather features vegetation Tabriz - Extreme cold weather in winter and warm weather in the summer - A very high temperature differences between day and night temperatures - Low air humidity - Heavy snowfall The mean temperature of Tabriz in July (the hottest month of the year) is 25.4 C, in January (the coldest month of the year) -2.5 C, in March 10.5 C and in October 14.1 C and the mean annual temperature is 11.9 C. Average annual rainfall of Tabriz is about 330.1mm. During the summer, rainfall is usually minimal and it rarely occurs. Mashhad Shiraz Mashhad, due to the special geographical situation (in border region between north and south of Khorasan) that it is located, and also because of the interaction of different weather fronts, has a special weather and climate characteristics, and the majority of Mashhad plain- Neishabour, is from cold and dry climate and a part of Mashhad plain- Ghouchan is from semi-dry and cold climate and a small part of the highest-altitude Binalood and thousands mosques mountain ranges is wet-cold and in total, the city of Mashhad has a variable weather, but it is warm and a little cold and dry and it has dry-warm summers and wet-cold winters. The highest temperature is 35 C in summers and the lowest is -15 C in winters and the rainfall is variable and its average annual rainfall is about 253mm. In terms of political division of the city of Shiraz, it is the capital of Fars province and in terms of climate it is in the temperate zone of the province with annual rainfall of more than 450 Plant species: Acacia, silver cypress, black pine, crock cypress, hackberry, corms, ghatlanghoush, osku oak, haloxylon, Japanese maple, atriplex, juniper, mulberry, Conventional Elaeagnus Angustifolia, Lake-bleak, American Lake, ash, Zygophyllum, tamarisk, white willow, Euphrates poplar, new leaf, crawling Zhiny russia. Shrubs suited to the climate: Hollyhock, yellow jasmine, Peacock Jasmine, Rainbow Rose, ordinary Rose, Japanese, Dry milk, Berberis thunbergii, and the tail of a mouse, ice flowers, winter Magnolia, typical boxwood, Japanese maple, Wisteria sinensis, honeysuckle, jacaranda, love-ivy, witch-hazel, aspirated, mouse tail, Acacia,, barberry, thistle, Indian cloves, Camellia Common box wood, Japanese maple, clematis, hollyhock, red maple, acacia, Kriya, barberry, thistle The type of implement ation system in climate All four types of green roof systems could be performed in this region. But because of the long winters we have to use vegetation that it stay green in winter. All four types of roof systems are applicable in this area. All four types of roof systems are applicable Page 102

10 to 600mm. the average height of the city is about 1120 meters above sea level. This height is 1520 meters above sea level in the highest place and in the lowest place it is 820 meters above sea level. General slop of the city is from the northwest to the southeast. in this area. 4. CONCLUSION Expansion of production and instruments that will have more short-time profitable in investments is the cause of increasing the amount of land use in the short-term economic benefits. Nowadays residents of large cities such as Tehran, due to poor quality of life in the cities, need to take advantage of the healthy and sustainable conditions of the city more than ever. In Iran, according to Iran`s history, people use mud bricks, moss and lichens covering and herbaceous plants in its architecture, on the roof of mountain buildings and villages in different parts of the country such as Azerbaijan, Gilan and Mazandaran. Today, with the increase of population and turning all urban areas in to urban places, increasing traffic and the indiscriminate use of fossil energy, and construction and instruments to accommodate new forms of urban areas mainly causes urban areas such as gardens go under construction. Hence we see a lot of environmental instability and problems in our cities. Because of the lack of urban green spaces and land for construction of urban green spaces, the cities of our country have been faced with many problems. According to the placement of urban areas of Iran on the dry zone in the world, creating a sustainable green space should be based on ecological characteristics and climate. Therefore we must use such technologies that support the goals of sustainable development. It seems that because of the lack of land and its high price in cities, the green roofs are the best option to improve environmental and sustainable architecture and urbanism for the construction of new urban green spaces. According to advantages that green roof has, it can be an action plan in construction and it can lead to more sustainable architecture and urbanism in order to use of clean energy and paying attention to the environment and its residents in unlimited time range. REFERENCES Aalamrasi, M. (2014). Studying the effects of green roofs on improving the quality of urban life", the first national conference on architecture, civil engineering and urban environment. Abdi, B., & Esmailian, S. (2014). The effect of plant species on green roofs. Abdollahi Far M., Fatehi far, E., & Vosough Mohammadi, S. (2009). The feasibility of the use of green roofs in cities, the third congress and exhibition of environmental engineering conference. Abddollahzade, S., & Litkouhi, S. (2013). Green roof, new approach in architecture along with environment and in order to reduce energy consumption and tackling climate change", the third conference on energy and environment. Alikhani, M., & Salehi, R. (2013). Echo parks, creation of a sustainable perspective along with maintaining stability of the urban ecology, the first international conference on ecology landscape. Aybaghi, Esfahani, H. (2011). Green roof, a strategy to improve environmental conditions and energy savings in Tehran", first national conference on development, Zibakenar, Iran, March. Moradi, A., & Mohammadighafari P. (2013). the feasibility of increasing the per capita green area of Bandar Abbas by using green roofs, the third national conference on environmental health and sustainable development. Mirkouhi, M. (2010). The implementation of green roofs in Tehran, second national student scientific conference on geography. Nemati, M. A., Bemanian. M., Pourjafar, M.R., (2013). The feasibility of the development of green roof systems in Shiraz, the first national conference on geography, urbanism and sustainable development. Sepehri, J., & Zarei, Z. P. (2006). Sport and heat island phenomenon in cities, the first national conference of cities and sport. Page 103

11 Shavardi, N. (2013). Green roof, national conference on engineering and management of sustainable agriculture, environment and natural resources. Singari, M., & Badrinam, N. (2012). Feasibility of using green roof systems in various parts of the Municipality of Tabriz, National Conference on air stream and pollution. Raisivanani, A.R., Miralai, M.R. (2011). Studying performance of the green roof layers with an approach to replacement of local and cheap materials, Fourth National Conference on Civil (retrofitting and maintaining sustainable buildings) Page 104