The Benefits and Functions of Green Architecture

Vol-7, Special Issue3-April, 2016, pp743-749 http://www.bipublication.com

Review Article

The Benefits and Functions of Green Architecture

Behnush Khoshmanesh, Saba Izadyar

and Behnaz Aghapanah

1_{Assistant Professor of environment department of Islamic Azad University,}

Parand branchE-mail: behnoush84@yahoo.com

2_{MA student of environment department of Islamic Azad University,}

Parand branchE-mail: sabaizadyar@yahoo.com

3_{MA student of environment department of Islamic Azad University,}

Parand branchE-mail: aghapanahbehnaz@yahoo.com

ABSTRACT

Green architecture or sustainable architecture is one of the new architectural approaches receiving much attention in recent years by many contemporary designers around the world. This architecture is based on the concepts of sustainable development and attempts to coordinate with environment as one of the basic needs in the present world. Now, 2% of dry area of the world is dedicated to cities and city dwellers apply ¾ of natural resources. By development of urbanization, natural resources are reduced considerably. Therefore, green roof technology as one of the advanced techniques of green space with the problems of application of vegetation units, they are economical and can be a good alternative for urban parks. Green roof is not only a surface covered with green, but also it is a live surface of growing plants in soil layer above roof. This covering is with root barrier and a drainage layer under it and dry resistant plants grow in it. Green roofs are also called “living roofs”.

Keywords: Green roof, Benefits, Barriers, Solution

INTRODUCTION

The development of urban green space and its fair distribution in townships namely in center of cities consistent with the urban construction is one of the main challenges of contemporary metropolises. The urban green and open spaces don’t have direct economic values, development of constructions with more benefits in short-term in investment of local and state sectors can increase using earth at the benefit of short-term economic advantages. The development of urban green spaces compared to other investment has low financial support. This problem exists in developed and developing countries namely in city centers but in developing countries, it is much emphasized due to the special attention of municipal authorities on economic benefits in

where the land price and shortage of open and green space namely in city center and populated areas are turned into urban management challenges. In the present world, development is one of the greatest factors of environment change and construction as big industries in stability of human resources (hundred thousands of construction workers and relevant techniques) led into destruction of fields, soil erosion, environment pollution, bad condition of health and energy crisis. The development of urban green space and its fair distribution in townships namely in city center is consistent with urban construction. The urban open and green spaces don’t have direct economic values and development of constructions has great benefits in local investment and can increase using land in short-term economic benefits. The development of urban green spaces compared to other investment has low financial support. Green roof is one of the new architecture and urbanization approaches based on concepts of sustainable development and it is used to increase green space per capita, improvement of quality of environment and urban sustainable development. These roofs have many advantages including rain water absorption, creating insulation layer on the roof, providing a new habitat for various species and reduction of temperature in cities and fighting against the thermal island in cities namely in big and populated cities[4]. Green buildings as called environment friendly buildings are the structures providing optimal use of valuable natural resources including water, wind, sun energy beside the effective and construction recycling materials. Green buildings in recent years are encountered with great progress in design and new technology and this has reduced environmental pollution and healthy environment inside and outside of buildings. The pollutions were created based on destruction of buildings and also they affect the air and soil quality and consumption of non-clean energy. By development of building with green technology in state and private sectors and acceptance of construction experts and

artisans, an organized plan is required in this regard.

Figure 1- A general view of a green roof [4]

Study method

This study is content analysis and comparative method. Via logical reasoning, some results are proposed and study measure is via library and internet studies and existing papers.

The history of green roofs

Island and Swiss, plant growth on roofs is common as construction method and in hot areas as Tanzania, the outside heat is prevented. Since 18th century, we observed different examples of establishing gardens on roof in different countries [3].These examples were considered with the development of cities and shortage of open space namely in city centers and due to functional use of roofs. In the early 20th century, a new movement of using roof or balcony as applied space was considered.

Le corbusier and frank lloyd wright were the first modern followers of using roof or balcony as green space.

None of these two architects had an image of great environmental, socio-economic benefits of green roof. The roof space was used for functional aspects and its technique was different from its new concept. The gardens on the roof and balconies need definite depth of soil and the plants are placed in pre-fabricated flowerbed and vases. In the early 60s and by considering the environment quality in urban texture and environmental challenges of big cities including air pollution, shortage of urban green space namely in central regions of city, the urban thermal island and energy crisis, new wave of approaches to green roofs in their new concept due to their environmental benefits and as ecological solution have been started from northern Europe and it was accepted very so on in European countries. Germany, France and Austria were pioneers in this regard. In Germany (80s), green roofs were extensive at urban scale and its annual growth reached 15-20%. In 1996, 10 million square meter of green roof were established in Germany. The great share of this growth is dedicated to the rules approved by government and subsidy of municipalities to establish green roof.

According to 2006, more than 75 European municipalities had great planning for green roofs and its quantitative development in the city and green roofs in that cities were approved as a rule. In 70s, US continent after one decades compared

to Europe, applied this new technology. Today, green roof is an executive instruction in urban planning of North America in some

Figure 2-Structural components of establishing green roof by intensive method[8]

regions including Chicago, Portland, Orgen and Toronto of Canada. The current world from Europe and US to Asia and even Africa has observed the increase of cities making efforts to develop green roofs at urban scale [9]

Green roof technology

The term “Green roof” is a lightweight system consisting of pre-fabricated layers and creates a unit system with the building roof and plants growth is possible in special medium in all or some parts of roof.

The growing layer of green roof is different from ordinary soil and it needs less depth to growth different plants and is lightweight. The layers of green roof from top to down include vegetation, growing medium or

growing layer, root barriers, drainage layer, aeration and water storage, moisture protective layer and insulation to protect the roof structure layers [5]

Intensive system

Traditional flower beds on the roof need thickness 150-1500 of soil to growth plants or ordinary grass and these roofs are intensive ones. They need regular irrigation, maintenance, fertilizer and other aspects. It is an accessible roof with park-like features of trees and shrubs [8]

Extensive system

It needs the lowest maintenance or irrigation and is covered by grass or decumbent. The soil is dispersed. The soil height is 50-100mm. In this system, plants have the root the depth of 40-100mm. It is an inaccessible system. This covering applies the least weight and is installed on any roof. The final load of roof is ranging 50-100kg/m2 at saturation. This covering is suitable in industrial structures as it acts as insulation and

avoids torrent [7]

Figure 3- The structural components of

establishing green roof by extensive method [7]Modular system or planter box

This system is used on the roof of buildings in which roof garden is not implemented. Figure 4- The structural components of establishing green roof by modular method [7]This method is suitable for buildings with one owner due to low cost. Irrigation in this system is done via simple drop irrigation. In non-modular system, growing medium is a continuous layer on green

thermal island. The vegetation of green roofs makes the surrounding cool via natural cycle of evaporation-Transpirationand if it is implemented widely at urban and township scale, the city temperature is reduced considerably and the city air is healthy. According to the studies of national council of Canada researches, only 6% of Toronto roofs are green. The city air is cooler 1-2 (Benjamin et al,2009). Another advantage of green roof compared to traditional roofs is energy storage and reduction of heating and cooling costs of building. The plant growth on roofs can reduce temperature around the building in summer and due to insulation of cultivation layers and plants, the outside heat entrance to inside be prevented. This feature of green roof insulation in winter reduces the need to thermal energy in the building and helps the energy storage of building. In Canada, a one-story building with grass roof and growing layer with the depth 10cm was studied and the researches showed that green roof reduces 25% of cooling energy in summer. Due to the experience of green roofs of Chicago Municipality, due to the reduction 1 , 1.2% is saved in energy consumption. With the development of green roofs at urban scale, great energy saving in private and state sectors based on energy crisis of present century can be useful at global scale.

Other environmental effects of green roofs is reduction of noise pollution namely in big cities. Green roof acts as noise insulation and can reduce noise pollution via noise waves. The green roof growing layer reduce low frequencies and its vegetation can reduce high frequencies and these roofs are good in the buildings in proximity to airport, train stations, highway, factories and other noisy industrial centers. According to the researches of “Canada housing organization” , the growing layer with the depth 12cm can reduce 40dB noise pollution.

By providing habitat for plant species and absorption of animal and bird species, they are of great importance in terms of ecology and biodiversity. Green roofs namely its extensive

type not accessible by creating beauty in urban environment are good habitat for the growth of different types of insects, birds and their eggs. Despite the public opinion, green roofs have economic benefits. Environmental benefits of these roofs have economic aspects. The use of roofs as public or private green space (special for the residents) is another economic benefit for private and state sectors.

The increase of average life of roof is another economic benefit of green roof. As the growing layer and vegetation of green roofs protects the roof shell against the damages of ultraviolet ray, these roofs have high durability compared to traditional and conventional roofs. Insulation of roof with tar has average life of 20 years (salonen et al., 2009). The vegetation of green roof avoids ultraviolet ray to the external surface of traditional roofs and can increase the average life of roof. The experience of green roofs in Germany shows that some established green roofs have been new after 40 years.

Another economic benefit of green roof is storage of cooling and heating energy in winter and summer and also it leads to reduction of energy consumption costs. According to the studies of national council of Canada researches, by creating green roofs in Toronto as 6%, the temperature was reduced 1-2 . Annually, one million dollar is saved due to reduction of electricity energy demand. Cultivation of agriculture products and food, vegetable and fruit are other economic benefits of green roofs. The roofs are suitable to cultivate vegetable and fruit. The increase of house value due to green space and aesthetics of its external façade are economic benefits of private sector, construction experts, owners and local governments. Aesthetics of urban view and improvement of surrounding views can be the social benefits of this new technology.

urban green space. Cultivation of agriculture products and food besides economic benefits in terms of health of citizens and gardening to help the mental health are other social benefits of green roofs [8]

The barriers to apply green roof

With great environmental benefits of green roofs and its extension ranging from Europe to US and recently in Asia, due to its vague economic and social dimension, this technology has not been accepted well:

- High installation costs

- Suitable irrigation system

- Extra costs to improve the structure of existing

buildings

- Expenditure of retention of green space of

these roofs

- Irrigation and potable water and above all, the

lack of adequate recognition and distrust to this new technology are important issues [8]

SOLUTIONS

1- Conducting extensive researches about the type of plants consistent with the climatic conditions to be established on the roof. 2- If it is with economic incentives of urban

authorities, it leads to high saving in energy and the costs of torrents and rain in a city are reduced and great benefit is achieved of this investment.

4- The design of a system for using rain water for roof irrigation

5- Using the materials not only economical but also not imposing any damage on the roof and urban space.

6- The change of height of building chimney and fans to improve the conditions of using roof for people.

7- The government responsibility to establish green roof in the buildings relevant to state organizations to encourage people in municipalities, environment, university and public places as hospitals, cultural-recreational and commercial centers [9]

DISCUSSION AND CONCLUSION

By focusing on the environment quality in urban texture and environmental threats in big cities including air pollution, urban Thermal Island, energy crisis and etc., making the roofs green is considered due to its environmental benefits and as an ecological solution. With all great environmental benefits of green roofs, high installation costs, irrigation and maintenance of green space, this new technology has not found its great position in contemporary sustainable cities. In the past, the roofs were green due to their functional benefits and now due to their environmental benefits. By integrating these two ideas and adding great social benefits of making these spaces as functional, local governments can take big steps for sustainable development of green roofs and urban sustainable management. This function can be consistent with the building application. Based on the problem of most metropolises regarding the development of urban green space and fair division of township green space regarding urban construction, functional use of roofs as public or private green space is a great step to development and increase of green space per capita beside the work place or life of citizens. Also, it creates a safe green space for people namely the old and children beside their living place[10]

REFERENCES

1. Asnaashari,(2012) ,The certificate of energy management and environmental designSemnan 2. GorjiMahlebani, 2010.Sustainable architecture and its criticism in environment.Scientific and research journal of scientific association of architecture and urbanization of Iran Tenth edition. Tehran.

3. Karol, Elizabeth & Brunner,(2009), Tools for Measuring Progress towards Sustainable Neighborhood Environments, Sustainability1, 612-627

Building Research and Information 27 (4-5) 206-20

5. Saberi, Sanei, 2006. The design and execution of solar building with green roof in district 10 of Tehran.

6. Salonen, Arto O &Tast, Sylvia,(2013), Finnish Early Childhood Educators and Sustainable Development, Journal of Sustainable Development; Vol. 6, No. 2

7. Stein, Benjamin, Reynolds, John S, Grondzik, Walter T, Kwok, Alison G. Mechanical and Electrical Equipment for Buildings, John Wiley & Sons, Inc. 11edition, US, 2009 8. Shahabi, 2006. Green architecture.Jihad

Daneshgahi publications.Mashhad. Mashhad 9. Vileniske, IndreGrazuleviciute&Narvydas,

Arturas,(2012), Environmental Ethics and Sustainability in Housing Design, Environmental Research, Engineering and Management, No. 4(62), P. 68-80