CASBEE Assessment System, a Technical Approach to Assessing the Environmental Sustainability of Green Buildings in Japan

After the era of the Industrial Revolution and the emergence of the modern age, many environmental hazards have been appeared. All of intellectual developments led humans to interact more with nature and the environment. The emergence of eco-technical, sustainable and green approaches were as a result of these changes and tried to establish more communication between the artificial environment and the natural environment. Among these, the field of architecture and construction has great importance due to the extent of the impact on the environment. In this regard, and in the field of architecture, many efforts were made in different countries of the world, such as the United States, the United Kingdom, etc. Therefore sustainable Assessment systems were designed and used to better control the construction process. In Japan, the CASBEE system is designed for this purpose. This article tries to study the structural features of CASBEE system as one of the most advanced systems for Assessing sustainable buildings with a descriptive-analytical approach with emphasis on studies. The CASBEE Assessment System technically and accurately calculates the environmental assessment of a building and its effects on its surroundings. While it has paid less attention to the social and economic aspects of sustainable development.


Introduction
Most countries have tried to achieve optimal sustainable development systems. It seems that their experiences and achievements can help to find the right path to achieve sustainable residential buildings and complexes in Iran.
Therefore, in this article, one of the most important environmental assessment systems of green buildings in the world, called CASBEE system, which has been used in Japan, is examined by reviewing the concepts of sustainability and green buildings. More specifically, the concepts of sustainability are examined to answer the following research questions: 1. What are the components of sustainability in the CASBEE assessment system? 2. How does this system examine the sustainability of buildings?

The Evolution of the Concept of Sustainability
The verb "sustain", from the root of "hold" or "maintain", has been used in English since 1290 AD. The Oxford Dictionary dates the adjective "sustainable" back to about 1400 AD [1]. The concept of sustainability has been considered vastly in the 1970s and after the oil crises of 1973 as a result of the growing awareness of countries about the global problems of environment and development. In fact, this issue seeks to address serious environmental problems, such as air pollution and depletion of biodiversity, greenhouse effects, global warming, etc [2]. Thus, the issue of sustainability in the form of sustainable development was formally placed on the political agenda by the World Commission on Environment and Development in 1987 through a report called the "Brandt Land Report" entitled "Our Common Future". Moreover, in 1992, at the UN Summit in Rio de Janeiro under the title of "The World Commission on Environment and Development (WCED)", a document was signed by 178 countries, which was published as "Agenda 21"". Thus, the concept of sustainability has been shaped and become the main topic of scientific circles in less than two decades.

Concepts of Sustainability
The definition given in the Brandt Land report broadly encompasses all concepts of sustainable development: "Sustainable development enables meeting today's needs without losing the ability to meet the needs of the next generation." [3] The above definition emphasizes three key words: "development", "needs", and "next generation".
Thus, simply, sustainable development is an intelligent method of developing life quality to pursue three goals: improving collective life, improving the environment and making economic progress. Therefore, sustainability does not reduce the cost of living. Rather, it points to the fact that no man-made artificial environment can survive without the participation of ecological systems.

Environmental Sustainability
The environmental dimension of sustainability is related to the protection and enhancement of physical, biological and ecological resources and deals with the relationship between nature and man [4].

Economic Sustainability
Economic sustainability means strengthening the economic foundations and achieving economic security in terms of access to sustainable livelihood, beneficial employment, reliable financial resources, and ultimately, environment-friendly technology for the exploitation of human resources.

Social Sustainability
Principle 1 of the Rio Declaration (Agenda 21) states that human beings are the focus of sustainable development that deserves a healthy life in harmony with nature [4].

Green Architecture
Green design is a practice in which natural resources are minimally damaged before, during, and after the manufacturing process. In addition, materials must have a long useful life and be recyclable in nature [5]. The principles of green architecture can be summarized in six categories: energy conservation, working with climate, reducing resource use, respect for users, respect for the site and totalitarianism [6].

Evaluation Systems of Green Buildings
In many developed countries of the world, the degree of compliance of buildings with sustainable development policies is monitored through sustainability assessment systems. These systems are mainly divided into two categories of Life Cycle Assessment (LCA) and Criteria-Based Tools (CBT). CBT systems evaluate buildings by covering a wide range of sustainability categories. These systems are generally approved by the World Green Building Council [7].

CASBEE Evaluation System
The CASBEE system is based on three general principles and goals: complete review of the building life cycle, assessment of the building environmental quality and environmental load, and evaluation of the environmental productivity indicators of the newly constructed buildings. The CASBEE system is therefore a way to evaluate and grade the environmental performance of buildings. This system comprehensively evaluates the quality of buildings, including their interior comfort, sound comfort, and aesthetics, and assesses their environmental impact, including materials and equipment with high energy efficiency and less harmful environmental effects.

Evaluation Components in CASBEE System
The main concept of this system is environmental productivity, which provides an integrated assessment of the factors affecting the quality of indoor space and the negative environmental impact of outdoor space, and presents a model of environmental productivity called "BEE". In all versions of the CASBEE evaluation, quality is evaluated in three sections: internal environment, service quality and external environment of the site. Environmental load assessment is also performed in three sections: energy, materials and off-site environment [8]. Hence, a five-point evaluation is done and a red star is given to the building at the value of the obtained credit [9].

Carbon Dioxide (CO2) Life Cycle
In 2008, CO2 life cycle assessment system was introduced in the CASBEE. In this system, the amount of emission of this substance during the life cycle of a building is measured from the time of construction and operation to the time of demolition; it is rated in a 5-star rating in green.

CASBEE Certificate
The CASBEE system provides a three-part certificate for buildings. • The first part includes the building specifications, such as location, use, land and infrastructure area, number of floors, number of residents, hours of presence, and the building image. • The second part includes the building evaluation charts and diagrams. • The third part includes all considerations related to the building quality and environmental burden.

CASBEE Criteria and Sustainability Framework
The main focus of the CASBEE sustainability assessment system is on the environmental components, and the indicators of social and economic sustainability are not well considered. Therefore, energy components, materials and resources, off-site components and off-site environment quality are mostly focused on environmental problems, and the indoor environment quality component can be put under the category of social components whereas the services quality component can be put under the economic category of sustainable development [5].

Conclusion
The CASBEE evaluation system in Japan accurately studies the environmental sustainability of the buildings by providing computational tools, examining the architectural sub-components, and considering regional coefficients and their impact on each component. Therefore, it is one of the most accurate sustainability assessment systems. Also, assessing the amount of CO2 emissions from the buildings is one of the most important advantages in this system. Therefore, this system is reliable in dealing with environmental issues of the buildings and it can be used in Iran through localization. However, this system has a disadvantage; it neglects the other two components of sustainable development, i.e., the social and economic components, and there are no appropriate criteria for assessing them in the CASBEE system.