1. Introduction

More than half of the world’s population lives in cities; in 2050 the people living in urban areas are expected to increase up to 70% [1]. Cities are the major reasons of pollution; it produces 60% of carbon dioxide and greenhouse gas emissions, through using energy generations, industry, vehicles, and biomass use. Therefore, now climate change is challenging cities to reduce their impacts and adjust to changing condition [2]. Therefore, the increasing demand towards sustainability is pushing toward rapid changes in policies, laws, and regulations around the world regarding products and processes to encourage more sustainable projects [3]. Also, sustainability solves the local issues of communities in innovative progress, for implementing sustainability is different for every community, but they share common goals for a healthy environment, smart growth, and human well-being [4]. Consideration to sustainability principles in building industry is vital for natural environment and human being. Adopting passive strategies and measures that respond to and achieve the responsive design lies directly under the responsibility of architectural designers [5]. Green architecture principles and science are usually not given enough thought and consideration. Factors such site characteristics, climate, and orientation, environmental design of the building, and choice of building materials are being neglected in most cases. In the best cases, some thought is given to such factors but without a scientific methodology that takes into consideration using the appropriate climatic data and the appropriate assessment tools. Consequently, buildings often have a poor indoor environment quality which in turn affects human comfort, health, and efficiency [6, 7]. Most importantly, the interference of the environmentalist in architecture projects comes usually very late in the design processes. Consequently, buildings often have a poor indoor environment quality which in turn affects human comfort, health, and efficiency. Most importantly, the interference of the environmentalist in architecture projects comes usually very late in the design processes. The integration of these green principles in the field at the early stages of the design processes lies at the core of the current research. However, to get the best benefits of these strategies and measures, detailed target identification must be set. Adopting these concepts has driven most countries to adopt official strategies and policies in order to insure appropriate building desig

2. Sustainability and green buildings initiatives

The application of sustainability is carried out by different stakeholders including academic initiatives, government initiatives, other sector initiatives, in addition to private sector initiatives. Moreover, these initiatives vary in its nature and way of application; some of them are building standards and codes, framework and programs, in addition to rating systems [8].

The standard is a set of guidelines and criteria to assure the quality of the products. Standards related to building industry are created by organizations such as the International Standards Organization (ISO), which defines and develops worldwide standards that frequently become law or form the basis of industry norms. ISO defines a standard as “a document, established by consensus, approved by a recognized body that provides for common and repeated use as rules, guidelines, or characteristics for activities or their results.” There are other institutions such as the American National Standards Institute (ANSI), the American Society for Testing and Materials (ASTM), or the American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) [8].

Green codes could be classified into two types: prescriptive and performance, with outcome-based as a third option. A prescriptive path is a fast, definitive, and conventional approach to code compliance. It provides tables to quantify certain levels of strictness for materials and equipment. Performance-based codes are designed to achieve certain results, rather than meeting prescribed requirements for individual building elements. Outcome-based codes establish a consumption target for energy, water, etc. One example of the green codes is the International Green Construction Code (IgCC) that provides a comprehensive set of requirements in order to reduce the harmful effects of buildings on the natural environment [8].

Programs and frameworks are database that provide datasets relating to most aspects of sustainability. Examples of such programs and frameworks are the RFCS, CPI, CPDP, and UNEP-SBCI. The reference framework of sustainable cities (RFSC) encourages sustainability and integrated urban development aligned with Europe 2020 guidelines and objectives [9]. The city prosperity initiative (CPI) measures sustainability at the urban level to allow local and central governments to use data [10]. The climate positive development program (CPDP) addresses the challenges of rapid urbanization and climate change [11]. In addition, there is the United Nations Environment Program-Sustainable Building and Climate Initiative (UNEP-SBCI), which is a partnership of major public and private sector stakeholders in the building sector, working to promote sustainable building policies and practices worldwide [12]. The Passivhaus standard was developed in Germany in the early 1990s, and the first dwellings to be completed to the Passivhaus standard were constructed in Darmstadt in 1991 [13].

Rating systems assess the environmental impacts of buildings, constructions, infrastructure, urban-scale project, and community projects. The rating systems designed to assist projects to be more sustainable by providing frameworks with a set of criteria’s that cover several aspects of a project’s environmental impact [14]. Rating systems utilize the key performance indicators (KPI) to assure high quality of sustainability applications [14]. KPI are employed for building designers and decision-makers to measure the socioeconomic and environmental impacts on environment, infrastructure, waste system, regulations, pollutions, citizen’s access to services, and more [15]. The significance of the sustainable design increased in the 1990s. The Building Research Establishment’s Environmental Assessment Method (BREEAM) was the first green building rating system in the UK that addressed the required KPIs for better environmental performance of buildings. In 2000, the U.S. Green Building Council (USGBC) developed another rating system, which is the Leadership in Energy and Environmental Design (LEED). Others also responded to the growing interest and demand for sustainable design including additional rating systems that most of them were influenced by these early programs but are tailored to their own context with specific priorities. Other trails for rating systems intended to address broader issues of sustainability or evolving concepts such as social aspects, net zero energy, and living and restorative building concepts. It is estimated that there are nearly 600 green product certifications in the world with nearly 100 in use in the USA, and the numbers continue to grow [16]. Many other rating systems became a great evidence of adapting the sustainability principles in building industry [17, 18]. The rating system is based on four major components [14].

• Categories: These form a specific set of items relating to the environmental performance considered during the assessment.

• Scoring system: This is a performance measurement system that cumulates the number of possible points or credits that can be earned by achieving a given level of performance in several analyzed aspects.

• Weighting system: This represents the relevance assigned to each specific category within the overall scoring system.

• Output: This aims at showing, in a direct and comprehensive manner, the results of the environmental performance obtained during the scoring phase.

Figure 1 and Table 1 present the most common green rating systems all over the world chronologically. Table 1 summarizes the most important features of those rating systems, in terms of year of establishment, coverage, main categories for building rating, level of certifications, its development base, and main aim with the main link of the source.