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
