This standard specifies the terms and requirements related to the application of the Global Sustainability Assessment System (GSAS) to assess the sustainability of buildings during their different stages. This standard is based on the principles of sustainable development and applies to the life cycle of building works from the inception of the idea to the end of the building’s function. This standard applies to new or existing building works, separately or in combination. It also applies to materials, products, services and procedures in relation to their life cycle. The following parts of this standard contain the performance criteria related to the stages of the building life cycle, each separately. This standard contains the requirements and procedures for the different GSAS certificates, including the GSAS Design & Build (GSAS-D&B) Certificate, the GSAS Construction Management (GSAS-CM) Certificate, and the GSAS Operations (GSAS-OP) Certificate.