The document provides an overview of four major green building rating systems: LEED, BREEAM, CASBEE, and SI 5281. It describes the general principles, categories, weighting methods, and criticisms of each system. The rating systems take different approaches to assessing the environmental impact of buildings but generally evaluate categories like energy use, water efficiency, materials selection, and indoor air quality. They differ in their weighting of categories and how credits are structured within each system.