GRESB (Global Real Estate Sustainability Benchmark) is a sustainability index. This index measures the sustainability performance of real estate investment funds and investment trusts worldwide. GRESB considers many factors to measure the sustainability performance of real estate investors and investors, among them energy efficiency, water management, environmental studies, social responsibility, and management practices. GRESB allows real estate investors and investors to consider sustainability performance when making investment decisions and creates a competitive environment for them to improve their sustainability performance. The GRESB index evaluates real estate mutual funds and partnerships and compares their performance, especially regarding sustainability. It also provides guidance and training to improve the sustainability performance of participants. The GRESB index covers real estate investment funds and partnerships from many countries and regions worldwide.