In the U.S. 38% of total CO2 emissions come directly from the operation of buildings (not including their construction and demolition); even more than the 31% produced by the entire transportation industry each year, and this in a country with the 3rd highest cars per capita in the world. Additionally, 13.6% of the water and 71% of electricity usage flow into U.S. buildings; while 136 million tons of landfill come from the demolition and renovation of real estate projects each year. Still, in 2014 many people don-t even know what a green building or sustainable real estate means. Americans and Europeans spend on average 90% of their lives indoors. The quality of people-s lives is therefore largely related to the quality and habitability of the buildings in which they spend the vast majority of their time. This thesis will attempt to demonstrate the importance of minimizing the negative impact of the real estate sector on the environment and improving the quality of life for the users of buildings, as well as identify the most important factors relevant to increasing the market penetration of sustainable real estate through an examination of the evolution of several green building rating systems, and a number of other issues relating to human health and well-being.