In 2000 the state of New York introduced a green building tax credit, the first one of its kind in the United States, that has allowed some developers of environmentally friendly buildings to write off as much as $6 million on their tax bill. The city's Department of Design and Construction developed a set of guidelines in 1999 that encourage environmentally sound building methods for municipal projects. The guidelines had led to approximately $700 million in green city construction projects by the end of 2005. In 2005, New York City mandated that nonresidential public buildings costing $2 million or more be built to standards set by Leadership in Energy and Environmental Design (LEED), which grade buildings in areas like energy and water consumption, indoor air quality and use of renewable materials. The legislation also applies to private projects that receive $10 million or more in public funds or half of whose budgets come from public money.