LEED stands for "Leadership in Energy and Environmental Design." It is a set of standards developed and maintained by the Washington, D.C.-based U.S. Green Building Council (USGBC). This group is a 501(c)3 organization committed to a sustainable future through cost-efficient and energy-saving green buildings.

With a community comprising 79 local affiliates, more than 16,000 member companies and organizations, and more than 160,000 LEED Professional Credential holders, USGBC is a leader in an industry projected to contribute $554 billion to the U.S. gross domestic product from 2009-2013. USGBC leads a diverse constituency of builders and environmentalists, corporations and nonprofit organizations, elected officials and concerned citizens, and teachers and students.

Buildings in the United States are responsible for 39% of CO2 emissions, 40% of energy consumption, 13% of water consumption, and 15% of GDP per year, making green building a source of significant economic and environmental opportunity. Greater building efficiency can meet 85% of future U.S. demand for energy. USGBC claims that a national commitment to green building has the potential to generate 2.5 million American jobs.

Four levels of certification are:

1. Certified - 40 - 49 points

2. Silver - 50 - 59 points

3. Gold - 60 - 79 points

4. Platinum - 80 points and above

In general - and for building replacement especially - the higher certifications mean that much of the material from the old building is re-used in the new, not an easy feat.