The U.S. Green Building Council (USGBC) has stiffened the energy-performance requirements for buildings seeking Leadership in Energy and Environmental Design (LEED) certification.

The new standard, approved in June, requires projects to earn at least two "Optimize Energy Performance" points. That increased requirement will improve the energy performance of LEED-certified new buildings by 14 percent and existing buildings by 7 percent. The new requirement will help maximize a building's energy performance.

The USGBC raised the bar for energy efficiency because buildings generate nearly 40 percent of the carbon dioxide (CO2) produced by the United States.

A greenhouse gas that contributes to climate change, CO2 has increased 18 percent since 1990 because of rising energy use. Buildings cause CO2 emissions through energy use, water consumption and other operational requirements.

To view the energy optimization section of LEED, visit http://www.usgbc.org/ShowFile.aspx?DocumentID=2303. For more information on USGBC or LEED visit www.usgbc.org.