The 2009 update of the city's policy reflects an energy efficiency improvement from the original LEED Gold requirement for all city-owned projects. The new construction and major remodels of city-owned facilities must register with the U.S. Green Building Council and certify at the Gold level, in addition to specific criteria for recycling, water conservation, energy conservation and onsite generation, commissioning, and cool roofs. Tenant Improvements and Leased Spaces must register and certify at LEED Commercial Interiors (CI) Silver, or use the Bureau of Planning and Sustainability's Green Tenant Improvement Guide. Existing Buildings must pursue LEED EB Silver, with specific criteria for roof replacements. Additional standards are in place for historic buildings and operations and maintenance.