"Prior to the sale of an existing residential structure, all toilets must be retrofitted with high efficiency toilets that meet the most recent requirements of the EPA Water Sense program. All city buildings with 5,000 square feet or more and all commercial buildings with 10,000 square feet or more must attain a LEED rating of silver. Select city buildings are required to achieve a gold rating. Commissioning is required for city buildings as a prerequisite for LEED. The energy performance and CO2 emissions for green buildings must be calculated to ensure that the structure exceeds the California Code by 15%."