California has this week unveiled a raft of new building regulations designed to improve the energy efficiency of new commercial and residential buildings.

The California Energy Commission (CEC) has updated the standards to include tighter regulations for lighting, windows, roofing, skylights, swimming pool and spa equipment, heating and air-conditioning systems.

For example, higher performance windows will be required in all new homes to improve insulation, while new "cool roof" standards will govern the use of new insulated roofing materials that can keep roofs up to 40 degrees cooler in summer conditions and save homeowners up to 20 per cent off their energy bill.

The new standards will also encourage wider use of skylights in an attempt to cut down on energy used for lighting. For instance, the current rule requiring skylights are installed in commercial warehouses larger than 25,000 square feet have been changed to include warehouses starting at 8,000 square feet.

The CEC said as well as saving money for both businesses and homeowners, they would also take the pressure off California's electricity grid. It said that the standards had been designed to cut peak energy use on hot summer days when demand for power from air-conditioning units can cause electricity demand to nearly double. The updated standards are expected to cut peak energy demand by 129MW in the first year they take effect and increase cumulatively over time.

"By 2013, the new building code will save as much energy as a large (500MW) power plant," said Noah Horowitz, senior scientist at green group the Natural Resources Defense Council. "These advanced performance standards place California on course to meet its future energy needs and help achieve its ambitious global warming reduction goals."

The announcement comes a day after Los Angeles passed a package of new building laws designed to cut carbon emissions by 80,000 tonnes by 2012.

The Private Sector Green Building Plan has been put together by the Mayor's office and the city council and will deliver a series of new requirements and incentives designed to encourage developers to ensure their buildings comply with the US Green Building Council's Leadership in Energy and Environmental Design (LEED) standards.

Under the plan, all building projects at or above 50,000 square feet will have to comply with the general LEED certification standard, while builders who commit to attaining silver LEED accreditation or above will receive faster processing of applications by the city's planning and public works departments.

The city has also pledged to streamline planning rules for green building features, such as more energy-efficient rooftops and cisterns, and develop a checklist of all available green incentives to help guide developers through the green building process.

"Our city is growing fast and growing up, and we are holding the private sector accountable to their commitment to be friends to our environment," said Mayor Antonio Villaraigosa. "Already the city of Los Angeles has the largest, most aggressive municipal green building plan of any large city in America. Now it is time for green building to go private."