LOS ANGELES, May 9 (Xinhua) -- California's primary energy policy and planning agency unanimously approved a building rule Wednesday that requires solar systems be installed in all new homes, making it the first U.S. state to issue such a rule.

To cut energy use in new homes by more than 50 percent in order to reduce greenhouse gas emissions, the California Energy Commission adopted building standards that require solar photovoltaic systems starting in 2020, according to the California Energy Commission.

The agency hopes that the energy efficiency standards for new buildings will help to reduce greenhouse gas emissions by an amount equivalent to taking 115,000 fossil fuel cars off the road.

According to the new rule, solar systems will be installed on all new houses as well as condominiums and apartments up to three stories high.

Under the new standards, non-residential buildings will use about 30 percent less energy due mainly to lighting upgrades. For residential homeowners, based on a 30-year mortgage, the Energy Commission estimates that the standards will add about 40 U.S. dollars to an average monthly payment, but save consumers 80 dollars on monthly heating, cooling and lighting bills.

"Under these new standards, buildings will perform better than ever, at the same time they contribute to a reliable grid," said Commissioner Andrew McAllister, who is the Energy Commission's lead on energy efficiency, in a press release of the agency.

"The buildings that Californians buy and live in will operate very efficiently while generating their own clean energy. They will cost less to operate, have healthy indoor air and provide a platform for 'smart' technologies that will propel the state even further down the road to a low emissions future," McAllister said.

Although some critics worried that the new rule will increase the cost of building a new home, California Building Industry Association CEO and President Dan Dunmoyer said that the homebuyers will recoup their money over the life of the dwelling.

"With this adoption, the California Energy Commission has struck a fair balance between reducing greenhouse gas emissions while simultaneously limiting increased construction costs," said Dunmoyer in a press release.