BEIJING -- The government will require new urban buildings to reach mandatory energy-saving standards, as well as renovate existing buildings, to make them more environmentally friendly by 2015, the country's top economic planner has said.

A "green" building code will be adopted for all government-invested buildings built from 2014 on ward, said an official with the National Development and Reform Commission who declined to be named.

As of 2014, the standard will also be applied to affordable housing projects in China's provincial-level cities, provincial capitals and vice-provincial-level cities, as well as to public construction projects with an area of more than 20,000 square meters per building, the official said.

The cost of meeting the minimum requirements will be just 50 yuan ($8) per square meter, according to the official.

Renovations will also be carried out for urban buildings to improve the efficiency of their heating systems.

Chinese buildings consume too much energy and resources and use them inefficiently, while many buildings are demolished as fast as they are erected in some places, leading to significant waste, the official noted.

China currently has more than 40 billion square meters of existing buildings, with about 2 billion square meters being added each year.

The government aims to construct green buildings totaling 1 billion square meters in area during the 2011-2015 period and ensure that green buildings account for 20 percent of all new buildings in the country's cities in 2015, according to a government plan released last month.

Houses in China's northern regions will have their indoor heating systems upgraded to become more efficient starting from 2015, according to the plan.

The plan also calls for renovating 120 million square meters of public buildings in order to make them consume less energy.

The government is trying to convert China's economy into a low-carbon economy following years of breakneck growth that strained energy and resources and worsened pollution.

By the end of 2015, China will lower its energy consumption per unit of GDP by 16 percent from 2010 and lower its carbon dioxide emission per unit of GDP by 17 percent, according to the government's 12th Five-Year Plan (2011-2015).