BEIJING - Most buildings in China are not up to the country's energy-efficient standards even though it is trying to save energy to fulfill emission reduction commitments, an official has said.

"There is great room for mandatory energy-efficient measures to be introduced to buildings," said Chen Zhong, chief engineer with the Ministry of Housing and Urban-Rural Development, during an online exchange with netizens on Tuesday.

According to the ministry, only 23 percent of the country's buildings in urban areas were energy-efficient last year, while wastes of energy are common in buildings in rural areas, particularly in northern regions.

Apart from energy saving in the industrial and the transport sectors, China has been working hard in recent years to promote energy saving inside buildings. That work saw the equivalent of 100 million tons of coal saved in the period between 2006 to 2010, equating to cutting about one-fifth of the country's total energy.

Chen said buildings are expected to consume more energy and account for about 40 percent of China's total energy consumption in the future due to urbanization, compared with 27.5 percent now.

Renewable energy such as solar and geothermal power will be used in more buildings to reduce the use of fossil energy like coal and natural gas, according to the official.

The Chinese government has pledged to reduce carbon dioxide emissions per unit of gross domestic product by 40 to 45 percent by 2020 compared to 2005 levels.

The government is also aiming to have green buildings account for 30 percent of new construction projects by 2020.

"Green buildings" require construction projects to be as economical as possible with energy, land, water and materials.