China faces the grave challenge of cutting energy consumption in its building sector as the country seeks to achieve its green energy goals, a senior official said on Monday.

"As much as 30 percent of China's total energy consumption is now operational energy consumption in buildings," said Li Bingren, chief economist of the Ministry of Housing and Urban-Rural Development, at a press conference organized by the State Council Information Office.

Meanwhile, the energy efficiency of buildings in China remains low, with a general energy-saving standard of 50 percent, he acknowledged.

"Even if the standard rises to 65 percent by 2020, the energy consumption for heating in China's buildings will still be 50 percent higher than the average in developed countries with the same climate," Li said.

By the end of 2009, the total construction area of energy-saving building in China reached 4.08 billion square meters, accounting for only 21.7 percent of the urban construction area.

In 2009, the floor area of new energy-saving building was 960 million sq m, resulting in an annual energy-saving capacity of 9 million tons of coal and a 23.4-million-ton reduction of CO2 emissions, according to the ministry's latest statistics.

Li said 150 million sq m of residential buildings will be modified for metering and conserving heat by the end of the year.

However, he said he anticipates energy consumption in buildings will continue to rise sharply across the country.

"As a result of accelerated urbanization, a large number of new buildings are added annually. People also now have higher living standards and use more domestic appliances, which contribute to the increase in energy consumption," he said.

Energy consumption in rural buildings also increased markedly, he noted.

For instance, daily energy consumption per capita in rural areas in 2007 was 1.8 times that in 2000.

Analysts and officials say that the country needs to strengthen its supervision of conserving energy in buildings to achieve its green energy goals.

Qiu Baoxing, vice-minister of Housing and Urban-Rural Development, said in March that energy conservation in some buildings had dropped 6 to 7 percent when compared to the original design standard.

"Energy conservation in buildings needs to be taken into account early in the construction process. For instance, if ordinary windowpanes are used instead of energy-saving ones to cut costs, the energy-saving effect will be reduced," said Ye Qing, dean of Shenzhen Academy of Building Research.

"The public should be made aware of energy conservation, which currently takes place on a voluntary basis," she said.

In a related development, the country's top planner has ordered local governments not to restrict the use of electricity or cut the power supplies to residential buildings and public service institutes.

The National Development and Reform Commission issued the order on Sunday after more provinces, such as Jiangsu, Zhejiang, Anhui and Hebei, resorted to restricting the use of electricity to meet their energy conservation goals, which triggered complaints from residents about the impact of the move on their daily lives.