China needs to spend 2.6 trillion yuan to cut the amount of energy wasted while heating and cooling buildings and to help ease fuel shortages, Qiu Baoxing, deputy minister for construction, said Thursday. About a third of China's buildings need to have heat- retaining windows and fitted doors, Qiu told reporters in Beijing. The amount China needs to spend is equivalent to $323 billion

"The market potential for such construction projects is huge," Qiu said. "It can bolster domestic consumption and achieve the aim of saving energy."

China's economy expanded 9.9 percent last year, spurring demand for power in factories and homes. The country had a power shortfall of 25,000 megawatts when demand peaked in the summer, with shortages affecting major cities and 18 provinces.

Greater energy efficiency would help curb growth in China's oil demand, which may reach 7 percent this year, the state-run Xinhua News Agency said Sunday. China's government plans to halt property sales for new projects that fail to meet mandatory energy-efficient building standards to be introduced this year, Qiu said.

New buildings will need a minimum energy efficiency rating of 50 percent, achieved, for example, by halving coal use through recycling and new technology. The benchmark will be raised to 65 percent by 2010, Qiu said.

Beijing buildings typically use 25 kilograms, or about 55 pounds, of standard coal to heat each square meter of floor area during winter, said Wang Tiehong, a chief engineer at the Construction Ministry.

China is setting up a certification system for new buildings, rating levels of energy, water and land conservation, Qiu said. The government in the next two years will change the system of pricing the heating supplied to households, and will start to charge consumers for the amount used, rather than on a per-square-meter basis, Qiu said.

Construction costs for energy-efficient buildings are typically as much as 8 percent higher than the current average, Qiu said. The government is studying the feasibility of cutting property taxes to offset the impact of this, he said.

Chinese households' use of electricity is rising, with power for air-conditioning contributing the bulk of the demand, Qiu said. Air- conditioning accounts for about one-third of electricity used in cities such as Shanghai, and demand is increasing at an average of 4 percent a year, he said.