"It is definitely not economical in terms of energy efficiency to install public heating in the south," said Han Xiaoping of China5e.com, an energy information website.

"The coldest time in the south may not exceed 60 days in each year, compared with 120 to 180 days in the north," Han told China National Radio, "thus it does not do justice to build a complicated heating network from scratch."

He said the problem in the south also lay in insufficient insulation, with many houses having single-layer window glass installed.

Studies by Professor Jiang Yi of Tsinghua University estimated that if the government built public heating networks in the south, it would increase total energy consumption of China's urban buildings by 4 percent.

According to a report by China Academy of Building Research, 10 provinces in the south witnessed a surge in power consumption for heating by electric devices, from less than 100 million kilowatt-hours in 1996 to 39 billion kilowatt-hours in 2010.

Qiu Baoxing, vice minister of Housing and Urban-Rural Development, worries that providing public heating in the south may jeopardize China's energy supply.