In ravaging cold, when Chinese people living in northern cities are enjoying indoor warmth, southerners wonder how long they have to wait for before the government decides to install a public heating network.

The problem is they are trapped by a line drawn by late Premier Zhou Enlai six decades ago.

The line, which stands between 32 and 34 degrees north latitude, almost along the Huaihe River and Qinling Mountains, not only defines China's northern and southern parts, but also determines different winters for the people.

Cities to the north of the line have public heating which circulates hot water generated by government heating stations through pipelines and radiators inside almost every resident's building and public facility.

Room temperatures in the north could be more than 20 degrees Celsius.

However, people living in cities to the south of the line, including the country's largest city Shanghai and other major metropolitans Chongqing, Nanjing, Wuhan, have to use various private and isolated heating devices to warm their freezing and humid houses.

The southerners have been plagued by the winter chill and have been complaining, especially after cold-air outbreaks when snow and ice have frozen southern provinces such as Hunan and Guangdong.

"Without heating indoors, even getting up takes a lot of courage," "wangzikai" said on the popular twitter-like Sina Weibo.

Dai Tongtong, a freshman studying in central China's Wuhan City, is a northerner. She said the cold mixed with moisture in the south affects her no matter how thick her clothes are.

To get away from cold of the dormitories, she and her fellow students cram into libraries and public reading rooms to share warmth generated by air conditioners.

In an opinion poll conducted by qq.com on Thursday, 88 percent of a total of 104,618 participants voted to install a collective public heating network in the south.

Some local governments in the south have started to build trial heating networks in urban communities, while national legislators and political advisors still endeavor to persuade the central government in giving local governments the option to construct public heating networks covering whole cities.

Zhang Xiaomei, a member of the Chinese People's Political Consultative Conference, China's top political advisory body, said pushing the line southward can not only warm the public, but also expand domestic demand and increase employment.

Zhang added it is also "a solution for energy conservation and emission reduction," on which industry insiders and experts have yet to reach a consensus.

"It is definitely not economical in terms of energy efficiency to install public heating in the south," said Han Xiaoping, CIO 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," said Han in an interview with China National Radio, "thus it does not do justice to build a complicated heating network from scratch."

He added that the problem in the south also lies in insufficient heat insulation designs in architecture, which sees single-layer window glass installed in houses, making it difficult to keep warm.

Studies by Professor Jiang Yi with Tsinghua University, also an academician of the Chinese Academy of Sciences, estimated that if the government build public heating networks in the south, it will increase the total energy consumption of the country's urban buildings by 4 percent.

Voices who favor the construction of public heating in the south warned that electricity-powered devices may not put these energy-efficiency-concerned experts at ease.

According to a report by China Academy of Building Research, ten major provinces in the south have witnessed a big 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.

Netizens even started a verbal attack on Shen Herong, an expert living in Jiangsu Province who said people in the south are used to wet winters and might not adapt themselves to indoor radiators which often make the air dry.

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

Meng Fei, a famous TV anchorman, also joined the debate, "what does the southern region refer to in China? People in the northeast consider others southern people, while those in the southmost Hainan Province call all the rest northern people."

Meng on his Sina Weibo wrote, "Several provinces in central China, although lying to the south of the Qinling-Huaihe line, also have a freezing winter."