Growing up in Mao Tse-tung's hometown of Shaoshan in southern China, Tan Huiyan remembers the wintertime sensation of stepping inside through her front door — and into the cold.
"People in my hometown always say it's colder in your home than outside in winter," recalled Tan, 31, who now lives in Beijing. "When I came home, I had to change into warmer clothes. After taking off my winter jacket, I had to put on very thick and padded pajamas. My Nike sneakers were not warm enough to be used at home, I always had to change into boots with furs inside, like those Ugg boots."
Temperatures in Shaoshan can dip to as low as 23 degrees in January, and the average is around 46 degrees from December to February. But a key dividing line — established by Communist Party officials almost 60 years ago — bisects China into wintertime central heating haves and have-nots, and Tan was on the wrong side of it.
On Saturday, and every Nov. 15, people who live in apartment complexes in Beijing, Harbin and hundreds of other cities north of the boundary will rejoice as government central heating plants are fired up, flooding warmth into citizens' abodes for four months. Those who live south of the line — even by a mile — will suffer the season with nary a puff of steam from a radiator.
The great heating divide, which traces the Huai River and Qin Mountains near the latitude 33 degrees north, dates from the 1950s. Back then, China started to install centralized systems for residential areas with assistance from the Soviet Union. But China was facing an extreme energy shortage in those years, and Premier Zhou Enlai suggested the Qin-Huai line, a well-known demarcation between north and south, as a cutoff point.
The divide was not ironclad. The Huai River runs through Xinyang in Henan province, but because more than 75% of the people live south of the river, the city was left out of the heating club. About 66 miles north, Zhumadian in Henan enjoys central heat. But go 43 miles north to Luohe, and there are no radiators in sight.
The line divides two of China's largest leading cities, with Shanghai, where the temperature average is about 40 degrees in January, just below the line while Beijing, at a chillier 25-degree average for the month, is well above it.
It's not an easy inequity to resolve, perhaps made all the more difficult this week by the announcement of an agreement between China and the U.S. to curb greenhouse gas emissions. If China took the unlikely step of providing central heating to all the residential urban areas in the south, it would need to burn an additional 50 million tons of coal each year, Jiang Yi, director of a building energy research center at Tsinghua University, told the Beijing News.
Unlike the U.S., where housing codes typically require residential buildings to meet certain indoor temperature minimums in cold weather, Chinese cities do not have such standards. In areas where the government doesn't provide central heating for the whole city, residents are left to deal with the cold on their own.
Historically, many northern residents would have a kang, a brick bed heated by wood burned underneath it. But southerners had no such tradition.
These days, with economic growth raising standards of living and private developers building homes and apartments, the Qin-Huai line is increasingly considered anachronistic, inconvenient and even inhumane. Some cities have experienced blackouts because so many people are plugging in space heaters.
Pan Yiqun, a professor from the Institute of Heating, Ventilating and Air Conditioning and Gas Engineering at Tongji University in Shanghai, said using the Qin-Huai line "doesn't suit people's needs today.... Outdoor temperature should be the decisive factor on where heating should be provided."
Two years ago, a member of the National Committee of the Chinese People's Political Consultative Conference submitted a proposal to extend the heat southward. And a writer for the Communist-run newspaper last year reiterated the call.
"We are no longer a country in shambles," wrote Shu Meng. "The Chinese government has the ability to let more people live in warm conditions in the winter."
Pan and her colleagues are doing research on possible solutions. Citywide systems like those in the north, she said, are inefficient because a lot of energy is lost moving hot water through pipes. Systems for each household or building are better.
In Shanghai, where heating is not provided by the government, many new apartments have their own systems. But expenses for the residents are significantly higher than in cities with government-provided heat.
For a 1,076-square-foot apartment in Beijing, a resident pays about $490 for four months of heating. Shanghai residents using individual gas boilers or electric heaters pay almost double that for gas or electricity.
Tan, who moved to Beijing in 2004, said she's reluctant to visit her parents during the winter. Though the outdoor temperature might be warmer in Shaoshan than in the capital, she can no longer endure the "room temperature," which can dip below 50 degrees.
"I only spend Chinese New Year with my parents once every two years and stay with them for only two to three days each time," she said. "Because it's really impossible for me to stand how cold it is indoors there."
Tommy Yang in The Times' Beijing bureau contributed to this report.