The heating supply in Changchun, capital of northeast China's Jilin Province, will not come on until Oct. 28, but the outdoor temperature has already dropped to below zero at night.

The temperature inside Li Guiling's house was 14 degrees Celsius on Friday, warmer than before a government-funded renovation on the building was done.

"The indoor temperature would rarely reach 16 degrees Celsius in the past, even when the heating was on," she said.

Millions of other Chinese living in communities where houses were built before the 1990s still suffer through the cold winters as their houses are not well insulated.

Zhang Wenhai, an energy efficiency expert with the Jilin Provincial Society of Earthwork Construction, said nationwide, 40 billion square meters of buildings need to be renovated to save energy and make homes warmer.

The Chinese government introduced a program in 2006 which aims to renovate 150 million square meters of buildings in north China by the end of this year.

As a result of the program, Li's house was renovated this year.

"A 6-cm thick wall board was affixed on the outside walls of the building and workers also replaced aluminum alloy windows with plastic steel windows for us," said the elderly lady.

Gong Wenyi, general manager of Jilin Tongxin Heating Group, said 60 percent of buildings in the province still needed such renovations to improve energy efficiency.