Kong Xia's family apartment with green and new LED lights. [Photo by Sun Ye/China Daily]

One low-carbon solution to the problem is turning to new materials that insulate better than what many old-fashioned apartments still rely on: changing aluminum window panes to broken bridge ones that keep the cold out, or overlaying insulation membranes that conserve the heat. Green plants in the house also help with humidifying and keeping indoor temperatures stable.

"These changes improve your life," says Wang. "Low-carbon households let you live better while also conserving energy," he says.

Smog, another worrying problem Beijing residents face, can also be reduced by low-carbon households.

Luo, for one, has learned to build 300 yuan air cleaners at her workshop.

Luo, as 17 others that joined the workshop this year, completed a draft design plan by herself and went through a mock thesis defense where she explained her plans from sockets to a water system to an expert panel.

FoN subsidizes each household with no more than 10,000 yuan.

Wu Jingshan, independent architect and consultant who has been working with energy-conservation architecture since the early 2000s, says: "They may not be professional designers, but they know what they need better than any outsiders could ever know.