The local government has begun accepting applications for a program that subsidizes green wall and rooftop garden projects on public buildings across the city, local officials announced at a press conference Tuesday.

The Shanghai Municipal Afforestation and City Appearance and Environmental Sanitation Administration launched the subsidy program to encourage public institutions, such as schools, hospitals, libraries and museums to make full use of their space to expand the overall green space of the city.

"Green walls and rooftop gardens offer an alternative solution to expanding green space because land for creating public parks and green spaces in the city is limited," said Li Li, director of the agency's afforestation office. "These projects will add more greenery to the city's landscape, which is dominated by concrete high-rises."

Green walls and rooftops can help reduce a building's temperature by 2 C to 5 C in the summer, while keeping it 2 C warmer on average during the winter, Li said. 

"These green walls and rooftops can help save electricity by reducing the need for heating and air conditioning. They can also increase humidity and help purify the air," said Dai Xingyi, director of the Center of Urban Environmental Management Studies at Fudan University.

The agency will subsidize projects that cover more than 1,000 square meters at a rate of 200 yuan ($32) per square meter for rooftop gardens and green walls, and 50 yuan per square meter for rooftop lawns.

"It costs between 300 yuan and 2,000 yuan per square meter to install a rooftop garden, depending on the complexity of the engineering and drainage systems. Green walls are more complex, so they cost more than 2,000 yuan per square meter," said Li Jianguo, a project manager at Shanghai Gardening and Landscaping Construction Co Ltd.

Although the one-time subsidies cannot cover daily maintenance costs, they can still reduce the overall cost of construction and serve to encourage institutions to undertake such projects, Li said.