FEATURING a rooftop garden that can collect rainwater and is full of local green plants, a residential building in Gangxiacun, Futian District, has contributed to the construction of a Sponge City with its own ecological approach, the Shenzhen Special Zone Daily reported.

Meanwhile, the rooftop garden, lined with steel frames and boxes of green plants, is probably the first Sponge City project to be launched in an urban village in China.

Encircling the small terrace, the steel frames form a green barrier on the rooftop. Xiao Wenhang, the chief designer of the project, explained that this is also one of the original design purposes: to add a touch of greenness to the “handshake buildings” and provide more privacy for residents living in the urban village.

The hollow steel frames are painted with white fluorocarbon paint and separated into a grid of about 33.5 centimeters in length and 32.5 centimeters in height. The secret to collecting rainwater lies in the boxes, as there is an aqueous stratum at the bottom of each box.

The aqueous stratum can collect about four liters of rainwater. Additionally, there is an opening in the box where excess rainwater can be drained to prevent the plant’s roots from rotting.

According to Xiao, when the water in the box overflows, it is collected and discharged into a storage tank, which can store 400 liters of water that can be used to water the flowers when it doesn’t rain.

Moreover, the green infrastructure includes more than 300 boxes of green plants, a swing, and some tables and chairs.

Liu Ting, the project’s plant designer, said that in order to meet the requirements of being low maintenance and having low energy consumption, she chose many local plants, which account for more than one-third of the total species of green plants.

Also of note, there is a buoy in the corner of each box, which conveniently indicates how much water is in the aqueous stratum.

It is estimated that the green facility can help reduce runoff by 65 percent, far exceeding the requirement of the Sponge City initiative for rainwater control in residential estates like urban villages.

According to Xiao, the whole project adopts a low-tech approach that is easy to replicate. He hopes it will serve as an example for more possible ways to make use of the rooftops in urban villages. (Zhang Yu)