A next chapter in Sino-Dutch Sponge city development: Cooperating on sponge, breathing buildings

A sponge absorbs water, and will let it go again when squeezed: that is normal. Now what would happen if we apply this concept on a larger scale, say for example a building or even a city? Sponge cities are no futuristic concept, they are being built right now. China has severe problems when it comes to water (too much, too little, too polluted) and is urbanizing very fast. Though a long tradition with water and delta management, the Dutch also have some urban water challenges. So it is no wonder that there is ample of room for cooperation.

Since 2013, when the Chinese government started to talk about the concept and implementation of Sponge City Construction, the Dutch government (and representative network in China) started cooperating with the Chinese government and affiliated organizations. With water management in their genes, the Dutch are a very welcome cooperation partner for the Chinese to work on sponge cities, both from the urban planning as well as from the water technology perspective. Yesterday we saw the start of yet another cooperation in Dalian, between Hengji Water Group and Hanging Water Tank. Both parties signed for the start of the Sino-Dutch Sponge Building Research Demonstration Project which will take place in the coming year.

Making the most of rain water

So how are buildings, water and sponges exactly connected? The core concept of a sponge building is the reuse of rain water. Rain water is stored on the roofs and in green building facades and can be released whenever it is needed. This creates new possibilities to use rain water instead of ground water, thereby reducing the use of scarce groundwater for fresh water purposes. Sponge buildings not only restore the water balance in the city, but also minimize the chance of floods – as water will be held – ease water management and save water.

“And that is not all,” emphasizes mr. Hong Jiang, vice-CEO of Hengji Water Group. “Besides being sustainable, green and ecological, sponge buildings help collecting rainwater through its roof, this water can be used for watering the plants or washing your car.” Mr. Jiang explains that the use of rain water could even become broader. “Rain water is alkaline water, which is beneficial for your hair so you can use it to shower. After washing your hair, the water could be used again in a factory.” Controlled infiltration of rain water in a city can replenish the ground water. Continued use of rain water could even restore the natural ground water level.

Breathing buildings

Another important effect of sponge buildings is that they reduce the heat in urban areas. Since cities have large concrete and asphalt surfaces, they warm up easily and radiate this heat in all directions. “Therefore, even putting on the air conditioning at home does not have a lot of effect when it is so hot outside. But sponge buildings can reduce the heat through their walls and roofs. They actually are like breathing buildings.” Mr. Jiang mentions.

Succesful cooperation on an important topic

The cooperation with Hanging Water Tank is not a coincidence. The Dutch company participated in a trade delegation from Overijssel that visited the province of Liaoning in November 2016. During an information meeting on Dutch innovative and sustainable technology in Dalian, organized by NBSO Dalian, Hanging Water Tank presented their concept and caught the attention of Mr. Jiang. The two companies sealed their cooperation yesterday. The building of the demonstration project was also subsidized by Dutch government.

Sponge cities remains an important and relevant topic throughout China. There will be a lot of attention on the topic again next week when the Dutch government network will organize Sino-Dutch seminars in Chongqing and Shanghai. Besides the project mentioned here, many other Sino-Dutch cooperation projects will be presented during that event.