Cooling underground

As the transportation business fights for more space in the sky, Shenzhen's Qianhai economic development zone is mapping out a "super" urban underground project covering more than 600 hectares, including more than 130 hectares of commercial space and public passages, 9.8 kilometers of highways, and a six-level public transportation hub, as well as a district system supplying cool energy for skyscrapers in the region.

Shenzhen Qianhai Energy Technology Development Co built and operates the region's district cooling system. At its No 5 cooling plant under a bus terminal, machines make ice at night — an off-peak electricity consumption period for commercial districts — and melt the ice during the day. The cold energy released when the ice melts will be collected to lower the temperature of water, which will be piped into users' buildings to provide cold energy for their air conditioning systems.

Fu Jianping, director of Shenzhen Qianhai Energy Technology Development, says the district cooling system helps property owners save an average of 6 percent of floor area, as the property owners would not have to install an individual air conditioning system on their premises.