A library in Guangzhou, capital of Guangdong province, is using cold water pipelines instead of air conditioners to beat the heat and cut electricity consumption.

"In addition to saving on electricity, the cost of buying cold water as a cooling source is much lower than installing an air conditioning system," said Huang Zhenxiong, director of the asset and property management department of Guangzhou Library.

The centralized cooling system, installed with inlet and outlet water pipes, cools the air by using water pumps, according to Huang.

"It is more like central air conditioning using water, which delivers cold air through pipelines to keep the indoor temperature constant at around 26 C," said Huang.

Cold water pipes supplied from a third-party cold station have a constant inlet temperature of around 2 C, and the outlet temperature is about 7 C, with an overall temperature difference of over 4 C, according to Huang.

Located in booming Zhujiang New Town, the library received more than 700,000 visitors in July, with the daily number of visitors surpassing 40,000 at weekends, according to Zeng Qian, who works for the library's publicity department. "The huge flow of visitors has an impact on the temperature changes at the library," she said.

Cold water is supplied from a nearby cold station, which was built in 2008, according to Zeng.

The ice for the station is made at night when the cost of electricity is lower, said Teng Lin, general manager of Guangzhou Pearl River New Town Energy Co.

"The ice melts after the water is injected in the daytime. The ice water is then delivered to the users' facilities via pipes, which will cool the air. A secondary pump fans out the cool air," said Teng.

Making ice at night for the cooling system sharply reduces the cost of electricity, said Teng. The price of commercial electricity in summer during its lowest usage time from midnight to 8 am is 0.19 yuan per kilowatt-hour. This compares with 1.63 yuan per kWh during the daytime peak, said Teng.

"Ice will be stored as much as possible with the cheap electricity price at night and delivered to buildings nearby," he said.

The company's cooling services cover building areas of 2 million square meters, including nearby subways, theaters and office buildings.

With a growing number of cities including Jinan, Shandong province, and Wuhan, Hubei province, issuing high-temperature alerts this summer, the centralized cold water cooling system is gaining traction across the country.

In Shenzhen, Guangdong, the construction of a large cold station in Qianhai, which is part of a pilot free trade zone, will soon be completed. The station will help cool nearly 1 million sq m of office space.

Construction of nine more cold stations, with a cooling pipeline network of 90 kilometers, is planned to eventually help cool 15 million sq m of building space in Qianhai.