HAIKOU -- Sanya, a resort city on China's tropical island of Hainan, has replaced air conditioners with a centralized supply of cold water in several high-end hotels and duty-free shops, raising new prospects for a greener solution to the summer heat in China.

The district cooling system, in which chilled water is produced and distributed by a central source to cool multiple buildings in an area, has become a talking point on China's internet amid the current heatwave. It has gained attention for its promise of providing cool environments with more efficient energy use.

In Sanya, seven hotels, as well as the Sanya International Duty Free City, in Haitang Bay have started using the service, according to EDF Changfeng (Sanya) Energy Co., Ltd., which runs the city's district cooling system.

Haitang Bay is home to a cluster of luxury hotels, including Westin, Edition and Fairmont.

The district cooling network in Sanya sends out water at 7 degrees Celsius via a pipe system. District cooling systems enjoy economies of scale and optimized central management, making them much more energy efficient than individual air conditioners.

Launched in 2021, the Sanya system is capable of saving about 28,000 tonnes of standard coal and reducing 76,000 tonnes of carbon dioxide emissions every year when running at full tilt, according to the supplier.

For hotels, the use of district cooling can also reduce bacteria and noise pollution compared to traditional cooling systems, said Liu Guoyang, secretary-general of Hainan's hotel engineering association.

"More and more hotels in Sanya have become aware of the importance of energy saving and carbon reduction," Liu said.

Central air conditioning accounts for about 40 percent of the total energy consumption of public buildings, said Bai Shouyue with the China Association of Building Energy Efficiency.

District cooling that features lower energy consumption is therefore significant for the green development of cities like Sanya, where the service industry is growing rapidly along with the number of high-end public buildings, said Bai.