Rooftop sprinkler system cools homes in Yuncheng

A video shared by Foreign Ministry spokeswoman Mao Ning on overseas social media platforms garnered interest in an innovative "rooftop rain" cooling system installed at a residential complex in Yuncheng, Shanxi province.

The mist-dispersing cooling system "drops surface temperatures by 5-8 degrees in minutes", Mao said.

The video, posted on July 1, has also drawn attention from French media, which praised the rooftop sprinkler setup as an innovative outdoor mist-spraying system. The footage was filmed at the Xijian Tianmao Guobinfu residential compound in Yuncheng's Yanhu district. All seven apartment buildings in Phase 1 of the compound are equipped with the spraying system. High-pressure atomizing nozzles are mounted on three sides of each building, excluding the street-facing facades.

The equipment was activated regularly during peak hot summer days, ensuring that over 1,000 households benefited from its cooling effect. Activation saw thick mist surging out of the nozzles and cascading down like water curtains surrounding the building, providing residents with some respite from the heat.

According to Li Yuan, a worker at the residential compound, the sprinkler system cost over 10 million yuan ($1.48 million) and was officially put into operation in August 2024.

A single spray session lasts roughly 10 minutes, with personnel able to adjust water volume and spray duration based on real-time temperatures. After each round of artificial rainfall, the ambient air temperature drops by 5 to 8 C on average, while ground temperatures can fall by up to 12 C, Li said.

Yang Dandan, a resident living in the compound, regularly took her daughter out after a spraying session. "It becomes noticeably cooler with much fresher air after the roof rain, and my daughter has a wonderful time playing here," she said.

Liu Zhongsen, a senior official from Shanxi Tianmao Real Estate Development Co, the project developer, explained that the rooftop cooling system was never just an impromptu gimmick intended to garner internet buzz but was included in the original construction blueprints. "Our original intention is to better serve residents," he said.

When asked about the inspiration behind the sprinkler design, Liu, a Xi'an University of Architecture and Technology graduate, shared that the idea came from a method that is common in construction sites. "Sprinkler systems on construction sites work effectively for dust control and heat reduction. I wondered if we could adapt this equipment for residential neighborhoods to bring natural cooling to residents during hot summers," he said.

Despite its high-tech appearance, the system operates on a straightforward physical principle. The core innovation lies in integrating pipeline embedding and equipment installation into early-stage architectural planning with precise technical calculations.

During the design stage, engineers accurately calculate the capacity of water storage tanks in advance and fine-tune water pressure for rooftops of varying heights, as pressure directly impacts the length of cascading water mist.

Residents bear no extra costs for the operation of the roof rain system, according to Liu. Property fees remain at 1.3 yuan per square meter each month, plus an elevator fee of 0.5 yuan per square meter monthly, with no price hikes linked to the sprinkler facility. In addition, an artificial snowfall system is activated during the winter to further enrich residents' experiences.

Guo Jizhong, an elderly resident, praised the dual seasonal artificial weather systems: "Last winter, the artificial snow greatly purified the air and benefited seniors. This summer, the roof rain sessions quickly reduced temperatures, bringing tremendous comfort to us."

Li Jincong, a property management worker at the compound, analyzed the comprehensive economic and social value of the sprinkler system. "The water mist suppresses floating dust and reduces our cleaning labor. The moisture penetrates 3 to 5 centimeters deep into soil across the green space, protecting vegetation from drought and lowering our long-term landscape maintenance costs," Li said.

The cooling system showcases innovative measures being implemented in China as extreme heat events grip parts of the world. Widespread heatwaves swept across Europe in June and July, shattering historical temperature records in numerous countries.

Contact the writers at zhuxingxin@chinadaily.com.cn