In the time before air-conditioning, southern China's sky wells played a key role in keeping people's homes cool. Could they do it again today?

A skywell, or "tian jing", is atypical characteristic of traditional homes in southern and eastern China. Different from a northern Chinese courtyard, or "yuan zi", a skywell is smaller and less open to the outdoor environment. Its size and design differ from place to place.

Skywells were designed to cool buildings at a time well before air-conditioning existed. When wind blows above a skywell house, it can enter the indoor space through the opening. Because outdoor air is often cooler than indoor air, the incoming wind travels down the walls to the lower stories and create airflows by replacing warmer indoor air, which rises and leaves through the opening.

Although skywell buildings have existed in China for hundreds of years, in recent times they have often been forgotten by people who prefer modern buildings. Over the past two decades, however, skywell buildings have been making a comeback.

Yu Youhong, 55, has spent more than 30 years restoring(修复) skywell homes in Wuyuan county of Jiangxi province, apart of the old Huizhou. One of the skywell homes restored by Yu is in the village of Yan, in Wuyuan county. The deserted 300-year-old house was bought by Edward Gawne, a former marketing director from the UK, and his Chinese wife, Liao Minx in, in 2015. The couple turned the three-storey house into a 14-room hotel with the help of Yu. They kept the spaces surrounding the sky wells in their original state: open and with natural airflow. Gawne says that even without air conditioning the skywell areas are very comfortable in summer.

Yu says he expects sky wells to be more and more popular among younger generations especially as sustainability(可持续性) becomes an important element for new buildings.