Throughout history, architecture has often been shaped by the environment. One fitting example is the ancient Chinese “skywell” or “tian-jing.” This is an ingenious architectural feature used for centuries to keep homes cool in humid and warm climates. They are more common in southern and eastern China’s historic buildings — in areas such as Jiangsu, Anhui, Jiangxi, and Sichuan.
Also known as a “courtyard house,” the skywell is a testament to the resourcefulness of ancient builders. They understood the concept of cooling before electricity and modern HVAC systems.
These skywells have stood the test of time as sustainable and energy-efficient solutions for cooling homes since the Ming Dynasty (14th century). As the Chinese government pushes toward “greener” building standards to reduce carbon emissions, modern architects borrow a page from the ancient ones. Today, more and more buildings are being designed around these antique features.
The concept of Chinese skywells
In Chinese traditional architecture, a skywell is an open courtyard or well-like space usually located at the heart of a building or group of buildings. It is often a square or rectangular layout surrounded by the building’s rooms and wings. Their designs often featured the classic Chinese dou gong (beams and bracket eaves) overhangs to provide shade and collect water into a central basin.
Natural ventilation
Chinese skywells were so effective in cooling homes because they could harness natural ventilation. Cool air is drawn into the building from the lower levels, and warm air escapes and rises through the upper levels. This promotes fresh air flow, especially during hot summer days.
Thermal regulation
The skywell’s layout and construction materials also helped in thermal regulation. During the day, the courtyard absorbs heat from the sun, acting as a thermal mass. The stored heat is gradually released as the outdoor temperature drops at night. This day-night cycle helps maintain a balanced and consistent temperature indoors.
Shade and protection
Surrounding walls, buildings, and overhangs provide much-needed shade from direct sunlight. The courtyard was also meant to be a gathering point for families and communities, and skywells maintained a pleasant and comfortable environment for the occupants. Additionally, inward-facing rooms provided privacy and security.
Evaporative cooling
Most traditional skywells include water features, such as fountains or ponds. A recent study has shown that the most significant part of a skywell’s cooling effect comes from these water bodies. It’s probably why temperatures around them are 2.6° to 4.2°C lower than the average external temperatures.
As water evaporates from these features, it absorbs heat from the surrounding air. This reduces the temperature within the courtyard and surrounding rooms. This evaporative cooling was advantageous in regions with hot and dry climates.
Ample natural light
Besides their cooling effects, skywells provide ample natural light to the interior spaces. This reduces the need for artificial lighting during the day and contributes to a sense of openness and connectivity with nature.
The “flowing silver” (flowing water) around the skywells also symbolized wealth in ancient China.
Revival of Chinese traditional architecture
As mentioned, the Chinese central government has been pushing for greener home designs in the past decade. A 2019 government directive required that 70 percent of buildings built in 2022 should meet the “green” standards. These regulations include eco-friendly materials and sustainable insulation design.
Today, architects are adopting the concept of skywells and other traditional architecture in new buildings to conserve energy. One example is the National Heavy Vehicle Engineering Technology Research Centre in Jinan. This 18-story building has a giant open space at its heart from the fifth floor to the top floor. The toilets, elevators, and meeting rooms surround this space. This enhances natural ventilation, lighting, and natural energy consumption, according to the Shanghai-based CCDI Group.
Other designers have used the principles of skywell ventilation without building a courtyard because of space and practicality. For instance, the 68-story Dongguan TBA Tower in Guangdong Province directs natural airflow to every floor using internal “windpipes” that use the concept of skywells.
Some homeowners have also restored derelict skywells or added them as a feature. One such home is the once-derelict 300-year-old house bought by Edward Gaine and his Chinese wife, Liao Minxin, in 2015. The couple employed the expertise of Yu Youhong, 55, to restore the skywell in their home.
After restoring the skywell in their house, Gawne said the area’s aura is quite comfortable in summer.
“Everyone notes how naturally cool it is when they enter the house.”
Yu has been restoring skywells for almost three decades and has seen a resurgence of them in Wuyuan County of Jiangxi Province. He also expects more and more people to adopt this architectural feature because sustainability and conservation are becoming essential parts of buildings.
Conclusion
Passive cooling involves using design and technology to cool a building without power. The legacy of skywells is a true testament to the remarkable ingenuity of ancient builders in harnessing nature’s elements to create energy-sufficient and sustainable living spaces. These timeless architectural wonders continue to inspire architects in their pursuit of environmentally friendly solutions for cooling homes and buildings.
Wang Zhengfen, a postdoctoral researcher in environmental humanities, says modern architects should seek inspiration from “ancient green wisdom.” She also advocates for a change in how we live our lives to make an environmental impact and reduce pollution.
“Perhaps changes in the way of life could also trigger vernacular nostalgia among people living in concrete and glass forests.”
