2024 - Fairness and Freedom of Sunlight

Heaven bestowed upon Sichuan the finest piece of land in China, and Sichuan, in turn, granted Chengdu its most precious land. However, despite the many advantages of the Sichuan Basin, there is a fatal flaw: sunlight exposure. If you examine the map of solar radiation distribution in China, you will be surprised to find a vast, nearly circular lowland area in the southwest: this is the Sichuan Basin. The humid monsoon winds enter the basin and are trapped by the surrounding mountains, leading to cloud formation and rain, which results in Sichuan, especially Chengdu, having the lowest annual sunshine duration and total solar radiation in the country. This greatly disadvantages the lighting conditions in local residents’ lives.

In such a lighting environment, we still want to defend the fairness and freedom for residents to enjoy sunlight. How can we retain as much sunlight as possible, allowing it to shine fairly into every room of the building, whether it’s the lower or upper floors, inside or outside? Let the sunlight not just stop on the ground or walls after entering through the windows, but traverse through floors and rooms, illuminating the entire building freely. We hope to start with this intention, to offer a new style of mountainous residential building design that responds to lighting conditions and basin climate, providing residents with fair and free sunlight. We chose a south-facing hillside in Dujiangyan to carry out the residential design, and then extend it to this area. We believe it can provide an answer, allowing residents here to enjoy the same right to sunlight as residents in other regions.

The original residence we are going to transform is located on a south-facing hillside at the junction of urban and suburban areas in the northern part of Dujiangyan City, Chengdu, Sichuan Province, with coordinates of 31°00′46″N, 103°37′15″E, and an altitude of 776 meters.

The site has an average annual sunshine duration of only 967 hours, about one-third of that of Lhasa City in China, and is in one of the areas with the lowest annual sunshine duration in the country. At the same time, the site has an average annual total solar radiation of only 3172 MJ/㎡, about 43% of that of Lhasa City, also one of the lowest in the country. This unfavorable sunlight situation is not only directly related to the overall climate of Chengdu but also related to the micro-terrain of the site: the site is located on the east side of the alluvial fan at the mouth of the Minjiang River flowing out of the Tibetan Plateau. There is a mountain with an altitude of 1054 meters in the west and northwest directions, which largely blocks the afternoon sunlight from the west, making the sunlight situation here even more pessimistic.

According to the site environment, we have twisted the frame structure of the building to increase lighting at different times, with the central courtyard as the core light bucket placed in the center of the building, intertwined with the surrounding rooms, allowing light to enter every room equally. The form is like the core corridor of a long house that penetrates the depth of the building for lighting. Four rooms climb up according to the terrain and increase the infiltration of outdoor space. At the same time, planting holes are left for plants to follow the seasons and adjust the indoor light permeability, further enhancing the natural affinity of the building. The transparent light experience brought by the staggered floors, combined with the lighting windows and local light buckets brought by the twisting of the volume, constitutes a three-dimensional system of free light spread. This architectural form is in line with the terrain, blends with nature, is transparent and free, and people can live comfortably and enjoy the freedom and hope brought by sunlight because of such space and lighting.

Architecture is the learned game, correct and magnificent, of forms assembled in the light. – Le Corbusier