The skywell is a typical feature of Huizhou architecture and an important space; thus, there is the saying that “all halls are wells” ^[1][2][1,2]. In traditional Huizhou architecture, the skywell, as a transition space between the interior and exterior [3], not only has positive significance for the lighting and ventilation of the building interior but also contains a lot of traditional Huizhou culture. Huizhou is famous for Huizhou merchants, who do not lack money and pay more attention to the construction of their own houses and the comfort and beauty of their houses; they set up skywells in their houses to acquire the aura of the “unity of heaven and man” and the pride of “standing on top of the sky” [4]. On sunny days, the sun shines through the skywell to the front of the hall and the rooms, which means “sprinkling gold” [5]; in rainy and snowy weather, rainwater flows down from the eaves around the skywell and sinks into the tank below the skywell, which means “flowing silver” and is a metaphor for wealth, also known as the “four waters to the hall” [6]. In the skywell, combined with the through corridors and open halls, when the outdoor wind speed is high, wind pressure ventilation makes up the majority of the wind entering into the room from the skywell out, reducing the amount of indoor ventilation. When the outdoor wind is still, the skywell-shaped thermal pressure, which promotes indoor and outdoor ventilation, thus forms a complete ventilation system and plays the role of “hiding wind and gathering air”.

According to the research statistics, the traditional group of village architecture in the Huizhou area is compact in layout and variable in form. The layout of a single house is mostly formed in the shape of a rectangle or, within a nearly rectangular courtyard, is symmetrically arranged around the central axis, and the village buildings generally contain three rooms with wide faces, a hall in the middle, two side rooms, and a skywell connected to the hall and entrances [7]. According to the location and layout of the skywell, the plan types of traditional village architecture in Huizhou can be summarized into the following four forms: AO-shaped, HUI-shaped, H-shaped, and RI-shaped.

The enclosed interface of the skywell in the traditional village architecture of the Huizhou region is: top interface, vertical interface, and bottom interface. The characteristics of these three surfaces are as follows. The first point is the top interface of the skywell space of Huizhou houses: the opening of the skywell will face the sky, and the eaves on the roof of the building will extend into the range where the opening is located, so the opening and the “eaves” form the top interface. The second point is the vertical interface of the Huizhou folk house skywell space: the horizontal interface of a Huizhou folk house skywell is in the space; to define the space from a horizontal perspective, the medium of the enclosed “surface” in the horizontal direction will make people feel it first, the horizontal interface can block the line of sight, and the vertical interface is the outer wall of the room adjacent to the horizontal interface. The vertical interface is the exterior wall of the room adjacent to the horizontal interface. The third point is the bottom interface of the skywell space of Huizhou houses: this interface needs to consider rainwater in the planning and design stage, which enters from the top of the building and needs to be drained at the bottom, so the top interface and the bottom interface are in a “symbiotic relationship”; the bottom interface is also the base of the skywell space, which can accommodate various functions of the internal courtyard [8].Re In thisearchers  paper, we focus on the vertical enclosure scale of the vertical interface of the skywell.

TIn this paper, the vertical enclosure scale of the vertical interface of the skywell was measured by the ratio of the width of the enclosure interface and the height of the enclosure interface, D/H, which has been described above. The ratio of the width-to-height ratio D/H of Yoshinobu Ashihara was mainly focused on 1. For the architectural skywell, when the D/H value is greater than 1, the architectural skywell space shows openness, and when the D/H value is less than 1, the architectural skywell space shows closedness. In order to investigate the scale ratio of architectural skywells in traditional villages in the Huizhou region, the authors counted the D/H values of the skywells of representative residential buildings in Huizhou houses and Dongyang houses in Zhejiang Province as follows: the skywells of Huizhou houses are mainly narrow and long, while the skywells of Dongyang houses are mainly open.

The width-to-height ratio D/H of traditional dwellings in Huizhou is generally low, and the maximum D/H value does not exceed 0.7. In the data, the D/H value is mainly 0.3–0.4. Through field investigation, it can be found that the plain of traditional dwellings in Huizhou is a long rectangle, and the space of the skywell is narrow and tall. The residential buildings in Dongyang, Zhejiang Province consist mainly of two floors. The plain of Dongyang folk houses is approximately square, and their skywell space is open and bright. The courtyard spaces of traditional folk houses in Huizhou and Dongyang folk houses in Zhejiang are the two extremes of the courtyard space enclosure scale of traditional Chinese folk houses, and the D/H value of most other traditional folk houses is between 1 and 2. Through field measurement, the author found that the enclosure scale of the skywell is only one aspect that affects the feelings of people living in it. The interior space of the skywell of Huizhou folk houses is rich and colorful, and there are many influencing factors.

Most of the studies on skywells have focused on natural ventilation, the thermal environment, the height, and the opening area ^{[9][10][11][12][13][14][15][16][17][18]}[9,10,11,12,13,14,15,16,17,18]. Studying the indoor environment of skywell dwellings, Yang Yang et al. [4] showed that the internal space of traditional skywell dwellings is comfortable and the transition space of skywells has a significant cooling effect through the summer in the thermal environment of skywell dwellings in the Huizhou region. Huang, Zhijia et al. [19] concluded that back-shaped skywells in traditional dwellings have better control over natural ventilation than one-character skywells and can achieve the effect of both increasing natural ventilation in the transitional season and reducing outdoor cold air intrusion in winter. Zeng Zhihui et al. [20] concluded that a high and narrow skywell has a significant effect on the transition space and can effectively reduce and delay the effect of outdoor air temperature on the interior, and the more skywells there are, the better the ventilation effect is; in a study of the effect of different geometric skywell sizes on the effect of indoor natural ventilation, Liu Sheng et al. [21] quantitatively analyzed the relationship between different forms of skywell, whether to provide additional ventilation openings, and the effect of indoor natural ventilation. Lin Borong et al. [22] analyzed the effect of different sizes of courtyard space and the height of the house on the natural ventilation effect of the courtyard. Mousli K et al. [23] showed that skywells had been widely used in the Middle East as a passive ventilation and cooling measure. Al-Hemiddi N A et al. [24] studied the effect of skywells on the indoor cooling in summer by measuring skywell buildings. Kubota T et al. [9], in their study of the indoor thermal environment of traditional skywell buildings in Chinatown in Malaysia’s hot and humid climate zone, concluded that the evaporation of water and transpiration of plants at the bottom of the skywell can take away some of the heat from the room, and the effect of the skywell on the internal wind environment of residential buildings is also influenced by the form of building construction and the temperature of the wall of the envelope. Micallef D et al. [10] conducted a study on the through-air of skywell buildings; the results showed that the ventilation rate increases with the increase in skywell height and the airflow flows from outside to inside the skywell.

In a study of natural ventilation simulation and the optimization of skywell dwellings, Kobayashi et al.’s [25] evaluation of the ventilation performance of monitor roofs in a residential area was based on simplified estimation and CFD analysis. Gou, S et al. [26] studied the climate response strategies of traditional dwellings in ancient villages in hot summer and cold winter regions; it was found that utilizing buffer spaces such as internal balconies and patios can effectively promote natural ventilation in buildings. Zhong et al. [27] conducted a study entitled Numerical Investigations on Natural Ventilation in Atria of China’s Southern Yangtze Vernacular Dwellings; rethisearchers study presented a numerical investigation of natural ventilation in a skywell of Southern Yangtze dwellings using a validated computational fluid dynamics (CFD) model. The Reynolds-averaged Navier–Stokes (RANS) modeling approach with the RNG k-ε turbulence model was used for the numerical simulation performed in Open FOAM. Kotol et al. [28] carried out a study of current ventilation strategies in Greenlandic dwellings. Cardoso et al. [29] studied a labelling strategy to define the airtightness performance ranges of naturally ventilated skywells: an application used in Southern Europe. Prakash et al. [30] studied the ventilation performance of low-rise courtyard buildings with various courtyard shape factors and roof topologies.

Liu Xiangmei et al. [31] quantitatively studied the effect of skywell scale on airflow velocity in the courtyard space by applying certain transformations to the length, width, and proportion of skywell scale, and arrived at the optimal skywell scale for natural ventilation. Chen Qiuyu et al. [32] simulated the effect of different skywell shapes and changing the location of the ventilation openings on the indoor ventilation effect, and the results showed that a long vertical skywell has the best comprehensive effect on the indoor environment, and additional ventilation openings on the windward side can significantly improve the indoor ventilation effect. Qian Wei et al. [33] conducted a study on the optimal design of a skywell dwelling, taking into account the natural ventilation and lighting in the room. Rajapaksha I et al. [11] analyzed indoor environmental parameters for five different skywell opening area conditions in a temperate and humid region of Sri Lanka and showed that a proper skywell design can achieve the natural ventilation needed for the building, thus improving the thermal comfort of the building.

ReThisearchers study uses simulation experiments through the PHOENICS (2019) software to quantitatively analyze the relationship between the outdoor wind environment and skywell morphology of traditional Huizhou buildings, and proposes optimization strategies for the skywell morphology of traditional Huizhou Village buildings. The optimization strategies proposed in the research results will provide more valuable theoretical and quantitative criteria for the design and renovation of architectural skywells in traditional Huizhou villages. In-depth research on the outdoor wind environment condition of traditional villages in China is conducive to the inheritance of traditional village culture; the condensation, excavation, and inheritance of Huizhou traditional village architectural planning and design ideas and techniques; and the exploration of construction techniques that can both adapt to modern architecture and retain the characteristics of a traditional architectural style.