Balancing spatial ethic and climate justice of elderly: optimizing natural ventilation in traditional Chaoshan residential buildings

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By 2020, the elderly population in the region had risen to 11.42%, with a large proportion of low-income seniors. Due to financial constraints, they cannot afford air conditioning, and natural ventilation in their living spaces, particularly the rear halls of traditional dwellings, is severely inadequate. This not only causes discomfort but also poses potential health risks, highlighting a distinct climate vulnerability gap. Traditional dwellings in Chaoshan villages, standardized into Types A, B, and C, follow a strict spatial hierarchy that places the elderly in rear zones. Measurements reveal striking ventilation inequality: wind speeds reach approximately 2 m/s in front areas but drop to near 0 m/s in rear spaces. To address this, the study employs CFD simulations to test potential solutions. Expanding courtyards shows limited effectiveness, whereas roof skylights, especially the front-rear dual design, significantly improve rear hall ventilation. In a typical dwelling, rear hall wind speed increases from 0.025 m/s to 0.232 m/s.This low-cost, heritage-compatible intervention directly targets the climate health needs of a marginalized group, ensuring their right to thermal comfort amid climate change. By reconciling traditional spatial order with equitable climate adaptation, the study offers a model for climate action that centers justice, prioritizing vulnerable populations' needs while respecting cultural identities in traditional rural context of southern China. Earth and environmental sciences/Climate sciences Earth and environmental sciences/Environmental social sciences Social science/Environmental studies Climate justice Spatial ethic Natural ventilation Rural elderly Traditional residential buildings Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 1 Introduction 1.1 A dilemma of summer cooling for rural elderly in southern China In the process of global climate change, climate justice is receiving increasing attention [1,2], particularly for vulnerable groups such as the elderly, who are facing risks in adapting to climate change [3], such as issues related to thermal comfort and air quality in their living spaces [4,5]. Urbanization in China has led to a rapid increase in the proportion of urbanized population, accompanied by rising residential energy consumption. As a result, growing numbers of urban residents are experiencing healthy indoor living environments [6,7]. However, the living conditions of a large rural elderly population have not been effectively improved, and they still face indoor health risks posed by summer heatwaves [8,9]. An remarkable case arises in the Chaoshan region along China's southeast coast, a densely populated area in Guangdong Province comprising the cities of Chaozhou, Shantou, and Jieyang. As shown in Fig. 1, according to incomplete statistics of local government data, there are approximately over 3,000 traditional villages inhabited mainly by aging population in the Chaoshan region, primarily distributed around urban built-up areas. In a typical Chaoshan traditional village, the built-up area is typically divided into two sections: the old district dominated by traditional dwellings and the new district characterized by modern residences. A significant proportion of elderly low-income individuals continue to reside in the traditional houses within the old district, unable to secure a suitable living environment due to their inability to afford and install indoor cooling facilities. Consequently, they are exposed to heightened health risks compared to other demographics, posing a social issue that cannot be overlooked. With the aggravation of population aging, the number of elderly individuals in Chaoshan region has been rising annually. As illustrated in Fig. 2, based on the Sixth and Seventh National Population Census data released by the National Bureau of Statistics of China ( https://www.stats.gov.cn/sj/pcsj/rkpc/d7c/ ), the proportion of the elderly population aged 65 and above in China has surpassed 10%. In the Chaoshan area, the proportion of this demographic group has risen from 7.42% in 2010 to 11.42% in 2020, outpacing the average growth rate in Guangdong Province by nearly 3 percentage points, and Chaoshan has become one of the regions with the highest density of elderly population in rural southern China. In recent decades, the extensive adoption of air conditioning equipment has led to a decrease in attention to natural ventilation measures, with residential spaces becoming increasingly reliant on mechanical ventilation and cooling [10, 11]. The elderly low-income residents cannot bear the burden of air conditioning cost in summer, and are reluctant to seek healthier housing options due to the constraints imposed by the spatial ethics, which makes the solution of social problem mentioned above in a dilemma. The natural ventilation techniques employed in traditional dwellings have gained widespread application due to their dual benefits of enhancing indoor air quality and promoting thermal comfort [12,13], especially in tropical regions and during summer periods, where ventilation efficiency is closely correlated with occupants’ health [14,15]. As a crucial design strategy, natural ventilation measures, for instance, installing ventilation openings and shafts in buildings based on wind pressure differences and air temperature gradients plays a crucial role in regulating the indoor environment of vernacular architecture [16, 17]. These measures, characterized by their low cost, low energy consumption, and eco-friendly, serve as the preferred approach to addressing the aforementioned dilemma. However, in the rural area of Chaoshan, where the tradition of familial clustering is deeply ingrained, the implementation of these ventilation measures continues to encounter obstacles stemming from the traditional spatial ethical order. Balancing spatial ethics with architectural ventilation strategies is a pivotal issue in resolving the deficiency of ventilation and cooling in dwellings for elderly. 1.2 Conflict between spatial ethic and the climate justice of the rural elderly Traditional residences in Chaoshan region represent a type of courtyard-style buildings widely found in the eastern Guangdong province. These residences, which were extensively constructed during the Ming and Qing dynasties and have been continuously occupied ever since, have become the most prevalent form of vernacular buildings in rural Chaoshan areas. Currently, a large number of residents, particularly the elderly population, still inhabit these dwellings, and these buildings are characterized by two main features. The first characteristic lies in its highly standardized architectural form, with the building's plan consisting of modular spaces. As shown in Fig. 3a, 3b and 3c, the basic planar unit encompasses three prototypes: Type A, Type B, and Type C, and even a grand residential complex is constructed through the repetitive arrangement and variations of these three fundamental forms. Type B is the most standardized form, commonly referred to as Si Dian Jin (Four Points of Gold) , which includes three parts: a front hall, a rear hall, a central courtyard and auxiliary chambers. Type A is derived from Type B through the reduction of front spatial depth, popularly known as Xia Shan Hu (Tiger Descending the Mountain) . This variant features a shallower plan and simplified form, making it the most prevalent residential type in ChaoShan villages due to its compact scale. Type C originates from expanding the central part of Type B, referred to as San Ting Gen (Three Halls and Courts) . This form exhibits increased plan depth, incorporating two tiers of courtyards, auxiliary spaces, and a more elaborate spatial organization. Through the strategic combination and expansion of these three basic units, integrated with alleyway circulation systems and auxiliary spaces, more complex mansion-type residences emerge. Notable examples include the Si Ma Tuo Che (Four Horses Towing a Cart) , composed of four A or B units and one C unit (Fig. 3d); the Jiu Long Tu Zhu (Nine Dragons Spitting Pearls) , comprising eight A or B units and one C unit (Fig. 3e), and the Bai Niao Chao Feng (A hundred birds and a Phoenix) , comprising more basic units (Fig. 3f). Most traditional villages in ChaoShan are structured as agglomerations of these modular units. The second feature is a rigid spatial ethical hierarchy, manifested in the allocation of internal spaces that adheres to feudal family rituals and ethical codes. Within the social framework of extended family cohabitation, distinct spatial functions were assigned to ancestors, elders, juniors, family members, and outsiders. As shown in Fig. 3a, 3b, and 3c, in Type A, B, and C residential units, residential interior spaces marked with different colors belong to different membersthe. Specifically, front central hall was primarily designated for guest reception, while bedrooms in lateral wings were allocated to junior family members. The central courtyard functioned as the family’s internal communal activity space, with side rooms serving as storerooms and kitchens. The rear central hall was exclusively reserved for ancestral worship, while adjacent bedrooms were designated for senior family members. The rear space, serving both as the ancestral hall and the bedroom for elders, represents not merely a physical space, but also an expression of the concept of "honoring elders" within clan etiquette. People's emotional dependence on specific spaces is not solely based on physical attributes, but rather, over long-term life experiences, they integrate personal emotions, family memories, and spaces closely together [18, 19]. In traditional Chaozhou residential architecture, the elderly generation's adherence to the layout where the rear hall is considered the most respected area exemplifies this attachment to one's place of origin. The rear hall, serving as a place for family rituals and the residence of elders, holds memories of several generations, and the elderly' s affection for it reflects their profound identification with family roots. Field surveys of multiple traditional villages in Chaoshan have revealed that the spatial allocation within these residences still follows this spatial ethical hierarchy, which means the primary living and activity areas for seniors are centered around the back hall, including the bedrooms, central courtyard, and connecting corridors adjacent to it, serving as their exclusive living spaces. Measurements of wind speed and interviews reveal that elderly residents commonly complain that "the back hall feels like a steam room in summer, causing one to sweat even when sitting still." However, when asked if they would be willing to relocate to a room in the front yard with improved ventilation, most responded, " It's a tradition for the younger generation to live in the front yard; we can't disrupt that." This contradiction validates the inadequate ventilation in the back hall and underscores the restrictions imposed by spatial ethics on residential preferences. The rigid trend of allocating spaces specifically for the elderly, while historically accommodating their socio-psychological needs, is now in conflict with the climate justice of the growing elderly population due to inadequate ventilation and thermal comfort during summer, emerging as one of the health housing problems to be solved in rural areas of southern China. This study aims to develop natural ventilation optimization strategies for elderly in traditional ChaoShan dwellings through CFD simulations and numerical comparative analysis. By integrating a "data driven-technology adaptive-ethics compatible" research framework, the study seeks to address ventilation dilemmas while compatible with spatial ethical order. 2. Ventilation simulations of elderly occupied space and potential optimization strategies 2.1 Simulation of natural ventilation of three basic residential units Located by the sea, the ChaoShan region is influenced by the sea-land breeze circulation, making north-south winds the predominant wind directions. To achieve good ventilation, traditional villages in the ChaoShan region are primarily oriented north-south. Using Rhino software and its ladybug plugin, combined with Chinese standard meteorological datasets, wind speeds and directions when air temperatures exceed 28°C from June to September in Shantou City were selected to create a summer wind rose diagram (Fig. 4). It can be observed that the wind directions with higher frequencies in summer are S, ESE, SE, SSW, and SW. Additionally, considering the orientation characteristics of traditional residential buildings, the simulation wind direction was set to south. Based on the observational data from the Shantou Meteorological Station (station number: 59316, longitude: 116°41′E, latitude: 23°24′N) from 2000 to 2020, the average wind speed and daily average temperature over the past 20 years in Shantou City were statistically analyzed. As shown in Fig. 5, the average wind speed decreased from 2.5 m/s in 2000 to 1.7 m/s in 2020. Combining this with actual wind speed measurement data, the initial simulation wind speed was set to 2.1 m/s, with the wind direction being south. As shown in Fig. 6, the daily average temperature from June to September ranges from 25°C to 39°C, with the most frequent interval being 31°C to 34°C. Based on the temperature distribution frequency, 32°C was set as the initial simulation temperature. Utilizing Rhino software, a spatial model was created, with the height of the residential model set to 3.5 meters according to actual survey findings. Subsequently, the model was imported into computational fluid dynamics (CFD) software. Referencing the " JGJ/T449-2018 Standard for Green Performance Calculation of Civil Buildings " and related research cases, the model was meshed with a precision of 200mm*200mm*250mm, and the boundaries of the model, except the base, were extended outward by three times its height, namely 10.5 meters, to better simulate the wind flow field effects in the real environment. To ensure the stability and accuracy of the simulation results, the number of iterations for the calculation was set to 500. Under the premise that the calculation results converge, the wind speed calculation results were output (Fig.7). Based on the wind speed distribution patterns of the three basic residential typologies described above, a consistent trend emerges: wind velocities gradually decrease from the front to the rear sections of the dwellings, with notable disparities between front and rear zones. Under the condition of summer ventilation dominated by southerly winds, the front area, including the hall and bedroom zones, exhibit favorable ventilation performance, as windows and door openings could effectively channel natural breezes into the interior spaces. Notably, the front halls record the highest wind speeds, reaching approximately 2 m/s, while the front bedrooms register maximum velocities of 0.6–0.8 m/s. The middle areas, including the central courtyards and surrounding corridors also benefit from widespread natural ventilation, characterized by relatively uniform wind speed distributions. In the deeper-plan of Type B and Type C units, courtyard wind speeds attain approximately 1.2 m/s, whereas the shorter-span of Type A units exhibit courtyard velocities up to 1.9 m/s. The back areas, including the rear halls and bedrooms (Space occupied by the elderly), in contrast, suffer from inadequate natural ventilation. In Type B and Type C units, wind speeds near the northern exterior walls and in zones distant from openings approach 0 m/s on average. For Type A units, while the rear halls achieve average wind speeds below 0.3 m/s, the rear bedrooms remain poorly ventilated, with negligible air movement. Results from on-site wind speed measurements and resident interviews in traditional dwellings verify the simulation findings, identifying the rear rooms as primary zones of summer ventilation deficiency. Significantly, these rear rooms serve as the principal daily activity and rest areas for elderly rural residents in ChaoShan. Existing research highlights that older adults exhibit reduced sensitivity to indoor thermal environmental changes compared to younger populations [20,21], yet their diminished physiological adaptability and regulatory capacity increase vulnerability to health risks in unsuitable indoor environments [22,23]. This is particularly critical for elderly individuals with dementia or other chronic conditions, where indoor environmental quality directly impacts disease management and recovery [24, 25]. In the context of hot-humid summer climate in Chaoshan region, and given the economic constraints faced by the elderly and low-income population, enhancing natural ventilation efficiency holds profound significance for improving thermal comfort among elderly residents, while also mitigating health risks associated with stagnant indoor air. 2.2 Optimize d natural ventilation solutions Clifford Geertz's theory of cultural interpretation holds that culture is a social phenomenon expressed through symbols and meaning systems [26]. The architectural form of Chaoshan traditional dwellings can be regarded as a cultural symbol, and its spatial layout contains rich cultural connotations. The solemn layout and special functions of the rear hall symbolize the continuity of the family and the authority of the elders, and the overall layout of dwellings reflects the unique cultural values and social order of Chaoshan region. The implementation of ventilation optimization measures will change the physical space of residential buildings, and then affect the meaning conveyed by these cultural symbols. Therefore, when designing the optimization scheme, it is necessary to be careful about the potential impact of spatial changes on cultural significance, so as to ensure the continuity of traditional spatial ethics. Based on the aforementioned ventilation simulation, replacing B-type and C-type residential units with A-type, which have superior ventilation performance, can significantly enhance the natural ventilation of traditional Chaoshan dwellings by reducing the depth of the building and cumulative wind resistance. Nevertheless, this solution is not feasible for widespread implementation, primarily due to the fact that villages in Chaoshan region are predominantly populated by clan-based extended families (The family community bonded by blood ties, exhibits strong social cohesion.), and the size and layout of A-type residences do not cater to the cohabitation requirements and ethical standards of these multi-generational households. Additionally, reducing building density by demolishing some overly concentrated buildings can improve the ventilation around buildings. However, these traditional buildings are increasingly being recognized as architectural heritage by government authorities, and the cultural symbolic value conveyed therein has garnered widespread attention from society. Given both heritage conservation considerations and emotional attachments to the land, demolition is not a viable option. Consequently, specific renovation measures targeting the individual units of types A, B, and C represent more feasible and effective solutions. The improvement principles to enhance natural ventilation efficiency of Chinese traditional vernacular buildings mainly focus on strengthening thermal pressure effects and wind-driven forces, and the optimization measures are usually derived based on these principles [27,28], such as the adoption of optimized courtyards [29,30], underground spaces [31], window opening [29, 32], building layout [33,34], open space and spatial form [35, 36] and these measures could be combined with the solar chimney and evaporate cooling system to improve thermal comfort further. For traditional Chaoshan dwellings, the above simulation and interpretation reveals the ventilation dilemma of the elderly living space, and feasible ventilation optimization measures must possess social adaptability and cultural compatibility. Given the constraints imposed by multiple factors, including traditional spatial ethical order, architectural heritage protection requirements, and low-income economic conditions. Among these measures, those that neither compromise the integrity of the architectural heritage nor incur high costs are of greater practical value. Based on this understanding, this study selected two innovative approaches to enhance the natural ventilation in elderly living spaces: expanding courtyard sizes and installing roof skylights. During the subsequent research, we constructed spatial models featuring varying courtyard and skylight dimensions, and employed CFD simulation to validate the natural ventilation of these two measures. As shown in Fig. 8, to analyze the wind speed distribution across three housing types, wind speed monitoring points were established 1.5 meters above the ground in four areas (hall, bedrooms, courtyard, and corridors) where elderly are frequently active. The average wind speed values of monitoring points within the rooms were utilized to assess natural ventilation performance. 3 Simulation of expanding courtyards and adding skylights for improving ventilation 3.1 E xpanding the scale of courtyard 3.1.1 Design of different courtyard scales The design and construction of traditional Chaoshan residential buildings involve various groups of craftsmen, including geomancers, carpenters, bricklayers, and painters. These craftsmen typically employ five types of measurement units: the tile layer (distance between the centerlines of two roof tiles), the construction ruler, the purlin (distance between the centerlines of two roof purlins), the pace, and the measuring rod (a flat wooden rod with size scales on both sides). Although each craft tradition focused on distinct scale modules, all units were fundamentally anchored in the construction ruler, with interconvertible relationships documented in Table 1. Shaped by local social customs and feng shui theory (The traditional Chinese philosophy of spatial layout emphasizes the harmonious relationship between humans and the natural environment) of Chaoshan region, different building areas, such as halls, bedrooms, and courtyards, required specific length units for dimensional calculations, with distinct mathematical rules governing scale prescriptions [37]. Table 1 Units of measurement for dimensions in traditional Chaoshan residential buildings. Scale unit Large tile layer Small tile layer Construction ruler (CR) Purlin Pace Measuring rod Actual length 298mm 268mm 298mm 450-600mm 1350mm 5543mm Crafts men Bricklayer Bricklayer Carpenter Carpenter - Carpenter Application Room width Room width General dimensions Roof depth Scale of courtyard and square Plane scale, height Conversion with CR 1 0.9 - About 1.5-2 About 4.5 18.6 The scale of three basic residential types is quantified in "Jian" (a traditional Chinese unit of measurement for room width), where the width of a "Jian" depends on the number of roof tile layers. In the ChaoShan region, roof tiles are categorized into large and small tiles, with different corresponding dimensions. As shown in Fig. 9, a "Layer" refers to the width between the midlines of two adjacent tiles, typically 3% to 5% wider than the tile itself . Influenced by feng shui theory, the number of tile layers in the central "Jian" is usually odd, while those in the side "jian"s are even. The width of the northern hall ranges from 17 to 21 layers, while the side living rooms are between 12 to 14 layers. To maintain cohesive residential cluster morphology, villages in ChaoShan region exhibit standardized external contour dimensions for similar dwelling types, while allowing flexibility in internal courtyard, hall, and bedroom dimensions. Hall and side bedroom widths are calibrated according to tile layers, with the hall’s width never less than that of side bedrooms. Courtyard dimensions are proportionally linked to hall dimensions, generally maintaining equivalent on widths, while the depth is more flexible but must adhere to the restriction of "Pace" count, which should be an odd number and non-integer. Under these planimetric constraints, the three basic types (A, B, C) usually share identical plan contours and building heights. Three common courtyard scales, based on 17, 19, and 21 tile layers for both length and width were selected, resulting in nine types of distinct plan forms (A1 to C3) with different courtyard proportions (Table 2). Table 2 Dimensions of 9 types of building plane forms. Building type Building contour Scale(mm) Building area (m²) The width of main hall (layers of tiles) Courtyard scale (Construction ruler) Courtyard area (㎡) Type A A1 14065.6*17105.2 (east-west * north-south) 240.58㎡ 17 15*15 19.98 A2 19 16.8*16.8 25.06 A3 21 18.6*18.6 30.71 Type B B1 14065.6*22350 (east-west * north-south) 314.35㎡ 17 15*15 19.98 B2 19 16.8*16.8 25.06 B3 21 18.6*18.6 30.71 Type C C1 14065.6*30694 (east-west * north-south) 431.65㎡ 17 15*15 19.98 C2 19 16.8*16.8 25.06 C3 21 18.6*18.6 30.71 3.1.2 Comparison of ventilation of different courtyard scales As shown in Fig. 10, under the same operational parameters to the aforementioned simulations, Ansys-Icepak software was employed to model ventilation across the nine plans with different courtyard scale, and wind speed distribution maps and observation point data (Table 3) were extracted. The simulation results exhibit similar trends in wind speed changes, indicating that within comparable planes and spaces of the same type, wind speed does not experience a notable increase as the courtyard scale expands. In hall spaces frequented by elderly residents, average wind speeds remain below 0.2 m/s for Type A plans and below 0.05 m/s for Type B and C plans. These halls, serving as both ritual preparation areas and communal living spaces for the elderly, exhibit insufficient airflow to support comfortable daily activities, as indicated by the stagnant wind condition in plans of ventilation. The bedrooms, serving as primary zones of sleeping and resting for elderly, show average wind speeds below 0.35 m/s for Type B and C plans, and below 0.1 m/s for Type A plans, and airflow is predominantly concentrated around door and window openings, with negligible movement on the northern sides of bedrooms, which fail to achieve adequate air circulation necessary for thermal comfort. The corridors spaces in front of halls show more favorable conditions: Type A plans exhibit wind speeds exceeding 0.4 m/s, while Type B and C plans range between 0.1–0.4 m/s. As transitional zones connecting outdoor courtyards to indoor living areas, and activity spaces for the elderly, these corridors demonstrate higher average wind speeds than halls or bedrooms, offering improvements to indoor ventilation. The courtyard space, where elderly engage in daytime activities, show the strongest ventilation performance: Type A plans exceed 0.65 m/s, while Type B and C plans range between 0.3–0.4 m/s, which effectively mitigate tie air stagnation situation around the courtyard. Table 3 Average wind speed in the spaces for the elderly. position Average wind speed in the rear hall (m/s) Average wind speed in bedroom (m/s) Average wind speed in the corridor (m/s) Average wind speed in the courtyard (m/s) Courtyard area ratio A A1 0.134 0.080 0.406 0.682 8.30% A2 0.156 0.076 0.566 0.740 10.42% A3 0.150 0.091 0.420 0.680 12.76% B B1 0.010 0.216 0.203 0.364 6.36% B2 0.014 0.313 0.360 0.310 7.97% B3 0.025 0.280 0.266 0.376 9.77% C C1 0.007 0.300 0.130 0.396 4.63% C2 0.011 0.253 0.140 0.348 5.81% C3 0.017 0.258 0.153 0.308 7.11% As illustrated in Fig.11, among the 9 types of plans, Type A exhibit the optimal natural ventilation performance, while Type C demonstrates the poorest. Within the Type A category, the A2 variant, featuring a courtyard area of 16.8×16.8 construction rulers (accounting for 10.42% of the total built-up area), achieves the best ventilation efficiency. Although the courtyard significantly enhances airflow in adjacent corridors and halls, its performance margin over A1 and A3 types remains statistically insignificant. Similarly, across Type B and C buildings, no notable ventilation disparities were observed among plans with varying courtyard scales. These results indicate that during summer, when the prevailing wind direction is southerly, the courtyard scale in traditional Chaoshan residences has a negligible impact on natural ventilation and wind speed distribution. Expanding courtyard size alone does not effectively improve ventilation performance. Compared to courtyard scale, the aspect ratios (length-to-width ratios) of the building has a greater influence on ventilation. As building length increases, natural ventilation energy loss through internal spaces escalates, progressively diminishing the dwelling’s ventilation capacity. This mechanism explains why, in Type B and Type C buildings, elderly-occupied rear spaces fail to achieve adequate air circulation. In summary, Type A buildings with lower aspect ratios (length-to-width ratios) demonstrate the highest suitability for natural ventilation in elderly living spaces. However, due to their compact living place, typically accommodating 2-5 occupants in two-generation households, Type A buildings are insufficient to meet the needs of multigenerational families prevalent in Chaoshan traditional villages. A substantial proportion of elderly residents continue to reside in Type B and Type C buildings, which could accommodate three-generation cohabiting households. This reality underscores the urgent need to develop targeted natural ventilation optimization strategies for these larger-scale building units. To address this gap, this study proposes a skylight intervention as a viable solution. 3.2 Add ing roof skylights 3.2.1 Scale s and location of roof skylights The roof structure of traditional Chaoshan dwellings consists of a timber framework, with construction layers arranged top-down as follows: roof tile layer, wooden plank layer, and timber purlin layer. When adding skylights into the roofs of rear rooms occupied by elderly residents, two structural constraints govern skylight dimensioning, derived from traditional roof construction principles: Firstly, the skylight’s depth-wise (north-south) length must align with roof purlin spacing, requiring the dimension to be an integer multiple of the purlin module. This ensures secure attachment of the skylight frame to purlins, maintaining roof structural integrity. As illustrated in Fig. 12a, on a typical lateral section of the rear hall space, the building’s depth is determined by the number of purlins. In a typical 13-purlins Chaoshan dwelling, the maximum skylight width (without compromising ridge or eave structures) can span up to 3 purlins, equivalent to approximately 50% of the roof’s single-side width. Secondly, the skylight’s width-wise (east-west) length must conform to the "tile layer" modular system, with dimensions restricted to integer multiples of tile layers. This preserves the continuity of roof tiling and structural stability. As illustrated in Fig. 12b, among traditional ChaoShan residential buildings, the tile layers of rear hall roof in the width direction are usually 17, 19, or 21. To maintain roof integrity on both hall sides, maximum skylight lengths range from 14 to 18 tile layers. However, to maintain the original roof style and preserve the facade appearance of the architectural heritage, the length of the skylight should not be excessive, and it is generally more appropriate for it to not exceed 50% of the hall's width. Taking the B3-type residence as a case study, this investigation examines the effects of skylight positioning on natural ventilation efficiency. The B3 front hall exhibits a width of 6.25 m (approximately 21 tile layers) and a depth of 6.85 m (approximately 23 tile layers). In adherence to the skylight dimension principles defined earlier, the skylight is designed with a width of 10 tile layers (2.98 m) and a depth of 8 tile layers (2.38 m). Three skylight positions were selected for comparative analysis: Front-slope installation (Skylights positioned on the southern roof slope), Rear-slope installation (Skylights positioned on the northern roof slope), and Dual-slope installation (Skylights installed on both southern and northern roof slopes). Under the operational parameters specified in Section 2.1, CFD simulations were conducted to quantify natural ventilation performance across the three ways of skylight. 3.2.2 Comparison of natural ventilation after adding skylights By comparing the wind speed distribution maps of B3-type without skylights (Fig. 10f) and with skylights opening (Fig. 13), it can be observed that opening skylights significantly improves the natural ventilation in the hall used, and the extent of improvement varies among the three different skylight opening methods. By comparing the wind speed distribution maps of the front skylight (Fig. 13a) and the rear skylight (Fig. 13b), it is evident that the optimization effect of the front skylight on natural ventilation is weaker than that of the rear skylight. The front skylight fails to effectively promote the deep penetration of natural ventilation, with its influence primarily concentrated in the front of the hall, as well as the corridor and courtyard (Fig. 13a). In contrast, the rear skylight opening method can more effectively guide natural ventilation to the rear of the hall, expanding its influence (Fig. 13b). Further comparison of the wind speed distributions between the rear skylight opening (Fig. 13b) and the front-rear dual skylight opening (Fig. 13c) reveals that the dual skylight method achieves better wind speed optimization. This method not only introduces natural ventilation into more areas at the rear of the hall but also slightly improves ventilation in the corridor and the bedrooms on both sides of the hall. The comparative analysis of the three skylight opening methods indicates that the front-rear dual skylight approach is most effective in enhancing natural ventilation in the elderly spaces. During peak summer heat, this method can effectively enhance indoor air circulation and cooling, benefiting the living conditions of elderly. Further comparison of the wind speed distribution in the cross-sections of buildings with and without skylights. As shown in Fig. 14a, in the cross-section without a skylight, natural ventilation cannot circulate sufficiently in the rear hall, and wind speed continues to decrease with the increase of building depth, especially in the rear and upper parts of the hall cross-section, forming large areas of dead air zones, which increases the air age in the hall. As shown in Fig. 14b, in the cross-section with front and rear double skylights, the skylight openings can convey the ventilation from the south side to the outside, allowing natural ventilation to circulate sufficiently in the rear hall, with only small dead air zones formed at the intersection of the rear wall and the ground. Most of the daily used areas have good natural ventilation. By comparing the wind speed distribution in the cross-sections, it can be seen that opening skylights significantly promote natural ventilation in the rear hall and the corridor space in front of it, guiding the natural ventilation that was originally flowing close to the ground to higher areas, improving ventilation and air exchange efficiency, and enhancing air quality above 1.5 meters from the ground. As shown in Table 4 and Fig. 15, comparing the wind speed before and after opening the skylight, it can be observed that after opening the skylight, the average wind speed in the rear hall increased significantly from 0.025 m/s to 0.232 m/s. This improvement in natural ventilation particularly benefits the public activity areas where the elderly spend most of their daytime. However, there was no significant change of wind speed in other areas frequently occupied by the elderly. For instance, the wind speed in the bedrooms on both sides of the hall decreased slightly from 0.280 m/s to 0.262 m/s, while the wind speed in the corridor in front of the hall increased slightly from 0.266 m/s to 0.279 m/s. Additionally, the average wind speed in the courtyard increased from 0.376 m/s to 0.413 m/s. These observations indicate that the impact of opening the skylight on natural ventilation is primarily concentrated in the hall area, with no significant optimization in other areas, especially the bedrooms on both sides of the hall, where wind speed even decreased slightly. Therefore, to effectively enhance the thermal comfort in bedrooms and other enclosed spaces during summer, it is also necessary to add skylights on the bedroom roofs. Table 4 Comparison of wind speeds for three skylight designs in B3-type. B3 type Skylight opening area (㎡) Average wind speed in the rear hall(m/s) Average wind speed in bedroom (m/s) Average wind speed in the corridor (m/s) Average wind speed in the courtyard (m/s) No skylight 0 0.025 0.280 0.266 0.376 Front skylight 7.10 0.104 0.262 0.272 0.387 Rear skylight 7.10 0.183 0.268 0.279 0.405 Dual skylight 14.20 0.232 0.275 0.269 0.413 4 Discussion 4.1 Efficiency differences in natural ventilation optimization methods Both expanding the courtyard scale and reducing the overall building length can enhance natural ventilation of ChaoShan traditional dwellings, but the differences in their effects on ventilation efficiency are significant. While courtyard geometry, scale, and orientation are generally considered important factors influencing building microclimate [ 38 , 39 ], the effect of courtyard scale on improving natural ventilation efficiency in ChaoShan dwellings is quite limited. Taking Type A buildings as examples (Table 3 ), from A1 to A3, the courtyard area increased from 19.98㎡ to 30.71㎡, the courtyard area ratio rose from 8.30–12.76%, and the wind speed in the rear hall increased from 0.134m/s to 0.150m/s, with only a 0.016m/s increase, a wind speed improvement rate of 11.94%. The wind speed improvement rate per additional 1㎡ of courtyard area was 1.11%, and per 1% increase in courtyard area ratio was 2.27%. The wind speed improvement efficiency in corridors and courtyards was even lower. In longer-depth buildings of Type B and C, enlarging the courtyard scale could even increase shaded areas, thereby reducing thermal pressure ventilation (A natural ventilation method that utilizes air pressure differences created by temperature variations in the air to drive airflow). Comparing A1 and C1, with a building depth increase of 13.59m, the hall wind speed decreased by 0.127m/s, a total reduction rate of 94.78%, with an average wind speed reduction rate of 6.97% per additional 1m of depth. This indicates that under summer southerly conditions, the "wind resistance accumulation" caused by building depth is the primary reason for insufficient natural ventilation of elderly-occupied spaces in ChaoShan traditional dwellings, and the impact of expanding courtyard scale on wind speed improvement is far less than that of shortening building depth. The installation of roof skylights primarily targets older residential buildings, especially the hall spaces. Both rear skylights and front-rear double skylights exhibit more pronounced and direct enhancements in natural ventilation performance. Rear skylights leverage the "thermal chimney effect" to create a low-pressure zone on the roof, thereby boosting natural ventilation efficiency. Taking the B3-type residential building as an illustration, a rear skylight with an area of 7.1 ㎡ can elevate the ground-level wind speed in the living hall from 0.025 m/s to 0.183 m/s, marking a 6.32-fold increase, with an average wind speed improvement rate of 89.01% per square meter of skylight. The front-and-rear double skylight further amplifies the natural ventilation pathway of "air inflow-through-outflow". With a combined skylight area of 14.2 ㎡, it can increase the ground-level wind speed in the living hall from 0.025 m/s to 0.232 m/s, representing an 8.28-fold increase, with an average wind speed improvement rate of 58.31% per square meter of skylight. The effectiveness of roof skylights in enhancing natural ventilation significantly surpasses adjustments to courtyard layout and depth. Furthermore, skylights exert a more notable influence on airflow trajectories, facilitating ground-level ventilation to flow towards areas nearer to human height. The front skylight primarily enhances ventilation in the front porch, while the rear skylight boosts the airflow rate at the rear of the living hall, validating the necessity of "active intervention at the airflow terminus." 4.2 Reconciliation of conflicts between spatial ethics and health needs The "rear hall" space of Chaoshan vernacular dwellings carries symbolic significance related to clan rituals and ethics, and its ventilation challenges fundamentally stem from the conflict between traditional communal living patterns and modern health standards. Research findings indicate that most elderly residents refuse to change the living arrangement of using the rear rooms as ancestral halls and bedrooms for elders, making strategies like "shortening the depth" and "rearranging rooms" difficult to implement. The optimization approach of adding skylights cleverly avoids this dilemma, improving ventilation without compromising spatial ethics. Additionally, by coordinating roof construction and dimensional modules, it minimizes damage to the building heritage, and also aligns with the principle of "minimum intervention" in heritage preservation. Moreover, the unique sea-land breeze circulation in the Chaoshan region offers double opportunities for natural ventilation design. During summer days, the sea breeze (south wind) drives air into the house through the front windows. Meanwhile, the rear hall skylights create thermal pressure due to the increased roof temperature, which enhances the horizontal through-draft and effectively introduces cool air from above the sea into the rear spaces. At night, when land breezes dominate, the height difference between the roof skylights, courtyards, and door and window openings can create a "chimney effect", strengthening vertical local wind circulation. Compared to traditional dwellings in arid and hot climates, such as the four-sided wind tower adjacent to the parlor and courtyard in Iran [ 40 ] and the air-drying shelter in the Turpan basin [ 41 ], traditional dwellings in Southeast Asia's hot and humid regions, especially those in the ChaoShan area deeply influenced by traditional clan rituals and ethics, exhibit a "hidden" characteristic in their passive ventilation methods. This implies that during the design process, factors related to natural ventilation and human comfort are not primary considerations, but rather secondary considerations after traditional spatial ethics. After the building is constructed, artificial modifications are often added to enhance the space comfort. Research reveals that residents in ChaoShan traditional dwellings spontaneously make minor modifications to the roof structure to improve ventilation and lighting, such as creating small-scale roof openings on the gaps between roof tiles and purlins. However, due to the small size of these openings, the improvement in ventilation is limited, and they cannot be automatically opened or closed, causing inconvenience during the rainy season. Integrating modern skylight design with the roof construction features of ChaoShan traditional dwellings can effectively address these drawbacks. This approach not only preserves the regional architectural culture but also enhances its climate control performance, increasing the feasibility of sustainable updates to ChaoShan traditional dwellings. As a result, it is the preferred method for improving ventilation on existing dwellings. 5 Conclusion This study focuses on the typical traditional dwellings in the ChaoShan region, using CFD simulations and comparative analysis to investigate the challenges of natural ventilation in elderly living spaces during summer and proposing optimization strategies. The main conclusions are as follows: Ventilation Challenges: Under summer southerly wind conditions, the three basic types of traditional dwellings in Chaoshan exhibit a ventilation pattern characterized by "strong in the front and weak at the back," indicating a significant tendency towards uneven ventilation distribution. Wind speeds in the front halls and courtyards can reach 0.6-2 m/s, while the average wind speeds in the rear halls and bedrooms where elderly occupied are below 0.3 m/s, with some areas approaching 0 m/s. The wind speed attenuation rate ranges from 70% to 90%, creating distinct no-wind zones. Ventilation relies on a planar network of "courtyard-door-window," but lacks mechanisms for vertical airflow guidance. The low height of the courtyards and door/window openings results in insufficient height differences, preventing the formation of an effective "chimney effect." Consequently, natural ventilation is neither uniformly distributed nor deeply penetrating. The cumulative wind resistance resulting from building depth is the primary cause of inadequate natural ventilation. Comparing Class A buildings (short depth) with Class C buildings (long depth) reveals that for every additional meter of depth, the wind speed in the hall decreases by 6.97%, significantly reducing natural ventilation efficiency in the rear spaces. However, due to the constraints of traditional clan rituals, elderly residents in Chaoshan prefer to stay in poorly ventilated areas, especially in Type C dwellings with depths exceeding 10 meters, where large no-wind zones exist in their living spaces, thus increasing their health risks in summer. Selection of optimization strategies: In the complex practical process of optimizing indoor ventilation in ChaoShan traditional dwellings during summer, several critical factors must be considered when selecting strategies. These include ventilation improvement rate, ethical compatibility, damage to building heritage, modification costs, and construction difficulty. For ChaoShan traditional dwellings designated as heritage buildings by the government, ventilation optimization strategies should prioritize the principle of "minimum intervention in heritage", with the preferred approach being the installation of roof skylights in core activity areas for the elderly. Adding skylights serves as a key strategy to balance the spatial ethics of traditional ChaoShan dwellings with modern health requirements, as it does not alter the original spatial hierarchy of "respecting the rear," but instead achieves improved natural ventilation through minor modifications that adapt to the roof purlin spacing and tile module. For the rear hall, where the elderly primarily gather, skylights should be installed on either side of the roof ridge or near the rear wall to directly address windless zones using the "thermal pressure ventilation" principle. For example, installing a rear skylight on the roof of the rear hall in a B3-type dwelling, which spans three purlins in depth and ten tile ridges in width, ensures that airflow reaches the rear of the hall. Additionally, for deeper C-type dwellings, a dual-skylight approach can be employed, with a front skylight introducing southern winds and a rear skylight expelling warm, humid air, creating a complete ventilation path of "inflow - cross - outflow," significantly increasing airflow in the hall while slightly enhancing ventilation in the bedrooms on both sides. The addition of skylights offers clear advantages in enhancing ventilation efficiency, compatibility with heritage preservation, and adaptability to regional climates, providing a "low-intervention, high-efficiency" reference for healthy renovation of traditional buildings in similar climates. For residences that are being planned and newly constructed, the depth dimension can be shortened to optimize natural ventilation, using Type A buildings as the basic unit for spatial layout, while moderately increasing the courtyard area, but the courtyard area ratio should not exceed 13%. For instance, when the courtyard area ratio of Type A3 is 12.76%, a slight decrease in wind speeds in corridors and courtyards is observed. When renovating non-heritage-protected old houses, if the courtyard space is too small to provide sufficient outdoor activity areas, it is advisable to prioritize expanding the courtyard dimensions. For example, during the renovation of Type A residences, increasing the courtyard area ratio from 8.3% to 10.4% can improve the wind speeds in the hall, courtyard, and corridor. However, expanding the courtyard entails higher construction costs, making it challenging to widely implement among low-income elderly residents. Additionally, in residential clusters like "Si Ma Tuo Che" and "Jiu Long Tu Zhu" removing side rooms or corridors to enlarge courtyards is not allowed, as it may disrupt the spatial sequence and potential heritage value. Limitations and Outlook: This study explores the balance between spatial ethics and natural ventilation optimization in traditional Chaoshan dwellings, with a focus on addressing the summer living challenges of elderly residents. However, several limitations remain, which also point to avenues for future research. Firstly, the analysis of "space ethics" remains confined to the descriptive level, insufficiently delving into how ethical norms are dynamically constructed through daily practices and renegotiated under environmental pressures. Secondly, empirical research has placed undue emphasis on physical ventilation data, neglecting the subjective experiences of elderly residents, such as their perception of thermal comfort and emotional attachment to space. Lastly, simulations have exclusively focused on summer conditions, overlooking the influence of seasonal climate variations and long-term urbanization on spatial ethics. Future research should integrate anthropological theories to explore how optimization measures can reshape "ethical spaces" without undermining traditional hierarchies. A hybrid approach combining microclimate monitoring with observations of elderly daily activities should be adopted to bridge the gap between physical data and lived experiences. Additionally, policy guidelines for "ethical adaptation" should be formulated, encompassing subsidies for heritage-compatible renovation projects, training for craftsmen in low-intervention techniques, and striking a balance between technical efficiency and cultural legitimacy. This framework serves as a reference for sustainable rural development in aging societies, prioritizing human experience and intergenerational equity. Declarations Funding declaration: This work was supported by the Humanities and Social Sciences Youth Foundation, Ministry of Education of China (grant number 23YJCZH142). The funder provided financial support for the study but had no role in the design of the study; in the collection, analysis, and interpretation of data; in the writing of the manuscript; or in the decision to submit the manuscript for publication. All authors are responsible for the content of this article. Data Availability: The data will be made available on request. 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Supplementary Files Supplementaryfile.rar Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 22 Dec, 2025 Reviews received at journal 25 Sep, 2025 Reviews received at journal 24 Sep, 2025 Reviews received at journal 23 Sep, 2025 Reviewers agreed at journal 05 Sep, 2025 Reviewers agreed at journal 04 Sep, 2025 Reviewers agreed at journal 02 Sep, 2025 Reviewers agreed at journal 02 Sep, 2025 Reviewers invited by journal 02 Sep, 2025 Editor assigned by journal 26 Aug, 2025 Submission checks completed at journal 10 Aug, 2025 First submitted to journal 10 Aug, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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2","display":"","copyAsset":false,"role":"figure","size":82222,"visible":true,"origin":"","legend":"\u003cp\u003eStatistics and comparison of the proportion of elderly population in 2010 and 2020.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7193386/v1/36769a33d2f969ce4e23ec08.png"},{"id":90875201,"identity":"1e1a2f3b-45bf-4aa0-88ce-cd4634a6bc43","added_by":"auto","created_at":"2025-09-09 08:48:53","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":180492,"visible":true,"origin":"","legend":"\u003cp\u003eThe three \u0026nbsp;\u0026nbsp;basic planar units and three expansion \u0026nbsp;\u0026nbsp;forms of Chaoshan traditional dwellings.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7193386/v1/3762e8db5f85a647d119f31a.png"},{"id":90872508,"identity":"bf3daad9-ff12-40a0-9e63-28e187f9a447","added_by":"auto","created_at":"2025-09-09 08:24:52","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":155450,"visible":true,"origin":"","legend":"\u003cp\u003eWind Rose of High Temperature Moments in Chaoshan region from June to September.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7193386/v1/61c25ee5a654aabdc25c43a2.png"},{"id":90871302,"identity":"8d2ae6ba-a8f1-4531-afa7-5c2f36ac68e3","added_by":"auto","created_at":"2025-09-09 08:16:52","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":61318,"visible":true,"origin":"","legend":"\u003cp\u003eAverage wind speed changes in Chaoshan region from 2000 to 2020.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7193386/v1/25ea7b572191c12612c686c7.png"},{"id":90872513,"identity":"4cf16efa-e156-45c3-a9f3-d459dc5ee4dc","added_by":"auto","created_at":"2025-09-09 08:24:52","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":281146,"visible":true,"origin":"","legend":"\u003cp\u003eDaily Average Temperature in Chaoshan region from 2000 to 2020.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7193386/v1/923cb554834d87e636ac6a3c.png"},{"id":90871297,"identity":"205db65c-cfc0-41d1-b2e4-7278ae58be9e","added_by":"auto","created_at":"2025-09-09 08:16:52","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":661846,"visible":true,"origin":"","legend":"\u003cp\u003eWind speed simulation of the three typical residential units.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-7193386/v1/0f514b71aeb49219229b3c4b.png"},{"id":90871295,"identity":"e5c96f8b-80f8-476b-b6e6-f304e82795cc","added_by":"auto","created_at":"2025-09-09 08:16:52","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":70366,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of wind speed observation points in three Units.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-7193386/v1/4dc4b00a5bf29e343611e0f6.png"},{"id":90874723,"identity":"f2e0e0ad-23fe-4de6-9594-8283a06f04b8","added_by":"auto","created_at":"2025-09-09 08:40:53","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":612545,"visible":true,"origin":"","legend":"\u003cp\u003eThe scale of one tile layer.\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-7193386/v1/ded94c8f4fbcf2ad25c9b94f.png"},{"id":90871307,"identity":"86bc3040-5c73-47c4-bf3a-cfe4723ad0fa","added_by":"auto","created_at":"2025-09-09 08:16:53","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":708707,"visible":true,"origin":"","legend":"\u003cp\u003eWind speed distribution of planes with different courtyard scales.\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-7193386/v1/fef3f67da7447814ea8221b5.png"},{"id":90871310,"identity":"8d49de8f-2f55-44f1-95cf-e0f40c1b1576","added_by":"auto","created_at":"2025-09-09 08:16:53","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":169041,"visible":true,"origin":"","legend":"\u003cp\u003eWind Speed Comparison of Spaces for elderly in 9 these Types.\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-7193386/v1/97c2bcf457e656030658b7a7.png"},{"id":90872523,"identity":"10e69163-8f34-43d3-801f-d7271070a432","added_by":"auto","created_at":"2025-09-09 08:24:53","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":315967,"visible":true,"origin":"","legend":"\u003cp\u003eScale constraints of skylights in traditional Chaoshan residential buildings\u003c/p\u003e","description":"","filename":"12.png","url":"https://assets-eu.researchsquare.com/files/rs-7193386/v1/22f614e329f4f247eb5f4446.png"},{"id":90873324,"identity":"adb1fbc3-cbf5-4a1c-bbe0-0351fd5063d3","added_by":"auto","created_at":"2025-09-09 08:32:53","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":522188,"visible":true,"origin":"","legend":"\u003cp\u003eThe planar wind speed distribution corresponding to three skylight designs of Type B3.\u003c/p\u003e","description":"","filename":"13.png","url":"https://assets-eu.researchsquare.com/files/rs-7193386/v1/9b964549d408607a6e661f96.png"},{"id":90871318,"identity":"21e7f1c8-85b6-4fbc-9728-a69ca203e609","added_by":"auto","created_at":"2025-09-09 08:16:53","extension":"png","order_by":14,"title":"Figure 14","display":"","copyAsset":false,"role":"figure","size":529102,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of sectional wind speed distributions in Type B3 before and after skylight opening.\u003c/p\u003e","description":"","filename":"14.png","url":"https://assets-eu.researchsquare.com/files/rs-7193386/v1/312233f0ba4d4bced425fa5e.png"},{"id":90873321,"identity":"e1e32f46-c6ed-4c08-95ca-4440db9b5b4e","added_by":"auto","created_at":"2025-09-09 08:32:53","extension":"png","order_by":15,"title":"Figure 15","display":"","copyAsset":false,"role":"figure","size":91080,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of wind speed improvement in elderly occupied spaces with different skylights.\u003c/p\u003e","description":"","filename":"15.png","url":"https://assets-eu.researchsquare.com/files/rs-7193386/v1/cb8019a34cbb7b27efee66bc.png"},{"id":91148505,"identity":"1bf04e51-94af-4a1c-bad1-6f4ab20aa0b0","added_by":"auto","created_at":"2025-09-12 06:44:44","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":7049270,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7193386/v1/aeefe98b-c744-4dd1-8bd0-22e694cfca12.pdf"},{"id":90871292,"identity":"31ab1c64-812e-4d7c-89a3-42282fe5c001","added_by":"auto","created_at":"2025-09-09 08:16:52","extension":"rar","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":885056,"visible":true,"origin":"","legend":"","description":"","filename":"Supplementaryfile.rar","url":"https://assets-eu.researchsquare.com/files/rs-7193386/v1/06807483991807d1724977bb.rar"}],"financialInterests":"No competing interests reported.","formattedTitle":"Balancing spatial ethic and climate justice of elderly: optimizing natural ventilation in traditional Chaoshan residential buildings","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003e\u003cstrong\u003e1.1 A dilemma of\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003esummer cooling for rural elderly\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003ein southern China\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn the process of global climate change, climate justice is receiving increasing attention [1,2], particularly for vulnerable groups such as the elderly, who are facing risks in adapting to climate change \u0026nbsp;[3], such as issues related to thermal comfort and air quality in their living spaces [4,5]. Urbanization in China has led to a rapid increase in the proportion of urbanized population, accompanied by rising residential energy consumption. As a result, growing numbers of urban residents are experiencing healthy indoor living environments [6,7]. However, the living conditions of a large rural elderly population have not been effectively improved, and they still face indoor health risks posed by summer heatwaves [8,9]. An remarkable case arises in the Chaoshan region along China\u0026apos;s southeast coast, a densely populated area in Guangdong Province comprising the cities of Chaozhou, Shantou, and Jieyang.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAs shown in Fig. 1, according to incomplete statistics of local government data, there are approximately over 3,000 traditional villages inhabited mainly by aging population in the Chaoshan region, primarily distributed around urban built-up areas. In a typical Chaoshan traditional village, the built-up area is typically divided into two sections: the old district dominated by traditional dwellings and the new district characterized by modern residences. A significant proportion of elderly low-income individuals continue to reside in the traditional houses within the old district, unable to secure a suitable living environment due to their inability to afford and install indoor cooling \u0026nbsp;facilities. Consequently, they are exposed to heightened health risks compared to other demographics, posing a social issue that cannot be overlooked.\u003c/p\u003e\n\u003cp\u003eWith the aggravation of population aging, the number of elderly individuals in Chaoshan region has been rising annually. As illustrated in\u0026nbsp;Fig. 2, based on the\u0026nbsp;Sixth and\u0026nbsp;Seventh National Population Census data released by the National Bureau of Statistics of China (\u003cem\u003ehttps://www.stats.gov.cn/sj/pcsj/rkpc/d7c/\u003c/em\u003e), the proportion of the elderly population aged 65 and above in China has surpassed 10%. In the Chaoshan area, the proportion of this demographic group has risen from 7.42% in 2010 to 11.42% in 2020, outpacing the average growth rate in Guangdong Province by nearly 3 percentage points, and\u0026nbsp;Chaoshan has become one of the regions with the highest density of elderly population in rural southern China.\u0026nbsp;In recent decades, the extensive adoption of air conditioning\u0026nbsp;equipment\u0026nbsp;has led to a decrease in attention to natural ventilation\u0026nbsp;measures, with residential spaces becoming increasingly reliant on mechanical ventilation and\u0026nbsp;cooling\u0026nbsp;[10, 11]. The elderly low-income residents cannot\u0026nbsp;bear the burden\u0026nbsp;of\u0026nbsp;air conditioning\u0026nbsp;cost\u0026nbsp;in summer, and\u0026nbsp;are reluctant to seek healthier housing options due to the constraints imposed by the spatial ethics,\u0026nbsp;which makes the solution of social problem\u0026nbsp;mentioned above\u0026nbsp;in a dilemma.\u003c/p\u003e\n\u003cdiv align=\"center\"\u003e\u003c/div\u003e\n\u003cp\u003eThe natural ventilation techniques employed in traditional dwellings have gained widespread application due to their dual benefits of enhancing indoor air quality and promoting thermal comfort\u0026nbsp;[12,13], especially in tropical regions and during summer periods, where ventilation efficiency is closely correlated with occupants\u0026rsquo; health\u0026nbsp;[14,15].\u0026nbsp;As a crucial design strategy, natural ventilation measures,\u0026nbsp;for instance, installing ventilation openings and shafts in buildings\u0026nbsp;based on\u0026nbsp;wind pressure differences and air temperature gradients plays a crucial role in regulating the indoor environment of vernacular architecture\u0026nbsp;[16, 17]. These measures, characterized by their low cost, low energy consumption, and eco-friendly, serve as the preferred approach to addressing the aforementioned\u0026nbsp;dilemma. However, in the rural area of Chaoshan, where the tradition of familial clustering is deeply ingrained, the implementation of these ventilation measures continues to encounter obstacles stemming from the traditional spatial ethical order. Balancing spatial ethics with architectural ventilation strategies is a pivotal issue in resolving the\u0026nbsp;deficiency of ventilation and cooling in dwellings for elderly.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.2 Conflict between spatial ethic and the climate justice of the rural elderly\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTraditional residences in Chaoshan region represent a type of courtyard-style buildings widely found in the eastern Guangdong province. These residences, which were extensively constructed during the Ming and Qing dynasties and have been continuously occupied ever since, have become the most prevalent form of vernacular buildings in rural Chaoshan areas. Currently, a large number of residents, particularly the elderly population, still inhabit these dwellings, and these buildings are characterized by two main features.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe first characteristic lies in its highly standardized architectural form, with the building\u0026apos;s plan consisting of modular spaces. As shown in\u0026nbsp;Fig. 3a, 3b and 3c, the basic planar unit encompasses three prototypes: Type A, Type B, and Type C, and even a grand residential complex is constructed through the repetitive arrangement and variations of these three fundamental forms. Type B is the most standardized form, commonly referred to as \u003cem\u003eSi Dian Jin\u0026nbsp;(Four Points of Gold)\u003c/em\u003e, which includes three parts: a front hall, a rear hall, a central courtyard and auxiliary chambers. Type A is derived from Type B through the reduction of front spatial depth, popularly known as \u003cem\u003eXia Shan Hu\u0026nbsp;(Tiger Descending the Mountain)\u003c/em\u003e. This variant features a shallower plan and simplified form, making it the most prevalent residential type in ChaoShan villages due to its compact scale. Type C originates from expanding the central part of Type B, referred to as \u003cem\u003eSan Ting Gen\u0026nbsp;(Three Halls and Courts)\u003c/em\u003e. This form exhibits\u0026nbsp;increased plan depth, incorporating two tiers of courtyards, auxiliary spaces, and a more elaborate spatial organization. Through the strategic combination and expansion of these three basic units, integrated with alleyway circulation systems and auxiliary spaces, more complex mansion-type residences emerge. Notable examples include the \u003cem\u003eSi Ma Tuo Che\u0026nbsp;(Four Horses Towing a Cart)\u003c/em\u003e, composed of four\u0026nbsp;A or B\u0026nbsp;units and one C unit\u0026nbsp;(Fig.\u0026nbsp;3d);\u0026nbsp; \u0026nbsp;the \u003cem\u003eJiu Long Tu Zhu\u0026nbsp;(Nine Dragons Spitting Pearls)\u003c/em\u003e, comprising eight\u0026nbsp;A or B\u0026nbsp;units and one C unit\u0026nbsp;(Fig.\u0026nbsp;3e), and the \u003cem\u003eBai Niao Chao Feng\u003c/em\u003e \u003cem\u003e(A hundred birds and a Phoenix)\u003c/em\u003e\u003cem\u003e,\u0026nbsp;\u003c/em\u003ecomprising\u0026nbsp;more\u0026nbsp;basic\u0026nbsp;units\u0026nbsp;(Fig.\u0026nbsp;3f).\u0026nbsp;Most traditional villages in ChaoShan are structured as agglomerations of these modular units.\u003c/p\u003e\n\u003cdiv align=\"center\"\u003e\u003c/div\u003e\n\u003cp\u003eThe second \u0026nbsp;feature is a rigid spatial ethical hierarchy, manifested in the allocation of internal spaces that adheres to feudal family rituals and ethical codes. Within the social framework of extended family cohabitation, distinct spatial functions were assigned to ancestors, elders, juniors, family members, and outsiders. \u0026nbsp;As shown in Fig. 3a, \u0026nbsp;3b, and 3c, in Type A, B, and C residential units, residential interior spaces marked with different colors belong to different membersthe. Specifically, front central hall was primarily designated for guest reception, while bedrooms in lateral wings were allocated to junior family members. The central courtyard functioned as the family\u0026rsquo;s internal communal activity space, with side rooms serving as storerooms and kitchens. The rear central hall was exclusively reserved for ancestral worship, while adjacent bedrooms were designated for senior family members. The rear space, serving both as the ancestral hall and the bedroom for elders, represents not merely a physical space, but also an expression of the concept of \u0026quot;honoring elders\u0026quot; within clan etiquette. \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePeople\u0026apos;s emotional dependence on specific spaces is not solely based on physical attributes, but rather, over long-term life experiences, they integrate personal emotions, family memories, and spaces closely together [18, 19]. In traditional Chaozhou residential architecture, the elderly generation\u0026apos;s adherence to the layout where the rear hall is considered the most respected area exemplifies this attachment to one\u0026apos;s place of origin. The rear hall, serving as a place for family rituals and the residence of elders, holds memories of several generations, and the elderly\u0026apos; s affection for it reflects their profound identification with family roots. Field surveys of multiple traditional villages in Chaoshan have revealed that the spatial allocation within these residences still follows this spatial ethical hierarchy, which means the primary living and activity areas for seniors are centered around the back hall, including the bedrooms, central courtyard, and connecting corridors adjacent to it, serving as their exclusive living spaces. Measurements of wind speed and interviews reveal that elderly residents commonly complain that \u0026quot;the back hall feels like a steam room in summer, causing one to sweat even when sitting still.\u0026quot; However, when asked if they would be willing to relocate to a room in the front yard with improved ventilation, most responded, \u0026quot; It\u0026apos;s a tradition for the younger generation to live in the front yard; we can\u0026apos;t disrupt that.\u0026quot; This contradiction validates the inadequate ventilation in the back hall and underscores the restrictions imposed by spatial ethics on residential preferences.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe rigid trend of allocating spaces specifically for the elderly, while historically accommodating their socio-psychological needs, is now in conflict with the climate justice of the growing elderly population due to inadequate ventilation and \u0026nbsp;thermal comfort during summer, emerging as one of the health housing problems to be solved in rural areas of southern China. This study aims to develop natural ventilation optimization strategies for elderly in traditional ChaoShan dwellings through CFD simulations and numerical comparative analysis. By integrating a \u0026quot;data driven-technology adaptive-ethics compatible\u0026quot; research framework, the study seeks to address ventilation dilemmas while compatible with spatial ethical order.\u003c/p\u003e"},{"header":"2. Ventilation simulations of elderly occupied space and potential optimization strategies","content":"\u003cp\u003e\u003cstrong\u003e2.1\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eSimulation\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;of natural ventilation\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eof\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;three basic residential units\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Located by the sea, the ChaoShan region is influenced by the sea-land breeze circulation, making north-south winds the predominant wind directions. To achieve good ventilation, traditional villages in the ChaoShan region are primarily oriented north-south. Using Rhino software and its ladybug plugin, combined with Chinese standard meteorological datasets, wind speeds and directions when air temperatures exceed 28\u0026deg;C from June to September in Shantou City were selected to create a summer wind rose diagram (Fig. 4). It can be observed that the wind directions with higher frequencies in summer are S, ESE, SE, SSW, and SW. Additionally, considering the orientation characteristics of traditional residential buildings, the simulation wind direction was set to south.\u003c/p\u003e\n\u003cp\u003eBased on the observational data from the Shantou Meteorological Station (station number: 59316, longitude: 116\u0026deg;41\u0026prime;E, latitude: 23\u0026deg;24\u0026prime;N) from 2000 to 2020, the average wind speed and daily average temperature over the past 20 years in Shantou City were statistically analyzed. As shown in Fig. 5, the average wind speed decreased from 2.5 m/s in 2000 to 1.7 m/s in 2020. Combining this with actual wind speed measurement data, the initial simulation wind speed was set to 2.1 m/s, with the wind direction being south. As shown in Fig. 6, the daily average temperature from June to September ranges from 25\u0026deg;C to 39\u0026deg;C, with the most frequent interval being 31\u0026deg;C to 34\u0026deg;C. Based on the temperature distribution frequency, 32\u0026deg;C was set as the initial simulation temperature.\u003c/p\u003e\n\u003cp\u003eUtilizing Rhino software, a spatial model was created, with the height of the residential model set to 3.5 meters according to actual survey findings. Subsequently, the model was imported into computational fluid dynamics (CFD) software. Referencing the \u0026quot;\u003cem\u003eJGJ/T449-2018 Standard for Green Performance Calculation of Civil Buildings\u003c/em\u003e\u0026quot; and related research cases, the model was meshed with a precision of 200mm*200mm*250mm, and the boundaries of the model, except the base, were extended outward by three times its height, namely 10.5 meters, to better simulate the wind flow field effects in the real environment. To ensure the stability and accuracy of the simulation results, the number of iterations for the calculation was set to 500. Under the premise that the calculation results converge, the wind speed calculation results were output (Fig.7).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eBased on the wind speed distribution patterns of the three basic residential typologies described above, a consistent trend emerges: wind velocities gradually decrease from the front to the rear sections of the dwellings, with notable disparities between front and rear zones. Under the condition of summer ventilation dominated by southerly winds, the front area, including the hall and bedroom zones, exhibit favorable ventilation performance, as windows and door openings could effectively channel natural breezes into the interior spaces. Notably, the front halls record the highest wind speeds, reaching approximately 2 m/s, while the front bedrooms register maximum velocities of 0.6\u0026ndash;0.8 m/s. The middle areas, including the central courtyards and surrounding corridors also benefit from widespread natural ventilation, characterized by relatively uniform wind speed distributions. In the deeper-plan of Type B and Type C units, courtyard wind speeds attain approximately 1.2 m/s, whereas the shorter-span of Type A units exhibit courtyard velocities up to 1.9 m/s. The back areas, including the rear halls and bedrooms (Space occupied by the elderly), in contrast, suffer from inadequate natural ventilation. In Type B and Type C units, wind speeds near the northern exterior walls and in zones distant from openings approach 0 m/s on average. For Type A units, while the rear halls achieve average wind speeds below 0.3 m/s, the rear bedrooms remain poorly ventilated, with negligible air movement. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eResults from on-site wind speed measurements and resident interviews in traditional dwellings verify the simulation findings, identifying the rear rooms as primary zones of summer ventilation deficiency. Significantly, these rear rooms serve as the principal daily activity and rest areas for elderly rural residents in ChaoShan. Existing research highlights that older adults exhibit reduced sensitivity to indoor thermal environmental changes compared to younger populations\u0026nbsp;[20,21], yet their diminished physiological adaptability and regulatory capacity increase vulnerability to health risks in unsuitable indoor environments\u0026nbsp;[22,23]. This is particularly critical for elderly individuals with dementia or other chronic conditions, where indoor environmental quality directly impacts disease management and recovery\u0026nbsp;[24, 25]. In the context of hot-humid summer climate in Chaoshan region, and given the economic constraints faced by the elderly and low-income population, enhancing natural ventilation efficiency holds profound significance for improving thermal comfort among elderly residents, while also mitigating health risks associated with stagnant indoor air.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2 Optimize\u003c/strong\u003e\u003cstrong\u003ed\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;natural ventilation solutions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eClifford Geertz\u0026apos;s theory of cultural interpretation holds that culture is a social phenomenon expressed through symbols and meaning systems\u0026nbsp;[26]. The architectural form of Chaoshan traditional dwellings can be regarded as a cultural symbol, and its spatial layout contains rich cultural connotations. The solemn layout and special functions of the rear hall symbolize the continuity of the family and the authority of the elders, and the overall layout of dwellings reflects the unique cultural values and social order of Chaoshan region. The implementation of ventilation optimization measures will change the physical space of residential buildings, and then affect the meaning conveyed by these cultural symbols. Therefore, when designing the optimization scheme, it is necessary to be careful about the potential impact of spatial changes on cultural significance, so as to ensure the continuity of traditional spatial ethics.\u003c/p\u003e\n\u003cp\u003eBased on the aforementioned ventilation simulation, replacing B-type and C-type residential units with A-type, which have superior ventilation performance, can significantly enhance the natural ventilation of traditional Chaoshan dwellings by reducing the depth of the building and cumulative wind resistance. Nevertheless, this solution is not feasible for widespread implementation, primarily due to the fact that villages in Chaoshan region are predominantly populated by clan-based extended families (The family community bonded by blood ties, exhibits strong social cohesion.), and the size and layout of A-type residences do not cater to the cohabitation requirements and ethical standards of these multi-generational households. Additionally, reducing building density by demolishing some overly concentrated buildings can improve the ventilation around buildings. However,\u0026nbsp;these traditional buildings are increasingly being recognized as architectural heritage by government authorities, and the cultural symbolic value conveyed therein has garnered widespread attention from society. Given both heritage conservation considerations and emotional attachments to the land, demolition is not a viable option. Consequently, specific renovation measures targeting the individual units of types A, B, and C represent more feasible and effective solutions.\u003c/p\u003e\n\u003cp\u003eThe improvement principles to enhance natural ventilation efficiency of Chinese traditional vernacular buildings mainly focus on strengthening thermal pressure effects and wind-driven forces, and the optimization measures are usually derived based on these principles [27,28], such as the adoption of optimized courtyards [29,30], underground spaces [31], window opening [29, 32], building layout [33,34], \u0026nbsp;open space and spatial form \u0026nbsp;[35, 36] and these measures could be combined with the solar chimney and evaporate cooling system to improve thermal comfort further. For traditional Chaoshan dwellings, the above simulation and interpretation reveals the ventilation dilemma of the elderly living space, and feasible ventilation optimization measures must possess social adaptability and cultural compatibility. Given the constraints imposed by multiple factors, including traditional spatial ethical order, architectural heritage protection requirements, and low-income economic conditions. Among these measures, those that neither compromise the integrity of the architectural heritage nor incur high costs are of greater practical value. Based on this understanding, this study selected two innovative approaches to enhance the natural ventilation in elderly living spaces: expanding courtyard sizes and installing roof skylights.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDuring the subsequent research, we constructed spatial models featuring varying courtyard and skylight dimensions, and employed CFD simulation to validate the natural ventilation of these two measures. As shown in \u0026nbsp;Fig. 8, to analyze the wind speed distribution across three housing types, wind speed monitoring points were established 1.5 meters above the ground in four areas (hall, bedrooms, courtyard, and corridors) where elderly are frequently active. The average wind speed values of monitoring points within the rooms were utilized to assess natural ventilation performance.\u0026nbsp;\u003c/p\u003e"},{"header":"3 Simulation of expanding courtyards and adding skylights for improving ventilation","content":"\u003cp\u003e\u003cstrong\u003e3.1\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eE\u003c/strong\u003e\u003cstrong\u003expanding the scale\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;of\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003ecourtyard\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.1.1 Design of different courtyard scales\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe design and construction of traditional Chaoshan residential buildings involve various groups of craftsmen, including geomancers, carpenters, bricklayers, and painters. These craftsmen typically employ five types of measurement units: the tile layer (distance between the centerlines of two roof tiles), the construction ruler, the purlin (distance between the centerlines of two roof purlins), the pace, and the measuring rod (a flat wooden rod with size scales on both sides). Although each craft tradition focused on distinct scale modules, all units were fundamentally anchored in the construction ruler, with interconvertible relationships documented in Table 1. Shaped by local social customs and feng shui theory (The traditional Chinese philosophy of spatial layout emphasizes the harmonious relationship between humans and the natural environment) of Chaoshan region, different building areas, such as halls, bedrooms, and courtyards, required specific length units for dimensional calculations, with distinct mathematical rules governing scale prescriptions [37].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 1 Units of measurement for dimensions in traditional Chaoshan residential buildings.\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"604\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 81px;\"\u003e\n \u003cp\u003eScale unit\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003eLarge tile layer\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003eSmall tile layer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003eConstruction ruler (CR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 80px;\"\u003e\n \u003cp\u003ePurlin\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003ePace\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 98px;\"\u003e\n \u003cp\u003eMeasuring rod\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 81px;\"\u003e\n \u003cp\u003eActual length\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e298mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e268mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e298mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 80px;\"\u003e\n \u003cp\u003e450-600mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e1350mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 98px;\"\u003e\n \u003cp\u003e5543mm\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 81px;\"\u003e\n \u003cp\u003eCrafts men\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003eBricklayer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003eBricklayer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003eCarpenter\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 80px;\"\u003e\n \u003cp\u003eCarpenter\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 98px;\"\u003e\n \u003cp\u003eCarpenter\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 81px;\"\u003e\n \u003cp\u003eApplication\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003eRoom width\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003eRoom width\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003eGeneral dimensions\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 80px;\"\u003e\n \u003cp\u003eRoof depth\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003eScale of courtyard and square\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 98px;\"\u003e\n \u003cp\u003ePlane scale, \u0026nbsp;height\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 81px;\"\u003e\n \u003cp\u003eConversion \u0026nbsp;with CR\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 80px;\"\u003e\n \u003cp\u003eAbout 1.5-2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003eAbout 4.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 98px;\"\u003e\n \u003cp\u003e18.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eThe scale of three basic residential types is quantified in \u0026quot;Jian\u0026quot; (a traditional Chinese unit of measurement for room width), where the width of a \u0026quot;Jian\u0026quot; depends on the number of roof tile layers. In the ChaoShan region, roof tiles are categorized into large and small tiles, with different corresponding dimensions. As shown in Fig. 9, a \u0026quot;Layer\u0026quot; refers to the width between the midlines of two adjacent tiles, typically 3% to 5% wider than the tile itself . Influenced by feng shui theory, the number of tile layers in the central \u0026quot;Jian\u0026quot; is usually odd, while those in the side \u0026quot;jian\u0026quot;s are even. The width of the northern hall ranges from 17 to 21 \u0026nbsp;layers, while the side living rooms are between 12 to 14 \u0026nbsp;layers. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTo maintain cohesive residential cluster morphology, villages in ChaoShan region exhibit standardized external contour dimensions for similar dwelling types, while allowing flexibility in internal courtyard, hall, and bedroom dimensions. Hall and side bedroom widths are calibrated according to tile layers, with the hall\u0026rsquo;s width never less than that of side bedrooms. Courtyard dimensions are proportionally linked to hall dimensions, generally maintaining equivalent on widths, while the depth is more flexible but must adhere to the \u0026nbsp;restriction of \u0026quot;Pace\u0026quot; count, which should be an odd number and non-integer. Under these planimetric constraints, the three basic types (A, B, C) usually share identical plan contours and building heights. Three common courtyard scales, based on 17, 19, and 21 tile layers for both length and width were selected, resulting in nine types of distinct plan forms (A1 to C3) with different courtyard proportions (Table 2).\u003c/p\u003e\n\u003cp\u003eTable 2 Dimensions of 9 types of building plane forms.\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"571\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 73px;\"\u003e\n \u003cp\u003eBuilding type\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003eBuilding contour\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eScale(mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003eBuilding area (m\u0026sup2;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003eThe width of main hall (layers\u0026nbsp;of tiles)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 109px;\"\u003e\n \u003cp\u003eCourtyard scale (Construction ruler)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003eCourtyard area (㎡)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\" style=\"width: 43px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eType A\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 30px;\"\u003e\n \u003cp\u003eA1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" style=\"width: 129px;\"\u003e\n \u003cp\u003e14065.6*17105.2 (east-west * north-south)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" style=\"width: 73px;\"\u003e\n \u003cp\u003e240.58㎡\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 109px;\"\u003e\n \u003cp\u003e15*15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e19.98\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 30px;\"\u003e\n \u003cp\u003eA2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 109px;\"\u003e\n \u003cp\u003e16.8*16.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e25.06\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 30px;\"\u003e\n \u003cp\u003eA3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 109px;\"\u003e\n \u003cp\u003e18.6*18.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e30.71\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\" style=\"width: 43px;\"\u003e\n \u003cp\u003eType B\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 30px;\"\u003e\n \u003cp\u003eB1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" style=\"width: 129px;\"\u003e\n \u003cp\u003e14065.6*22350\u003c/p\u003e\n \u003cp\u003e(east-west * north-south)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" style=\"width: 73px;\"\u003e\n \u003cp\u003e314.35㎡\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 109px;\"\u003e\n \u003cp\u003e15*15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e19.98\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 30px;\"\u003e\n \u003cp\u003eB2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 109px;\"\u003e\n \u003cp\u003e16.8*16.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e25.06\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 30px;\"\u003e\n \u003cp\u003eB3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 109px;\"\u003e\n \u003cp\u003e18.6*18.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e30.71\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\" style=\"width: 43px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eType C\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 30px;\"\u003e\n \u003cp\u003eC1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" style=\"width: 129px;\"\u003e\n \u003cp\u003e14065.6*30694\u003c/p\u003e\n \u003cp\u003e(east-west * north-south)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" style=\"width: 73px;\"\u003e\n \u003cp\u003e431.65㎡\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 109px;\"\u003e\n \u003cp\u003e15*15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e19.98\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 30px;\"\u003e\n \u003cp\u003eC2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 109px;\"\u003e\n \u003cp\u003e16.8*16.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e25.06\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 30px;\"\u003e\n \u003cp\u003eC3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 109px;\"\u003e\n \u003cp\u003e18.6*18.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e30.71\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cstrong\u003e3.1.2 Comparison of ventilation\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eof\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003edifferent courtyard scales\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAs shown in\u0026nbsp;Fig. 10, under\u0026nbsp;the same\u0026nbsp;operational parameters to the aforementioned simulations,\u0026nbsp;Ansys-Icepak\u0026nbsp;software was employed to model ventilation across the nine\u0026nbsp;plans with different courtyard scale, and\u0026nbsp;wind speed distribution\u0026nbsp;maps\u0026nbsp;and observation point\u0026nbsp;data\u0026nbsp;(Table 3)\u0026nbsp;were extracted. The simulation results exhibit similar trends in wind speed changes, indicating that within comparable planes and spaces of the same type, wind speed does not experience a notable increase as the courtyard scale expands.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;In hall spaces frequented by elderly residents, average wind speeds remain below 0.2 m/s for Type A plans and below 0.05 m/s for Type B and C plans. These halls, serving as both ritual preparation areas and communal living spaces for the elderly, exhibit insufficient airflow to support comfortable daily activities, as indicated by the stagnant wind condition in plans of ventilation. The bedrooms, serving as primary zones of sleeping and resting for elderly, show average wind speeds below 0.35 m/s for Type B and C plans, and below 0.1 m/s for Type A plans, and airflow is predominantly concentrated around door and window openings, with negligible movement on the northern sides of bedrooms, which fail to achieve adequate air circulation necessary for thermal comfort. The corridors spaces in front of halls show more favorable conditions: Type A plans exhibit wind speeds exceeding 0.4 m/s, while Type B and C plans range between 0.1\u0026ndash;0.4 m/s. As transitional zones connecting outdoor courtyards to indoor living areas, and activity spaces for the elderly, these corridors demonstrate higher average wind speeds than halls or bedrooms, offering improvements to indoor ventilation. The courtyard space, where elderly engage in daytime activities, show the strongest ventilation performance: Type A plans exceed 0.65 m/s, while Type B and C plans range between 0.3\u0026ndash;0.4 m/s, which effectively mitigate tie air stagnation situation around the courtyard.\u003c/p\u003e\n\u003cp\u003eTable 3 Average wind speed in the spaces for the elderly.\u0026nbsp;\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"607\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 71px;\"\u003e\n \u003cp\u003eposition\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003eAverage wind speed in the rear hall (m/s)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003eAverage wind speed in bedroom (m/s)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003eAverage wind speed in the corridor (m/s)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003eAverage wind speed in the courtyard (m/s)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003eCourtyard area ratio\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\" style=\"width: 27px;\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 44px;\"\u003e\n \u003cp\u003eA1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e0.134\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e0.080\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.406\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003e0.682\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 73px;\"\u003e\n \u003cp\u003e8.30%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 44px;\"\u003e\n \u003cp\u003eA2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e0.156\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e0.076\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.566\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003e0.740\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 73px;\"\u003e\n \u003cp\u003e10.42%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 44px;\"\u003e\n \u003cp\u003eA3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e0.150\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e0.091\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.420\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003e0.680\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 73px;\"\u003e\n \u003cp\u003e12.76%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\" style=\"width: 27px;\"\u003e\n \u003cp\u003eB\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 44px;\"\u003e\n \u003cp\u003eB1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e0.010\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e0.216\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.203\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003e0.364\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 73px;\"\u003e\n \u003cp\u003e6.36%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 44px;\"\u003e\n \u003cp\u003eB2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e0.014\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e0.313\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.360\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003e0.310\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 73px;\"\u003e\n \u003cp\u003e7.97%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 44px;\"\u003e\n \u003cp\u003eB3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e0.025\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e0.280\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.266\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003e0.376\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 73px;\"\u003e\n \u003cp\u003e9.77%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\" style=\"width: 27px;\"\u003e\n \u003cp\u003eC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 44px;\"\u003e\n \u003cp\u003eC1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e0.007\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e0.300\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.130\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003e0.396\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 73px;\"\u003e\n \u003cp\u003e4.63%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 44px;\"\u003e\n \u003cp\u003eC2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e0.011\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e0.253\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.140\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003e0.348\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 73px;\"\u003e\n \u003cp\u003e5.81%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 44px;\"\u003e\n \u003cp\u003eC3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e0.017\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e0.258\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.153\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003e0.308\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 73px;\"\u003e\n \u003cp\u003e7.11%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eAs illustrated in\u0026nbsp;Fig.11, among the 9 types of plans, Type A exhibit the optimal natural ventilation performance, while Type C demonstrates the poorest. Within the Type A category, the A2 variant, featuring a courtyard area of 16.8\u0026times;16.8 construction rulers (accounting for 10.42% of the total built-up area), achieves the best ventilation efficiency. Although the courtyard significantly enhances airflow in adjacent corridors and halls, its performance margin over A1 and A3 types remains statistically insignificant. Similarly, across Type B and C buildings, no notable ventilation disparities were observed among plans with varying courtyard scales. These results indicate that during summer, when the prevailing wind direction is southerly, the courtyard scale in traditional Chaoshan residences has a negligible impact on natural ventilation and wind speed distribution. Expanding courtyard size alone does not effectively improve ventilation performance. Compared to courtyard scale, the aspect ratios (length-to-width ratios) of the building has a greater influence on ventilation. As building length increases, natural ventilation energy loss through internal spaces escalates, progressively diminishing the dwelling\u0026rsquo;s ventilation capacity. This mechanism explains why, in Type B and Type C buildings, elderly-occupied rear spaces fail to achieve adequate air circulation.\u003c/p\u003e\n\u003cp\u003eIn summary, Type A buildings with lower aspect ratios (length-to-width ratios) demonstrate the highest suitability for natural ventilation in elderly living spaces. However, due to their compact living place, typically accommodating 2-5 occupants in two-generation households, Type A buildings are insufficient to meet the needs of multigenerational families prevalent in Chaoshan traditional villages. A substantial proportion of elderly residents continue to reside in Type B and Type C buildings, which could accommodate three-generation cohabiting households. This reality underscores the urgent need to develop targeted natural ventilation optimization strategies for these larger-scale building units. To address this gap, this study proposes a skylight intervention as a viable solution.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2 Add\u003c/strong\u003e\u003cstrong\u003eing\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;roof skylights\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2.1\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eScale\u003c/strong\u003e\u003cstrong\u003es and location of roof skylights\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe roof structure of traditional Chaoshan dwellings consists of a timber framework, with construction layers arranged top-down as follows: roof tile layer, wooden plank layer, and timber purlin layer. When adding skylights into the roofs of rear rooms occupied by elderly residents, two structural constraints govern skylight dimensioning, derived from traditional roof construction principles:\u003c/p\u003e\n\u003cp\u003eFirstly, the skylight\u0026rsquo;s depth-wise (north-south) length must align with roof purlin spacing, requiring the dimension to be an integer multiple of the purlin module. This ensures secure attachment of the skylight frame to purlins, maintaining roof structural integrity. As illustrated in\u0026nbsp;Fig. 12a, on a typical lateral section of the rear hall space, the building\u0026rsquo;s depth is determined by the number of purlins. In a typical 13-purlins Chaoshan dwelling, the maximum skylight width (without compromising ridge or eave structures) can span up to 3 purlins, equivalent to approximately 50% of the roof\u0026rsquo;s single-side width.\u003c/p\u003e\n\u003cp\u003eSecondly, the skylight\u0026rsquo;s width-wise (east-west) length must conform to the \u0026quot;tile layer\u0026quot; \u0026nbsp; modular system, with dimensions restricted to integer multiples of tile layers. This preserves the continuity of roof tiling and structural stability. As illustrated in Fig. 12b, among traditional ChaoShan residential buildings, the tile layers of rear hall roof in the width direction are usually 17, 19, or 21. To maintain roof integrity on both hall sides, maximum skylight lengths range from 14 to 18 tile layers. However, to maintain the original roof style and preserve the facade appearance of the architectural heritage, the length of the skylight should not be excessive, and it is generally more appropriate for it to not exceed 50% of the hall\u0026apos;s width.\u0026nbsp;\u003c/p\u003e\n\u003cdiv align=\"center\"\u003e\u003cbr\u003e\u003c/div\u003e\n\u003cp\u003eTaking the B3-type residence as a case study, this investigation examines the effects of skylight positioning on natural ventilation efficiency. The B3 front hall exhibits a width of 6.25 m (approximately 21 tile layers) and a depth of 6.85 m (approximately 23 tile layers). In adherence to the skylight dimension principles defined earlier, the skylight is designed with a width of 10 tile layers (2.98 m) and a depth of 8 tile layers (2.38 m). \u0026nbsp;Three skylight positions were selected for comparative analysis: Front-slope installation (Skylights positioned on the southern roof slope), Rear-slope installation (Skylights positioned on the northern roof slope), and Dual-slope installation (Skylights installed on both southern and northern roof slopes). Under the operational parameters specified in Section 2.1, CFD simulations were conducted to quantify natural ventilation performance across the three ways of skylight.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2.2 Comparison of natural ventilation after adding skylights\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBy comparing the wind speed distribution maps of B3-type without skylights (Fig. 10f) and with skylights opening (Fig. 13), it can be observed that opening skylights significantly improves the natural ventilation in the hall used, and the extent of improvement varies among the three different skylight opening methods. By comparing the wind speed distribution maps of the front skylight (Fig. 13a) and the rear skylight (Fig. 13b), it is evident that the optimization effect of the front skylight on natural ventilation is weaker than that of the rear skylight. The front skylight fails to effectively promote the deep penetration of natural ventilation, with its influence primarily concentrated in the front of the hall, as well as the corridor and courtyard (Fig. 13a). In contrast, the rear skylight opening method can more effectively guide natural ventilation to the rear of the hall, expanding its influence (Fig. 13b). Further comparison of the wind speed distributions between the rear skylight opening (Fig. 13b) and the front-rear dual skylight opening (Fig. 13c) reveals that the dual skylight method achieves better wind speed optimization. This method not only introduces natural ventilation into more areas at the rear of the hall but also slightly improves ventilation in the corridor and the bedrooms on both sides of the hall. The comparative analysis of the three skylight opening methods indicates that the front-rear dual skylight approach is most effective in enhancing natural ventilation in the elderly spaces. During peak summer heat, this method can effectively enhance indoor air circulation and cooling, benefiting the living conditions of elderly.\u003c/p\u003e\n\u003cp\u003eFurther comparison of the wind speed distribution in the cross-sections of buildings with and without skylights. As shown in Fig. 14a, in the cross-section without a skylight, natural ventilation cannot circulate sufficiently in the rear hall, and wind speed continues to decrease with the increase of building depth, especially in the rear and upper parts of the hall cross-section, forming large areas of dead air zones, which increases the air age in the hall. As shown in Fig. 14b, in the cross-section with front and rear double skylights, the skylight openings can convey the ventilation from the south side to the outside, allowing natural ventilation to circulate sufficiently in the rear hall, with only small dead air zones formed at the intersection of the rear wall and the ground. Most of the daily used areas have good natural ventilation. By comparing the wind speed distribution in the cross-sections, it can be seen that opening skylights significantly promote natural ventilation in the rear hall and the corridor space in front of it, guiding the natural ventilation that was originally flowing close to the ground to higher areas, improving ventilation and air exchange efficiency, and enhancing air quality above 1.5 meters from the ground.\u003c/p\u003e\n\u003cp\u003eAs shown in Table 4 and Fig. 15, comparing the wind speed before and after opening the skylight, it can be observed that after opening the skylight, the average wind speed in the rear hall increased significantly from 0.025 m/s to 0.232 m/s. This improvement in natural ventilation particularly benefits the public activity areas where the elderly spend most of their daytime. However, there was no significant change of wind speed in other areas frequently occupied by the elderly. For instance, the wind speed in the bedrooms on both sides of the hall decreased slightly from 0.280 m/s to 0.262 m/s, while the wind speed in the corridor in front of the hall increased slightly from 0.266 m/s to 0.279 m/s. Additionally, the average wind speed in the courtyard increased from 0.376 m/s to 0.413 m/s. These observations indicate that the impact of opening the skylight on natural ventilation is primarily concentrated in the hall area, with no significant optimization in other areas, especially the bedrooms on both sides of the hall, where wind speed even decreased slightly. Therefore, to effectively enhance the thermal comfort in bedrooms and other enclosed spaces during summer, it is also necessary to add skylights on the bedroom roofs.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 4 Comparison of wind speeds for three skylight designs in B3-type.\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"611\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003eB3 type\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 93px;\"\u003e\n \u003cp\u003eSkylight opening area (㎡)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 101px;\"\u003e\n \u003cp\u003eAverage wind speed in the rear hall(m/s)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003eAverage wind speed in bedroom (m/s)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003eAverage wind speed in the corridor (m/s)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 111px;\"\u003e\n \u003cp\u003eAverage wind speed in the courtyard (m/s)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003eNo skylight\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 93px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 101px;\"\u003e\n \u003cp\u003e0.025\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e0.280\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003e0.266\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 111px;\"\u003e\n \u003cp\u003e0.376\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003eFront skylight\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 93px;\"\u003e\n \u003cp\u003e7.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 101px;\"\u003e\n \u003cp\u003e0.104\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e0.262\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003e0.272\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 111px;\"\u003e\n \u003cp\u003e0.387\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003eRear skylight\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 93px;\"\u003e\n \u003cp\u003e7.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 101px;\"\u003e\n \u003cp\u003e0.183\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e0.268\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003e0.279\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 111px;\"\u003e\n \u003cp\u003e0.405\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 94px;\"\u003e\n \u003cp\u003eDual skylight\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 93px;\"\u003e\n \u003cp\u003e14.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 101px;\"\u003e\n \u003cp\u003e0.232\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e0.275\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003e0.269\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 111px;\"\u003e\n \u003cp\u003e0.413\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e"},{"header":"4 Discussion","content":"\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\u003ch2\u003e4.1 Efficiency differences in natural ventilation optimization methods\u003c/h2\u003e\u003cp\u003eBoth expanding the courtyard scale and reducing the overall building length can enhance natural ventilation of ChaoShan traditional dwellings, but the differences in their effects on ventilation efficiency are significant. While courtyard geometry, scale, and orientation are generally considered important factors influencing building microclimate [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e, \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e], the effect of courtyard scale on improving natural ventilation efficiency in ChaoShan dwellings is quite limited. Taking Type A buildings as examples (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), from A1 to A3, the courtyard area increased from 19.98㎡ to 30.71㎡, the courtyard area ratio rose from 8.30\u0026ndash;12.76%, and the wind speed in the rear hall increased from 0.134m/s to 0.150m/s, with only a 0.016m/s increase, a wind speed improvement rate of 11.94%. The wind speed improvement rate per additional 1㎡ of courtyard area was 1.11%, and per 1% increase in courtyard area ratio was 2.27%. The wind speed improvement efficiency in corridors and courtyards was even lower. In longer-depth buildings of Type B and C, enlarging the courtyard scale could even increase shaded areas, thereby reducing thermal pressure ventilation (A natural ventilation method that utilizes air pressure differences created by temperature variations in the air to drive airflow). Comparing A1 and C1, with a building depth increase of 13.59m, the hall wind speed decreased by 0.127m/s, a total reduction rate of 94.78%, with an average wind speed reduction rate of 6.97% per additional 1m of depth. This indicates that under summer southerly conditions, the \"wind resistance accumulation\" caused by building depth is the primary reason for insufficient natural ventilation of elderly-occupied spaces in ChaoShan traditional dwellings, and the impact of expanding courtyard scale on wind speed improvement is far less than that of shortening building depth.\u003c/p\u003e\u003cp\u003eThe installation of roof skylights primarily targets older residential buildings, especially the hall spaces. Both rear skylights and front-rear double skylights exhibit more pronounced and direct enhancements in natural ventilation performance. Rear skylights leverage the \"thermal chimney effect\" to create a low-pressure zone on the roof, thereby boosting natural ventilation efficiency. Taking the B3-type residential building as an illustration, a rear skylight with an area of 7.1 ㎡ can elevate the ground-level wind speed in the living hall from 0.025 m/s to 0.183 m/s, marking a 6.32-fold increase, with an average wind speed improvement rate of 89.01% per square meter of skylight. The front-and-rear double skylight further amplifies the natural ventilation pathway of \"air inflow-through-outflow\". With a combined skylight area of 14.2 ㎡, it can increase the ground-level wind speed in the living hall from 0.025 m/s to 0.232 m/s, representing an 8.28-fold increase, with an average wind speed improvement rate of 58.31% per square meter of skylight. The effectiveness of roof skylights in enhancing natural ventilation significantly surpasses adjustments to courtyard layout and depth. Furthermore, skylights exert a more notable influence on airflow trajectories, facilitating ground-level ventilation to flow towards areas nearer to human height. The front skylight primarily enhances ventilation in the front porch, while the rear skylight boosts the airflow rate at the rear of the living hall, validating the necessity of \"active intervention at the airflow terminus.\"\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\u003ch2\u003e4.2 Reconciliation of conflicts between spatial ethics and health needs\u003c/h2\u003e\u003cp\u003eThe \"rear hall\" space of Chaoshan vernacular dwellings carries symbolic significance related to clan rituals and ethics, and its ventilation challenges fundamentally stem from the conflict between traditional communal living patterns and modern health standards. Research findings indicate that most elderly residents refuse to change the living arrangement of using the rear rooms as ancestral halls and bedrooms for elders, making strategies like \"shortening the depth\" and \"rearranging rooms\" difficult to implement. The optimization approach of adding skylights cleverly avoids this dilemma, improving ventilation without compromising spatial ethics. Additionally, by coordinating roof construction and dimensional modules, it minimizes damage to the building heritage, and also aligns with the principle of \"minimum intervention\" in heritage preservation. Moreover, the unique sea-land breeze circulation in the Chaoshan region offers double opportunities for natural ventilation design. During summer days, the sea breeze (south wind) drives air into the house through the front windows. Meanwhile, the rear hall skylights create thermal pressure due to the increased roof temperature, which enhances the horizontal through-draft and effectively introduces cool air from above the sea into the rear spaces. At night, when land breezes dominate, the height difference between the roof skylights, courtyards, and door and window openings can create a \"chimney effect\", strengthening vertical local wind circulation.\u003c/p\u003e\u003cp\u003eCompared to traditional dwellings in arid and hot climates, such as the four-sided wind tower adjacent to the parlor and courtyard in Iran [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e] and the air-drying shelter in the Turpan basin [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e], traditional dwellings in Southeast Asia's hot and humid regions, especially those in the ChaoShan area deeply influenced by traditional clan rituals and ethics, exhibit a \"hidden\" characteristic in their passive ventilation methods. This implies that during the design process, factors related to natural ventilation and human comfort are not primary considerations, but rather secondary considerations after traditional spatial ethics. After the building is constructed, artificial modifications are often added to enhance the space comfort. Research reveals that residents in ChaoShan traditional dwellings spontaneously make minor modifications to the roof structure to improve ventilation and lighting, such as creating small-scale roof openings on the gaps between roof tiles and purlins. However, due to the small size of these openings, the improvement in ventilation is limited, and they cannot be automatically opened or closed, causing inconvenience during the rainy season. Integrating modern skylight design with the roof construction features of ChaoShan traditional dwellings can effectively address these drawbacks. This approach not only preserves the regional architectural culture but also enhances its climate control performance, increasing the feasibility of sustainable updates to ChaoShan traditional dwellings. As a result, it is the preferred method for improving ventilation on existing dwellings.\u003c/p\u003e\u003c/div\u003e"},{"header":"5 Conclusion","content":"\u003cp\u003eThis study focuses on the typical traditional dwellings in the ChaoShan region, using CFD simulations and comparative analysis to investigate the challenges of natural ventilation in elderly living spaces during summer and proposing optimization strategies. The main conclusions are as follows:\u003c/p\u003e\n\u003col\u003e\n \u003cli\u003eVentilation Challenges:\u0026nbsp;\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003eUnder summer southerly wind conditions, the three basic types of traditional dwellings in Chaoshan exhibit a ventilation pattern characterized by \u0026quot;strong in the front and weak at the back,\u0026quot; indicating a significant tendency towards uneven ventilation distribution. Wind speeds in the front halls and courtyards can reach 0.6-2 m/s, while the average wind speeds in the rear halls and bedrooms where elderly occupied are below 0.3 m/s, with some areas approaching 0 m/s. The wind speed attenuation rate ranges from 70% to 90%, creating distinct no-wind zones. Ventilation relies on a planar network of \u0026quot;courtyard-door-window,\u0026quot; but lacks mechanisms for vertical airflow guidance. The low height of the courtyards and door/window openings results in insufficient height differences, preventing the formation of an effective \u0026quot;chimney effect.\u0026quot; Consequently, natural ventilation is neither uniformly distributed nor deeply penetrating. The cumulative wind resistance resulting from building depth is the primary cause of inadequate natural ventilation. Comparing Class A buildings (short depth) with Class C buildings (long depth) reveals that for every additional meter of depth, the wind speed in the hall decreases by 6.97%, significantly reducing natural ventilation efficiency in the rear spaces. However, due to the constraints of traditional clan rituals, elderly residents in Chaoshan prefer to stay in poorly ventilated areas, especially in Type C dwellings with depths exceeding 10 meters, where large no-wind zones exist in their living spaces, thus increasing their health risks in summer.\u003c/p\u003e\n\u003col start=\"2\"\u003e\n \u003cli\u003eSelection of optimization strategies:\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003e\u0026nbsp;In the complex practical process of optimizing indoor ventilation in ChaoShan traditional dwellings during summer, several critical factors must be considered when selecting strategies. These include ventilation improvement rate, ethical compatibility, damage to building heritage, modification costs, and construction difficulty.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFor ChaoShan traditional dwellings designated as heritage buildings by the government, ventilation optimization strategies should prioritize the principle of \u0026quot;minimum intervention in heritage\u0026quot;, with the preferred approach being the installation of roof skylights in core activity areas for the elderly. Adding skylights serves as a key strategy to balance the spatial ethics of traditional ChaoShan dwellings with modern health requirements, as it does not alter the original spatial hierarchy of \u0026quot;respecting the rear,\u0026quot; but instead achieves improved natural ventilation through minor modifications that adapt to the roof purlin spacing and tile module. For the rear hall, where the elderly primarily gather, skylights should be installed on either side of the roof ridge or near the rear wall to directly address windless zones using the \u0026quot;thermal pressure ventilation\u0026quot; principle. For example, installing a rear skylight on the roof of the rear hall in a B3-type dwelling, which spans three purlins in depth and ten tile ridges in width, ensures that airflow reaches the rear of the hall. Additionally, for deeper C-type dwellings, a dual-skylight approach can be employed, with a front skylight introducing southern winds and a rear skylight expelling warm, humid air, creating a complete ventilation path of \u0026quot;inflow - cross - outflow,\u0026quot; significantly increasing airflow in the hall while slightly enhancing ventilation in the bedrooms on both sides. The addition of skylights offers clear advantages in enhancing ventilation efficiency, compatibility with heritage preservation, and adaptability to regional climates, providing a \u0026quot;low-intervention, high-efficiency\u0026quot; reference for healthy renovation of traditional buildings in similar climates.\u003c/p\u003e\n\u003cp\u003eFor residences that are being planned and newly constructed, the depth dimension can be shortened to optimize natural ventilation, using Type A buildings as the basic unit for spatial layout, while moderately increasing the courtyard area, but the courtyard area ratio should not exceed 13%. For instance, when the courtyard area ratio of Type A3 is 12.76%, a slight decrease in wind speeds in corridors and courtyards is observed. When renovating non-heritage-protected old houses, if the courtyard space is too small to provide sufficient outdoor activity areas, it is advisable to prioritize expanding the courtyard dimensions. For example, during the renovation of Type A residences, increasing the courtyard area ratio from 8.3% to 10.4% can improve the wind speeds in the hall, courtyard, and corridor. However, expanding the courtyard entails higher construction costs, making it challenging to widely implement among low-income elderly residents. Additionally, in residential clusters like \u0026quot;Si Ma Tuo Che\u0026quot; and \u0026quot;Jiu Long Tu Zhu\u0026quot; removing side rooms or corridors to enlarge courtyards is not allowed, as it may disrupt the spatial sequence and potential heritage value.\u003c/p\u003e\n\u003col start=\"3\"\u003e\n \u003cli\u003eLimitations and Outlook:\u0026nbsp;\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003eThis study explores the balance between spatial ethics and natural ventilation optimization in traditional Chaoshan dwellings, with a focus on addressing the summer living challenges of elderly residents. However, several limitations remain, which also point to avenues for future research.\u003c/p\u003e\n\u003cp\u003eFirstly, the analysis of \u0026quot;space ethics\u0026quot; remains confined to the descriptive level, insufficiently delving into how ethical norms are dynamically constructed through daily practices and renegotiated under environmental pressures. Secondly, empirical research has placed undue emphasis on physical ventilation data, neglecting the subjective experiences of elderly residents, such as their perception of thermal comfort and emotional attachment to space. Lastly, simulations have exclusively focused on summer conditions, overlooking the influence of seasonal climate variations and long-term urbanization on spatial ethics. Future research should integrate anthropological theories to explore how optimization measures can reshape \u0026quot;ethical spaces\u0026quot; without undermining traditional hierarchies. A hybrid approach combining microclimate monitoring with observations of elderly daily activities should be adopted to bridge the gap between physical data and lived experiences. Additionally, policy guidelines for \u0026quot;ethical adaptation\u0026quot; should be formulated, encompassing subsidies for heritage-compatible renovation projects, training for craftsmen in low-intervention techniques, and striking a balance between technical efficiency and cultural legitimacy. This framework serves as a reference for sustainable rural development in aging societies, prioritizing human experience and intergenerational equity.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding declaration:\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis work was supported by the Humanities and Social Sciences Youth Foundation, Ministry of Education of China (grant number 23YJCZH142). The funder provided financial support for the study but had no role in the design of the study; in the collection, analysis, and interpretation of data; in the writing of the manuscript; or in the decision to submit the manuscript for publication. All authors are responsible for the content of this article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data will be made available on request.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical approval:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis article does not contain any studies with human participants performed by any of the authors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInformed consent:\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis article does not contain any studies with human participants performed by any of the authors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLW: conceptualization and methods, writing-original draft, writing-review and editing, project administration and funding acquisition. MJ: data collection and analysis, drawing pictures and tables. HH: investigation, formal analysis. GH: software and simulation. All authors reviewed the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eWalker, S. E., Smith, E. A., Bennett, N., Bannister, E., Narayana, A., Nuckols, T., ... \u0026amp; Bailey, K. M. (2024). Defining and conceptualizing equity and justice in climate adaptation. Global Environmental Change, 87, 102885.\u003c/li\u003e\n\u003cli\u003eZhang, H., Luo, M., Pei, T., Liu, X., Wang, L., Zhang, W., ... \u0026amp; Liao, W. (2023). Unequal urban heat burdens impede climate justice and equity goals. The Innovation, 4(5).\u003c/li\u003e\n\u003cli\u003eYang, H., Lee, T., \u0026amp; Juhola, S. (2021). The old and the climate adaptation: Climate justice, risks, and urban adaptation plan. Sustainable Cities and Society, 67, 102755.\u003c/li\u003e\n\u003cli\u003eZhou, S., Li, B., Du, C., Liu, H., Wu, Y., Hodder, S., ... \u0026amp; Yao, R. (2023). 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Energy Build 172:525\u0026ndash;536. \u003c/li\u003e\n\u003cli\u003eZhang L, Sang G, Zhu Y et al (2023) Thermal regulation mechanism of air-drying shelter to indoor environment of earth buildings located in Turpan basin with extremely dry and hot climate conditions. Sustain Cities Soc 91:104416. \u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"humanities-and-social-sciences-communications","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"palcomms","sideBox":"Learn more about [Humanities \u0026 Social Sciences Communications](http://www.nature.com/palcomms/)","snPcode":"41599","submissionUrl":"https://submission.springernature.com/new-submission/41599/3","title":"Humanities and Social Sciences Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Nature AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Climate justice, Spatial ethic, Natural ventilation, Rural elderly, Traditional residential buildings","lastPublishedDoi":"10.21203/rs.3.rs-7193386/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7193386/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study explores the climate justice of summer cooling for rural elderly residents in Chaoshan region, China. By 2020, the elderly population in the region had risen to 11.42%, with a large proportion of low-income seniors. Due to financial constraints, they cannot afford air conditioning, and natural ventilation in their living spaces, particularly the rear halls of traditional dwellings, is severely inadequate. This not only causes discomfort but also poses potential health risks, highlighting a distinct climate vulnerability gap. Traditional dwellings in Chaoshan villages, standardized into Types A, B, and C, follow a strict spatial hierarchy that places the elderly in rear zones. Measurements reveal striking ventilation inequality: wind speeds reach approximately 2 m/s in front areas but drop to near 0 m/s in rear spaces. To address this, the study employs CFD simulations to test potential solutions. Expanding courtyards shows limited effectiveness, whereas roof skylights, especially the front-rear dual design, significantly improve rear hall ventilation. In a typical dwelling, rear hall wind speed increases from 0.025 m/s to 0.232 m/s.This low-cost, heritage-compatible intervention directly targets the climate health needs of a marginalized group, ensuring their right to thermal comfort amid climate change. By reconciling traditional spatial order with equitable climate adaptation, the study offers a model for climate action that centers justice, prioritizing vulnerable populations' needs while respecting cultural identities in traditional rural context of southern China.\u003c/p\u003e","manuscriptTitle":"Balancing spatial ethic and climate justice of elderly: optimizing natural ventilation in traditional Chaoshan residential buildings","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-09 08:16:47","doi":"10.21203/rs.3.rs-7193386/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-12-22T14:09:19+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-25T11:42:51+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-24T15:44:01+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-23T20:22:23+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"49831117001695772828059978079991412444","date":"2025-09-05T22:09:38+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"6341855986353177135123854828917567792","date":"2025-09-04T09:31:17+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"11340396763154748031250712008885341087","date":"2025-09-02T17:30:58+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"40342948011955565450655642063921926718","date":"2025-09-02T15:35:25+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-02T15:27:57+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-08-26T10:14:06+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-08-10T07:35:53+00:00","index":"","fulltext":""},{"type":"submitted","content":"Humanities and Social Sciences Communications","date":"2025-08-10T07:30:58+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"humanities-and-social-sciences-communications","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"palcomms","sideBox":"Learn more about [Humanities \u0026 Social Sciences Communications](http://www.nature.com/palcomms/)","snPcode":"41599","submissionUrl":"https://submission.springernature.com/new-submission/41599/3","title":"Humanities and Social Sciences Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Nature AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"2704a5eb-398a-45e4-b862-9ebb32d77791","owner":[],"postedDate":"September 9th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":54281711,"name":"Earth and environmental sciences/Climate sciences"},{"id":54281712,"name":"Earth and environmental sciences/Environmental social sciences"},{"id":54281713,"name":"Social science/Environmental studies"}],"tags":[],"updatedAt":"2026-05-08T10:26:08+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-09 08:16:47","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7193386","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7193386","identity":"rs-7193386","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}