The Impact of Courtyard Spatial Characteristics Across Historical Periods on Summer Microclimates: A Case Study from China

Abstract

This study investigates the impact of spatial changes over a 400-year period on the summer microclimate of a residential courtyard in China. Using ENVI-met simulations, we analyze how factors such as courtyard orientation, building height, and opening positions affect the thermal environment. The results show that east–west-oriented courtyards experienced 0.2–0.4 °C lower daytime temperatures compared to north–south ones. Additionally, taller surrounding buildings increased the courtyard’s average daytime temperature by approximately 0.3–0.5 °C, while courtyards with a single opening facing the prevailing wind maintained the lowest temperatures. These findings underscore the importance of historical spatial characteristics in shaping microclimates and offer key insights for contemporary urban planning. By incorporating design strategies based on these historical spatial features, such as optimizing courtyard orientation, enhancing building height variability, and creating appropriate openings for natural ventilation, urban planners can improve microclimate conditions, reduce reliance on mechanical cooling, and enhance energy efficiency. This approach not only contributes to lowering carbon emissions but also boosts resilience to extreme heat events in urban areas, especially in regions facing rapid urbanization and climate change challenges.

1. Introduction

Urban renewal is an essential aspect of a city’s growth, particularly during rapid urbanization. This process is shaped by political, economic, and social factors, often highlighting tensions between government, developers, and residents. Over the past few decades, China’s urban landscape has undergone profound changes due to accelerated urbanization [1]. In newly planned urban areas, construction proceeds with scientific validation, professional design, and strict oversight. In contrast, older districts face restrictions due to regulations aimed at preserving historical settings, making large-scale building renewal difficult. Despite this, the residents’ evolving needs have led to spontaneous, small-scale renovations in Xi’an’s Hui-inhabited areas. These unregulated changes have expanded living spaces while altering the local microclimates.

Climate change remains a critical global issue, and the degradation of urban microclimates has garnered increasing attention from scholars worldwide [2,3]. Research at various scales has been ongoing, including studies on the urban heat island effect [4], block-level microclimates, and courtyard-specific microclimates [5,6]. Traditional courtyards, long a feature of residential architecture, have proven effective in ensuring adequate sunlight and ventilation while mitigating the effects of external climate changes [7,8]. These courtyards serve as a passive cooling strategy, leveraging their spatial configurations to reduce indoor temperatures and improve thermal comfort without relying on mechanical cooling systems. The key factors influencing courtyard microclimates include geographic location and natural climate conditions [7,9,10,11,12,13], as well as human-driven variables like orientation, building height, materials, and vegetation [8,14,15,16,17].

Researchers have long explored the impact of a courtyard’s geometry on its microclimate. Most studies use microclimate simulation software to assess the correlation between a courtyard’s physical features and its thermal environment [18]. Among these tools, ENVI-met has become one of the most widely used microscale models for simulating urban microclimates due to its ability to predict atmospheric processes at fine resolutions. Numerous studies have applied ENVI-met to examine aspects such as courtyard ventilation, temperature reduction, and the cooling effect of vegetation. For example, one study evaluated the role of courtyard vegetation in reducing surface temperatures and improving thermal comfort in a hot, arid climate [19], while another quantified how courtyard aspect ratios affect heat dissipation and air circulation [20]. Field measurements are often employed alongside simulations to verify results. For example, a Spanish team quantified the impact of urban climate on building performance and evaluated the benefits of inner courtyards in mitigating extreme heat [21]. Other studies have demonstrated how courtyards contribute to passive cooling, reducing reliance on energy-intensive mechanical systems while enhancing overall energy efficiency [22]. Data from extensive field monitoring have further clarified trends in courtyard thermal performance, particularly in hot, dry climates [3].

Several studies have identified factors influencing courtyard microclimates, such as courtyard shape [7,11,23], the use of shading devices [24,25], building materials [26], building height [27,28,29,30], increased vegetation [31,32], and variations in aspect ratio [13,26,33,34,35,36,37,38,39].

While these studies have significantly advanced the understanding of microclimates, they primarily focus on contemporary courtyard designs or specific environmental conditions. Key limitations include the lack of long-term analyses and limited attention to how historical courtyard layouts, shaped by socio-cultural and climatic factors, evolved over time to achieve thermal efficiency. Additionally, while ENVI-met and other tools excel in predicting microclimate dynamics under current conditions, they are rarely used to analyze historical changes or connect past spatial configurations to modern design strategies. This creates a significant gap in understanding how historical spatial characteristics—such as courtyard orientation, building height, and openings—have contributed to passive cooling and thermal comfort.

To address this gap, this study focuses on the Ma Family Courtyard, a rare and well-documented traditional courtyard in Xi’an, China. This courtyard was selected because it is one of the few cases in which reliable official records clearly trace the spatial transformations of the courtyard over centuries. These detailed historical records allow us to reconstruct and analyze the evolution of courtyard spatial characteristics with accuracy, providing a unique opportunity to investigate the long-term impact of architectural and environmental changes on the microclimate. This study focuses exclusively on summer microclimates for two key reasons. First, Xi’an experiences extremely hot summers, with temperatures frequently reaching 35 °C to 41.8 °C, creating significant challenges for thermal comfort and urban living. Second, summer is the season with the highest energy demands for cooling, making it particularly relevant for exploring passive cooling strategies to reduce reliance on energy-intensive systems. By focusing on this critical period, this study aims to provide insights that address both immediate and long-term climate adaptation needs in regions with similar climatic conditions.

Specifically, this study examines the evolution of courtyard spatial characteristics over a 400-year period in Xi’an. By reconstructing and comparing six distinct courtyard models from different historical periods, we explore how spatial configurations, influenced by shifting climatic and social conditions, have shaped the thermal environment over time. This research hypothesizes that historical courtyard designs, shaped by specific climate and socio-cultural conditions, can offer insights into optimizing modern courtyard microclimates and inspiring sustainable architectural strategies. This long-term perspective is rare in current research, which often focuses on contemporary designs or single climatic scenarios. By linking passive cooling principles from historical designs with contemporary climate challenges, this study offers a novel contribution by integrating historical architectural strategies into modern climate-adaptive design. Additionally, the findings have significant implications for urban renewal projects in historical districts, in which the challenge lies in balancing preservation with climate adaptation.

2. Materials and Methods

2.1. Study Site Location and Description of Research Object

As illustrated in Figure 1, Xi’an is located in the southern part of the Guanzhong Plain in Shaanxi Province, lying between the Qinling Mountains to the north and the Wei River to the south, at coordinates 107°40′–109°49′ east longitude and 33°42′–34°45′ north latitude. As the provincial capital of Shaanxi, Xi’an is a major industrial and educational center in Northwest China. Historically known as Chang’an, it is recognized as one of the world’s oldest capitals, with a rich history of over 3100 years. Thirteen dynasties, including the Zhou, Qin, Han, and Tang, established their capitals here, marking it as a cradle of Chinese civilization and a key hub for economic and cultural exchanges dating back to the Western Han Dynasty (202 B.C.–8 A.D.). Today, Xi’an is renowned for its preserved historical landmarks, such as the Ming Dynasty city wall, earning its place among China’s seven most famous historical and cultural cities.

Xi’an experiences a warm temperate, semi-humid continental monsoon climate, characterized by four distinct seasons. The summers are hot and rainy, while the winters are cold with little precipitation. The annual average temperature ranges from 13.1 °C to 13.4 °C, with extreme highs reaching 35 °C to 41.8 °C and lows dropping to −16 °C to −20 °C. July, the hottest month, has an average temperature of 26.1 °C to 26.3 °C, with maximums around 32 °C. The annual average wind speed is 1.8 m/s, with a prevailing wind direction from the northeast.

This study focuses on a courtyard area within the Hui ethnic community in Xi’an’s old town, a culturally and historically significant neighborhood. The Hui-inhabited areas have preserved their Islamic cultural heritage, reflected in the unique architecture and spatial layouts of the courtyards surrounding mosques. These courtyards are distinguished by their high building density and low building heights, which contrast with other parts of the city. This dense urban fabric creates a distinct microclimatic environment while showcasing the rich history of cultural coexistence and architectural adaptation in the area. Over centuries, the Hui community has maintained many original structures despite ongoing small-scale construction and evolving residential needs. However, large-scale urban planning or redevelopment has not occurred, allowing the historic integrity of the area to remain largely intact. As China’s economy has grown, the demands for living space among residents have influenced the dynamic nature of the built environment in this historic neighborhood.

2.2. The Ma Family Courtyard

After conducting a comprehensive field survey of 232 courtyards in the Hui-inhabited area, the Ma Family Courtyard was selected for detailed analysis due to its well-documented spatial evolution, making it one of the few traditional courtyards with reliable official records of spatial changes over centuries. Originally built around 1600, the courtyard spans approximately 4700 square meters. Through local chronicles and interviews with residents, we traced the spatial layout changes of the Ma Family Courtyard over different historical periods, as illustrated in Figure 2.

The first model in Figure 2 shows that, when the courtyard was initially constructed, it consisted of single-story buildings with sloped roofs. Due to limitations in the available building materials, there were no significant changes in the height or layout of the structures for nearly 300 years. By 1960, part of the courtyard was nationalized and repurposed for government offices. This led to demolitions and reconstructions, particularly on the southern side, resulting in the destruction or disappearance of several historical buildings.

In the 21st century, as China’s economy flourished and living standards improved, the traditional courtyard design became insufficient to meet the growing needs of the residents. Periodic renovations altered much of the original architecture, as the awareness of historical preservation remained low. The rise in tourism also caused a sharp increase in the local population, leading to the construction of multi-story residential buildings in the area over the past 20 years. Despite these changes, the Ma Family Courtyard still retains most of its original layout, with new structures primarily added vertically.

2.3. Verification of Materials for Simulation

Between 23 and 25 August 2021, air temperature data were collected over three consecutive days in the study area. A single measurement point was used, located in the center of the courtyard in an unshaded area, to provide representative data for validating the simulation model. All the measuring instruments were calibrated before each sampling to ensure accuracy, and during the measurement process, the instruments were placed at a height of 1.5–2 m above the ground. To minimize the impact of sudden fluctuations (e.g., pedestrians passing by), we use the hourly average as the validation data for each time point. For instance, the temperature value at 10:00 was derived from the average temperature between 9:01 and 10:00. Although the data set for model validation is limited to three days from a single year (2021), the seasonal variations present in the meteorological inputs allow for a reasonable representation of the typical summer conditions in Xi’an. In future research, expanding the data collection to include measurements from different months and times of day, as well as utilizing more recent data sets, would enhance the robustness and representativeness of the validation process. This approach would help mitigate any potential bias introduced by using a limited set of data from a single season and year.

In this study, ENVI-met version 5.0 was used to model the urban microclimate and assess the impact of various factors on the thermal environment. ENVI-met is a three-dimensional, microclimate simulation tool designed for modeling the interactions between urban surfaces (such as buildings and vegetation), the atmosphere, and the energy balance within an urban environment. It is particularly suited for analyzing how urban design elements such as building geometry, material properties, vegetation, and wind patterns influence local weather conditions, energy usage, and environmental quality. The grid size was set at 1.5 m × 1.5 m × 5 m. In the vertical direction, all grid cells had the same height, except for the lowest cell, which was subdivided into five smaller sub-cells. The data were recorded at a height of 1.5 m. All buildings in the model were represented as hollow concrete blocks. The ground surface was categorized based on the paving materials: concrete pavement and smooth granite blocks. The settings were initialized using meteorological data for Xi’an’s summer, including average temperature, relative humidity, and wind conditions, sourced from the Weather Underground website [40]. These input parameters were applied through the forcing function, in which the hourly air temperature and relative humidity were imposed at the model boundaries to drive the simulation. The wind speed was set at 0.7 m/s, representing a calm and less-ventilated street canyon scenario for the analysis. The inflow direction was set to the northeast, which is the prevailing wind direction in Xi’an during the summer months.

To verify the accuracy of the simulation model and its boundary conditions, the measured data were compared with the simulation results. As shown in Figure 3, the five lines exhibited similar fluctuation patterns. Statistical analysis further confirmed a strong correlation between the simulated and measured temperatures, demonstrating that the model and boundary conditions were both valid and reliable [41].

3. Results

3.1. Influence of the Courtyard’s Orientation on Its Microclimate

The microclimate of the Ma Family Courtyard during six different historical periods was simulated using ENVI-met software version 5.0. Selected results of the potential air temperature distribution are presented in Figure 4. Despite the changes in the courtyard’s spatial layout over the centuries, the daily air temperature trends across all models showed a similar pattern: temperatures rose steadily from 7:00 a.m. (after sunrise) and began to decline slowly after reaching their peak around 5:00 p.m. This pattern aligns with both the field measurements from this study and previous research in Xi’an [42], reinforcing the accuracy and reliability of the simulation results.

The orientation of the Ma Family Courtyard is largely influenced by Xi’an’s long-standing grid-based urban planning, which has resulted in most buildings being aligned either parallel or perpendicular to the longitude. Consequently, most courtyards in Xi’an are oriented in either a north–south or an east–west direction. A comparison of air temperatures at various locations within a single simulation reveals a significant correlation between the orientation of the courtyard and its thermal environment.

For example, the simulation results from 1600 (Figure 5) show marked differences in the air temperatures between courtyards oriented north–south and those oriented east–west. The north–south-oriented courtyards experienced higher temperatures than those oriented east–west.

This trend was consistent across different historical periods. In 1600, as shown in Figure 6, the courtyard was oriented east–west, and by 1800, it had shifted to a north–south orientation. This shift resulted in an increase of over 0.2 °C in the daily average temperature, with the maximum temperature difference nearing 0.4 °C. By 1920, when the courtyard was rebuilt with an east–west orientation, the internal air temperature returned to levels similar to those observed in 1600.

The traditional dwellings of Xi’an, designed to maximize space in a dense urban environment, generally feature narrow, elongated layouts. The solar radiation patterns and shadow effects vary significantly depending on the orientation of the courtyard, influencing the microclimate within. When the longer side of a courtyard is oriented north–south, the east and west facades inside the courtyard are sequentially exposed to direct sunlight throughout the day. In the morning, the east facade absorbs significant solar radiation, while in the afternoon, the west facade experiences similar exposure. This continuous solar heating leads to a cumulative rise in air temperature within the courtyard, as shading is insufficient to mitigate heat gain during the peak hours of solar radiation.

Conversely, when the longer side is oriented east–west, the height-to-width ratio of the buildings plays a crucial role in moderating the microclimate. A height-to-width ratio exceeding 1.5 ensures that the buildings on the south side cast a consistent shadow over the courtyard for much of the day, particularly during midday when solar radiation is at its peak. This shadowing effect reduces the courtyard’s overall exposure to direct sunlight, thereby limiting heat accumulation. As a result, the east–west-oriented courtyards generally maintained lower internal air temperatures compared to their north–south counterparts.

These findings align with previous studies that emphasize the role of orientation and shadowing in shaping thermal environments. For instance, research on high-rise buildings in tropical climates has demonstrated that direct sunlight exposure on certain orientations can create “hot spots” behind structures, increasing local temperatures, whereas shadowing reduces this effect by mitigating solar heat gain [43]. Similarly, studies highlight that shading effectiveness depends on the interplay between solar radiation, building geometry, and airflow. In Xi’an’s traditional narrow courtyards, the east–west orientation allows for more effective shading and air temperature moderation, consistent with these observations.

In conclusion, for traditional narrow residences in Xi’an, the summer daytime temperatures of east–west-oriented courtyards are generally lower than those of north–south-oriented courtyards. This is due to the enhanced shadowing effects provided by the east–west orientation, which minimizes solar heat gain and contributes to a more thermally comfortable microclimate.

3.2. Influence of the Height of Surrounding Buildings on the Microclimate in the Courtyard

Scholars have established a link between building height and the surrounding microclimate [43,44]. In the Ma Family Courtyard, significant increases in building height occurred between 1960 and 2000, particularly around two east–west-oriented courtyards. The simulation results for these courtyards across different years are shown in Figure 7. Contrary to expectations, the increase in building height led to a rise in the average daytime temperature by approximately 0.3 °C, despite the assumption that taller buildings would create more shaded areas and reduce the courtyard temperature.

The cause of this temperature increase became clear upon analyzing the wind speed and the shadow distribution. Like many traditional residences in Xi’an, the Ma Family Courtyard initially allowed for vertical airflow due to its modest building heights and sloping roofs. However, as building heights increased, vertical ventilation diminished significantly. Simulation results reveal a marked decrease in wind speed at locations B and C as the surrounding buildings grew taller, leading to stagnant air within the courtyard.

In addition to the reduction in airflow, the distribution of shadows also contributed to the changes in temperature. As the building height increased, the shadow distribution within the courtyard shifted, impacting the amount of solar radiation reaching the ground and various surfaces. The areas with reduced shadow coverage became more exposed to direct sunlight, exacerbating the rise in temperature. This shift in shadow distribution further disrupted the thermal balance, as the cooling effect of shading was not sufficient to offset the diminished ventilation.

This phenomenon aligns with findings from previous studies, which show that taller buildings disrupt natural ventilation through stronger downwash and upwash flows, redirecting airflow laterally and reducing turbulence penetration into enclosed spaces [45]. While these effects can enhance airflow on the sides of buildings, they often result in stagnant air zones within enclosed courtyards, exacerbating heat retention. In the Ma Family Courtyard, taller buildings blocked vertical airflow, trapped heat, and altered shadow patterns, emphasizing the role of both ventilation and shadow distribution in regulating microclimates.

These findings illustrate the complex interplay between building height, shadow distribution, airflow, and microclimate dynamics, highlighting the need to balance shading effects and ventilation in urban design.

3.3. Influence of Opening Position of the Courtyard on Its Microclimate

In the Hui-inhabited areas of Xi’an, various building configurations result in courtyards with openings in different positions. These courtyards can be categorized into four groups based on the relationship between their openings and the prevailing wind direction (northeast by north): (1) courtyards with two openings, one in the prevailing wind direction and the other in the opposite direction; (2) courtyards with one opening located in the prevailing wind direction; (3) courtyards with one opening opposite the prevailing wind direction; and (4) fully enclosed courtyards. The position of these openings affects temperature fluctuations by altering shadow patterns and airflow within the courtyard.

By analyzing spatial variations across different historical periods, the area marked D in Figure 8 was selected for further study. This area was chosen because its spatial characteristics over time reflected all four enclosure types. In 1600, the courtyard at point D had two openings: one in the prevailing wind direction and one in the opposite direction. By 1960, it had only one opening opposite the prevailing wind. In 2000, the courtyard was fully enclosed, with no openings, while in 2020, an opening was introduced in the prevailing wind direction.

The air temperature fluctuations at point D are shown in Figure 8. While the general temperature trends across the four periods were similar, there were notable differences. The highest temperature was recorded in 2000 when the courtyard was enclosed, while the lowest was in 2020, when the opening was positioned in the prevailing wind direction. Specifically, the temperature curves for 1600 and 1960 rose in sync with the 2000 curve in the morning. Around 1:00 p.m., the 2000 temperature began to rise more rapidly before converging again with the 1600 and 1960 curves after 7:00 p.m. Conversely, the 1600 and 1960 curves overlapped with the 2020 curve between 4:00 p.m. and 6:00 p.m.

Courtyards with two openings—one facing the prevailing wind and one opposite—are expected to facilitate a ventilation corridor, allowing airflow to carry heat out of the space and lower temperatures. However, the results indicate that a single opening in the prevailing wind direction provides better thermal conditions than two openings due to the interaction between airflow pathways, heat dissipation, and shadow patterns. Specifically, the single opening directs the prevailing wind through the courtyard, creating a focused ventilation pathway that efficiently removes warm air while minimizing turbulent recirculation. In contrast, two opposing openings often result in airflow diffusion, reducing the overall effectiveness of the heat dissipation.

Additionally, shadow patterns play a critical role. Courtyards with a single opening in the prevailing wind direction experience consistent shadowing on key surfaces, reducing solar heat gain throughout the day. Conversely, fully enclosed courtyards trap heat due to stagnant airflow and the absence of effective heat dissipation pathways. These combined effects explain why the courtyard with a single opening in the prevailing wind direction recorded the lowest temperatures, while enclosed courtyards performed the worst in terms of thermal comfort.

In conclusion, the optimal thermal performance observed in courtyards with a single opening in the prevailing wind direction highlights the importance of strategically aligning openings with natural airflow patterns while accounting for shadow dynamics to maximize heat dissipation and thermal comfort.

4. Discussion

This study evaluates the impact of courtyard spatial characteristics, including orientation, building height, and opening positions, on summer microclimates in the Ma Family Courtyard over a 400-year period. By combining ENVI-met simulations with historical spatial analysis, the findings provide new insights into how design strategies can optimize microclimates in dense urban environments. The results align with previous research that employed ENVI-met to study courtyard microclimates in climates similar to that of Xi’an. For example, studies in Mediterranean and arid regions have demonstrated that courtyard orientation plays a critical role in moderating internal air temperatures. East–west-oriented courtyards, as observed in this study, consistently exhibited lower daytime temperatures compared to north–south orientations due to more effective shadowing patterns and reduced solar heat gain during peak hours. Similarly, prior ENVI-met studies have highlighted the influence of building height on airflow, showing that taller buildings can disrupt natural ventilation and create stagnant zones. Our findings extend these observations to enclosed courtyards, in which increased building height significantly reduces vertical ventilation and traps heat, leading to a rise in the average daytime temperatures.

The position of courtyard openings also revealed significant effects on thermal performance, which is consistent with findings in Mediterranean and tropical climates. Courtyards with openings aligned with the prevailing wind direction, as observed in our study, demonstrated the best thermal conditions. This is due to the focused airflow pathways created by a single opening, which efficiently dissipates heat while minimizing turbulence and recirculation. In contrast, multiple openings can diffuse airflow, reducing the overall effectiveness of ventilation. Fully enclosed courtyards, lacking any openings, performed the worst as they trapped heat and prevented effective air circulation. These findings reinforce the importance of aligning openings with prevailing wind directions to optimize ventilation and thermal comfort in enclosed spaces.

While this study primarily focuses on traditional courtyard designs, the fundamental principles regarding building height, orientation, and opening placement remain relevant for modern urban environments, albeit with some necessary adaptations. Modern urban buildings, being much taller than the traditional courtyard structures studied here, exhibit a more pronounced impact of the building height on airflow. Taller buildings can obstruct vertical ventilation, leading to heat retention and reduced airflow, a problem that is likely more pronounced in densely built areas. To address this challenge, urban planners may need to incorporate strategies such as green rooftops, vertical gardens, and the careful design of open spaces to ensure adequate airflow and natural cooling. Additionally, technologies like wind turbines or integrated ventilation systems in building facades could improve air circulation in high-density urban environments.

Although traditional courtyards often rely on fixed orientations and strategically placed openings to manage temperature, modern urban developments may lack such open courtyards. However, the principles of optimizing airflow by aligning building openings with prevailing wind directions can still be applied to the design of urban street canyons, plazas, or courtyards within high-rise residential or commercial complexes. The strategic positioning of windows, balconies, and other architectural openings can facilitate natural ventilation, reducing the need for mechanical cooling. Furthermore, in dense urban settings, microclimatic effects can be enhanced by incorporating green spaces and vegetation along streets, helping to reduce the heat island effect and improving overall urban comfort.

Several limitations of this study should also be acknowledged. The ENVI-met simulation tool, while effective in analyzing general thermal environments, has limitations in accurately modeling complex wind dynamics. Although it suffices for analyzing general airflow patterns, a more detailed analysis of wind pathways and turbulence could benefit from computational fluid dynamics (CFD) models, which are better suited for such tasks. Future research could combine ENVI-met and CFD simulations to provide a more comprehensive understanding of airflow and thermal interactions. Additionally, this study’s focus on summer microclimates, driven by the extreme high temperatures experienced in Xi’an during this season, limits its applicability to year-round microclimate management. Extending the analysis to other seasons, such as winter, would offer a more complete understanding of how courtyard spatial configurations influence thermal comfort throughout the year.

Moreover, this study focuses on a single historical case, the Ma Family Courtyard, which may limit the generalizability of the results. While this courtyard’s spatial characteristics are representative of traditional designs in Hui-inhabited areas, analyzing multiple courtyards across different cultural and climatic contexts (e.g., Mediterranean, arid, or tropical regions) would provide a broader foundation for validating these findings and strengthening their applicability. The results of this study underscore the importance of integrating thermal and ventilation considerations into courtyard design. Aligning openings with prevailing wind directions can significantly enhance airflow, while east–west orientations and strategic shadowing can mitigate solar heat gain. These insights are particularly valuable for urban renewal projects in dense historical districts, in which the dual objectives of climate adaptation and heritage preservation often conflict. By drawing on historical design principles and combining them with modern climate-responsive strategies, urban planners can create more sustainable and comfortable environments in rapidly urbanizing areas.

This study contributes to the growing body of research on courtyard microclimates by providing a historical perspective on spatial evolution over four centuries. By comparing the results with relevant studies and acknowledging the limitations, this research offers a foundation for future exploration of sustainable design strategies for both historical and contemporary courtyards.

5. Conclusions

This paper explores the impact of spatial variations on the thermal environment of courtyards by simulating the microclimate of the Ma Family Courtyard in Xi’an, China, across different historical periods. This marks the first study to simulate the microclimate of a single residential courtyard over 400 years.

The key findings are as follows:

Orientation: East–west-oriented courtyards exhibited lower daytime temperatures than north–south-oriented courtyards due to more effective shadowing patterns, particularly under summer conditions.

Building Height: Increasing building height led to a rise in the average daytime temperature by reducing vertical ventilation and airflow within the courtyard.

Opening Position: Courtyards with a single opening in the prevailing wind direction provided the best thermal conditions by facilitating focused airflow and efficient heat dissipation, whereas fully enclosed courtyards performed the worst.

These findings demonstrate how historical spatial configurations, shaped by the evolving needs of residents, significantly influence microclimates, particularly in regions with similar natural conditions to Xi’an. By integrating architectural design with environmental science, this study bridges the gap between historical urban forms and modern climate adaptation strategies, offering valuable insights into optimizing thermal comfort in both historical and contemporary courtyard layouts.

The novelty of this study lies in its longitudinal analysis of courtyard microclimates over four centuries, which is rarely addressed in the existing research. By revealing how evolving spatial characteristics influence heat dissipation and airflow patterns, this work contributes to the broader understanding of sustainable urban design. Furthermore, the study’s findings offer practical applications for urban renewal projects, highlighting design strategies such as optimizing courtyard orientation, maintaining appropriate building heights, and aligning openings with prevailing wind directions to improve thermal performance.

In practical terms, urban planners could apply these findings to modern cities, particularly in historical districts in which preserving the architectural heritage is essential. For example, by designing courtyards or open spaces with east–west orientations and controlling building heights, urban environments could better mitigate the effects of urban heat islands. Similarly, positioning openings to take advantage of prevailing wind directions could significantly enhance natural ventilation, reducing the need for mechanical cooling and contributing to energy conservation.

To further enhance sustainability, urban planners should consider incorporating these findings into new designs for mixed-use developments, urban parks, and public spaces in areas with similar climatic conditions. Integrating these principles could help to reduce energy consumption, improve air quality, and increase overall urban comfort, especially during extreme heat events.

Future research could build upon this work by conducting seasonal analyses to capture the year-round dynamics of courtyard microclimates. Expanding the study to include additional historical courtyard cases from different regions and climatic contexts would enhance the generalizability of the findings. Moreover, incorporating advanced simulation tools, such as computational fluid dynamics (CFD), and detailed field measurements could improve the precision and reliability of future analyses. By addressing these areas, future research can further explore how courtyard designs can adapt to both historical and contemporary climate challenges, ultimately guiding urban planning strategies that balance heritage preservation with climate adaptation.