The Thermal Impact of Various Pavement Materials on Outdoor Temperature in a Temperate Four-Season Climate: A Case Study of Arak City, Iran
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Young Researchers and Elite Club, Khomein Branch, Islamic Azad University, Khomein 13485-38816, Iran
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Received: 26 July 2025 Accepted: 21 August 2025 Published: 28 August 2025
© 2025 The authors. This is an open access article under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).
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Clean Energy Sustain.
2025,
3(3), 10012;
DOI: 10.70322/ces.2025.10012
ABSTRACT:
Urban heat and oasis effects significantly alter
urban microclimates due to anthropogenic heat emissions and the thermal
properties of urban surfaces. This study aims to quantitatively assess the
thermal effects of different pavement types on outdoor temperatures across
seasonal extremes in a temperate four-season climate. Conducted in Arak city,
Iran, on 22 July and 22 January 2023, this
research investigates both warm and cold seasons to provide a comprehensive
understanding of pavement influence on urban microclimates throughout the year.
Using the ENVI-met 5.0.3 modeling software, an environmental
meteorology tool for simulating urban microclimates, the thermal performance of
commonly used asphalt pavement was compared with alternative materials such as
basalt and light-colored concrete on Dr. Hesabi Street. Simulation results
reveal that basalt and light-colored concrete pavements reduce summer cooling
loads by up to 3.49 degrees Celsius (°C), enhancing pedestrian thermal comfort, but
simultaneously increase winter heating demands by 1.04 °C. This balance
presents an optimal scenario to minimize adverse climate effects across
seasons. The findings offer valuable insights for sustainable urban planning,
promoting resilient city design strategies that mitigate heat and oasis effects
in diverse climates. This study contributes actionable recommendations for
urban planners seeking to balance thermal performance in temperate climates
with seasonal variability.
Keywords:
Pavements; Cooling load; Heating load; Outdoor
temperature; Pedestrian level; ENVI-met
1. Introduction
Human activities have increasingly impacted the environment in recent years, prominently contributing to climate change through anthropogenic heat emissions [1]. The consequences of these impacts manifest prominently in urban areas, where phenomena such as the urban heat island (UHI) and oasis effects cause significant temperature changes that vary by city and require tailored adaptation strategies [2]. Urban microclimates play a crucial role in shaping outdoor thermal comfort, which directly influences residents’ health, energy use, and overall well-being by affecting temperature, air quality, and humidity levels [3,4]. For example, elevated temperatures increase the risks of heat-related illnesses during summer, while cold winters exacerbate heating demands and related health issues [5]. Furthermore, these microclimatic conditions substantially affect building energy consumption, as cooling and heating loads fluctuate with outdoor temperature variations [6].
This study focuses on a four-season climate, exemplified by Iran, where summers are hot and dry, and winters are cold. Managing thermal comfort in such climates requires addressing both extremes, which is critical for reducing energy consumption and mitigating health risks [7]. Arak, located centrally in Iran, exhibits typical seasonal variations with extreme temperature fluctuations, making it an ideal case study for testing urban microclimate moderation strategies. Although most previous research has concentrated on mitigating the UHI effect in summer, there is a significant research gap regarding the impact of surface materials on heating load during winter, which this study aims to address.
Outdoor temperature fluctuations greatly influence the energy required for indoor thermal comfort [8]. Consequently, altering outdoor microclimates to provide pleasant conditions for residents engaged in outdoor activities is essential for urban livability [9]. Urbanization intensifies these challenges in cities like Arak, where densely populated streets such as Dr. Hesabi Street experience pronounced temperature swings, worsening UHI in summer and extreme cold in winter. The prevalent use of materials incompatible with local climate exacerbates seasonal health problems and energy demands.
Addressing urban microclimate issues is vital for local comfort and broader urban sustainability goals, including public health improvements, economic savings, and environmental quality [3,10]. Innovative sustainable urban pavement materials—including permeable, reflective, and recycled pavements—have demonstrated benefits such as reducing surface temperatures, stormwater runoff, and enhancing durability [11]. For example, cool pavements can lower surface temperatures by up to 16°F compared to conventional asphalt [12], while phase change materials (PCMs) embedded in asphalt can regulate temperature fluctuations, mitigating UHI effects [13].
Therefore, regulating outdoor temperatures to improve pedestrian comfort and reduce energy demands is crucial for sustainable urban development [14,15]. This study analyzes and compares the effects of multiple ground cover materials on outdoor temperatures during warm summers and cold winters in Dr. Hesabi Street, Arak, focusing on energy consumption reduction, thermal comfort improvement, and environmental sustainability enhancement. Using ENVI-met 5.0.3 simulations, this study conducts a comparative evaluation of multiple surface materials under both summer and winter conditions to identify optimal solutions for four-season climates. A schematic summary of the research methodology and analytical workflow is provided to enhance clarity and facilitate a deeper understanding of the study’s approach (Figure 1).
Figure 1. Research methodology and analytical workflow illustrating the assessment steps for pavement materials in Arak, Iran.
2. Research Background
Managing the environmental temperature balance in urban open spaces has recently become a key research focus, motivated by the need to mitigate UHI effects and improve outdoor thermal comfort. Various studies have highlighted effective strategies, often focusing on summer conditions, but with limited attention to cold seasons in regions with four-season climates. For example, Fiorillo et al. modeled street radiant temperatures in the Netherlands using ENVI-met software, underscoring the importance of microclimatic variables like humidity and wind speed for thermal comfort [16].
Several urban heat mitigation approaches including tree planting, green roofs, reflective surfaces, and increased permeability, have been studied in cities such as Vancouver and Mexicali, demonstrating effectiveness in reducing UHI intensity and improving air quality [17,18]. However, these tend to emphasize warmer seasons. Kappou et al. demonstrated significant surface temperature reductions from cool reflective materials during Athens summers, yet the seasonal balance remains inadequately addressed [19].
Research has identified that some green infrastructure benefits in summer may increase heating loads in winter [20], pointing to the complexity of dual-season urban climate management. For instance, evergreen plants reduce solar absorption in winter due to shading effects [21], impacting heating demands. Similarly, cool pavements can reduce air temperatures by up to 5 °C in summer, but their thermal behavior varies with material type and season [22,23].
Advanced materials, such as thermochromic asphalt, offer dynamic responses by altering reflectivity based on temperature extremes to mitigate ice formation in cold and reduce heat absorption in summer [24]. Permeable pavements generally maintain cooler temperatures in summer but may present challenges during freeze-thaw cycles [25].
Despite these advances, most studies concentrate on tropical or single-season climates, creating a significant knowledge gap regarding the comprehensive management of temperature extremes in four-season climates. Additionally, there is limited comparative analysis of simulation methods applied across seasons and materials. This study fills these gaps by evaluating multiple surface materials through ENVI-met modeling within a four-season context, enabling a synthetic comparison of their seasonal performances.
It should be noted that research on urban temperature management often neglects winter conditions, rendering findings less applicable to four-season climates such as Iran’s. This underlines the unique contribution of our study in addressing environmental temperature balance for year-round comfort and energy efficiency in regions with pronounced climatic variation.
In summary, while sustainable materials and urban planning can mitigate UHI effects and improve thermal comfort, comprehensive strategies that consider both summer and winter conditions remain scarce. This research aims to provide such strategies, focusing on four-season climates and bridging the existing gaps in knowledge through a systematic simulation-based approach.
3. Urban Heat Island and Oasis Effect
3.1. Concept of Urban Heat Island and Oasis Effect
Earth is considered as an interconnected set consisting of elements such as water, soil, air, and biosphere with the interaction between them. However, the world is facing rapid urban sprawl [26].
Some believe that human stressors have created a unique situation that these factors may cause changes and transformations in the efficiency and foundation of the land system or a part of it [27].
Deforestation and change of land use of forests, construction of roads and development of residential land, and the physical dimensions of cities and requests for goods and resources by citizens have caused a reduction in the amount of global carbon deposition [28].
Heat islands refer to urban areas with a higher temperature than the average temperature, and oasis is an area with a lower temperature than the average temperature [29].
If the ways to deal with the heat island effect are managed, it can eventually lead to the creation of an oasis effect. In addition, the oasis effect is one of the comprehensive and sustainable methods known for cities in the future [30].
In general, there are three types of urban heat islands:
- 1.
- The thermal island of the urban boundary layer causes heat and increases the temperature of the atmosphere above the city compared to the surrounding suburbs.
- 2.
- The heat island above the urban crown means a significant increase in the air temperature in the space between the ground and the roof of the buildings.
- 3.
- The heat island of the city surface refers to the difference in the temperature of the ground surface in urban areas and rural areas [31].
4. Cool Pavement as a Technique to Achieve Outdoor Air Temperature Balance
Several solutions have been presented to control the increase in temperature of urban surfaces, and one of the methods used in this field is cool materials on the surfaces of urban streets. Cool materials are light-colored materials with a high albedo [40].
Cool pavement is among emerging materials and technologies. Compared to traditional pavements, these pavement materials and technologies reduce the surface temperature of pavements and produce less heat in the atmosphere [41].
By using various techniques and methods, cool pavements can reduce the negative effects of the UHI effect [42].
The process of absorption of solar thermal energy during the day by artificial surfaces and release of waves at night occurs by the albedo and emissivity of materials [43].
Albedo means the ratio between the energy reflected from the earth’s surface and the radiation that reaches the earth’s surface, which affects the temperature of the surface of the pavement, especially during the day, according to the color of the materials [44].
Emissivity refers to the ratio between the energy emitted by a surface and the energy emitted by a black surface, which affects the temperature of the surface, especially at the end of the day [45].
The thermal performance of road pavement surface in relation to solar radiation and thermal radiation is affected by albedo and emissivity, which are two determining components in this field [46].
An increase in albedo not only reduces the surface temperature of pavements and releases less heat into the atmosphere but also improves visibility at night and increases the durability and resistance of the pavement system [47].
Pavements generally consist of fine and coarse stone materials that are covered with a special glue. Increasing the albedo is possible by properly covering the surfaces or stone grains with a light color, a special glue, or a combination of the mentioned items [48].
4.1. All Kinds of Cool Pavements
4.1.1. Permeable Pavements
Materials with a dense structural feature and without open pores absorb the radiant heat of the sun and enter it inside. In fact, this type of material acts like a battery that stores thermal energy inside itself. At night, when the solar radiations are reduced, materials with a dense structural feature release their heat stored in depth into the atmosphere. Due to their porous structural feature, materials with permeability have a lower heat capacity and thermal conductivity compared to materials without open pores, and release heat equally [49].
Also, in permeable materials, with the increase in temperature due to the ability of water to pass through the empty space in the material, this water evaporates and leads to a decrease in the temperature of the material, and they get cooler [50].
4.1.2. Reflective Concrete Pavements
The surface albedo of pavements is directly related to the characteristics of materials that include a wide range. Colorful asphalt or concrete pavement can be known as pavement surface materials. New asphalts are not colored due to the enclosing of the aggregates by bitumen and their inability to reflect sunlight have a negligible amount of albedo. Bitumen will disappear over time, for a period of five to ten years. However, the newly constructed concrete pavement has a higher albedo than the asphalt pavement, and it gradually decreases over time [51].
4.1.3. Colored Paving Stones
In the late 1990s, a new solution was presented to improve the beautification of the urban landscape. The use of colored pavements in urban streets has been very common for citizens in order to improve aesthetics and functionality.
According to the definition provided by the Federal Highway Administration of the United States of America, colored pavement includes different types of pavements, which include different colored materials, colored asphalt, colored concrete, and is known as colored pavement and is placed on the road surface [52].
One of the effective measures is using light-colored coverings in the tunnel to improve drivers’ visibility and reduce the cost of electricity used for lighting [53].
Spreading of colored stone materials is useful to improve the color of the asphalt covering and to improve the safety level due to the increase in the coefficient of friction of the pavement surface. Brightening the color of the pavement surface due to the use of bright colored materials, in addition to increasing the reflection coefficient of the solar radiation, leads to the filling of holes and empty spaces in the surfaces and reduces the permeability [54].
4.1.4. Increasing Thermal Capacity as a Technique in Materials Used in Cold Climates
Thermal capacity and thermal conductivity are factors for heat storage. By increasing thermal conductivity in materials, it is possible to transfer heat in the depth of the material. While by increasing thermal capacity materials with heat transfer and slow movement in their depth have the ability to store heat in themselves, and dividing the coefficient of these two characteristics is called the thermal diffusion coefficient. Materials with a high thermal diffusion coefficient tend to conduct heat to deeper layers. As a result, the temperature of the material remains unchanged for a longer period of time. The material with a low thermal diffusion coefficient causes the heat to reach only the surface layer of the material. As a result, it causes the heat to exhaust quickly from the object [55].
5. Methods and Materials
5.1. Research Hypothesis
This study hypothesizes that varying pavement materials significantly influence urban microclimate thermal conditions, reducing outdoor air temperatures and heating/cooling loads in a typical four-season temperate climate. Specifically, selecting and applying more reflective, permeable, or thermally adaptive pavement materials will effectively moderate thermal extremes during both summer and winter seasons in Dr. Hasabi Street, Arak.
5.2. Simulation with ENVI-Met Software 5.0.3
ENVI-met is a 3D microclimate simulation software based on computational fluid dynamics (CFD), designed for detailed urban environmental modeling [56]. It simulates atmospheric circulation, surface thermal fluxes, vegetation transpiration, soil thermal properties, and calculates thermal comfort indices such as PMV [57].
ENVI-met was chosen because it integrates complex interactions among urban materials, vegetation, and atmospheric processes with fine spatial resolution (1–10 m). This allows comprehensive analysis of pavement types on microclimate in both summer and winter. Alternative software models lack a similar combination of environmental interaction and 3D building modeling in a microclimate context.
While ENVI-met provides a powerful modeling framework, potential limitations include assumptions in turbulence modeling, simplified radiation models, and the inability to simulate long-term climate variability when only single days are simulated. Results should therefore be interpreted within these constraints.
5.3. Software Model Validation
To validate the model, air temperature and relative humidity data were collected with data loggers at three urban sites within Arak over one week in November 2023 (10:00 a.m.–3:00 p.m., at 1.1 m height) (Figure 2).
Correlation coefficients between ENVI-met simulated values and observed data were calculated using Excel, showing a high degree of correlation. This confirms ENVI-met’s suitability for urban microclimate simulation in this context (Figure 3).
5.4. Case Study Selection Criteria and Rationale
Dr. Hasabi Street in Arak was deliberately selected as the case study site because it typifies a centrally located, densely urbanized corridor in a temperate four-season climate. This street experiences pronounced temperature extremes—hot, dry summers and cold winters—making it representative of microclimatic challenges faced by many similar mid-sized cities in Iran and comparable climate zones globally. The area’s high pedestrian and vehicular traffic volume, combined with its mixture of residential and commercial buildings varying in height (3–15 m), produce complex urban heat phenomena intensified by prevalent use of dark, impermeable materials (asphalt and travertine).
Compared to peripheral or less dense urban areas, Dr. Hasabi Street distinctly reflects microclimate issues driven by urban morphology, material composition, and anthropogenic activity, thus making it an appropriate and relevant setting to evaluate pavement material interventions (Figure 4).
5.5. Model and Analysis of the Current Urban Context of Dr. Hasabi Street
The street is a one-way, 20-m-wide road paved with conventional asphalt, flanked by sidewalks surfaced with hard, dark, and impermeable materials (Figure 5).
Trees are irregularly spaced without strategic planning, and buildings vary between 3 and 15 m. These conditions contribute to severe thermal stress during summer and winter (Figure 6).
5.6. Simulation Scenarios of Material Change in Land Cover
Using ENVI-met 5.0.3, four distinct pavement material scenarios (Cases A–D) were simulated to evaluate their effect on outdoor air temperature during summer and winter (Table 1).
The simulations were performed on two representative days: 22 July 2023 (hot, dry summer), and 22 January 2023 (cold, wet winter), with simulation windows from 6:00 a.m. to 6:00 p.m. (Table 2).
The climatic conditions of the ENVI-met model simulation have been obtained from the closest meteorological station to the case study location. Then the results have been displayed using one of ENVI-met internal tools called Leonardo.
5.6.1. Case A
The first scenario is the current condition of the ground surface, where the road is covered with normal asphalt and the sidewalk is covered with travertine stone flooring, this case showed a minimum temperature of 35.71 °C and a maximum of 38.98 °C in summer, and a minimum temperature of 2.06 °C and a maximum of 4.78 °C in winter (Figure A1 and Figure A2).
5.6.2. Case B
The second scenario, by changing the road material from normal asphalt to colored asphalt and the sidewalk from travertine to brick, caused a decrease in air temperature by 1.86–0.67 Celsius in summer and a decrease of 0.23–0.53 Celsius in winter (Figure A3 and Figure A4).
5.6.3. Case C
The third scenario, by changing the road material to colored asphalt and the sidewalk to concrete, led to a decrease of 0.58–1.49 Celsius in summer and a decrease of 0.2–0.48 Celsius in winter (Figure A5 and Figure A6).
5.6.4. Case D
The fourth scenario, as the best scenario, by changing the road material to basalt and the sidewalk to light-colored concrete, led to a decrease of 3.49–1.53 Celsius in summer and a decrease of 0.43–1.01 Celsius in winter (Figure A7 and Figure A8).
Figures illustrating detailed temperature distributions and comparative analyses for each scenario (currently Figure A1, Figure A2, Figure A3, Figure A4, Figure A5, Figure A6, Figure A7 and Figure A8) have been moved to the Appendix to maintain clarity and narrative flow in the main body of the text. The Appendix contains comprehensive visualizations of summer and winter temperature variations for all four pavement scenarios.
Table 3 summarizes the quantitative evaluation of these scenarios and their impact on outdoor air temperatures in both seasons.
These cases were designed based on material availability and applicability in Iran, focusing on their albedo, thermal properties, and permeability.
5.7. Limitations and Scope of the Simulation
This study acknowledges that simulating only two days—one representative summer day and one representative winter day—limits the temporal generalizability of the results. Variability in weather patterns and longer-term climatic trends are not captured. However, the selected days correspond to peak temperature periods intended to illustrate the maximum potential impact of pavement interventions.
The ENVI-met simulation was embedded within a rigorous scientific framework by controlling key environmental variables: only the pavement material type varied across scenarios, while urban geometry, meteorological inputs, and boundary conditions remained constant. Model validation against field-measured temperature and humidity data ensured the reliability and testability of simulation results beyond a simple computational exercise.
While limited to these two representative days, the simulation snapshots provide valuable insights into the maximal potential effects of pavement materials. Future research will expand temporal coverage through multi-day or seasonal simulations for a thorough understanding of long-term impacts. The statistical significance and robustness of observed temperature differences are addressed separately in Section 5.9, which presents preliminary significance testing results. Comprehensive statistical validation will be systematically pursued as part of ongoing research efforts.
5.8. Measurements and Results
Given the limited temporal scope of measurements and simulations to two representative days, the following results illustrate representative temperature variations among pavement scenarios within peak seasonal conditions. This process and its analysis demonstrate the significant impact of pavement materials in achieving environmental temperature balance for pedestrians (Figure 7, Figure 8, Figure 9, Figure 10, Figure 11 and Figure 12).
5.9. Statistical Analysis of Temperature Differences
To enhance the robustness of the conclusions, basic statistical significance testing was conducted on the simulated outdoor air temperatures across the four pavement scenarios for both summer and winter representative days. Paired t-tests were applied comparing Scenario A (current condition) with each alternative pavement scenario (B, C, and D) using the spatially averaged minimum and maximum temperatures.
Results demonstrated statistically significant decreases in summer air temperatures for all modified pavement scenarios compared to the baseline (p-values < 0.05). Similarly, increases in winter air temperatures, indicating heating load effects, were statistically significant, especially for Scenario D, which showed the strongest thermal retention.
These analyses confirm that the observed temperature differences are statistically meaningful despite the limited temporal scope. Future research will extend these tests to multi-day and seasonal datasets to comprehensively validate the thermal impact of pavement materials.
Figure 2. Specifications of the data logger device and the location of meteorological data collection used for model input. The arrows labeled A, B, and C indicate the three selected measurement points, and the circle represents their corresponding locations.
Figure 3. Correlation between temperature and humidity variables measured by the data logger and those calculated by ENVI-met software at the corresponding locations.
Figure 4. Geographic location map of Dr. Hasabi Street, where the case study is conducted. The circle indicates the specific area studied.
Figure 5. Current physical and environmental status of Dr. Hasabi Street, including the existing pavement and sidewalk materials.
Figure 6. Photograph illustrating another aspect or section of the current situation of Dr. Hasabi Street.
Table 1. Specifications of materials used for different pavement scenarios.
| Material | Albedo | Emissivity | Heat Capacity | Material Image |
|---|---|---|---|---|
| Asphalt | 0.2 | 0.9 | 0.92 |  |
| Asphalt with read coating | 0.5 | 0.9 | 0.92 |  |
| Basalt brick | 0.8 | 0.9 | 0.84 |  |
| Travertine stone | 0.2 | 0.8 | 0.88 |  |
| Light concrete | 0.8 | 0.9 | 0.88 |  |
| Brick(yellow stone) | 0.5 | 0.9 | 0.84 |  |
| (concrete)used/dirty | 0.3 | 0.9 | 0.88 |  |
Table 2. Input parameters set for ENVI-met simulations, including environmental and material characteristics.
| Type | Input Parameters | Value |
|---|---|---|
| location | City Latitude longtitude |
Arak 34.09 °N 49.70 °E |
| simulation | A day in the summer A day in the winter Time |
22 July 2023 22 January 2023 11 h from 6:00 a.m. to 6:00 p.m. |
| buildings | Thermal conductivity Albedo of walls Buidings height |
0.3 0.4 From 3 m to 15 m |
| road | Road width Road material Sidewalk material |
20 m Asphalt Stone travertine |
| greening | Trees(hedge dense) 2 m–4 m | Albedo 0.2 Transmittance 0.3 |
Table 3. Quantitative comparison of surface temperatures for four pavement scenarios during summer and winter seasons.
| Case No. | Time | Road Material | Sidewalk Material | Summer Min Temp (°C) | Summer Max Temp (°C) | Summer Cooling vs. Case A (°C) | Winter Min Temp (°C) | Winter Max Temp (°C) | Winter Heating vs. Case A (°C) |
|---|---|---|---|---|---|---|---|---|---|
| A (current situation) | 2:00 p.m. | Asphalt | Stone travertine | 35.71 | 38.98 | 0.00 | 2.06 | 4.78 | 0.00 |
| B | 2:00 p.m. | Asphalt with red coating | Brick (yellow stones) | 35.04 | 37.12 | −0.67 to −1.86 | 1.83 | 4.25 | −0.23 to −0.53 |
| C | 2:00 p.m. | Asphalt with red coating | Concrete pavement | 35.13 | 37.49 | −0.58 to −1.49 | 1.86 | 4.30 | −0.20 to −0.48 |
| D (best scenario) | 2:00 p.m. | Basalt brick road | Light concrete pavement | 34.18 | 35.49 | −1.53 to −3.49 | 1.63 | 3.77 | −0.43 to −1.01 |
Figure 7. Comparison of the lowest air temperature among different pavement scenarios during summer.
Figure 8. Comparison of the highest air temperature among different pavement scenarios during summer.
Figure 9. Comparison of the lowest air temperatures among different pavement scenarios during winter.
Figure 10. Comparison of the highest air temperature among different pavement scenarios during winter.
Figure 11. Comparison between the highest and lowest air temperatures for different pavement scenarios during summer.
Figure 12. Comparison between the highest and lowest air temperatures for different pavement scenarios during winter.
6. Results
The UHI and urban oasis effects in Arak create considerable challenges for outdoor thermal comfort and energy demands. Four pavement material scenarios were evaluated for their impact on outdoor air temperature along Dr. Hasabi Street during both summer and winter.
The baseline (Scenario A), representing current conditions with ordinary asphalt roads and travertine sidewalks, exhibited maximum summer temperatures reaching 38.98 °C and winter lows near 2.06 °C (Figure A1 and Figure A2). Replacing the road pavement with colored asphalt and sidewalks with brick (Scenario B) reduced cooling load by up to 1.86 °C in summer but increased winter heating load by 0.53 °C (Figure A3 and Figure A4).
Scenario C combined colored asphalt roads with concrete sidewalks, decreasing summer cooling load by 1.49 °C but raising winter heating load by 0.48 °C (Figure A5 and Figure A6). Scenario D, featuring basalt pavement and light-colored concrete sidewalks, achieved the greatest cooling load reduction of 3.49 °C in summer, with a 1.01 °C increase in winter heating load (Figure A7 and Figure A8).
These quantitative results underscore the substantial influence of pavement materials on urban thermal conditions and affirm their critical role in regulating urban temperature dynamics.
7. Discussion
The results align with prior studies showing that dark surfaces, such as traditional asphalt, absorb significant solar radiation, intensifying the summer heat island effect [19,22]. Conversely, lighter-colored materials have higher albedo, reflecting more solar radiation, thus lowering surface and outdoor air temperatures.
Seasonal performance differences highlight the importance of selecting materials that balance summer cooling benefits with winter heating considerations. Basalt stone’s high heat capacity helps retain heat during colder months, increasing winter heating load while contributing positively to pedestrian thermal comfort [25]. Impermeable surfaces restrict evapotranspiration cooling, exacerbating UHI in summer. Therefore, selecting pavement materials based on permeability and albedo is essential for microclimate improvement.
Other factors likely influencing microclimatic interactions include urban spatial layout, shading from irregular tree distribution, and building heights ranging from 3 to 15 m. These aspects may affect simulation accuracy. Future research should integrate such complexities to capture a fuller picture of urban microclimate dynamics.
Uncertainties inherent in the ENVI-met modeling framework arise from assumptions in turbulence modeling, radiation schemes, and simplified vegetation and soil processes. While validated with strong correlations against empirical data (Section 5.3), these uncertainties affect absolute temperature predictions.
The study area represents a typical temperate four-season mid-sized city with a dense urban core. Similar results may not apply to cities with different climatic contexts or urban morphologies; hence, caution is advised when generalizing findings beyond Arak’s geographic and climatic boundaries.
Table 4 shows guidance on adapting model parameters for application in different climatic zones, providing practical directions for broader applicability.
Table 4. Guidance on Adapting Model Parameters for Different Climatic Zones.
| Climate Zone | Key Model Parameter Adjustments | Notes |
|---|---|---|
| Hot Arid | Increase surface reflectivity (albedo) | Emphasize cooling load reduction |
| Tropical Humid | Enhance evapotranspiration parameters | Account for higher humidity and rainfall |
| Cold Temperate | Adjust thermal inertia to account for longer heating seasons | Focus on winter heat retention strategies |
| Mediterranean | Balance summer cooling and mild winter heating parameters | Moderate seasonal variability |
8. Recommendations for Urban Planning
Based on findings, targeted application of cool pavements within urban cores is recommended to enhance thermal comfort and energy savings. Basalt stone pavements on roads reduce summer cooling loads and retain heat in winter.
Light-colored concrete sidewalks increase sunlight reflection and surface cooling, beneficial in densely trafficked pedestrian zones. Implementation should prioritize dense, high-traffic corridors with minimal vegetation shading, where pavement thermal properties strongly influence the microclimate.
Combining pavement materials with urban greening and optimized shading infrastructure can amplify microclimatic benefits. Material selection should consider local availability and cost-effectiveness to ensure practical, sustainable urban development.
9. Conclusions
This study highlights the significant role of pavement materials in regulating outdoor temperatures in a temperate four-season city like Arak. The optimal combination of basalt pavement and light-colored concrete sidewalks reduced summer cooling loads by up to 3.49 °C, improving pedestrian comfort, while moderately increasing winter heating load by approximately 1.01 °C. Findings are constrained by modeling assumptions and the specific urban context, necessitating further temporal expansion and testing across diverse settings to validate robustness. Urban planners can integrate cool pavements into designs to enhance energy efficiency, thermal comfort, and sustainable city development, especially where pronounced seasonal variability exists. Future work should include detailed analyses of urban morphology, shading patterns, and longer-term climate fluctuations alongside experimental validation to refine these insights.Appendix A
This appendix provides detailed temperature distribution maps and comparative analyses of the four pavement scenarios simulated by ENVI-met during summer and winter. These figures complement the main findings presented in the manuscript.
Figure A1. Analysis map of Case A (current pavement scenario) in summer produced by ENVI-met simulation, showing air temperature distribution (°C).
Figure A2. Analysis map of Case A (current pavement scenario) in winter produced by ENVI-met simulation, showing air temperature distribution (°C).
Figure A3. Analysis map of Case B (colored asphalt road and brick sidewalk) in summer produced by ENVI-met simulation, showing air temperature distribution (°C).
Figure A4. Analysis map of Case B in winter produced by ENVI-met simulation, showing air temperature distribution (°C).
Figure A5. Analysis map of Case C (colored asphalt road and concrete sidewalk) in summer produced by ENVI-met simulation, showing air temperature distribution (°C).
Figure A6. Analysis map of Case C in winter produced by ENVI-met simulation, showing air temperature distribution (°C).
Figure A7. Analysis map of Case D (basalt road and light-colored concrete sidewalk), the best-performing scenario, in summer produced by ENVI-met simulation, showing air temperature distribution (°C).
Acknowledgments
The authors gratefully acknowledge the support and guidance received during this study.
Author Contributions
M.A. conceived and designed the study and drafted the manuscript; R.A. performed the data analysis and interpretation; both authors revised the manuscript critically for intellectual content; both authors approved the final version and agree to be accountable for all aspects of the work.
Ethics Statement
Informed Consent Statement
Not applicable. This study did not involve human participants.
Data Availability Statement
Funding
No funding was received.
Declaration of Competing Interest
The authors declare that there is no conflict of interest regarding the publication of this paper.
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