СОЛНЕЧНОЕ ИЗЛУЧЕНИЕ И ВЛИЯНИЕ СТРОИТЕЛЬНЫХ МАТЕРИАЛОВ НА ТЕПЛОИЗОЛЯЦИЮ В ЖИЛЫХ ЗДАНИЯХ

УДК 1418.69

Abstract

This study aimed to model and study building materials to determine their thermal insulation properties. Thermal insulation in building materials is a critical factor in improving energy efficiency and reducing consumption, especially in regions with hot or fluctuating climates (IEA, 2022; IPCC, 2022). This scientific research examines the thermal properties of three commonly used construction materialsin Yemen especially in Aden: cement, stone, and clay, comparing their performance in terms of thermal conductivity, heat capacity, and time lag (Asadi et al., 2018). It also discusses how the microstructure and chemical composition of each material affect its ability to limit heat transfer, in addition to the role of density and porosity in enhancing insulation performance (Kehl, 2018).

The article aims to highlight the advantages and practical limitations of each material within contemporary architectural contexts and to provide scientific recommendations for selecting the most suitable material according to climatic and economic conditions (Sayigh, 2013). The findings indicate that low-density natural materials such as clay generally offer better insulation performance, while high-density materials such as stone-based concrete require complementary solutions to achieve high thermal efficiency (Straube & Burnett, 2005).

Аннотация

Целью данного исследования было моделирование и изучение строительных материалов для определения их теплоизоляционных свойств. Теплоизоляция в строительных материалах является критически важным фактором повышения энергоэффективности и снижения потребления, особенно в регионах с жарким или переменчивым климатом (IEA, 2022; IPCC, 2022). В данном исследовании изучаются тепловые свойства трех распространенных строительных материалов в Йемене, в частности в городе Аден: цемента, камня и глины, сравниваются их характеристики с точки зрения теплопроводности, теплоемкости и временной задержки (Asadi et al., 2018). В исследовании также рассматривается, как микроструктура и химический состав каждого материала влияют на его способность ограничивать теплопередачу, а также роль плотности и пористости в повышении теплоизоляционных характеристик (Kehl, 2018).

Цель статьи — осветить преимущества и практические ограничения каждого материала в контексте современной архитектуры и предоставить научные рекомендации по выбору наиболее подходящего материала в соответствии с климатическими и экономическими условиями (Сайиг, 2013). Результаты показывают, что природные материалы низкой плотности, такие как глина, как правило, обеспечивают лучшие теплоизоляционные характеристики, в то время как материалы высокой плотности, такие как бетон на основе камня, требуют дополнительных решений для достижения высокой тепловой эффективности (Штраубе и Бернетт, 2005).

Keywords: Thermal insulation , Solar radiation , building materials, cement, stone, clay.

Ключевые слова: теплоизоляция, солнечное излучение, строительные материалы, цемента, камня и глины.

Introduction

In light of the escalating challenges posed by rising global temperatures and the continuous growth in energy demand, achieving thermal efficiency in buildings has emerged as a fundamental pillar of sustainable architecture and building material science (Intergovernmental Panel on Climate Change, 2022; International Energy Agency, 2022).

Contemporary building design extends beyond aesthetic and structural considerations; it increasingly relies on a comprehensive understanding of the interplay between material properties, building orientation, and the functional organization of interior spaces (Hugo Hens, 2007). The selection of construction materials such as cement, stone, and clay influences not only structural integrity and economic feasibility, but also plays a decisive role in regulating heat transfer, thermal storage, and heat release—factors that directly affect occupants’ thermal comfort and overall indoor environmental quality (ASHRAE, 2021).

Building orientation represents a critical passive design strategy for enhancing thermal performance (Victor Olgyay, 1963; Norbert Lechner, 2014). The strategic positioning of façades and openings in accordance with solar trajectories and prevailing wind patterns can significantly reduce excessive heat gains during summer while optimizing beneficial solar exposure in winter (Lechner, 2014). Furthermore, the functional zoning of interior spaces—such as allocating service or intermittently occupied areas to zones with higher solar exposure, while orienting living and sleeping spaces toward thermally moderate directions—facilitates the achievement of natural thermal equilibrium with minimal dependence on mechanical cooling systems (Olgyay, 1963).

Thermal comfort itself is understood as a dynamic condition influenced by environmental, physiological, and behavioral factors (P. O. Fanger, 1970; Richard de Dear & Gail Brager, 2002). This integration of appropriate material selection and climate-responsive architectural orientation reinforces thermal comfort as a systemic outcome of the interaction among materials, design strategies, climatic conditions, and occupant behavior (ASHRAE, 2020). From this standpoint, investigating the thermal characteristics of traditional building materials and assessing their performance within a holistic design framework that incorporates orientation and spatial functionality becomes essential (Kehl, 2018). Such an approach enables the development of architectural strategies aimed at reducing energy consumption, mitigating environmental impact, and enhancing indoor environmental quality, particularly in regions characterized by hot, arid, or thermally extreme climates (IPCC, 2022; Sayigh, 2013).

Table 1 presents the 24-hour temperature profile of a building, recorded hourly. It includes the roof, various walls (East, West, South, North), windows, and the door. The data shows a significant temperature fluctuation throughout the day. The roof temperature peaked at 41.9°C at 2:00 PM, which was the highest temperature recorded across all surfaces. The lowest temperatures were observed in the early morning, around 6:00 AM, with most surfaces dropping to approximately 27-28°C. The South wall consistently maintained a lower temperature compared to other walls, staying between 27°C and 28°C for the entire 24-hour cycle.

Discussion: The high temperatures recorded on the roof and the East/West walls during the afternoon are expected, as these surfaces receive the most direct solar radiation. The peak temperature of 41.9°C on the roof highlights its role as a major source of heat gain for the building. The relative stability of the South wall's temperature suggests it was either shaded or not directly exposed to intense solar radiation during the measurement period. These field measurements provide a realistic baseline for understanding the building's thermal behavior and serve as a crucial reference for validating the simulation models.

Table 1.Temperature from the actual field measurement

Table 2: and the corresponding bar chart in Figure 1 show the simulated average temperatures at four different locations (P1, P2, P3, P4) for rooms constructed with cement, clay bricks, and stone. Stone consistently resulted in the highest average temperature (34.34°C). Clay bricks consistently resulted in the lowest average temperature (33.59°C). Cement produced an intermediate average temperature (33.96°C). CFD Simulation Results (Table 2 and Figure 1 – Bar Chart)

Table 2 and Figure 1 summarize the simulated average temperatures at four locations (P1–P4) inside rooms constructed with cement, clay bricks, and stone.

• Clay bricks showed the lowest average temperature (33.59°C).
• Cement had a moderate temperature (33.96°C).
• Stone recorded the highest average temperature (34.34°C).
  Figure 1 confirms this visually:
• Green bars (Stone) are the highest,
• Blue bars (Cement) are intermediate,
• Red bars (Clay bricks) are the lowest at all points (P1–P4).

The CFD analysis demonstrates that clay bricks have the best thermal performance, as they maintain lower indoor air temperatures. Their lower thermal conductivity and higher thermal mass reduce the rate of heat transfer, making them more suitable for hot regions. Stone performed the worst because of its high conductivity, causing greater internal heat accumulation. Cement fell in between, showing moderate insulating behavior. These findings align with theoretical expectations that materials with lower thermal conductivity and higher heat capacity perform better in hot climates by reducing heat gain.

Table 2. Temperature from the CFD

Figure 1: visually confirms this trend, with the green bars (Stone) being the highest and the red bars (clay bricks) being the lowest at all four locations.

-The CFD simulation results indicate that clay bricks offer the best thermal performance among the three materials by maintaining the lowest internal air temperature. Stone, conversely, appears to be the least effective insulator, leading to the highest indoor temperatures. This suggests that for the climate conditions being simulated, the thermal properties of clay bricks (likely lower thermal conductivity/or higher thermal mass) are more effective at mitigating heat gain compared to cement and stone.

Figure 1. Comparison of the temperature variation between Cement, Stone and clay bricks at different location

Table 3: Compares the average simulated indoor temperatures for each material with thermal comfort standards:

• Clay bricks: 33.59°C
• Cement: 33.96°C
• Stone: 34.34°C

According to ASHRAE Standard 55, the comfort range is 23.0–26.0°C, and the Libyan climate literature suggests 23.9–30.9°C.

- All three materials exceed both comfort limits, particularly the ASHRAE range, meaning none of the materials alone can ensure indoor comfort under the tested climatic conditions. This highlights the limitations of passive construction using traditional wall materials in hot environments. Therefore, additional design measures such as:

• Thermal insulation,
• Reflective roof coatings,
• Natural ventilation, or
• Shading devices are necessary to achieve comfort levels in accordance with international and local standards.

Table 3.Comparison of the air temperature for Cement, Stone and clay bricks material at different location rooms

• Figure 2 (Cement): Shows temperature distribution with noticeable heat concentration near the roof and upper wall regions.
• Figure 3 (Stone): Displays even higher temperature gradients, especially in roof-adjacent areas, confirming greater heat retention.
• Figure 4 (Clay Bricks): Exhibits the lowest overall temperature distribution, with smoother gradients and lower peak temperatures.

Visual CFD contours reveal how material choice influences internal air temperature gradients.

• Clay bricks show cooler, more uniform temperature fields, verifying their superior insulating capability.
• Stone results in the most intense heat zones, confirming its inefficiency.
• Cement behaves intermediately, suggesting moderate thermal resistance.

These contour plots validate numerical and experimental results, demonstrating a clear correlation between material properties and indoor thermal conditions.

Figure ‎2. Baseline case for Cement Material: Temperature distribution in June (a) Isometric view of temperature (b) Plan A-A  (c) plan B-B for CFD

Figure ‎3. Case 1- Stone material: (a) Isometric view of temperature (b) Plan A-A and (c) plan B-B for CFD

Figure ‎4. Case 2- clay bricks: (a) Isometric view of temperature (b) Plan A-A and (c) plan B-B for CFD

Combining field data and CFD simulations leads to these conclusions, as analyzed above and illustrated by figures and diagrams:

Conclusion

Based on the experimental measurements and CFD simulation results, the following recommendations are proposed:

1. Use of clay bricks in hot climates: clay bricks are recommended as the preferred building material for residential buildings in hot climatic regions such as aden, yemen, due to their superior thermal insulation performance and lower indoor temperature levels compared to cement and stone.
2. Improvement of roof thermal insulation: since the roof recorded the highest heat gain during field measurements, additional roof insulation techniques such as reflective coatings, insulated systems, or double-layer roofing should be implemented to minimize solar heat transfer.
3. Integration of passive cooling strategies: traditional construction materials alone are insufficient to achieve indoor thermal comfort under extreme climatic conditions. Therefore, passive design strategies including natural ventilation, external shading devices, optimized building orientation, and green roofing systems should be integrated into building design.
4. Reduction of energy consumption: the adoption of thermally efficient materials and passive cooling methods can significantly reduce dependence on mechanical air-conditioning systems, thereby lowering energy consumption and environmental impacts.
5. Consideration of building orientation: proper orientation of buildings and openings should be carefully considered during the design stage to reduce direct solar exposure on east and west façades, which experience the highest thermal loads.
6. Development of local sustainable materials: further investment in locally available and environmentally sustainable construction materials with enhanced thermal properties is strongly encouraged to support sustainable architecture in Yemen and similar regions.

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