Search Results (92)

Rammed earth (RE), a traditional material aligned with circular economy (CE) principles, has been gaining renewed interest in contemporary construction due to its low environmental impact and compatibility with sustainable building strategies. Though not a modern invention, it is being reintroduced in response to the increasingly strict European Union (EU) regulations on carbon footprint, life cycle performance, and thermal efficiency. RE walls offer multiple benefits, including humidity regulation, thermal mass, plasticity, and structural strength. This study also draws attention to their often-overlooked ability to mitigate indoor overheating. To preserve these advantages while enhancing thermal performance, this study explores insulation strategies that maintain the vapor-permeable nature of RE walls. A parametric analysis using Delphin 6.1 software was conducted to simulate heat and moisture transfer in two main configurations: (a) a ventilated system insulated with mineral wool (MW), wood wool (WW), hemp shives (HS), and cellulose fiber (CF), protected by a jute mat wind barrier and finished with wooden cladding; (b) a closed system using MW and WW panels finished with lime plaster. In both cases, clay plaster was applied on the interior side. The results reveal distinct hygrothermal behavior among the insulation types and confirm the potential of natural, low-processed materials to support thermal comfort, moisture buffering, and the alignment with CE objectives in energy-efficient construction. Full article

The construction sector presently consumes about 40% of global energy and generates 36% of CO₂ emissions, making facade retrofits a priority for decarbonising buildings. This review clarifies how ventilated facades (VFs), wall assemblies that interpose a ventilated air cavity between outer cladding and the insulated structure, address that challenge. First, the paper categorises VFs by structural configuration, ventilation strategy and functional control into four principal families: double-skin, rainscreen, hybrid/adaptive and active–passive systems, with further extensions such as BIPV, PCM and green-wall integrations that couple energy generation or storage with envelope performance. Heat-transfer analysis shows that the cavity interrupts conductive paths, promotes buoyancy- or wind-driven convection, and curtails radiative exchange. Key design parameters, including cavity depth, vent-area ratio, airflow velocity and surface emissivity, govern this balance, while hybrid ventilation offers the most excellent peak-load mitigation with modest energy input. A synthesis of simulation and field studies indicates that properly detailed VFs reduce envelope cooling loads by 20–55% across diverse climates and cut winter heating demand by 10–20% when vents are seasonally managed or coupled with heat-recovery devices. These thermal benefits translate into steadier interior surface temperatures, lower radiant asymmetry and fewer drafts, thereby expanding the hours occupants remain within comfort bands without mechanical conditioning. Climate-responsive guidance emerges in tropical and arid regions, favouring highly ventilated, low-absorptance cladding; temperate and continental zones gain from adaptive vents, movable insulation or PCM layers; multi-skin adaptive facades promise balanced year-round savings by re-configuring in real time. Overall, the review demonstrates that VFs constitute a versatile, passive-plus platform for low-carbon buildings, simultaneously enhancing energy efficiency, durability and indoor comfort. Future advances in smart controls, bio-based materials and integrated energy-recovery systems are poised to unlock further performance gains and accelerate the sector’s transition to net-zero. Emerging multifunctional materials such as phase-change composites, nanostructured coatings, and perovskite-integrated systems also show promise in enhancing facade adaptability and energy responsiveness. Full article

In the context of intensified construction and stricter requirements for the energy efficiency of buildings, the use of thermal insulation materials and technologies is becoming particularly important. One promising area in this field is the use of thermal insulation mixtures, which are versatile, adaptable, and highly reliable in operation. Mixtures based on fillers with a porous structure and materials that impart thermal insulation properties, which provide higher thermal insulation properties, are of great interest. However, the development of dry thermal insulation mixtures is hampered by insufficient study of their physical, mechanical, and operational characteristics. This article presents the results of research work on the development and study of dry building thermal insulation mixtures. A distinctive feature of the work is the creation of a composition of dry building thermal insulation mixtures based on local raw materials, such as diatomite, its thermal modification at a temperature of 900 °C, the use of expanded perlite sand, lime, and Portland cement. Research into the properties of modified diatomite has shown that its surface after thermal treatment differs from the surface of unburned diatomite in that it becomes more active and has a 3–4 times higher increase in strength. Modified diatomite and expanded perlite sand have low thermal conductivity, and this property was used in the creation of building thermal insulation mixtures, which was confirmed by research, as the thermal conductivity coefficient ranged from 0.128 to 0.152 W/m °C. The developed dry thermal insulation lime–cement mixture is intended for both interior and exterior finishing works, which is confirmed by the results obtained for determining the frost resistance of the solution and the frost resistance of the contact zone, and corresponds to the F35 grade and has a strength of up to 3.59 MPa. Full article

The significant waste generated by construction has increased interest in sustainable solutions, including prefabricated interior partition panels. Although different types of alternative panels have been proposed, their performance as interior partitions remains underexplored in systematic comparative studies. To narrow this knowledge gap, this paper presents a comprehensive evaluation and classification of drywall, OSB (Oriented Strand Board), cement–wood, and honeycomb panels, regarding physical, mechanical, microstructural, thermal, acoustic, and combustibility characteristics, in addition to conducting a cost evaluation. The results indicated that the OSB panels exhibited superior results for interior partition applications, showing notable advantages in physical strength, mechanical performance, and thermal insulation, while offering acoustic properties comparable to those of drywall panels. Nevertheless, OSB panels showed lower fire resistance and were associated with the highest cost among the materials analyzed in the present research. Drywall panels, on the other hand, provided the most favorable fire resistance but exhibited the least effective thermal insulation. The findings also indicated that both wood–cement and honeycomb panels require further improvements in their manufacturing processes to meet performance standards suitable for interior partition. Full article

Prefabricated components inevitably generate numerous assembly joints during installation, with each 1 mm increase in joint width correlating to a 15–20% elevation in the annual occurrence frequency of the frost formation risk. In the Inner Mongolia Region, the water migration at wall connection interfaces during winter significantly exacerbates freeze–thaw damage due to persistent thermal gradients. A coupled heat–moisture transfer model incorporating gas–liquid–solid phase transitions was developed, with the liquid moisture content and temperature gradient as dual driving forces. A validation against internationally recognized BS EN 15026:2007 benchmark cases confirmed the model robustness. The prefabricated sandwich insulation walls reconstructed with region-specific volcanic ash materials underwent a comparative evaluation of temperature and relative humidity distributions under varied winter conditions. Furthermore, we analyze and assess the potential for freezing at connection points and identify the specific areas at risk. Synergistic effects between assembly gaps and indoor–outdoor environmental interactions on wall performance degradation were systematically assessed. The results indicated that, across all working conditions, both the temperature and relative humidity at each wall measurement point underwent periodic variations influenced by the outdoor environment. These fluctuations decreased in amplitude from the exterior to the interior, accompanied by a noticeable delay effect. Specifically, at Section 2, the wall temperatures at points B2–B8 were higher compared to those at A2–A8 of Section 1. The relative humidity gradient remained relatively stable at each measurement point, while the temperature fluctuation amplitude was smaller by 2.58 ± 0.3 °C compared to Section 1. Under subfreezing conditions, Section 1 demonstrates a marked reduction in relative humidity (Cases 1-3 and 2-3) compared to reference cases, which is indicative of internal ice crystallization. Conversely, Section 2 maintains higher relative humidity values under identical therma. These findings suggest that prefabricated building joints significantly impact indoor and outdoor wall temperatures, potentially increasing the indoor heat loss and accelerating temperature transfer during winter. Full article

As energy-efficient buildings become central to climate change mitigation, the opportunity for interior and interstitial moisture accumulation and mould growth can increase. This study investigated the potential simulation-based mould growth risks associated with the current generation of insulated low-rise timber framed external wall systems within southeastern Australia. More than 8000 hygrothermal and bio-hygrothermal simulations were completed to evaluate seasonal moisture patterns and calculate mould growth potential for nine typical external wall systems. Results reveal that the combination of increased thermal insulation and air-tightness measures between the 2010 and 2022 specified building envelope energy efficiency regulations further increased predicted Mould Index values, particularly in cool-temperate climates. This was in part due to insufficient moisture management requirements, like an air space between the cladding and the weather resistive layer and/or the low-water vapour permeability of exterior weather resistive pliable membranes. By contrast, warmer temperate climates and drier cool-temperate climates exhibit consistently lower calculated Mould Index values. Despite the 2022 requirement for a greater water vapour-permeance of exterior pliable membranes, the external walls systems explored in this research had a higher calculated Mould Index than the 2010 regulatory compliant external wall systems. Lower air change rates significantly increased calculated interstitial mould growth risk, while the use of interior vapour control membranes proved effective in its mitigation for most external wall systems. The addition of ventilated cavity in combination with either or both an interior vapour control membrane and a highly vapour-permeable exterior pliable membranes further reduced risk. The findings underscore the need for tailored, climate-responsive design interventions to minimise surface and interstitial mould growth risk and building durability, whilst achieving high performance external wall systems. Full article

Natural and liquefied petroleum gases are widely used in industrial heat treatment. However, the rising cost of gas, combined with increased demand, has significantly impacted production costs and the environment. The annealing process typically relies on natural or liquefied petroleum gases as the primary heat source. In this study, we aimed to investigate the use of biomass fuel as a replacement for fossil fuels and to evaluate the mechanical properties and microstructure of wire rod steel after annealing using indirect heat from a gasifier. We experimented to examine the effects of annealing temperatures of 650 °C, 700 °C (below the critical temperature Ac1), and 750 °C (above Ac1 but below the upper temperature Ac3). The batch furnace, made of stainless steel, was modified from a traditional wire annealing furnace that originally used CNG and LPG gas burners. It was adapted into a wire annealing furnace connected to a cross-draft gasifier. The furnace’s interior was designed with spiral cooling fins to minimize energy consumption and shorten annealing time. Additionally, it was modified to use biomass as a substitute fuel, reducing environmental pollution. The furnace was coated with thermal insulation, and the biomass gasifier stove was a cross-draft device with primary air feeding at 20 m³/h and secondary air supplied at a constant flow rate of 32 m³/h, 36 m³/h, or 40 m³/h. As a fuel source, we used eucalyptus. The mechanical properties of wire rod steel were measured in terms of tensile strength and torsion, following the TIS 138-2562 standard. This standard specifies that the tensile strength must be at least 260 MPa. Regarding torsion, the TIS 138-2562 requirements state that the wire must withstand at least 75 rounds of twisting without breaking. Our results showed that after annealing at 650 °C, 700 °C, or 750 °C, with a soaking time of 30 min and subsequent cooling in the furnace at natural temperature for 24 h, the tensile strength values were 494.82, 430.87, and 381.33 MPa, respectively. The torsion values were 126.92, 125.8, and 125.76 rounds, respectively. Additionally, ferrite grain size increased with annealing temperature, reaching a maximum of 750 °C. The total annealing duration for each batch was 2 h and 40 min at 650 °C, 2 h and 10 min at 700 °C, and 2 h at 750 °C. Full article

Wineries require a significant energy demand for cooling interior spaces. As a result, designing energy-efficient winery buildings has become a crucial concern for winemaking countries. The objective of this study was to evaluate six winery building models with bioclimatic designs, located in the Guadalupe Valley, Baja California, using data on thermal performances (indoor temperature and relative humidity) and energy consumption obtained through dynamic thermal simulation. A baseline winery building model was developed and then enhanced with bioclimatic strategies: a semi-buried building; an underground cellar; an underground cellar with the variants of a green roof, double roof, shaded walls, and polyurethane insulation. The last solution entailed the requirement of a reduction in cooling in the warm season by 98 MWh, followed by the one with a green roof, corresponding to 94 MWh. This study provides valuable insights into the effectiveness of different architectural approaches, offering guidelines for the design of functional buildings for wine production, besides presenting energy-efficient solutions for wineries tailored to the climatic conditions of the study region. These findings highlight the importance of a function-based and energy-efficient architectural design in the winemaking industry, which leads to the definition of buildings with a compact arrangement of the functional spaces and a fruitful integration of the landscape through a wise adoption of underground solutions. Full article

Composite phase-change materials (PCMs) exhibit significant potential for enhancing the thermal performance of building walls. However, previous studies have generally lacked detailed investigations of the performance of PCM-integrated walls under cold climate conditions. Therefore, in order to evaluate the thermal performance and wall adaptability of hollow bricks with composite PCMs in cold climates, a brick model was created by filling the hollow bricks with PCMs. Then a comparative test was conducted between the PCM-filled bricks and the conventional non-PCM-filled hollow bricks. The comparative experimental method and the thermal performance index evaluation method resulted in the following: (1) Compared with conventional hollow bricks, PCM-filled bricks showed an increase of approximately 0.99 °C in inner surface temperature and 3.85 °C in midsection temperature. This demonstrates that PCM-filled bricks can retard the rate of temperature drop, significantly enhancing the insulation performance of walls. This improvement contributes to enhance indoor thermal comfort and reduce energy consumption. (2) The temperature difference between the interior and exterior surfaces of the non-PCM-filled hollow bricks is 23.54 °C, which is 5.62 °C higher than that of the PCM-filled bricks. This indicates that bricks filled with PCMs possess superior heat storage capacity, effectively reducing indoor heat loss, which aligns with the principles of green building design. (3) Compared with the conventional non-PCM-filled hollow bricks, the heat flow on the inner surface of the PCM-filled bricks is significantly lower, with the average heat flow reduced by 8.57 W/m². This suggests the ability of bricks filled with PCMs to moderate heat flux fluctuations through a “peak-shaving and valley-filling” effect, contributing to reduced energy consumption and enhanced occupant thermal comfort. Full article

This study focused on examining the reinforcement of milkweed fibers in polylactic acid (PLA) bio-composites used for dashboards in car interiors. Milkweed fiber is a natural fiber with a hollow structure that provides tremendous thermal insulation and noise resistance properties. Firstly, the milkweed fibers were blended with PLA fibers in a weight ratio of 75:25 using an air-laying process. Then, several layers of nonwoven material were compressed in a hydraulic press to obtain bio-composites. Finally, three bio-composites were obtained with different numbers of layers. The density, microstructure, thermal conductivity, sound transmission loss (STL), mechanical properties, dynamic mechanical analysis (DMA), and contact angles of the bio-composites were evaluated. The microstructure analysis revealed that some milkweed fibers collapsed due to the high-pressure molding process, which does not affect the bio-composite properties. The bio-composite with a higher number of nonwoven layers presented a poor interface between PLA and milkweed fibers, thus making it less homogeneous. This bio-composite showed a decrease of 5% in thermal conductivity values and a 19% increase in STL values. In addition, it exhibited a 160% increase in specific flexural strength and a 335% increase in specific flexural modulus compared to samples with a lower number of nonwoven layers. Therefore, it offers the best mechanical-property-to-density ratio, with values that conform to the specifications required for automotive dashboards. Full article

In this paper, the ceramic coating of thermal barrier coatings (TBCs) was prepared on the surface of the tube specimens by Electron Beam Physical Vapor Deposition (EB-PVD) process. Subsequently, a service simulation was conducted using a simulation device to analyze the failure behavior of the TBCs. The effects of high-temperature sintering and CaO-MgO-Al₂O₃-SiO₂ (CMAS) corrosion on the microstructural evolution, phase structural changes, and insulation performance of the thermal barrier coatings were investigated. The results indicated that with increasing high-temperature sintering time, the “feather” structures at the boundaries of the columnar grains evolve into the “tentacle” structure that facilitates the fusion of adjacent columnar grains, resulting in increased grain diameter and wider gaps. No transformation from t’-ZrO₂ to the monoclinic phase m-ZrO₂ occurred during the high-temperature sintering process. Over time, CMAS wets the coating surface and infiltrates the interior of the coating, causing corrosion to the Yttria-stabilised zirconia (YSZ) and accelerating sintering. A new phase, ZrSiO₄, was formed after corrosion without inducing the transition. Full article

Adequate school buildings are essential for the development of children, young people, and adolescents, as they must provide conditions that support their well-being and health. A healthy and comfortable indoor environment is critical for students’ performance in the learning process. This study aims to evaluate the indoor environment in kindergartens located in northern Portugal, with a primary focus on thermal comfort and indoor air quality. To achieve this, five buildings with varying construction characteristics were monitored, with temperature and relative humidity measurements taken in classrooms of different orientations over time. Additionally, the outdoor climate was also monitored. Based on the collected data, thermal comfort was evaluated using the adaptive model defined by the European standard EN 16798. Continuous monitoring of carbon dioxide concentration was also conducted in three of these buildings. The results reveal significant heterogeneity among the buildings, demonstrating the influence of construction characteristics on the interior thermal conditions. The recorded temperatures ranged from 10 °C to 27 °C, highlighting a substantial variability in performance across the different buildings. Particularly, the orientation and size of glazed openings, together with the lack of thermal insulation in the building envelope, especially in the roof, were found to have an important impact on the thermal comfort of the occupants. Furthermore, a relationship was observed between the daily maximum carbon dioxide concentration and the outdoor temperature, as a result of users’ efforts to minimize uncontrolled air infiltration, by limiting the opening of doors and windows, with consequences in the air exchange between the interior and exterior. Full article

In recent decades, the sustainable development of the planet has been negatively affected by a number of factors, including the construction industry. The construction industry includes, among other things, the highly topical energy reconstruction of existing prefabricated residential housing, which is implemented to improve their condition from a thermal engineering and energy perspective. Composite materials, known as external thermal insulation composite systems (ETICSs), have come to the fore, bringing a number of undeniable benefits to society. After more than 20 years of experience, it turns out that in addition to the benefits, ETICSs also bring new research challenges to the discussion, which are related to the issue of the biocorrosion of the external envelope of ETICSs, and also to the issue of the indoor microclimate. Based on the literature review and case studies, we aim to show that ecologically friendly building materials require a multidisciplinary approach. At the same time, we want to contribute to the discussion of whether the diversity of microorganisms on ETICS composites is a potential source of health risks and whether the transport of microorganisms to the indoor environment can be ruled out through natural ventilation from the outdoor environment to the interior. Full article

Focusing on solving the adverse laser-inducing damage problem, high-power laser-resistant strategies have attracted more attention. In order to improve the laser-resistant property, a novel dynamic porous structure generation idea for laser irradiation was presented in this study, both of high-reflection and reaction endothermic effects. A detailed investigation on phase structure change, optical properties variation, micro-structure evolution, and substrate temperature development during laser irradiation was performed. The initial reflectivity of two coatings at 1064 nm was high, around 80–90%. During laser irradiation, the reflectivity grew continuously, reaching a maximum of 93%. During laser irradiation, a skeleton porous structure formed, promoted by the endothermic reaction of aluminum tri-hydroxide, whose structure contributes to the heat insulation from surface to interior. Thus, the prepared coating showed excellent anti-laser ablation performance, being dependent on its thermal insulation by the reaction-generated porous structure; high reflectivity by surface; and heat dissipation by endothermic reaction. Under 2000 W/cm², 10 s laser irradiation (spot area is 10 mm × 10 mm), the back-surface temperature is just 159 °C, which is far away from the melting point of aluminum substrate. The coatings and strategy mentioned in this study have a great potential to be applied in the anti-laser field. Full article

In practical applications, polyurethane (PU) foam must be rigid to meet the demands of various industries and provide comfort and protection in everyday life. PU foam components are extensively used in structural foam, thermal insulation, decorative panels, packaging, imitation wood, and floral foam, as well as in models and prototypes. Conventional technology for producing PU foam parts often leads to defects such as deformation, short shots, entrapped air, warpage, flash, micro-bubbles, weld lines, and voids. Therefore, the development of rigid PU foam parts has become a crucial research focus in the industry. This study proposes an innovative manufacturing process for producing rigid PU foam parts using silicone rubber molds (SRMs). The deformation of the silicone rubber mold can be predicted based on its wall thickness, following a trend equation with a correlation coefficient of 0.9951. The volume of the PU foam part can also be predicted by the weight of the PU foaming agent, as indicated by a trend equation with a correlation coefficient of 0.9824. The optimal weight ratio of the foaming agent to water, yielding the highest surface hardness, was found to be 5:1. The surface hardness of the PU foam part can also be predicted based on the weight of the water used, according to a proposed prediction equation with a correlation coefficient of 0.7517. The average surface hardness of the fabricated PU foam part has a Shore O hardness value of approximately 75. Foam parts made with 1.5 g of water added to 15 g of a foaming agent have the fewest internal pores, resulting in the densest interior. PU foam parts exhibit excellent mechanical properties when 3 g of water is added to the PU foaming agent, as evidenced by their surface hardness and compressive strength. Using rigid PU foam parts as a backing material in the proposed method can reduce rapid tool production costs by about 62%. Finally, an innovative manufacturing process for creating large SRMs using rigid PU foam parts as backing material is demonstrated. Full article