Search

Abstract Background To reduce heat loss underwater, marine mammals cover their bodies with insulation. Cetaceans in particular rely solely on blubber for insulation which has low conductivity. Blubber establishes a great thermal gradient between the warmer body core and cooler body surface, reducing heat transfer to the environment. A temperature gradient within the blubber determines the conductive heat transfer from the body trunk, where conduction and convection are the primary heat transfer mechanisms in cetaceans. Therefore, measuring the temperature at the innermost part of the blubber, i.e., the temperature at the muscle–blubber interface (Tmbi), can enhance our understanding of thermoregulatory mechanisms in cetaceans. In thermoregulation, activity-induced heat produced by increased muscle metabolism is another factor that plays an important role, however, the effects of activity on Tmbi have not been investigated in cetaceans. To assess this relationship in free-swimming cetaceans, we measured Tmbi and activity levels in a captive Risso’s dolphin (Grampus griseus) using an implantable biologging device. Results Tmbi and activity data were analyzed for 11 days. The average Tmbi was 35.1 ± 0.6 ºC and the temperature gradient between Tmbi and the water temperature was 13.0 ± 0.7 ºC. Tmbi was higher during the daytime and lower in the early morning. The variation in Tmbi was best explained by both the activity levels and time of day. Tmbi did not simply increase with activity levels; it appeared to remain relatively constant at most activity levels. However, Tmbi appeared to decrease when the animal was inactive and increase when it was intensely active. Conclusion Our results provide important insights into how a dolphin regulates its body temperature underwater. Thermal insulation by blubber and heat production by activity were suggested to play important roles in thermoregulation. Whole-body heat dissipation might be used to regulate temperature increases when heat production is excessive due to intense activity. During inactive periods, decreasing temperature gradient may help reduce heat loss from the body.

This study investigates the impact of insulation on energy consumption and CO2 emissions in high-rise commercial buildings across various climate zones. Through a simulation-based approach using the Hourly Analysis Program (HAP), the effectiveness of insulation in reducing energy demand and carbon emissions are evaluated. The research includes multiple climatic regions of Afghanistan, including arid, semi-arid, and mountainous zones. Methodologically, detailed building characteristics, climatic data, and insulation materials are considered, with energy modeling techniques applied to assess the performance of insulation measures. Results indicate varying degrees of energy savings and CO2 emissions reduction associated with insulation across different climate zones, in cities such as Kabul, Herat, Mazar, and Kandahar. Furthermore, the study calculates CO2 emissions reduction resulting from insulation addition, emphasizing the importance of sustainable building practices in mitigating environmental impacts. By underscoring the scientific value of this research in addressing a pressing global challenge and providing actionable insights for building design and energy policy, this study contributes to the advancement of knowledge in the field of sustainable construction and environmental engineering.

The building and construction industry consumes a significant amount of natural resources alongside contributing to the generation of waste materials. Addressing the dual challenge of waste management and recycling in this sector is imperative. This study begins with a bibliometric assessment to identify waste materials used as insulation in building and construction systems. The assessment of 2627 publications revealed mattress waste materials were seldom considered. The aim of this research focuses on exploring alternative methods for repurposing mattress materials in construction, aiming to mitigate waste generation. While various materials are being recycled for building applications, this research emphasises the potential of incorporating recycled polyurethane foam (PUF) from mattresses as insulation products. A transient plane source (TPS) was employed to determine the thermal conductivity of waste mattress PUF obtained from a recycling plant in Victoria, Australia. The results exhibited promising thermal resistance, with a mean value of 0.053 Wm/K. However, optimal thermal performance was observed with increased thickness, suggesting that a thickness of 215mm aligns with industry standards for building fabric systems. Further research is required to comprehensively analyse moisture resistance and fire retardation of waste mattress materials. This paper presents key findings of current trends, limitations, and future research directions to the use of waste mattress PUF as an insulation material.

Background: To reduce heat loss underwater, marine mammals cover their bodies with insulation. Cetaceans in particular rely solely on blubber for insulation which has low conductivity. Blubber establishes a great thermal gradient between the warmer body core and cooler body surface, reducing heat transfer to the environment. A temperature gradient within the blubber determines the conductive heat transfer from the body trunk, where conduction and convection are the primary heat transfer mechanisms in cetaceans. Therefore, measuring the temperature at the innermost part of the blubber, i.e., the temperature at the muscle–blubber interface (Tmbi), can enhance our understanding of thermoregulatory mechanisms in cetaceans. In thermoregulation, activity-induced heat produced by increased muscle metabolism is another factor that plays an important role, however, the effects of activity on Tmbi have not been investigated in cetaceans. To assess this relationship in free-swimming cetaceans, we measured Tmbi and activity levels in a captive Risso's dolphin (Grampus griseus) using an implantable biologging device. Results: Tmbi and activity data were analyzed for 11 days. The average Tmbi was 35.1 ± 0.6 ºC and the temperature gradient between Tmbi and the water temperature was 13.0 ± 0.7 ºC. Tmbi was higher during the daytime and lower in the early morning. The variation in Tmbi was best explained by both the activity levels and time of day. Tmbi did not simply increase with activity levels; it appeared to remain relatively constant at most activity levels. However, Tmbi appeared to decrease when the animal was inactive and increase when it was intensely active. Conclusion: Our results provide important insights into how a dolphin regulates its body temperature underwater. Thermal insulation by blubber and heat production by activity were suggested to play important roles in thermoregulation. Whole-body heat dissipation might be used to regulate temperature increases when heat production is excessive due to intense activity. During inactive periods, decreasing temperature gradient may help reduce heat loss from the body. [ABSTRACT FROM AUTHOR]

This study investigates the effect of positive temperature coefficient (PTC) fillers, i.e., barium strontium titanate (BST‐60) and nano hexagonal boron nitride (h‐BN) fillers, on thermal and dielectric insulation properties of epoxy (EP). The electrical resistivity, DC breakdown strength, space charge, thermal conductivity, thermogravimetric analysis, and glass transition temperature (Tg) of EP composites were measured. Results indicate that, below curie temperature, the EP composites containing 0.5 and 1 wt% of BST and 5 wt% of h‐BN have superior electrical resistivity, breakdown strength, and thermal conductivity. However, above curie temperature, the EP composites containing 2 and 2.5 wt% of BST and 5 wt% of h‐BN have superior insulation properties than the pure EP and other composites. While the thermal properties of EP improve with an increase in h‐BN loading to 10 wt%, its dielectric properties are slightly compromised due to the presence of tiny defects in the composite material. It is hypothesized that the BST‐60 suppresses the negative temperature coefficient effect (NTC) of EP by regulating the electrical resistivity above the curie point, whereas nano h‐BN enhances the thermal conductivity of EP by constructing a heat dissipation path. The proposed mechanism for charge dynamics along with heat conduction‐dissipation explains the fillers' behavior at different temperatures. Highlights: Analysis of epoxy composites with polydopamine‐modified BST and h‐BN fillers.PTC fillers are used to mitigate the negative temperature effect of epoxy.Optimal fillers wt% improves dielectric and thermal properties.This study shows that optimized epoxy composites can be used for packaging. [ABSTRACT FROM AUTHOR]

Functional energy-saving materials with coupled cooling effect have become particularly urgent because traditional cooling systems require high industrial energy inputs and high labor costs. Biomass-derived materials are highly desirable for the environment and energy-related applications, but raw biomass materials cannot satisfy cooling demands for more environment and energy-efficient processes. Herein, inspired by the transpiration of natural plants and radiation cooling of metal materials, this study presents the silver nanoparticles–coated wood with a coupled cooling effect for dual-mode cooling. The silver nanoparticles–coated wood with a natural hollow ordered pore structure can achieve the cooling effect by the capillary phenomenon where water absorption and evaporation. The results revealed that silver nanoparticles with high infrared reflectivity were firmly embedded in the surface of the wood by magnetron sputtering, which empowers the wood with high infrared heat dissipation properties. Compared to the bare porous wood, the surface temperatures of silver nanoparticles coated wood were decreased from 34.6–35.8 to 30.3–31.2 °C. In addition, by combining with the evaporative and radiative heat dissipation, the silver-coated wood obtained the coupled cooling effect under simulated solar radiation, which further improves the cooling effect. Owing to the silver coating, the material possesses an excellent antibacterial property which extends durability. Therefore, the tree-inspired water vapor evaporation and radiation cooling show good harmony and can be well combined by the directional structure design of the material. This dual-mode cooling mechanism provides a novel design concept of cooling materials and further promises to benefit the sustainability of society in many aspects, from health to economy. [ABSTRACT FROM AUTHOR]

Precast concrete sandwich wall panels (PCSPs) are popular for building exteriors due to their high thermal efficiency, composite performance, and low manufacturing and maintenance costs. Researchers have investigated the possibility of reducing the panel thickness while maintaining the cladding components' thermal efficiency and strength to further improve efficiency and to reduce material consumption. However, limited research has been conducted on the shear bonding of steel plates, which is critical to ensuring durability and energy efficiency. This study investigated the shear behaviour of PCSPs with an S-type shear connector (SSC) through nine push-off tests and non-linear finite element modelling using Abaqus. Parametric studies were carried out to investigate the influence of the geometric properties of the SSC, the yield strength of the steel and the insulation thickness. The results suggest that the maximum secant stiffness for SSCs was achieved at a width of 101.4 mm and a thickness of 2 mm. Therefore, it is recommended that the width of the SSCs be limited to this value or less. Furthermore, the study found that increasing the yield strength of the steel beyond a thickness of 2 mm and a width of 101.4 mm did not improve the results and had a negative impact on the secant stiffness of the SSCs. [ABSTRACT FROM AUTHOR]

By using 6,6-((sulfonylbis (4,1-phenylene)) bis (azanediyl)) bis (thiophen-2-ylm- ethylene)) bis (6H-di-benzo[c,e][1,2]oxaphosphinine 6-oxide (DOPO-N) as phosphorus-nitrogen flame retardant, the polyurea (PUA) with flame retardant properties (PUA/DOPO-N) was prepared. In addition, organically modified montmorillonite (OMMT) and magnesium hydroxide (MH) were used as co-effectors respectively, and the flame retardant PUA (PUA/DOPO-N/OMMT and PUA/DOPO-N/MH) were also prepared. Thermal properties, flame retardant properties, flame retardant mechanism and mechanical properties of PUA/DOPO-N, PUA/DOPO-N/OMMT and PUA/DOPO-N/MH were investigated by thermogravimetric (TG) analysis, limiting oxygen index (LOI), UL 94, cone calorimeter test, scanning electron microscopy (SEM), and tensile test. The results show that the LOI value of PUA/20%DOPO-N, PUA/18%DOPO-N/2%OMMT and PUA/15%DOPO-N/5%MH are 27.1%, 27.7%, and 28.3%, respectively, and UL 94 V-0 rating is attained. Compared with PUA, the peak heat release rate (pk-HRR), total heat release (THR) and average effective heat combustion (av-EHC) of PUA/20%DOPO-N, PUA/18% DOPO-N/2%OMMT and PUA/15%DOPO-N/5%MH decrease significantly. SEM results indicate that the residual chars of PUA/20%DOPO-N, PUA/18%DOPO-N/2%OMMT and PUA/15% DOPO-N/5%MH are completer and more compact. The complex of DOPO-N/OMMT and DOPO-N/MH have synergistic flame retardancy. The mechanical properties of PUA can be improved by the addition of DOPO-N, DOPO-N/OMMT and DOPO-N/MH, respectively. The insulation performance test shows that the volume resistivity of PUA/20%DOPO-N is 6.25×1016 Ω.cm. Furthermore, by using modified boron nitride (MBN) as heat dissipating material, the complex of PUA/MBN was prepared, and the thermal conductivity of PUA/MBN was investigated. The thermal conductivity of PUA/8%MBN complex coating at room temperature is 0.166 W/(M·K), which is a 163% improvement over pure PUA. [ABSTRACT FROM AUTHOR]

Cooling system is in charge of a high percent of total energy consumption in buildings. Different cooling systems and devices have different effects on the cooling load and energy consumption. The main objective of this paper is to study the effects of floor and ceiling temperature in comparison with other parameters including location of air diffusers and application of insulation and sealant. On the other hand, hospitals are huge buildings with high energy requirements and systems compared to other buildings such as universities, schools and offices. In this paper the impacts of these different cooling parameters on the temperature and cooling load in a room of a hospital are studied using Design of Experiments (DOE) and the Taguchi method. The experiments are simulated in Energy Plus to achieve the comfort temperature in one hospital’s room in Iran during six months of spring and summer. Using different cooling systems such as chilled floor (during night to decrease the peak load during day) and ceiling in combination with air handling unit can provide people satisfaction while optimizing energy consumption. The results show that the location of inlet and outlet diffusers has the most effect while the chilled floor (when the other systems are off) has the less impact on reaching comfort temperature. The ranking of parameters and their interactions has been discussed through the paper. [ABSTRACT FROM AUTHOR]

Numerous studies are exploring methodologies to enhance flame resistance and minimize the emission of toxic gases and chemicals from building materials in the event of a fire, aiming to mitigate risks and save lives. To that end, this study produced an insulation material using stabilized fiber based on polyacrylonitrile (PAN). Stabilized fiber provides flame retardancy by forming aromatic bonds in existing PAN fiber through heat treatment. To manufacture an insulation material with fiber, a separate adhesive is needed to maintain the shape, and cellulose was selected as the adhesive. Cellulose is an environmentally friendly material that can be obtained from natural sources and has the additional advantages of excellent stability and heat resistance. For this study, PAN-based stabilizing fiber (PSF) insulation was prepared and further processed using cellulose adhesive (PSF-C). Combustion experiments and gas analysis were performed to assess the combustion risks of the developed PSF insulation, and the contents of the hazardous gases and smoke generated were measured. The hazardous gases and smoke released during combustion were considerably reduced, and the heat resistance of the insulation was improved. Furthermore, the pyrolysis reaction and thermal stability were investigated. The results demonstrated a substantial reduction in the combustion hazards associated with the PSF when cellulose was used, i.e., PSF-C was used. The findings of this study are expected to substantially contribute to advancing the practical applicability of PSF-C insulating materials and the development of safe building and fire prevention systems. We developed PAN-based stabilized fiber insulation to enhance fire safety and minimize human casualties. We utilized an eco-friendly cellulose adhesive for structural integrity and studied its fire-safety properties, including HCN emissions. The developed insulation with cellulose adhesive (PSF-C) significantly reduced HCN emissions compared with a PAN insulator alone (PSF). PSF-C reduces human casualties [ABSTRACT FROM AUTHOR]

The building and construction industry consumes a significant amount of natural resources alongside contributing to the generation of waste materials. Addressing the dual challenge of waste management and recycling in this sector is imperative. This study begins with a bibliometric assessment to identify waste materials used as insulation in building and construction systems. The assessment of 2627 publications revealed mattress waste materials were seldom considered. The aim of this research focuses on exploring alternative methods for repurposing mattress materials in construction, aiming to mitigate waste generation. While various materials are being recycled for building applications, this research emphasises the potential of incorporating recycled polyurethane foam (PUF) from mattresses as insulation products. A transient plane source (TPS) was employed to determine the thermal conductivity of waste mattress PUF obtained from a recycling plant in Victoria, Australia. The results exhibited promising thermal resistance, with a mean value of 0.053 Wm/K. However, optimal thermal performance was observed with increased thickness, suggesting that a thickness of 215mm aligns with industry standards for building fabric systems. Further research is required to comprehensively analyse moisture resistance and fire retardation of waste mattress materials. This paper presents key findings of current trends, limitations, and future research directions to the use of waste mattress PUF as an insulation material. [ABSTRACT FROM AUTHOR]

In recent years, there has been a paradigm shift in the building sector towards more sustainable, resource efficient, and renewable materials. Bio-based insulation derived from renewable resources, such as plant or animal fibres, is one promising group of such materials. Compared to mineral wool and polystyrene-based insulation materials, these bio-based insulation materials generally have a slightly higher thermal conductivity, and they are significantly more hygroscopic, two factors that need to be considered when using these bio-based insulation materials. This study assesses the hygrothermal properties of three bio-based insulation materials: eelgrass, grass, and wood fibre. All three have the potential to be locally sourced in Sweden. Mineral wool (stone wool) was used as a reference material. Hygrothermal material properties were measured with dynamic vapour sorption (DVS), transient plane source (TPS), and sorption calorimetry. Moisture buffering of the insulation materials was assessed, and their thermal insulation capacity was tested on a building component level in a hot box that exposed the materials to a steady-state climate, simulating in-use conditions in, e.g., an external wall. The tested bio-based insulation materials have significantly different sorption properties to stone wool and have higher thermal conductivity than what the manufacturers declared. The hot-box experiments showed that the insulating capacity of the bio-based insulators cannot be reliably calculated from the measured thermal conductivity alone. The results of this study could be used as input data for numerical simulations and analyses of the thermal and hygroscopic behaviour of these bio-based insulation materials. [ABSTRACT FROM AUTHOR]

Exposure to radon gas in households presents serious health risks, including an increased likelihood of lung cancer. Following the COVID-19 pandemic, the change in individual habits has led to more time spent in indoor environments with remote activities; thus, the need to raise the awareness of air quality in dwellings and to mitigate the exposure of inhabitants to radon has emerged. This study investigated radon gas concentrations in the air of Latvian dwellings. RadTrack2 passive detectors were deployed in a representative sample of households across 106 municipalities of Latvia (98% of the territory), yielding data from 487 households (973 detectors). The data revealed a median radon concentration of 52 Bq/m3 (Q1 and Q3 were 29 and 93 Bq/m3), with the majority of samples (95.6%) falling below the national reference limit of 200 Bq/m3. The building type and presence of a cellar significantly impacted radon levels, with structures lacking cellars and older buildings exhibiting higher concentrations. Mechanical ventilation proved to be more effective in reducing radon levels, compared to natural ventilation. These findings emphasize the necessity of proactive measures to mitigate indoor radon exposure and to ensure the well-being of occupants. Additionally, the dissemination of research data on radon exposure through open-access scientific publications is vital for raising awareness and implementing effective mitigation strategies. [ABSTRACT FROM AUTHOR]

Thermal balance is paramount to human comfort and safety. To better understand the effects of the material and environment, a modified sweating-hot-plate test was used to incorporate environmental parameters such as the ventilation and microclimate thickness. It was found that at wind speeds ≤ 0.5 m/s, the environment has the most significant effect on the insulation. However, at an increased wind speed (1.3 m/s), the construction of the material has a large influence on the insulation of the system. At a low metabolic rate, the heat storage can be compensated for through dry heat loss; but, at a higher metabolic rate, substantial differences in the sweating rates are required based on the material and environment. The various aspects of the environment wind speed, microclimate thickness, and ventilation are crucial, but, in certain combinations, the material can have a significant impact as well. [ABSTRACT FROM AUTHOR]

The consumption of poly(ethylene terephthalate) (PET) has experienced a surge in recent times, owing to the widespread use of single-use plastic bottles, particularly in the context of beverages and drinking water. PET, a thermoplastic polymer, is known for its recyclability, and the recycled variant is referred to as rPET. The incorporation of rPET in fiber manufacturing is favored due to its cost-effectiveness, and the functionalized rPET fibers present an innovative product that can be used in a variety of applications. This study aimed to functionalize rPET fibers using the spun-bond technique, imparting antibacterial and flame-retardant properties, which are commonly employed in thermal insulator products. Nano zinc oxide (nano-ZnO) was used to confer antibacterial functionality, while phosphorus flame retardant (PFR) was used to impart flame-retardant properties. The core-sheath bicomponent fiber structure was employed to achieve the desired outcomes. The extrusion process was used to incorporate PFR and ZnO as the core and sheath components, respectively, at various ratios. The presence of nano-ZnO on the fiber shell was confirmed by the EDX data. The flame retardant study was utilized to observe the level of burning damage. The findings of the study demonstrated that increasing the percentage of PFR (maximum 8%) resulted in a significant decrease in the damage distance of the nonwoven material, with reductions of up to 60% was observed. Furthermore, the results of the antibacterial test indicated that the inclusion of an additional 3 wt% of ZnO resulted in a considerable reduction of the bacteria S. aureus and K. pneumoniae by about 99.96 and 98.79%, respectively. Based on the results obtained, it was determined that the most effective functionalized fiber was synthesized by including 3 wt% of ZnO and 5 wt% of PFR. Moreover, the incorporation of varying proportions of additives resulted in modifications to the mechanical and thermal characteristics of the fibers. This work highlights the potential of functionalized rPET bicomponent fibers as viable candidates for thermal insulator products. The utilization of functionalized rPET bicomponent fibers as a sustainable alternative for thermal insulator products showcases the commitment to environmentally friendly solutions, contributing to the overall goal of sustainability in the manufacturing industry. [ABSTRACT FROM AUTHOR]

One of the most important factors in the LPDC process is the heat transfer during the solidification of the molten alloys, which is responsible for the resulting microstructure and, thus, the quality of the cast piece. The use of foundry coatings has been lately suggested as a proper strategy to control the heat transfer while protecting bonded moulds from aluminium adhesion by providing a barrier between the surface and the liquid metal. LPDC die coating failures usually come from the loss of adherence or excessive wear originated in the successive filling processes, which requires stopping production for the reapplication of the coating. In the present work, coatings with different insulation capabilities have been evaluated, in terms of adherence and wear tests, in order to select the most promising alternative for LPDC die coating. This study confirmed that surface preparation and cleanliness are vital for an adequate adhesion of the coatings to ensure their durability. The results evinced that the use of a primer layer provided a higher adhesion of the coatings and considerably improved their perfomance. The coating that presented the best results in terms of adhesion and wear resistance under different abrasive testing conditions was coating B3. [ABSTRACT FROM AUTHOR]

Plasma sprayed thermal barrier coatings (TBCs), applied in internal combustion engines, can have a profound impact on the apparent rate of heat release. Upon fuel jet contact with the piston wall, the heat loss seems to increase compared to an uncoated piston and combustion appears delayed. Permeable porosity of plasma sprayed TBCs is identified as one of the possible causes for this unwanted effect. In this article the impact of open porosity and sealing of the TBC surface are investigated with single cylinder engine experiments and with simulations. Based on the results, a mechanism is presented to explain the observations. [ABSTRACT FROM AUTHOR]

The rapid development of new energy automobile industry has put forward higher requirements for the temperature resistance of insulating enameled wire of automobile motor. The preparation of high-performance and low-cost enameled wire coating has become a research hotspot in this field. In this paper, the one-step solvent-thermal method was used to prepare pentagonal star-like ZrO2 particles. In situ polymerization method was used to prepare a PI/ pentagonal star-like ZrO2 composite film with high performance and low cost. The results showed that the prepared pentagonal star-like ZrO2 particles were uniformly distributed, which improved the dispersion of ZrO2 in PI polymer. Compared with pure PI films, the hydrophobic properties and tensile stress of PI/ pentagonal star-like ZrO2 composite films are improved by 4. 8 times after adding 3% of ZrO2 nanoparticles. The initial thermal decomposition temperature was increased by 8.30%. The dielectric constant is increased by 3. 2 times. It can be seen that the five-pointed star ZrO2 has significantly improved the insulation and high temperature resistance of pure PI film. This work has important guiding significance for developing new formula of high performance enameled wire. [ABSTRACT FROM AUTHOR]

Following the invasion of Ukraine and the associated energy policy tensions with Russia, the EU began looking at how it could replace Russian energy sources. One of the proposed solutions is to decrease energy consumption. Buildings have been the principal target, owing to their high energy usage – especially of natural gas, which the EU is particularly keen on reducing. This literature review article summarises existing knowledge on the potential energy savings that can be made through energy efficiency improvements to existing buildings in Central and Eastern Europe. The countries in this region share common traits due to their Communist past and associated legacy of poor energy efficiency, both generally and in buildings in particular. At the same time, Central and Eastern Europe contains a range of geographical and climatic regions, and so, the findings of this paper are applicable to other regions. This bibliometric analysis identifies three main areas (insulation, heating source and policy) in which the academic literature has identified potential for energy efficiency improvements to buildings. On the basis of these findings, this paper looks at the policy implications for reducing energy consumption in buildings and thus helps the EU to become less dependent on energy supplies from Russia. [ABSTRACT FROM AUTHOR]

The paper is devoted to an overview of the development of insulating materials and media used in high-voltage equipment over the past 150 years. The transition from traditional dielectrics such as air, porcelain, and glass to modern developments based on polymers and polymeric composites is considered. The increase in the use of synthetic liquids such as silicone and specialty oils is discussed, and the emergence of alternatives, such as liquid nitrogen for technological applications of superconductivity, is considered. Special attention is paid to the use of different gases, for example, fluoronitriles and ketones at different pressure values as an alternative to air and gas for gas insulation of high-voltage equipment. [ABSTRACT FROM AUTHOR]

Cross-Laminated Timber (CLT) panels have many structural benefits but do not have much thermal resistance. We have developed a solution to insulate CLT structures that uses high-performance insulation panels that provide R-values up to R40/inch. The CLT panels are made of layers of wood laminates (three, five, seven or more). The solution replaces some of the wood laminates in the CLT production with the insulation panels in a staggered fashion so that the wood laminates maintain contact throughout the panel, ensuring the CLT panel's structural integrity. The insulated CLT panels have factory-installed water-resistive barriers reducing the installation time by eliminating installing insulation and water-resistive barriers on site. Per simulations, the CLT/insulation panel achieved code-required insulation levels with commonly available insulation materials. The significance of the thermal mass of CLT/insulation hybrid building envelopes was quantified by comparing the whole building energy performance and peak demand of traditional low mass and CLT wall assemblies resulting in up to 7% reduction in peak demand for cooling in Knoxville, TN, in a multifamily building. Buildings contribute over 40 percent of carbon emissions. The proposed CLT/insulation hybrid building envelope addresses both operational and embodied carbon by having high thermal resistances due to the embedded insulation sections and eliminating the use of high embodied carbon materials such as steel and concrete. The carbon benefit is estimated. [ABSTRACT FROM AUTHOR]

This paper attempts to ascertain the thermal and acoustic impacts of introducing a vegetative roof layer on insulated and uninsulated metal roofs for tropical climates, through field measurements in Skudai, Johor, Malaysia, that were conducted for both dry and wet days. Four small-scale roof modules were tested, namely an uninsulated metal roof (uiMDR), an insulated metal roof (iMDR), and two identical corresponding modules with an additional vegetative component (uiGR and iGR, respectively). Outdoor ambient temperature (Tamb) was the most influential correlated variable affecting the roof outer surface temperature (RTOS) in 50% of the assessed scenarios. On the selected dry day, the inter-quartile ranges (IQR) of iGR, iMDR, uiGR, and uiMDR were 6.21 °C, 8.32 °C, 6.69 °C, and 1.66 °C, respectively; the IQRs were 1.6 °C, 4.11 °C, 2.59 °C, and 1.78 °C, respectively, on the selected wet day. Based on design U-value calculations, iGR was better than iMDR and uiMDR for both dry and wet days. The U-value of uiGR was also better than iMDR under dry-day conditions. The Wilcoxon signed-rank test also indicated a statistically significant difference in the roof inner surface temperature (RTIS) measurements (p-value = 0.00) during Malaysian daylight hours, between 8.00 a.m. and 6.00 p.m., regardless of the weather. In terms of sound level reduction under dry-day conditions, the Kruskal–Wallis and Wilcoxon signed-rank tests showed statistically significant differences in sound level reductions, with iGR and uiGR performing better than iMDR and uiMDR (p-values = 0.00). The sound level reductions for iGR, iMDR, and uiGR were 51%, 32%, and 31%, respectively, while uiMDR experienced sound level amplifications by 6%, possibly due to the acoustic resonance effect. This proof of concept may encourage a broader application of extensive GRs in Malaysia using metal roofs, beyond the conventional RC base construction method. [ABSTRACT FROM AUTHOR]

Copyright of Online Journal of Art & Design is the property of Online Journal of Art & Design and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Vortex generators are very effective tools in increasing heat transfer from one region to another, especially by convection, and appear to be a very promising concept to be coupled with heat recovery systems. On the other hand, Thermoelectric Generators (TEGs) are devices able to convert differences in temperature into electrical power using the Seebeck effect, the main advantage being working on high or even low differences in temperature. These TEG modules could be very effective tools in the hybridization of heat recovery systems. In this context, the present paper suggests an innovative system that couples three important energy axes together such as Heat recovery, TEGs, and Vortex generators. The current study employs a TEG in a rectangular channel to analyze the influence of the TEG on the flow and the effect of the effect of flow regime on producing electric power in order to assess the viability of this recently proposed concept. The investigation is conducted by varying the Reynolds number in a range of five values: 1000, 2000, 4000, 7000, and 10,000, applying six different configurations. Consequently, the results show that several factors affect the electrical power generated by TEG such as the emplacement, angle of attack, and absence/presence of vortex generators. On the other side, the heat recovered by the flow is affected by the TEG and Re, where the highest heat recovery is achieved at Re = 10,000 for configuration 4 with electrical power of 7.4 W, and for configuration 5 heat recovered by the flow of 1913 W. Besides, it was concluded that TEGs decreased the losses in both hot and cold sides by 1.42 times.

The uncontrollable rise in energy consumption become a most significant issue in recent decades. One of the largest consumers of energy resources across all industries is the residential building sector. Researchers have suggested several strategies to reduce energy loss, including enclosing insulation in wall structures because air conditioning systems account for the majority of energy use inside homes. The main goal of this article is to increase residents' thermal comfort (Tc) while reducing their heating load (HL) and cooling load (CL). Using the EnergyPlus program, the building model was simulated in sample cities with various climatic conditions. For optimization, the first seven design variables were determined in Jeplus software and then multi-objective optimization was performed by the Non-dominated Sorting Genetic Algorithm (NSGA-Ⅱ) algorithm. As a result, Tc, HL, and CL values improved by 38–62, 61 to 100, and 17 to 39 percent, respectively.

The global surge in environmental pollution, largely attributed to industrialization, has fueled a pressing need for sustainable solutions. In response, the construction sector is increasingly focusing on bio-based materials such as hemp, recognized for its low environmental footprint and prominent carbon-negative quality. As designers, housebuilders, and an environmentally conscious society pivot towards ecological alternatives to standard building materials, hempcrete emerges as a promising candidate. As a composite material mainly made from hemp hurd/shiv, water, and lime, hempcrete offers the ability to sequester carbon long after its incorporation into structures. As a result, the hemp cultivation process—which can be completed within less than four months—ensures that more carbon is absorbed during production and deployment than emitted, e.g., per one study, sequestration on the order of 300 kg of CO2 per m3 of hempcrete. In comparison to concrete, hempcrete offers a more sustainable footprint, given its recyclability post life cycle. This state-of-the-art review paper delves deep into different aspects of hempcrete, summarizing its multifaceted attributes, particularly its compressive strength. Based on the study conducted, the paper also suggests strategies to augment this strength, thereby transitioning hempcrete from a non-load-bearing material to one capable of shouldering significant weight. As architects and designers consistently strive to align their projects with high ecological standards, focusing not just on aesthetic appeal but also environmental compatibility, hempcrete becomes an increasingly fitting solution for the future of construction.

This study investigates the partial discharge inception voltage (PDIV) in turn-to-turn insulation of form-wound windings in inverter-fed motors under nine different air pressures, ranging from 1013 mbar to 10 mbar. The research evaluates three voltage waveform excitations: 50 Hz AC, unipolar positive (UP), and bipolar (BP) steep-fronted square waves. The pulse width modulation (PWM) excitations are characterized by a switching frequency of 2.5 kHz, a rise time of 80 ns, and a pulse width of $100~\mu $ s. The experimental analysis focuses on peak and peak-to-peak PDIV values, comparing the variations between 50 Hz AC and PWM excitations across different air pressures. In addition, a novel predictive PDIV model is developed using Schumann’s streamer inception criterion (SCSIC) to account for air pressure variations across the three waveform excitations. As another innovation, the model examines streamer inception parameters (SIPs) in rectangular turn-to-turn insulation, incorporating factors such as critical field line length (CFLL), effective ionization coefficient ( $\alpha _{\mathrm {eff}}$ ), partial discharge inception field ( $E_{\mathrm {inc}}$ ), and firing voltage ( $V_{\mathrm {firing}}$ ) under varying air pressures and voltage waveforms. This study provides critical insights into partial discharge phenomena and their potentially destructive effects on rectangular insulated wires. These findings are vital for insulation designers seeking to develop PD-free designs by considering the impact of air pressure, voltage waveform, and variations in SIPs.

Previous studies on discharge dynamics have primarily focused on the generation and migration of the charged particles and neglecting the influence of neutral excited-state particles. In this study, an integrated approach combining experiment and simulation was used to investigate the effect of neutral excited particles on discharge development. Firstly, partial discharge was induced by applying voltage to a pin-plate electrode in a darkroom environment and the emission spectrum of discharge was captured using an ultra-sensitive spectrometer. Then the formation mechanism of the main neutral excited particles in air corona discharge was analyzed based on the principle of quantum optics, and the collision cross-section data of the non-local thermodynamic equilibrium (NLTE) plasma chemical model for air was updated accordingly. Simulations revealed the process of electron pulses initiates the electron avalanche, which leads to dielectric breakdown. Results indicated that overvoltage can lead to the formation of electron avalanches at defect sites, which is capable of causing dielectric breakdown within the nanosecond time scale. The competitive mechanism of the excitation reactions to ionization reactions results in the dissipation of free electrons’ energy, effectively suppressing the development of electron avalanches and preventing electrical breakdown.

Gas-insulated systems are widely utilized in the electric power sector to transmit and distribute electrical energy. Sulphur-hexafluoride (SF6) has dominated gas insulation in high-voltage insulation technology since the early 60s. It is a greenhouse gas with a protracted lifespan in the atmosphere. This paper proposes an economical and comparatively more environmentally friendly R507 gas alternative to SF6 for medium-voltage applications. R507 has been analyzed experimentally through power frequency breakdown and lightning impulse testing to validate the performance and theoretical concepts. R507 has a very low liquefication temperature of $-46.7^{\circ }\text{C}$ , but it must still be mixed with buffer gases such as CO2, N2, or dry air to meet the diverse liquefaction temperature applications. Various field utilization factors under AC and lightning impulse voltages are used in the experiments, along with different electrode geometries, including sphere-to-plane and rod-to-plane (i.e., quasi-homogeneous and inhomogeneous electric field distribution). For comparison, identical experiments are conducted with pure SF6. R507 gas was found to be a promising substitute for SF6 gas, with its dielectric strength being approximately 0.95 times that of SF6 gas. A positive synergistic effect is present between R507 and CO2, along with the good self-recoverability property of the gas mixture. The current research study serves as a fundamental resource for characterizing the R507/CO2 gas mixture insulation properties to be utilized in practical applications.

Lightweight and high-toughness carbon fiber/phenolic ablator (CFPA) is required as the Thermal Protection System (TPS) material of aerospace vehicles for next-generation space missions. To improve the ablative properties, silica sol with good particle size distribution prepared using tetramethoxysilane (TMOS) was blended with natural rubber latex and deposited onto carbon fiber felt, which was then integrated with phenolic aerogel matrix, introducing nano-silica into the framework of CFPA. The modified CFPA with a low density of 0.28–0.31 g/cm3 exhibits strain-in-fracture as high as 31.2% and thermal conductivity as low as 0.054 W/(m∙K). Furthermore, a trace amount of nano-silica could effectively protect CFPA from erosion of oxidizing atmosphere in different high-temperature environments. The oxyacetylene ablation test of 3000 °C for 20 s shows a mass ablation rate of 0.0225 g/s, a linear ablation rate of 0.209 mm/s for the modified CFPA, which are 9.64% and 24.82% lower than the unmodified one. Besides, the long-time butane ablation test of 1200 °C for 200 s shows an insignificant recession with mass and linear ablation rate of 0.079 g/s and 0.039 mm/s, 16.84% and 13.33% lower than the unmodified one. Meanwhile, the fixed thermocouple in the test also demonstrates a good thermal insulation performance with a low peak back-face temperature of 207.7 °C, 12.25% lower than the unmodified one. Therefore, the nano-silica modified CFPA with excellent overall performance presents promising prospects in high-temperature aerospace applications.

Biobased foams have the potential to serve as eco-friendly alternatives to petroleum-based foams, provided they achieve comparable thermomechanical and physical properties. We propose a facile approach to fabricate eco-friendly cellulose nanofibril (CNF)-reinforced thermomechanical pulp (TMP) fiber-based foams via an oven-drying process with thermal conductivity as low as 0.036 W/(m·K) at a 34.4 kg/m3 density. Acrodur®, iron chloride (FeCl3), and cationic polyacrylamide (CPAM) were used to improve the foam properties. Acrodur® did not have any significant effect on the foamability and density of the foams. Mechanical, thermal, cushioning, and water absorption properties of the foams were dependent on the density and interactions of the additives with the fibers. Due to their high density, foams with CPAM and FeCl3 at a 1% additive dosage had significantly higher compressive properties at the expense of slightly higher thermal conductivity. There was slight increase in compressive properties with the addition of Acrodur®. All additives improved the water stability of the foams, rendering them stable even after 24 h of water absorption.

In this paper, the thermal insulation performance of silica aerogel was studied. Aerogel heat insulation blankets can be widely used in the military, cold storage, aerospace, automotive and other industries. The heat insulation principle of aerogel was analyzed theoretically, and the heat transfer model of aerogel was established. Experiments are designed to verify the accuracy of the model, and it is concluded that the distance between the aerogel and the target is more important for the thermal insulation effect than the thickness of the aerogel.

Enhancing the energy efficiency and climate resilience of existing buildings is crucial amid growing environmental challenges. While extensive research has focused on non-residential buildings, studies on thermo-hygrometric conditions in warehouse-type buildings, particularly in subtropical climates, remain limited. This study investigated the impact of building envelope deficiencies on indoor thermal and moisture regulation at the Nori Distribution Center. Using infrared thermal imaging and long-term environmental monitoring, significant thermo-hygrometric fluctuations were identified, primarily due to design and construction deficiencies. Poor insulation, inadequate sealing, and the lack of moisture barriers contributed to unstable indoor temperature and humidity. Seasonal analysis showed that during summer, the median second-floor air temperature reached 28.8 °C, peaking at 39.2 °C, with relative humidity exceeding 70% for 45% of the time. First-floor relative humidity surpassed 70% for 72% of the time. While condensation risk remains low year-round, it increases significantly with air infiltration through gaps in the building envelope. This study recommends enhancing the sealing of the building envelope, upgrading insulation materials and moisture barriers, particularly in the roof, and optimizing the HVAC system to improve energy efficiency and storage conditions. These findings offer valuable recommendations for retrofitting warehouse-type buildings in subtropical climates to improve energy efficiency and climate resilience.