Additional Insulation Layer Research Articles

An Ultra-Compact and Low-Cost LAMP-Based Virus Detection Device.

Timely and accurate detection of viruses is crucial for infection diagnosis and treatment. However, it remains a challenge to develop a portable device that meets the requirement of being portable, powerless, user-friendly, reusable, and low-cost. This work reports a compact ∅30 × 48 mm portable powerless isothermal amplification detection device (material cost ∼$1 USD) relying on LAMP (Loop-Mediated Isothermal Amplification). We have proposed chromatographic-strip-based microporous permeation technology which can precisely control the water flow rate to regulate the exothermic reaction. This powerless heating combined with phase-change materials can maintain a constant temperature between 50 and 70 °C for a duration of up to 49.8 min. Compared with the conventional methods, it avoids the use of an additional insulation layer for heat preservation, greatly reducing the size and cost. We have also deployed a color card and a corresponding algorithm to facilitate color recognition, data analysis, and storage using a mobile phone. The experimental results demonstrate that our device exhibits the same limit of detection (LOD) as the ProFlex PCR for SARS-CoV-2 pseudovirus samples, with that for both being 103 copies/μL, verifying its effectiveness and reliability. This work offers a timely, low-cost, and easy way for respiratory infectious disease detection, which could provide support in curbing virus transmission and protecting the health of humans and animals, especially in remote mountainous areas without access to electricity or trained professionals.

Thermal behaviour of a gypsum board incorporated with phase change materials

This study investigates the influence of a microencapsulated Phase Change Material (mPCM) on building systems in a subarctic climate which is not commonly studied for PCM applications. The mPCM is incorporated into gypsum to make a composite board with a volume fraction of 30 vt%. The fabricated composite board is then used to make a box model. This model along with a reference model built only with gypsum boards are placed inside a climate chamber where temperature is regulated to a summer day of a subarctic country, where large temperature variation exists between day and night. In addition, a Finite Element Method (FEM), is also used for the validation of the experimental data. The thermal-physical properties of the mPCM gypsum board including the specific heat capacity and thermal conductivity are measured. The microscopic features of the composite board are also studied. In addition, the temperature variation and the thermal energy storage of the boards of the two models have been studied. Results indicate that incorporation of mPCM into gypsum will change the thermal properties of the material. PCM can work as an additional insulation layer due to its low thermal conductivity. Further, the temperature fluctuation inside of the model with mPCM is reduced. In addition, the energy stored in the mPCM composite is around 3 times higher than that of gypsum board, making it promising for building energy improvement and load shifting.

Corrugated veneer joinery and construction material and its sound insulation properties

The article presents a new joinery and construction material made of corrugated veneer. The material under consideration can be used to create lightweight internal enclosing structures of residential premises (interior partitions) and for interior decoration. Within the framework of this study, the tasks related to the determination of sound insulation properties and characteristics of a new joinery and building material and the search for ways to improve its design are considered. The analysis of the regulatory requirements for interior partitions of residential premises and the requirements of standards for the experimental determination of the degree of isolation of air noise by enclosing structures in field conditions is carried out. Methods for determining the sound insulation properties and characteristics of various materials and structures, as well as equipment used for research, have been studied. An experimental installation has been developed to evaluate the effectiveness of insulation from air noise of samples of the proposed joinery and construction material. Samples of the material necessary for the experiment were made, and an experiment plan was drawn up. It has been established that the highest efficiency of isolation from air noise is achieved in the high frequency range from 4800 dB and above. In the area of low and medium frequencies, the sound insulation of the material under study is not effective enough, which requires the use of additional sound insulation layers. The assessment of ways to improve carpentry and construction material to improve its sound insulation properties in the low and medium frequencies has been carried out.

Straw bale construction towards nearly-zero energy building design with low carbon emission in northern China

With the aim of achieving carbon neutrality, bio-based construction is of increasing interest for decarbonization globally. Among the potential candidates, straw bale is promising due to its ready availability and energy efficiency benefits. However, thermal conductivities of straw bales can vary greatly due to construction details, which may lead to failures in meeting nearly-zero energy building (nZEB) design standards in real practice. In the context, this study applied thermal property and carbon emission assessment of full-size straw bale walls (SBWs) and construction of an experimental building in northern China. The results demonstrated that the thermal conductivities of different monitoring portions of the SBWs ranged from 0.067 to 0.088 W·m−1·K−1. This resulted in U-values (0.16 W·m−2·K−1) marginally higher than the lower limits of nZEB design, indicating the importance of addressing thermal bridging issues of SBWs. The SBWs without additional insulation layers therefore can satisfy nZEB design standards in the severe cold region after certain adjustments. Besides, when not accounting for carbon sequestration, SBWs generated the lowest emissions among the schemes in meeting U-value limits for nZEB design (at least 14.6% lower than those of timber walls), with increasing emission reductions as U-value limit decreased. The results indicated that SBW demonstrated effectiveness in carbon reductions with high thermal performance. The findings of the research can facilitate application of straw bales and development of clean construction and net-zero design in northern China.

A Dynamic Insulation Technique for Building Envelop by Using Microchannels

Abstract Initially designed for electronic system cooling, microchannels represent innovative technologies that can also be harnessed to augment the thermal resistance of building walls. When employed as an additional insulation layer within the building envelope, they have the potential to replace traditional insulating materials like wool, polystyrene, wood fiber, and cotton denim. This article explores modeling and simulation results pertaining to the performance of microchannels integrated into a standard building wall, aiming to provide dynamic thermal resistance for the building envelope. The simulations were conducted using aluminum microchannels featuring a rectangular profile, and various working fluids (air and water) were considered to assess system performance under different fluid conditions. To ensure laminar flow conditions in both working fluids, the Reynolds number was controlled within the range of 100–900 across multiple runs. The simulation and analysis outcomes underscore the viability of fluid flow through microchannels within building walls as a promising insulation technique capable of delivering dynamic thermal resistance and enhancing energy efficiency across diverse building types. Furthermore, the results emphasize that the utilization of water-based fluid within microchannels outperforms air-based fluid flow, particularly in terms of heat transfer and heat dissipation capabilities.

Resonance dependence of electrically reconfigurable VO2-based THz metadevice for memory information processing

A terahertz hybrid metamaterial incorporated with active media VO2 holds great promise for the realization of a new generation of reconfigurable and multifunctional devices. However, for the electrical control, many efforts on reducing high working threshold are usually based on the utilization of patterned VO2 patches or additional insulation layers, which will increase the complexity of the fabrication procedure. Here, we have proposed an effective strategy only by combining the surface microstructure and the unpatterned VO2 film to realize the tunability of working current and uncover its highly dependent correlation with the structural resonance responses. It is shown the fully modulated current in our hybrid metastructures can be reduced with the prominently separated hysteresis loops. Further developed binary encoders can perform not only the information transformation of the fixed code symbols but also the arbitrary encoding with the programmable current pulse. Additionally, the dynamic color display can be accomplished to illustrate the intriguing function of the information encryption and multi-image reappearance with the current as the decryption key. Our work provides an approach to reduce the operating current and paves a pathway for the development of photonic memory information processors.

Study of the effect of an additional layer of insulation on the rate of heat loss in the cabin of an electric vehicle in conditions of extremely low arctic temperatures

This article examines the reduction of speedand heat loss in the passenger compartment of an electric vehicle (EV) when installing an additional thermal insulation gasket on the doors. The study was conducted in conditions of extremely low outdoor temperatures that occur in the winter season in the northern and arctic regions. To conduct a series of observations, the doors of the passenger compartment of an electric car were equipped with an additional (second) heat-insulating rubber gasket. The results were recorded for two groups of measurements, at an outdoor temperature of -25 ... -30 0C and at outdoor temperature -35 ... -40 0C.

Shear behaviour of infra lightweight concrete (ILC) without stirrups

ILC stands for “Infra” Lightweight Concrete, a versatile construction material that contributes significantly to building sustainability and opens up innovative architectural prospects. The prefix “infra” reflects a level of lightness that falls below the range of the structural LC in international standards. The novelty of ILC arises from combining such lightness (dry density ≤ 800 kg/m3) with both moderate strength and good heat insulative characteristics, rendering its application in monolithic cross sections without additional insulation layers feasible. This implies that complex multilayer façade systems including highly insulative materials can be substituted with a single layer of ILC, resulting in substantial improvements in terms of planning and construction simplicity, energy savings and recyclability. Recently, ILC has received great research attention, allowing for a better understanding of its physical and mechanical properties, which resulted in the successful construction of several ILC buildings in Germany. However, the structural behaviour of ILC has not been completely investigated and some structural concerns remain unanswered. This paper focusses on the diagonal cracking of ILC without web reinforcement as part of a comprehensive study into understanding the overall shear behaviour. 26 simply supported beams were tested until failure in 4-point bending configuration tests in order to study the role the concrete strength, the longitudinal reinforcement ratio and the a/d ratio play in the diagonal cracking of ILC. It was found that the excessive shrinkage of ILC significantly reduces the diagonal cracking load and results in rather wider cracks. Therefore, a design approach has been developed, where the excessive shrinkage impact was processed by reducing the tensile strength of ILC based on the shrinkage strain value. The diagonal cracking load seemed to be connected to the reduced tensile strength and the depth of the compressed zone, with no influence of aggregate interlocking or dowel action.

A Novel Composite Reinforced Mortar for the Structural and Energy Retrofitting of Masonry Panels

Existing masonry buildings become more and more outdated depending on the actual state of conservation, but also in relation to the renovation of the performance requirements stated in current code and guidelines. Therefore, two fundamental aspects emerge as drawbacks: mechanical resistance and thermal conductivity. The structural retrofitting often consists of a covering by means of Composite Reinforced Mortar (CRM), which involves a pre-impregnated fiber mesh into an inorganic binder (e.g. lime-based mortar), while an additional insulation layer is designed for thermal scope. In this study a new composite, concerning a fly-ash based geopolymer and a glass fiber mesh (namely Composite Reinforced Geopolymer Mortar - CRGM), is proposed. The goal is to demonstrate its ability of improving both the shear strength and the thermal resistance of a masonry panel (simulating an existing structure). At this scope, an experimental investigation put in contrast the proposal with respect to a traditional CRM-system (i.e. lime-based matrix and the same glass fiber mesh). The results confirmed the validity of the CRGM. Moreover, a theoretical simulation evidenced the potential impact of the CRGM on the commonly used types of masonry all around Italy from the thermal point of view.

Laboratory Testing of Small Scale Solar Facade Module with Phase Change Material and Adjustable Insulation Layer

Active building envelopes that act as energy converters—gathering on-site available renewable energy and converting it to thermal energy or electricity—is a promising technological design niche to reduce energy consumption in the building sector, cut greenhouse gas emissions, and thus tackle climate change challenges. This research adds scientific knowledge in the field of composite building envelope structures containing phase-change materials for thermal energy storage. In this study, the focus lies on the cooling phase of the diurnal gain and release of solar energy. The experimental setup imitates day and night environment. Six alterations of small-scale solar facade modules are tested in two different configurations—with and without the adjustable insulation layer on their outer surface during the discharging phase. Modules explore combinations of aerogel, air gap, and Fresnel lenses for solar energy concentration. The results allow us to compare the impact of the application of an additional insulation layer at “night” for different designs of solar facade modules. The results show that modules with an air gap provide higher heat gains but do not take full advantage of the latent heat capacity of phase-change materials.

Full-Fledged Use of Semi-Basement Space by Building Seismic-Resistance, Energy-Efficiency, Microclimate and Preventing Influences of Thermal Bridges and Mold Growth

The known theory and experience of energy-saving architecture allow solving the article's task and ensuring sufficient insolation, passive solar heating, and occupants contact with nature through semi-basement windows. The goal is a full-fledged use of the semi-basement space achieved for seismically active regions with a moderate, cold, and hot climate by ensuring the normative seismic-resistance, energy-efficiency, and microclimate of the building and preventing influence of thermal bridges and mold growth. The set of recommendations also covers the provision of the required sanitary-hygienic conditions in the semi-basement rooms. The multidisciplinary problem is solved by integrating the methodologies of various fields of science. By means of numerical investigations, it established that the soil adjacent to the semi-basement foundation wall increases the thermal mass and building envelope heat-protection capacity. The isotherms and the intensity of heat fluxes made it possible to eliminate the effect of thermal bridges that interact with the soil and outside air. The expedient thickness and width of the additional layer of thermal insulation of thermal bridge zones in excess of the normative layer of the enclosure's thermal insulation were established. The graphical dependence of the wall's inner corner temperature from this width allows selecting the microclimate level. A multilateral contribution to building improvement is derived from a single-family home example: comfortable microclimate conditions have been created in the semi-basement for placing main rooms there; energy savings for heating this space is 16-20%; saving of monolithic frame and foundation concrete is 10-12% ensuring the higher than normative building seismic-resistance.

Controlling the thermal regime of the road surface in the cryolithic zone

The thermal regime of the road surface of automobile roads in the cryolithic zone determines its reliable and safe exploitation. An important indictator of the thermal regime is the thawing depth of the road foundation (the underlying soil). The purpose of this research was to determine the influence of the Biot number, characterizing the thermal resistance of the structural layers of the road, on the thawing depth of the road surface. On the basis of simple engineering formulas, the basic qualitative and quantitative regularities of the influence of Fourier and Stefan numbers on the Biot number value which allows thawing of the road foundation up to a given depth in the warm period of the year were surveyed. 3D charts allowing to determine the required Biot number in a wide range of initial data were created. Knowing the Biot number, it is possible quickly to determine the thermal resistance and to select a fitting material for the additional thermal insulation layer for the structure of the road surface.

Constitutive relations and finite element modelling of Infra Lightweight Concrete (ILC)

ILC stands for “Infra” Lightweight Concrete, a high-performance Lightweight Aggregate Concrete (LWAC) with a dry density of no more than 800 kg/m3. It possesses a unique combination between a sufficient bearing capacity and good insulation properties. Therefore, monolithic cross sections of ILC can meet the energy consumption requirements without adding additional insulation layers. ILC, hence, allows for a simple and a sustainable construction as the complex, highly insulation, multi-layered exterior walls of buildings can be replaced by one material only. During recent years, ILC has been thoroughly investigated and several ILC houses were successfully built. However, predictive formulas and constitutive models for the structural analysis were not fully developed. This paper deals with the derivation of constitutive mechanical relationships and the flexural behavior of ILC. Relationships for estimating the elastic modulus, peak compressive and tensile strength have been proposed. A stress-strain behavior in compression and a simplified tension-stiffening model are presented. The flexural behavior of different grades of reinforced ILC beams has been experimentally and numerically carried out. The comparison between the numerical and the experimental results in terms of moment-displacement curves showed significant agreement, thereby validating the proposed relationships. Furthermore, an analytical approach for estimating the flexural strength of ILC is also introduced.

Analysis of newborn thermal comfort in a textile incubator

Data published by European and World Health Organizations show that since 1990 the number of births has been steadily decreasing, which poses the risk of lack of generational replacement. According to WHO report, every year, 2.6 millions of newborns in the world die in the first month of their life. One million of them in the first 24 h so they require special care and medical supervision, so for the first days or even months of their lives they remain in incubators. The purpose of the research was to develop the construction and build a prototype of a textile incubator, whose most important function is to keep the baby warm, with the possibility of cooling it during therapeutic hypothermia. The incubator model was built in three variants of material packages, and each of them consisted of five material layers. An innovative solution is using for the external thermal insulation layer a composite connecting a knitted fabric with aerogel. The total thermal conductivity resistance for the developed material packages of the incubator was measured using a thermally insulated sweating hot plate known as the ‘skin model’. The obtained values of thermal resistance coefficient R ct are within 2.07–2.83 clo, and in case of the package with an additional insulation layer R ct = 3.68 clo. It turned out that when the infant was placed in a textile incubator without a functional heating and cooling mat its heat balance for the adopted ambient temperatures from −5 to 24 °C was negative and ranged from −0.04 up to −50.50 W. In cases of positive heat balance, especially for all ambient temperatures, which took place for the second package where ΔQ = 0.10 ÷ 6.51 W, there is a risk of overheating the baby. The analysis of the heat balance components shows that convection and radiation have the greatest impact on the total heat loss, as on average they constitute 85.6% of the heat lost by a baby in a textile incubator.

PROVIDING THE THERMAL RELIABILITY OF WINDOW JUNCTIONS DURING THE THERMAL MODERNIZATION OF CIVIL BUILDINGS

In order to assess the possibility of condensation on an internal window jamb surface, the temperature fields of window junctions to brick and precast concrete walls of civil buildings were analyzed, which were massively produced in the second half of the twentieth century. This study obtained the dependences of the jamb temperature on the thickness of the additional insulation layer and the outdoor temperature. Additionally, it showed the possibility of adjusting the jamb temperature by shifting the window frame inside the building. Outside air temperatures at which no condensation will occur in the initial junction structures and after thermal modernization by additional facade insulation were determined. The results can be used to replace worn-out windows and during the thermal modernization of buildings.

Building wall corner structures, its microclimate and seismic resistance

Widespread low-rise residential buildings with a seismically resistant concrete frame and brick infill walls have lower microclimate levels in cold seasons due to low temperatures on the inner wall corner surfaces.These temperatures are lower if there is a corner column. For Bishkek, this temperature is 4.6 °C lower than that for permissible microclimate, even when the external wall has the required 70 mm of mineral wool slab insulation. It is caused by the negative effect of the wall corner thermal bridge. This effect is determined by ArchiCAD 20 software packages by visualizing the temperature distribution in the cross-section of the corner, which needs an additional thermal insulation layer of 40 mm. Using the LiraSAPR 2013 software package, the authors reduced the square cross-section dimensions of the column by 40 mm to allow for that additional thermal insulation layer. The optimal width of this layer is determined for different options for the meeting angle of two external walls from 70° to 180°. For a typical 90° angle, an acceptable width is 860 mm. With this insulation, it is possible to achieve the required temperature at the corner. The authors eliminated the negative thermal effect of the corner by rounding it with cement-sand plaster. Using the isotherms, it was determined that the rounding radius of 300 mm allowed for equal temperatures on the corner and inner surface of the external walls. The achieved results show that the microclimate formed as in a room without external wall corners.

Hygrothermal properties of an early 20th century clay brick from eastern France: Experimental characterization and numerical modelling

This paper deals with the experimental hygrothermal characterization of an early 20th century clay brick, representative of historical industrial buildings in eastern France. The renovation and adaptive reuse of industrial heritage buildings require accurate knowledge of the properties of these existing buildings envelopes, for which few data are available in literature. Hence, for example, the application of the French Thermal Regulation to existing old buildings can lead to unexpected damages, like brick spalling due to freeze–thaw phenomenon if a poorly suited additional interior insulation layer is installed. Despite its hygrothermal advantages, external insulation must be avoided for aesthetic and historical values of heritage buildings and it is often prohibited by city codes or historic building preservation regulations. In this context and as literature is scarce, it is relevant to deepen the knowledge of this ancient material in order to better understand the hygrothermal behaviour of old industrial buildings to better preserve them. As a first step towards this goal, the main objective of this paper is to give new data about the hygrothermal properties of an early 20th century brick from eastern France. A comparison between models and measured experimental data is also proposed. In particular, the temperature-dependent hysteretic sorption phenomenon, which occurs in brick, is experimentally and numerically investigated.

Assessment of the Effect of Energy Saving and Heat Loss Through External Enclosure Structures with Low Resistance to Air Penetration

The features of heat and mass transfer through external enclosure structures with capillary - porous material, which are not taken into account in the norms of thermal protection of buildings, are considered. Such features more often occur in buildings with a long service life because of the increasing heat loss, caused by the violation of the terms of repair for a long time. For structures, located in the lower part of the building and having little resistance to air penetration, a calculation model is considered to determine the value of the economizer effect and the saving of thermal energy in conditions of cold air infiltration. The developed model clearly demonstrates, that for two - and twelve-story houses the saving of thermal energy, as a result of the economizer effect, is about 3% and 10% respectively. A computational model of exfiltration of warm air through similar structures, located in the upper part of the building, is proposed. An additional value of heat loss during exfiltration of the warm air from the rooms is determined, using an example of old building with a wooden floor of a cold attic and bulk insulation in the absence of layers with high resistance to air penetration. This value is 3.5 times higher, then that determined by the standard method, which does not take into account the redistribution of cold and warm air densities along the height of the building. This leads to a deterioration of the indoor climate and an increase in heat loss. By calculation, the dependence of the value of heat losses on the total thermal resistance of the attic floor and on the number of floors was established. A number of measures, aimed at improving the energy efficiency of existing residential buildings, are proposed, such as laying a vapor barrier layer and an additional layer of effective thermal insulation on top of the bulk insulation as part of the attic floor and installing a cement-sand screed for this insulation.

Mechanical and Thermal Performance Characterisation of Compressed Earth Blocks

The present research is focused on an experimental investigation to evaluate the mechanical, durability, and thermal performance of compressed earth blocks (CEBs) produced in Portugal. CEBs were analysed in terms of electrical resistivity, ultrasonic pulse velocity, compressive strength, total water absorption, water absorption by capillarity, accelerated erosion test, and thermal transmittance evaluated in a guarded hotbox setup apparatus. Overall, the results showed that compressed earth blocks presented good mechanical and durability properties. Still, they had some issues in terms of porosity due to the particle size distribution of soil used for their production. The compressive strength value obtained was 9 MPa, which is considerably higher than the minimum requirements for compressed earth blocks. Moreover, they presented a heat transfer coefficient of 2.66 W/(m2·K). This heat transfer coefficient means that this type of masonry unit cannot be used in the building envelope without an additional thermal insulation layer but shows that they are suitable to be used in partition walls. Although CEBs have promising characteristics when compared to conventional bricks, results also showed that their proprieties could even be improved if optimisation of the soil mixture is implemented.

Thermal Conductivity of Olive Cake Compost (OCC) as Affected by Moisture and Density: An Experimental and Mathematical Modeling

The behaviors of bioactive compounds treating gaseous pollutants in biofilters and in the compost used as soil amendment and in green roof buildings are controlled by their thermal properties. There is a lack of information on thermal conductivity of olive cake compost (OCC), K as affected by water content and bulk density. Thermal conductivities (K) of 40 samples of (OCC) were determined experimentally at bulk densities (400–950 kg/m3) and moisture contents (10%–90%) using a single thermal probe method. The results showed that thermal conductivity increased linearly as water content, and bulk density increased and with a decrease in air filled porosity. Simple linear relationships were developed between compost thermal conductivity and dry bulk density and the degree of saturation. The experimental values were close to those reported recently for leaf compost and green roof soils. The compost at water content of 90% showed the highest thermal conductivity (K) of 0.60 W/m.k, which indicate that compost, can be used as good cheep insulator in geothermal heat storage application and as an additional echo-friendly insulation layer in green roof building which might be considered as a good means of passive energy saving there.