Thermal Insulation Of Buildings Research Articles

Building a sustainable future: Exploring the nexus between climate awareness and thermal insulation choices in new home construction

Climate change is considered a major threat to the environment and society as a whole. Reducing building energy consumption through the use of thermal insulation is one way of combating climate change. This study examines the impact of climate change awareness on the pre-construction decision of Lebanese homeowners to use thermal insulation in their new homes. A model building consisting of a typical 160 m2 single-family home was used and its thermal loads were calculated in two cases: insulated and uninsulated case, in three different locations in Lebanon: Beirut, Chtaura, and Bcharre-Arz. The thermal loads were calculated using two methods: the degree-days empirical method, and the Hourly Analysis Program software numerical method. The computations showed energy reduction ranging between 23% in the coastal region to 52% in high mountains when thermal insulation of thickness 5 cm was used. The investment payback period ranged from 4.3 years in the coastal region to 1.5 years in the high mountains. A survey addressed to 100 respondents was used to understand how Lebanese homeowners’ decision to use thermal insulation was affected by knowledge of the obtained results. The survey results showed that climate change awareness has a high impact on this decision; however, the cost seems to play an important role in the owners’ final decision on whether or not to use thermal insulation. Spreading awareness about climate change and the payback periods of building thermal insulation will increase its use since the number of respondents refusing to use thermal insulation drastically decreased after being informed about its payback period.

Experimental study on chemical and thermomechanical properties of concrete incorporating Washingtonia robusta fibres

The aim of this work is to provide a new composite material for applications in the thermal insulation of buildings. The composite was made with mortar reinforced with natural fibres extracted from the petiole of the Washington robusta (WR) palm tree. The fibres used were first chemically characterised by energy-dispersive X-ray spectroscopy, scanning electron microscopy, X-ray and infrared diffractometry spectroscopies alongside tensile testing to discover their morphological structure. Afterwards, the fibres were incorporated into mortar with mass percentages varying from 0 to 4% to determine experimentally the thermomechanical properties of the manufactured samples. The chemical findings indicated that WR fibres are rich in cellulose, hemicellulose and lignin, and possess a high crystallinity index, which enhances the mechanical properties and durability of the composite. The density obtained for the composite W2RC4% is 1305 kg/m3 and less than 2000 kg/m3; this composite can thus be classified as a lightweight concrete according to the standard NF EN 206 + A2/CN (2022). The thermal conductivity and thermal effusivity dropped by about 60% and 42%, respectively. Moreover, the WR reduces the compressive strength (76%) and the flexural strength (36%) to minimum values, respectively, of 5.9 MPa and 3.8 MPa. These values meet the mechanical requirements of lightweight concretes (> 3.5 MPa).

Analysis of the Cooperation of a Compressor Heat Pump with a PV System

The decarbonization of heating systems is one of the present political and legislative directions of the European Union and its Member States. The main activities concern the energy performance of buildings and energy efficiency. The mentioned UE directives are the basis for the financial support of high-emission fossil fuel thermal energy source replacement with emission-free ones, in particular heat pumps. Other aspects are the support of PV installations and the thermal insulation of buildings. 85% of EU buildings were built before 2000, and among those, 75% have poor energy performance. Therefore, a significant number of buildings have only high-temperature wall radiators, and this was a motivation to prepare this article. The main innovation of this research was a new theoretical design of a high-temperature heat pump based on ecological refrigerants. The presented solution allows wall radiators to receive a hot water supply with temperatures of up to 85 °C during external temperatures of up to −20 °C. Typical heat pumps do not have these kinds of parameters, so the authors decided to verify the possibility of operating this device in such a wide temperature range. Another important aspect was the analysis of PV support. Finally, this paper investigates the possibility of heating an energy-efficient house with the newly designed high-temperature heat pump. Depending on the location in Poland, i.e., Suwałki, Warsaw, and Wrocław, the total electric energy supplied to the compressors was 2538–3364 kWh. The energy provided by the PV to supply power to the compressors is 482–570 kWh. The achieved PV energy self-consumption is 16.9–19.0%. The Seasonal Coefficient of Performance (SCOP) of the heat pump is 1.825–2.038 without PV and 2.515–2.970 with PV.

Physico-mechanical, thermal insulation properties, and microstructure of geopolymer foam concrete containing sawdust ash and egg shell

Recently, energy conservation through building thermal insulation has gained significant importance in solving sustainability-related issues. In this context, this study investigates the potential for manufacturing geopolymer foam concrete (GFC) containing eggshell powder (ESP) and sawdust ash (SDA) using aluminium (Al) powder as a foaming agent. The role of Al-powder percentages on the mechanical and thermal properties of GFC was thoroughly investigated. The effect of ESP and SDA incorporation as partial replacements of precursors (from 0 to 20 %) on the thermal properties, durability, and microstructure of GFCs were also discussed. The experimental findings demonstrate that the bulk density and compressive strength of GFC with different Al-powder contents ranged between 1928 and 1798 kg/m3 and 17.45 and 9.37 MPa, respectively. The SEM images and MIP tests show that foams with different numbers of micro- and macropores are formed in GFCs. The ESP-based GFC had an apparent porosity range of 13.09 %–10.29 % and a bulk density range of 1823 to 1713 kg/m3. The SDA-based GFC had an apparent porosity range of 14.21 %–12.96 % and a bulk density range of 1834 to 1807.8 kg/m3. It was found that the 10 % ESP and 5 %, SDA mixtures enhanced the strength by 16.54 % and 4.45 %, respectively, compared to the control mix. The thermal conductivity, thermal diffusivity, and specific heat of 10 % ESP-mixture and 5 % SDA-mixture were 1.237 and 1.167 W/(mK), 0.795 and 0.922 mm2/S, and 1.556 and 1.266 MJ/m3K, respectively. Finally, the residual strength and microstructure investigations demonstrate that ESP-based GFCs have more stability than SDA-based GFCs and the control mix when subjected to elevated temperatures.

Moisture absorption and desorption characteristics and prediction model analysis of building thermal insulation materials

Understanding the isothermal moisture absorption and desorption characteristics of building thermal insulation materials and how they affect thermal conductivity, is curial for accurate building thermal design and energy-saving calculation. In this paper, five types of building thermal insulation materials are selected for investigation. First, the variation trend of the equilibrium mass moisture content of materials in different moisture absorption and desorption stages is studied employing the saturated salt solution method and the constant temperature and humidity box method, and the effect of temperature on the moisture absorption and desorption processes is evaluated. Additionally, the applicable model of the material in the moisture absorption and desorption process is obtained through a fitting analysis of the experimental data. Finally, the influence of the material’s moisture absorption and desorption characteristics on the thermal conductivity is analyzed using the transient thermal conductivity test method. The results highlight that there is a need to consider the moisture absorption and desorption processes to accurately determine the wet material thermal conductivity, and the hysteresis effect of the material in the moisture absorption and desorption processes is directly related to its microstructure and the relative humidity at the initial moisture desorption. At a temperature of 25 oC, the autoclaved aerated concrete exhibits its highest hysteresis rate of thermal conductivity during the moisture desorption process of third stage, reaching 13.2%.

Fabrication of Porous Anorthite Ceramic Insulation Using Solid Wastes.

Porous anorthite (CaAl2Si2O8) ceramics, suitable for thermal insulation in buildings, were obtained using waste seashells as a source of CaO, kaolin as a source of Al2O3 and SiO2 and banana peel as a pore former. Changing the volume of banana peel as well as the processing temperature was found to be an effective approach to control the thermo-mechanical properties of the obtained anorthite ceramics. The sintering of powder compacts containing up to 30 wt% banana peel at temperatures ranging from 1100 to 1200 °C resulted in anorthite ceramics possessing up to 45% open porosity, a compressive strength between 13 and 92 MPa, a bulk density between 1.87 and 2.62 g/cm3 and thermal conductivity between 0.097 and 3.5 W/mK. It was shown that waste materials such as seashells and banana peel can be used to obtain cost-effective thermal insulation in buildings.

Pore structure characterization and effective thermal conductivity modeling of fibrous building thermal insulation materials based on X-ray tomography

The existing structural characterization methods of building materials as well as thermal conductivity calculation models can not be directly applied when considering fibrous building thermal insulation materials with intricate skeletons. In this study, rock wool is considered the research object, and the X-ray tomography method is used to characterize the pore structure and extract structural parameters. Based on the actual pore morphology of the material, the pores in the representative elementary volume (REV) are reasonably assumed to be cubic. Additionally, considering the contact thermal resistance of fibers and the randomness of pore distribution, the curved pattern of heat conduction pathway with the ever-changing diameter is reasonably simplified into a series-parallel form of the curved heat chain with the same diameter. On this basis, the fractal models of effective thermal conductivity are established in horizontal and vertical directions. Finally, a modified formula for the effective thermal conductivity calculation of fiber thermal insulation materials is proposed, taking into account the influence of fiber orientation on the material thermal conductivity. It was shown that the relative deviation between the calculated correction value and the experimental value of the effective thermal conductivity is all less than 16.13%.

Multifunctional and recyclable aerogel/fiber building insulation composites with sandwich structure

Fire, electromagnetic (EM) pollution, and sustainability require building insulation with fire resistance, EM interference shielding, and recyclability. However, fewer building insulation materials can fulfill these multifunctional requirements. Here, we report a multifunctional building thermal insulation material with a sandwich structure that uses SiO2 aerogel powder as the insulating filler phase, α-Al2O3 fiber as the refractory reinforcing phase, and carbon fiber mat (CFF) as the electromagnetic interference shielding layer prepared by the mixing-pressing-drying method. The effects of different SiO2 aerogel power contents on fire resistance, thermal insulation, and hydrophobicity, the effects of different carbon fiber contents on EMI performance, and the effects of CFF as an interlayer on compressive strength and recyclability were investigated. The results demonstrated exceptional fire resistance properties and low thermal conductivity (0.0529 W/m·K) with a SiO2 aerogel powder content of 11.2 wt%. Specifically, the structure of the aerogel/fiber composite remains intact and the temperature of the non-heated surface is lower than 75.8 ℃ after 4 min of continuous flame combustion. It can achieve a commercial shielding standard of 20 dB at a carbon fiber content of 5 wt%. In addition, CFF as interlayers can effectively improve the compression strength of the material and solve the problem of difficult recycling of carbon fiber. In conclusion, this sandwich structure of multifunctional aerogel/fiber composites provides new ideas for the manufacture of fire resistance, energy-saving, EM-protection, and recyclable building insulation materials.

Size-structure-property relationship of wood particles in aqueous and dry insulative foams

Three size-fractionated samples of pine beetle-killed wood particles were used to prepare lightweight insulative foams. The foams were produced by foam-forming an aqueous slurry containing wood particles (125–1000 μm), a polymer binder, and surfactant, followed by oven drying. The effect of wood particle size on the aqueous foam stability, structure, and performance of insulative foams was investigated. While all aqueous foams were highly stable, aqueous foam stability increased with decreasing particle size. For dry foams, the cell size distribution was similar for all particle sizes as it was primarily controlled by the surfactant; differences occurred within the cell wall structure. A size-structure-property relationship was identified using x-ray micro-computed tomography where smaller particles produced lighter cell wall frameworks, leading to lower densities and decreased thermal conductivity and compressive strength. Larger particles produced denser cell wall frameworks that were more resistant to deformation, although all dry foams had sufficient mechanical properties for use as insulation panels. Thermal conductivity for all wood particle size-fractionated samples was <0.047 W m−1 K−1 making the foams similar to expanded polystyrene/polyurethane and supporting their use as thermal insulation in buildings.

Impact of thermal conductivity of aerogel-enhanced insulation materials on building energy efficiency in environments with different temperatures and humidity levels

New building thermal insulation materials, such as aerogel-enhanced insulation materials, are constantly emerging. To study how cement-based aerogel-enhanced thermal insulation materials perform under temperature and humidity changes, various aerogel-enhanced hollow glass microsphere insulation boards (HGBs) have been developed as building thermal insulation materials. The thermal conductivity of aerogel-enhanced HGBs, expanded polystyrene (EPS), and foamed cement (FC) was measured at various relative humidity levels and temperatures, and the summer cooling load of buildings with aerogel-enhanced HGBs, EPS, or FC as the insulation layer was simulated for different building heights and thermal zones. The results show that (1) the new aerogel-enhanced HGB materials are more suitable for building insulation in humid and hot areas than FC; (2) the cooling load of small buildings with fewer floors is more sensitive to the variation in the thermal conductivity with temperature and humidity; (3) for buildings in areas with hot summers and warm winters, the impact of the outdoor relative humidity should be fully considered when calculating summer cooling loads.

Effective Utilization of Bio and Industry Wastes to Produce Thermal Insulation Concrete: A Novel Solution for Energy-Saving Buildings

The research addressed the effective and sustainable ways to enhance the thermal insulation properties of concrete without compromising its structural integrity. Traditional methods of enhancing thermal insulation in buildings, such as using thick layers of insulation materials, can be costly and may not always be practical in certain settings. Additionally, the disposal of waste materials such as date palm fiber, shopping plastic bags, and thermocol beads presents an environmental challenge. Therefore, this study aims to investigate the potential use of these waste materials as additives in concrete to improve its thermal insulation properties while also providing a sustainable solution for waste disposal. Date palm fiber is a natural material that is widely available in the Gulf region. Plastic bags are a huge waste from the shops every day, and from the packing materials, this thermocol is a huge waste product. We have to recycle it very efficiently to protect the environment. Three types of special materials, such as thermocol beads (30%), date palm fiber (3%) &amp; shopping plastic bag fiber (3%), were tested in this research. Thermocol beads, when used, reduce their strength and increase the thermal resistance of concrete, while date palm fiber and shopping bag waste fiber, when used, increase the strength of concrete and also increase the thermal resistance of concrete, so it is an excellent reinforcing material and thermal barrier for shopping plastic bags fiber and date palm fiber. Based on this research result, when thermocol beads are used, they prevent heat by 42 percent, while when added with date palm fiber and plastic fiber, they also block heat by an average of 30% percent; thus, all three ingredients are considered excellent thermal insulation material. The reduction in thermal conductivity was attributed to the formation of air voids and the low thermal conductivity of the waste materials. The density of the concrete decreased with the addition of the waste materials. The study suggests that the incorporation of date palm fiber, shopping bag waste fiber, and thermocol beads can be an effective way to enhance the thermal insulation properties of concrete while also providing an environmentally sustainable solution for waste disposal. It will boost green energy technology in the construction industry.

Level of Awareness on the Usage of Thermal Insulation among Building Professionals: Case of a Tropical City in Nigeria

Adoption of buildings’ thermal insulation in Nigeria is still at the developmental stage; evidence of its usage for high thermal performance buildings and energy efficiency connotes a very low rate as there is very little evidence-based research in this regard. This paper seeks to evaluate the level of awareness on the usage of building thermal insulation among professionals in the building construction sector within Akure, a tropical city in Nigeria, to identify factors that deter its adoption and raise the level of commitment of the professionals within the building construction sector to sustainable practices of reducing buildings’ energy consumption. This is to create a resilient built environment against the challenges of climate change. Well-structured questionnaires were administered to gather data for the investigation. Jupyter Notebook version 6.4.12 was employed for the analysis. Results indicated a fairly good level of awareness among the building professionals while the barriers that affect the level of usage of thermal insulation within the study area are the high cost of procuring thermal insulation materials, non-compliance to building regulations, and governmental policy on construction. The research concluded that a good number of professionals have a high level of awareness of the usage of building thermal insulation, but the cost of the materials and government policy deterred its level of usage in the study area. Consequently, propagation of the usage of thermal insulation should be done through education and training of the stakeholders. Furthermore, the government needs to strengthen policies that support the usage and availability of thermal insulation within the study area

Green recycling of red brick waste into aerogel panels for thermal insulation in buildings

Green recycling of red brick waste into aerogel panels for thermal insulation in buildings

Facile-Solution-Processed Silicon Nanofibers Formed on Recycled Cotton Nonwovens as Multifunctional Porous Sustainable Materials.

Limited efficiency, lower durability, moisture absorbance, and pest/fungal/bacterial interaction/growth are the major issues relating to porous nonwovens used for acoustic and thermal insulation in buildings. This research investigated porous nonwoven textiles composed of recycled cotton waste (CW) fibers, with a specific emphasis on the above-mentioned problems using the treatment of silicon coating and formation of nanofibers via facile-solution processing. The findings revealed that the use of an economic and eco-friendly superhydrophobic (contact angle higher than 150°) modification of porous nonwovens with silicon nanofibers significantly enhanced their intrinsic characteristics. Notable improvements in their compactness/density and a substantial change in micro porosity were observed after a nanofiber network was formed on the nonwoven material. This optimized sample exhibited a superior performance in terms of stiffness, surpassing the untreated samples by 25-60%. Additionally, an significant enhancement in tear strength was observed, surpassing the untreated samples with an impressive margin of 70-90%. Moreover, the nanofibrous network of silicon fibers on cotton waste (CW) showed significant augmentation in heat resistance ranging from 7% to 24% and remarkable sound absorption capabilities. In terms of sound absorption, the samples exhibited a performance comparable to the commercial standard material and outperformed the untreated samples by 20% to 35%. Enhancing the micro-roughness of fabric via silicon nanofibers induced an efficient resistance to water absorption and led to the development of inherent self-cleaning characteristics. The antibacterial capabilities observed in the optimized sample were due to its superhydrophobic nature. These characteristics suggest that the proposed nano fiber-treated nonwoven fabric is ideal for multifunctional applications, having features like enhanced moisture resistance, pest resistance, thermal insulation, and sound absorption which are essential for wall covers in housing.

Analyzing Thermal Images to Evaluate Thermal Protection in Residential Structures: Lessons from Russian Practices

Building thermography is a non-destructive and effective method for diagnosing the thermal insulation of buildings with various purposes. Regardless of the specifics of conducting thermographic surveys, the obtained thermal images (thermograms) can be analyzed both qualitatively and quantitatively. The first method of analyzing thermal images is implemented using specialized software typically provided with the thermal imaging camera. The second method is carried out based on the results of thermographic surveys following the methodologies regulated by the country’s normative documents. Using the example of thermographic inspection of enclosing structures in a multi-story residential building constructed from reinforced concrete panels, a qualitative assessment of thermal images was conducted to identify potential thermal defects. Thermal bridges were detected in the area of vertical joints of panel plates, and excessive heat losses were identified in the region where the heating device niche is located.Quantitative assessment of thermal images revealed that the thermal resistance in the temperature anomaly area is nearly twice as low as the thermal resistance in the baseline section of the thermogram. One of the variations for evaluating the error of indirect measurements of relative thermal resistance is presented, taking into account the range of measuring instruments used. Verification of the thermal resistance of the enclosing structure of the external wall of the residential building was conducted to ensure compliance with sanitary and hygienic requirements. According to the results of in-situ measurements, it was determined that the temperature on the inner surface of the enclosure was lower than the specified value.

Sustainable Micro‐ and Nanocomposites for Thermal Insulation in Buildings

Energy efficiency in buildings requires adequate materials for thermal insulation. Given the enormous number of buildings worldwide needing a retrofit to improve their energy efficiency, it is of capital importance to identify materials suitable for sustainable thermal insulation. Among the many available insulators, polyurethanes occupy a preeminent role, given their versatility and effectiveness, and are thus expected to be extensively used in retrofitting buildings for improving their energy efficiency. Herein, the currently available bio‐derived or recyclable polyurethane‐based composites, considering them as either foams (i.e., with gaseous filler) or fully solid (i.e., with solid filler) composites, are assessed. The first section of the review is devoted to bioderived PUs as matrices for thermally insulating composites; the second section focuses on bio‐derived/recyclable fillers adopted with PUs as matrices, with specific reference to silica‐based aerogels. The main issues of the surveyed bio‐based composites are analyzed, and the future prospects of these materials, that are actually sustainable but at the same time performance effective, are discussed.

Justification of the need to modernize the existing central heating points in Ukraine

The object of the research is central heating points (CTP) in Ukraine. The problem that is being solved in the work is the need to modernize and automate existing CTPs. The importance of the problem is the presence of a large number of CTPs in Ukraine, which require urgent modernization of morally outdated equipment and automation of management of their work modes, which must be carried out in stages without removing them from operational status. The need for modernization and further automation of the existing CTPs in Ukraine is substantiated, which is that this will allow increasing the efficiency of the CTPs through the use of modern technical equipment, software and trained specialists in the automated management of the process of heat supply to consumers. And it will also allow to reduce the cost of heat supply tariffs due to the reduction of non-production costs and to reduce the number of service personnel who manage work modes in manual mode. During the martial law, the timely resolution of problems with high-quality heat supply of the population acquires special importance. The result of the conducted research is a theoretical analysis of the quality work of CTPs in the EU countries, realization of their capabilities and prospects for further use in order to transfer their experience to Ukraine. A theoretical analysis of the number and modern technical equipment of CTPs in Ukraine at the present time was also conducted. As a result of the research conducted on the existing CTPs in Ukraine, a survey of their technical condition was carried out, specific directions for the phased modernization and automation of their equipment were developed and proposed, and additional measures were taken regarding the thermal modernization of main pipelines and modern thermal insulation of buildings and structures. The possibility of practical implementation – step-by-step modernization and automation of the CTP, increasing the technical and technological capabilities of the equipment and reducing the tariffs for heat and water supply for consumers.

Thermophysical characterization of concrete reinforced with baobab trunk fibers (Adansonia digitata L.) for thermal insulation of buildings

This work deals with characterizing concrete based on baobab trunk fibers for thermal in- sulation in buildings. The aim is to study the effect of the fiber content and the type of fiber treatment on the hygroscopic and thermo-physical properties of the concrete. Therefore, two types of treatment were carried out: an alkaline treatment and a thermo-alkaline treatment. Hygroscopic test results (34.25% to 54.92% for fiber content ranging from 14% to 28%) show that adding fibers to concrete makes them more sensitive to water. However, thermochemical treatment of the fibers reduces this water sensitivity. The thermal conductivities of concrete range from 0.202 to 0.086 W/m.K for the same fiber content. These results show that these biomaterials can be used in construction to improve building insulation.

Influence of Anatomy, Microstructure, and Composition of Natural Fibers on the Performance of Thermal Insulation Panels.

The growing interest in environmentally friendly materials is leading to a re-evaluation of natural fibers for industrial applications in order to meet sustainability and low-cost objectives, especially for thermal insulation of buildings. This paper deals with the chemical and physical characterization of fibers extracted from seagrass (Posidonia oceanica) and alfa grass (Stipa tenacissima) for a possible substitution of synthetic materials for thermal insulation. Hemp (Cannabis sativa), a fiber broadly used, was also studied for comparison. The parameters characterized include porosity, thermal degradation, elemental composition, skeletal and particle density of the fibers as well as investigation of the thermal conductivity of fiber-based panels. Several technologies were involved in investigating these parameters, including mercury intrusion, thermogravimetric analysis, fluorescence spectroscopy, and fluid pycnometry. The fibers showed a degradation temperature between 316 and 340 °C for Posidonia, between 292 and 326 °C for alfa, and between 300 and 336 °C for hemp fibers. A high porosity allied with a reduced pore size was revealed for Posidonia (77%, 0.54 μm) compared to hemp (75%, 0.61 μm) and alfa (57%, 2.1 μm) raw fibers, leading to lower thermal conductivity values for the nonwoven panels based on Posidonia (0.0356-0.0392 W/m.K) compared to alfa (0.0365-0.0397 W/m.K) and hemp (0.0387-0.0427 W/m.K). Bulk density, operating temperature, and humidity conditions have been shown to be determining factors for the thermal performance of the panels.

Metrological evaluation of facade coating systems regarding their resistance to microorganism growth

The presence of liquid water on the facade surface significantly contributes to the growth of microorganisms. This issue has become increasingly important with the growing use of thermal insulation in buildings. However, the formation of condensation on these façades is often increased due to low surface temperatures. Therefore, innovative coating systems with special physical parameters have been developed to prevent condensation formation and thus the growth of algae on the facade surface. These coatings should be evaluated with respect to their surface condensation to identify their resistance against condensation. Since no suitable method is available for this purpose, it is necessary to develop a method for controlling the wetness and drying out of façades. This paper presents the development and verification of innovative coating systems, as well as an active facade moisture detection system (ONE). The measuring method is designed to provide long-term non-destructive measurements of surface wetness. The measurement data obtained in this research are used to develop facade materials and coatings that improve their drying properties and the balance between hydrophilic and hydrophobic surfaces. This is aimed at preventing or reducing algae growth on the façade. A case study consisting of four test walls was conducted in Central Germany under real climate conditions to examine the resistance of coating systems with different pigments (conventional and modified pigments) to moisture formation on the surface. The results show that the developed coating system has significant potential to increase surface temperatures, leading to a reduced deviation of the dew point. This can help to prevent the growth of algae on the facade.