Wall Insulation Research Articles

Impact of grey energy on optimal wall insulation thickness

AbstractFor decades efforts have been made to reduce the greenhouse gases emissions of buildings by reducing their energy demand with governmental regulations in Europe, pushing towards very low thermal transmittances (U‐values) with ever thicker insulation layers for new buildings. However, there is no linear relationship between the insulation thickness and the heat losses. Therefore, above a certain thickness the consumption of buildings does not decrease significantly. Hereafter a life cycle analysis, including emissions before the building becomes operational is applied to evaluate the impact of the increasing thickness of components on the overall emissions. Publicly available product data sheets are used to compare four insulation materials under three scenarios. These analyses yield interesting results showing that energy‐intensive insulation materials lead to a negative impact in the overall energy balance after a certain thickness. Even though there is not always a pronounced optimum insulation thickness, it is logical that further reductions in U‐value for new buildings should hence be carefully evaluated. The results show that the optimal thickness is around 20 cm for most materials, while the important major savings come from the first 10 cm.

Multi-Stage Sensitivity Analysis of the Energy Demand for the Cooling of Grain Warehouses in Cold Regions of China

The early design parameters exert a considerable influence on the cooling energy demand of a granary building in operation. In order to investigate the impact of various parameters on energy use, a grain warehouse energy model was constructed using the Ladybug + Honeybee tools on the Grasshopper platform. Three global energy sensitivity methods were used to analyze the model, and the sizes of the influential parameters were determined and ranked. The study uncovered that the cooling energy demand of the grain warehouse was primarily influenced by factors such as the cooling set-point temperature, roof solar absorptance, roof and exterior wall insulation thickness, window type, and orientation. On this basis, a local sensitivity analysis was conducted for the highly sensitive parameters to identify their influence trend and optimal design range. The results showed that the cooling energy demand of the grain warehouse increases faster as the cooling set-point temperature decreases, with the highest growth rate occurring at a temperature below 18 °C. Lower solar absorptance of the roof is conducive to reducing the cooling energy demand of the grain warehouse. When the thickness of the roof thermal insulation is less than 120 mm and the thickness of the external wall thermal insulation is less than 60 mm, energy use decreases more quickly with greater insulation thickness. It is advisable to use traditional or new windows with thermal insulation and shuttered windows. Furthermore, the optimal position of the long side of the granary was between 10° west and 10° east of north. This research could provide guidance for the energy-saving design and renovation of granary buildings in cold regions of China.

Balanced Thermal Insulation, Flame-Retardant and Mechanical Properties of PU Foam Constructed via Cost-Effective EG/APP/SA Ternary Synergistic Modification.

To address the challenge of balancing the mechanical, thermal insulation, and flame-retardant properties of building insulation materials, this study presented a facile approach to modify the rigid polyurethane foam composites (RPUFs) via commercial expandable graphite (EG), ammonium polyphosphate (APP), and silica aerogel (SA). The resulting EG/APP/SA/RPUFs exhibited low thermal conductivity close to neat RPUF. However, the compressive strength of the 6EG/2APP/SA/RPUF increased by 49% along with achieving a V-0 flame retardant rating. The residual weight at 700 °C increased from 19.2 wt.% to 30.9 wt.%. Results from cone calorimetry test (CCT) revealed a 9.2% reduction in total heat release (THR) and a 17.5% decrease in total smoke production (TSP). The synergistic flame-retardant mechanism of APP/EG made significant contribution to the excellent flame retardant properties of EG/APP/SA/RPUFs. The addition of SA played a vital role in reducing thermal conductivity and enhancing mechanical performance, effectively compensating for the shortcomings of APP/EG. The cost-effective EG/APP/SA system demonstrates a positive ternary synergistic effect in achieving a balance in RPUFs properties. This study provides a novel strategy aimed at developing affordable building wall insulation material with enhanced safety features.

Consumer energy efficiency gap and the rebound effect across households income groups

The paper sets up a model which reconciles the energy efficiency gap and the decline of the rebound effect with households’ income. It is shown that the two phenomena can be explained in a framework with a utility-maximizing household that enjoys an income-independent endowment of energy services. Energy service endowment is a barrier against the adoption of the most energy-efficient appliances and leads to the so-called energy efficiency gap. Low-income households only use endowments and do not use energy-consuming appliances (cars, wall insulation, etc.). Higr-income households buy an appliance whose energy efficiency depends on the household’s income. Only households with income above a threshold buy the most efficient appliance. For households that replace their appliance with a more efficient one, there will be a rebound effect (the realized energy saving is less than the presumed one). It is shown that the rebound effect is higher at lower income levels because income and substitution effects from a decline in energy service prices are stronger. These stronger effects come from the endowment of energy services. The numerical example shows that the model can reproduce the patterns for the rebound effects of household income groups and their expenditure shares. It is also shown that other causes of the energy efficiency gap, such as credit constraints, do not lead to higher rebound effects at lower income levels.

Comparative analysis on heat and moisture transfer of composite insulation walls

Abstract Firstly, the influence of heat and moisture transfer on composite insulation walls was initially considered. Relying on the established theory of heat and moisture coupled transfer in walls and taking into account the specific climate conditions of regions with hot summers and cold winters, a non-steady-state heat and moisture coupled model was developed to simulate the processes of heat and moisture transfer. Subsequently, based on the one-dimensional stable heat transfer theory, the heat transfer situation for winter insulation was calculated. Then, practical methods for on-site temperature and humidity measurements were explored and implemented. Through analysis, comparison, and mutual verification of the calculated values and the measured values, it was observed that both sets of data showed consistent trends, thereby verifying their accuracy and correlation. The findings of this study provide valuable reference data for understanding the heat and moisture migration within building walls and offer solutions for optimizing thermal insulation strategies.

Effect of Applied Pressure on the Performance of Biodegradable Fiber Insulation Board Manufactured from Camphor Branches (Cinnamomum camphora)

Currently, the predominant thermal insulation materials in the construction industry are primarily derived from inorganic sources. While these materials demonstrate commendable thermal insulation capabilities, their widespread use raises significant environmental concerns. The utilization of wood fiber materials presents a promising solution to mitigate these drawbacks. This study focuses on the fabrication of biodegradable fiber insulation board (BFIB) using camphor branches. The manufacturing process avoids the use of chemical additives, employing a physical method that utilizes hot pressing and relies on the formation of intermolecular hydrogen and hydroxide bonds between the fibers. The study evaluates the influence of applied pressure on the properties of BFIB. SEM images reveal that, with an increase in applied pressure, the fibers exhibit a more regular pattern, subsequently enhancing the mechanical properties, hygric behavior, and fire resistance properties of BFIB. As an environmentally friendly and renewable material, BFIB holds the potential to substitute conventional insulation materials. It is particularly intriguing for energy-saving purposes when applied as building insulation for walls or ceilings.

Urban Building Energy Modeling to Support Climate-Sensitive Planning in the Suburban Areas of Santiago de Chile

Greenhouse gas emissions depend on natural and anthropic phenomena; however, to reduce emissions, we can only intervene in terms of anthropic causes. Human activity is very different in various countries and cities. This is mainly due to differences in the type of urban environment, climatic conditions, socioeconomic context, government stability, and other aspects. Urban building energy modeling (UBEM), with a GIS-based approach, allows the evaluation of all the specific characteristics of buildings, population, and urban context that can describe energy use and its spatial distribution within a city. In this paper, a UBEM is developed using the characteristics and consumption of eight typical buildings (archetypes) in the climate zone of Santiago de Chile. The archetype-based UBEM is then applied to the commune of Renca, a critical suburb of Santiago, with the use of QGIS to analyze the energy demand for space heating and the potential for energy saving after four retrofitting interventions. Knowing the costs of the retrofitting interventions and the energy price, the simple payback time was evaluated with the reduction in GHG emissions. Starting from the actual building stock, the results show that the most effective retrofitting intervention for the commune of Renca is the thermal insulation of walls and roofs; due to the type of dwellings, this particular intervention could be more convenient if associated with the installation of solar technologies. This methodology can be replicated with the data used by urban planners and public administrations available for many Chilean cities and in other countries.

Experimental and numerical study on seismic performance of prefabricated new fly ash foam concrete structure

In view of the current situation of solid waste resource utilization and the introduction of exterior wall insulation limit policy, this paper proposes a new type of assembled fly ash foam concrete structure for rural areas. After that, a 1:3 scaled specimen model was designed for the proposed static test with three actuators loaded synchronously, and the seismic performance of each floor of the structure was investigated by hysteresis curves, skeleton curves, ductility coefficients, equivalent damping ratios, and stiffness degradation curves, and compared with that of ordinary concrete structures. Finally, ABAQUS was used to establish the structural model with different porosity, and the effects of different porosity on the seismic performance of the structure were determined by comparing the results of tests and finite elements. The results show that the peak load of the assembled new fly ash foam concrete structure model is 84.9 kN, the ultimate displacement is 49.5 mm, the equivalent damping ratio is increased by 24.0 %, and the ductility coefficient is 2.15 compared with that of the ordinary concrete structure, with the increase of the pore rate, the damage location is mainly concentrated from the surface of the specimen to the corners of the doors and windows. The pore rate of 0.101 can simultaneously meet the requirements of structural lighting, economy, and load-bearing capacity. The proposal of an assembled new fly ash foam concrete structure enriches the structural form and lays the foundation for the design and application of this structure in the future.

Optimization of exterior wall insulation in office buildings based on wall orientation: Economic, energy and carbon saving potential in China

The aim of this study is to optimize the exterior wall insulation of different orientations to further reduce the heating and cooling energy consumption of office buildings, and to analyze its economic, energy and carbon saving potential in China. A six-story office building was selected as the case building and its energy consumption was evaluated using TRNSYS, considering variations in latitude, window-to-wall ratio, aspect ratio, and exterior wall U-values of four orientations. In addition, the exterior wall insulation in four directions was optimized by coupling artificial neural network and genetic algorithm. The main results showed that in the 20°N to 40°N region of China, the GA-optimized exterior wall U-values were highest in the southern direction, followed by the eastern and western directions, and finally the northern direction. In addition, overall, the optimal combination of exterior wall U-values showed a trend of high at low latitudes and low at high latitudes, and increased with increasing WWR and decreased with increasing AR. Finally, compared to the exterior wall requirements for energy efficient buildings in GB 55015-2021, the optimized office buildings at low altitude in China showed a 3.26 %, 6.77 % and 6.59 % reduction in ALCC, total energy consumption and total carbon emissions respectively.

Analysis of thermal characteristics and thermal storage performance of energy-saving phase change thermal storage materials in buildings

In order to explore the thermal characteristics and thermal storage performance analysis of energy-saving phase change heat storage materials in buildings, taking the common exterior wall insulation composite wall structure in southwestern China as an example, the influence of insulation board structure thickness design on the total cost of residential air conditioning energy consumption and insulation board cost is studied, thus clarifying the concept and calculation origin of economic insulation thickness. The experimental results show that by drawing mathematical functions of energy consumption cost, total cost, and insulation material cost in the same 2-D coordinate, it is intuitively demonstrated that the minimization of total cost can be ensured when the insulation thickness is in an economic state, and the specific economic thickness can be accurately calculated through example data. Therefore, specific measures for improving external wall insulation from refined insulation structure design are proposed. It has been proven that the design of the exterior wall insulation layer structure is an important way to improve the overall energy-saving benefits of building exterior wall insulation.

Numerical Simulation of Plasma Plume With an Insulated Wall in Sheath Region Using a DSMC‐PIC Parallel Algorithm

The spatiotemporal evolution of plasma plumes is accompanied by various phenomena such as chemical reactions, sheath layer formation, and secondary electron emission, which have a crucial impact on the working characteristics and performance improvement of plasma devices. This study uses a direct simulation Monte Carlo/particle‐in‐cell (DSMC/PIC) parallel coupling algorithm for numerical simulations, with the PIC method using full particle simulations. The main focus of the study is to explore, through numerical simulations, the effects of the initial injection density, electron temperature, and charge exchange reactions. Two energy spectrum models are used for secondary electron emission, namely, the Furman model and the vertical model. The modified Mozorov coefficient model simulates two types of insulation wall materials: boron nitride and silicon carbide. The spatiotemporal evolution of H2, H, X, H2+, H+, and e in the flow field is demonstrated by simulating a double cylindrical axisymmetric calculation example. This paper provides a detailed analysis of the structural characteristics of number‐density cloud images under different initial conditions. Increasing the injection density enhances the radial electric field and results in a low‐density region of ion distributions. Furthermore, the electron temperature increases the deposition of wall charges. Lastly, the charge exchange reaction has a weak effect on the specific distribution of particles in the convection field.

The impact of the new EPBD “Green Houses” in the Italian building context: Technical-economic analysis on improving the energy class of existing buildings

The new European directive “Green Houses” aims at the decarbonization of the existing building stock. In this work, three building types widespread in Italy are analysed, virtually positioned in Palermo, Naples, and Milan. Considering that almost 60% of Italian residential buildings fall within the G and F energy classes, three energy retrofit measures are proposed (thermal insulation of vertical walls and roofs; replacement of the methane gas boiler for building heating and domestic hot water with a high temperature air-to-water heat pump; installation of a photovoltaic system), in order to reach at least D energy class based on Italian energy performance certification. A simulation-based approach is used. A declining tendency is noted in the normalized prices of the interventions when moving from detached house to terraced house and from terraced house to apartment in a tower building. Shifting from an independent to a centralized air conditioning system results in the same savings. Considering equal building features, hotter and milder climate zones reach higher energy classes; this also results in more difficult energy efficiency improvement in colder climates. Potential inequalities result from the implementation of the new European directive. Economic incentives to support the energy efficiency transition should be tailored to more specific conditions.

Performance of Thermal Insulation of Different Composite Walls and Roofs Materials Used for Energy Efficient Building Construction in Iraq

Performance of Thermal Insulation of Different Composite Walls and Roofs Materials Used for Energy Efficient Building Construction in Iraq

Buildings made of massive timber logs with a derogation from the application of technical conditions for traditional masonry technologies

Timber log walls are a unique form of construction - erected from solid material, they are both a building structure and a thermal barrier. Walls of wooden logs have numerous advantages, especially favourable physical and mechanical properties, including insulation and thermal capacity. The technical conditions, which are the Polish interpretation of the Nearly Zero Energy Building (nZEB) building, which a newly designed building must meet, must meet 2 conditions simultaneously: the value of the EP index, which determines the annual calculated demand for non-renewable primary energy for heating, ventilation, cooling and preparation of domestic hot water for the entire building, and adequate thermal insulation of the external walls. Calculating the thermal insulation of a wood partition, relying only on thermal conductivity coefficients without considering other properties of the material, does not reflect the true insulating properties of wood. The lack of research on the insulating properties of wood, and thus the lack of national technical and installation requirements for log houses seriously limits the development of this type of construction and forces to undertake reliable research and development work in this area. The proposed introduction in this type of building of the methodology of the so-called Integrated Energy Design (IED) allows to carry out multi-criteria analysis of design variants at the stage of the virtual model in the BIM standard, in terms of the final energy efficiency of the building. Conducting various types of variant analyses and simulations allows to achieve optimal energy efficiency and to verify and correct the adopted solutions. The high energy efficiency of the building demonstrated by such simulations can be the basis for a deviation from the current regulations, which will allow the implementation of newly designed buildings in massive log technology, without the need for additional thermal insulation. As a result, it will be possible to preserve the unique architectural expression of buildings erected with this technology, with visible massive timber logs both on the exterior facades and on the interior.

BioForms: 3-D printed mycelium wall panel systems

Abstract BioForms integrates sacrificial formworks, agent-based computational algorithms and biological growth in the generation of biodegradable internal wall panel systems. These wall panel systems are intended to minimize material waste, utilize local botany and generate a symbiosis between the artificially made and the naturally grown. This is achieved by utilizing local waste as a structural compressive core, mycelium as the binder, and recycled pellets as the architectural skin. Leveraging mycelium’s structural, acoustic and thermal properties, this exploration delves into unique methods of incorporating fungi and waste into architectural construction. The motivations for this research stem from the need to address the building industry’s contribution to climate change, by considering the lifecycle of our materials. BioForms aims to retrofit existing buildings by replacing foam insulation and MDF (medium-density fiberboard) wall panels with biodegradable and recyclable 3D-printed skins embedded with a mycelium core. Analysing mycelium’s reaction to BioForms I, the second iteration, BioForms II, evolves in design complexity and materiality. BioForms II explored robotically fabricated wood-based polylactic acid plastic (PLA) composite materials. Within the second iteration of this research stream, mycelia was both embedded within the compressed fabricated skins and on the external surface. Whilst BioForms explored the generation of biodegradable wall panel systems, the broader aims of this research is aimed at infiltrating biological matter into human-occupied spaces, completely omitting the use of synthetic building materials within the construction industry and advancing the architects relationship to nature in the generation of form.

Development of cellular construction material-based flax shives: Physico-mechanical and thermal characterisation

The reduction of energy consumption in construction, production of thermal insulation materials, and the solution of environmental problems by recycling by-product derived several industrial sectors are becoming greater problems. In this context, vegetable by-products are an excellent alternative product to substitute mineral aggregates because they are easily available and renewable low-cost raw materials, and have higher advantage for economy and environment concerns. The viability of using vegetable materials such as flax shives for developing a sustainable Lightweight Cellular Construction Material (LCCM) is investigated in this paper. The produced material containing different volumes of flax shives (0V (control specimen), 1V, and 2V) was lightened by creating a porous structure in the matrix through a chemical reaction between Aluminium powder and free lime from pre-formulated Tradical PF70 binder. A study conducted on hardened material properties has indicated a significant reduction in sample unit weight, thereby resulting in a level of compressive strength compatible with a load-bearing wall. The reduction in flexural strength was lower than that in compressive strength. This study has also highlighted the effect of the porous structure on the thermal conductivity that lead to provide a high degree of thermal insulation. These results show that the cellular material based on flax particle can be used as suitable insulated load-bearing walls.

Анализ тепловой производительности радиационной системы жизнеобеспечения на основе экспериментальных данных

Solar energy is considered a renewable, most environmentally friendly and carbon-free form of energy. Solar collectors are one of the implementations of radiation life support systems. Their development requires a fairly large amount of initial data, such as the parameters of the premises, the required temperature, volume, thermal insulation of walls, floors and ceilings, the design of windows and doors, orientation to the cardinal points, the angles of inclination of the roof slopes, etc. The next group of factors is related to the location object, latitude, altitude above sea level, distance to large bodies of water, wind rose, etc. The third group is related to the weather itself: precipitation, cloudiness, outside air temperature, etc., a significant part of them, such as fog, haze, dew, shadow from each cloud affects the amount of insolation and all this cannot be taken into account in advance. The use of weather archives does not allow us to fully determine the specific thermal performance of solar collectors, since neither the average nor the current insolation is reflected in the archives. Without knowing the amount of real insolation and heat losses on the solar collector, it is impossible to determine the thermal performance of the radiation life support system per day, month, season or year. This paper discusses experimental and computational studies of the radiation life support system carried out in 2018–2022.

Application of new nanopolymer materials in intelligent thermal insulation system for building external walls

In response to the current problem of poor energy consumption control effect and overall high energy consumption of new nanopolymer materials for building exterior walls, the author proposes a thermal insulation energy consumption control technology based on the heat transfer performance model of exterior wall insulation panels. Calculate the current heat transfer performance parameters of exterior wall insulation panels using the reaction coefficient method, determine the proportional relationship between the effective heat transfer coefficients, and establish a heat transfer performance model for exterior wall insulation panels, based on the thermal conductivity index of the new nanopolymer material for the wall, the current control parameters are optimized. The optimal data algorithm is used to obtain the energy consumption decision variable value of the new nanopolymer material for the exterior wall of the building under the condition of clarifying the current heat transfer coefficient, and establish constraint conditions, based on the specific energy consumption data of new nanopolymer materials outside the current wall, establish the current thermal energy information transmission ratio relationship, analyze the current wall energy consumption hotspots, propose the K-means clustering analysis strategy, and apply it to the hot spot clustering control. Energy consumption control is achieved by locating the main cluster head parameters of the hot spot. Simulation results show that the hot spot fit of the aforementioned control methods has been improved by 29%, and the accuracy of the design method in cooling load control statistics is significantly higher than the two traditional methods used for comparison. Due to different weights, the final improvement ratio is determined to be 27%, further verifying the hypothesis. It has been proven that it can effectively improve the energy consumption control effect.

Analysis of thermal characteristics of building envelope structure for night storage heating

In order to understand the thermal characteristics analysis of nighttime thermal storage heating, the author proposes a study on the thermal characteristics analysis of nighttime thermal storage heating of building envelope structures. In some places, the writer will use an office room as a research object. The main purpose of the experiment is to measure, compare and analyze the surface temperature and heat flow rate of the room sample volume under two conditions: constant power 24 hour heating and night constant thermal power (12 hours) heating. In order to verify the accuracy of the dynamic thermal process of the heating room, the indoor air time variation will be performed along with the simulation results. Thermal performance parameters and characteristics of building thermal envelope heating effect of storage room were studied. The mathematical model of the thermal dynamic process of the heating room was established using the heat balance method and verified by experiments. According to the experiment, when the heating time increases from 5-12 hours, the additional heating consumption of the building heating system decreases by 500 Wh, and the additional heating consumption decreases to 19.4. In addition, it is important to change the heating time of the night-time packing model and the total heat accumulation. In addition, external wall insulation is useful in reducing additional heating consumption and building heating costs, but all heat transfer between model blocks is low. As the weather changes and the heat transfer coefficient of the external window increases, the additional amount of heat consumption and the additional value of heat consumption for heat storage of the building will increase. In the process of continuous heating operation, the additional heat consumption of the building heating system, the additional heat consumption gradually decreases, the heating equipment changes per hour, and the total heat accumulation of the night packing structure is important.

The Safe Insulation from the Inside as a Solution to the Energy and Climate Crisis

Abstract During the time when the European Union is facing an energy crisis, it is essential to understand ways to overcome it more easily. As one of the consuming sectors, buildings play a crucial role in improving energy efficiency. Therefore, one of the ways to fight with energy crisis and high energy consumption in buildings is insulation from the inside. This study assesses the hygrothermal performance of masonry walls with 9 interior insulation systems (mineral wool with vapor barrier, XPS, PIR, cork, expanded cork, aerogel blanket, wood fibre plates, perlite board) exposed to different external conditions in the climate chambers. Masonry walls were tested in a steady cycle with cold box temperature 18 °C and 40 % RH), a dynamic cycle that follows daily fluctuations, a dynamic cycle with rain. Also, an identical simulation of the hygrothermal process was carried out in the DELPHIN software to compare results of both testing methods. The temperature between the thermal insulation layer and the brick wall in all thermal insulation systems is approximately 7-8 hours behind the temperature of the outdoor climatic chamber. A dynamic cycle with rain simulation has a significant impact on the hygrothermal behaviour of thermal insulation systems. The study provides valuable data on hygrothermal processes in different wall insulation systems from the inside.