External Wall Thermal Insulation Research Articles

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.

Improving building energy efficiency and thermal comfort with natural fibre insulation

As part of the energy transition and global environmental problems, improving the energy efficiency of buildings has become an imperative aspect for the architecture, engineering and construction industries. Furthermore, the energy performance of a building depends directly on the quality of its thermal envelope and the insulation material applied. Therefore, the main aim of this study is to assess by means of simulations the impact of ecological insulation materials on thermal comfort and energy efficiency in the case of a residential building in a Mediterranean climate. The results of the simulation show that optimising envelope design parameters can reduce annual energy loads for heating and for cooling. The most efficient strategies for achieving this reduction involve the use of ecological thermal insulation of external walls, optimising glazing settings and use of efficient shading devices.

Combined numerical approach for the evaluation of the energy efficiency and economic investment of building external insulation technologies

The objective of this paper is to examine the energy efficiency and economic feasibility of different coating technologies used to improve the thermal insulation of external walls in buildings. The comparison is made between traditional coat insulation and ventilated façade, evaluating their impact on energy consumption to maintain a constant indoor temperature throughout the year by means of a combined numerical approach. . Furthermore, the paper investigates the effect of opening and closing the air gap in ventilated façades on thermal insulation during the winter and summer seasons. Energy efficiency calculations are employed to estimate the economic investment required for implementing the different insulation solutions.The paper proposes an innovative combined approach to determine the performance of the building insulation technologies. Firstly, a computational fluid dynamics (CFD) simulation is carried out on the full three-dimensional geometry of the building during two reference days representing extreme temperature and sun radiation conditions during the summer and winter. This modeling includes the effects of solar radiative heat transfer during the day: for a chosen date, time, and geographical location, the model computes sun altitude and azimuthal angles, along with the corresponding direct and diffuse solar fluxes. In addition, the model uses a multiband thermal radiation approach to capture the different nature of radiative heat exchange according to the light wavelengths. The total heat transfer coefficient of the building walls in each scenario is calculated through the computational fluid dynamic analysis and implemented in an in-house developed library based on the open source Open-Modelica platform to simulate the energy requirement of the building throughout the year. This combined numerical approach provides a comprehensive performance analysis of the studied technologies in terms of electric energy and fuel consumption required for maintaining a constant indoor temperature and internal ambient comfort.The results of the simulations demonstrate that by adopting the two proposed solutions, there was a potential to save approximately 37% of the fuel required for the heating system and more than 51% of electric energy required for the air conditioning systems. Finally, the payback period for each scenario is calculated, and it was found that coat insulation offers the best balance between thermal performance improvement and economic effort, with a payback time close to 20 years.

Preparation of a New Type of Expansion Flame Retardant and Application in Polystyrene

Polystyrene (PS) is a widely used building insulation material with good mechanical strength and strong temperature adaptability. However, PS itself is highly flammable and displays poor flame retardancy. At present, building fires caused by organic external wall thermal insulation materials prepared from PS represent a new fire hazard. In this study, the addition of an intumescent flame retardant (IFR) to reduce the flammability of PS was achieved. Using melamine (MEL), acrylonitrile-styrene-acrylate (ASA), and phytic acid (PA) as raw materials, a new type of flame retardant (MAP) was prepared by an electrostatic self-assembly method and was introduced to modify PS. Its effect on the flammability of PS composites was also investigated. The flammability of the PS composites was characterized using the limiting oxygen index (LOI) and vertical combustion. The effect of MAP on the morphology of the carbon layer formed from polymer decomposition was studied using scanning electron microscopy (SEM). By adding MAP to a PS/20%N-IFR flame-retardant composite, the flame-retardant property was significantly improved, the limiting oxygen index reached 37, and the vertical combustion reached a V-0 level. The fire performance index (FPI) of the PS/20%N-IFR composite reached 0.0054, which was significantly higher than that of the control PS (0.037) as determined by the cone calorimetry test. The SEM results showed that the introduction of MAP can increase the density of the carbon layer after combustion. The heat release rate for combustion was reduced. In addition, the mechanical properties of the PS/20%N-IFR composites were compared with those with no flame retardant. The tensile strength of the PS/20%N-IFR composite was 26.1 MPa and the elongation of the PS/20%N-IFR composite remained at 2.2%. The PS/20%N-IFR composite displayed better flame retardancy than the untreated material and good mechanical properties. The presence of MAP prevented the heat and oxygen transfer and interrupted the releasing of flammable products, thus protecting the PS from burning. This flame-retardant material may find broad applications in building insulation materials.

Investigation into the viability of the properties of porous glass-ceramics produced from granite dust and maize cob for use in thermal insulation of external walls of residential buildings

Given the enormous need for cost-effective wall insulation materials in the developing countries and Nigeria specifically, this study, explores the viability of porous glass-ceramics production from granite dust and maize cob using one-step sintering technology. The chemical compositions of the locally sourced materials used including granite dust, ball clay and maize cob were obtained using XRF. 300µm of granite dust and ball clay as well as 425µm of maize cob powder were used. Different amount of granite dust and maize cob powder were mixed with constant amount of a mixture of NaOH and Na2SiO3 in three different groupings to formulate the porous glass-ceramics samples. The formulated samples were uniaxially pressed at 10MPa and sintered in a gas kiln at 850oC for 3 hours. The sintered samples were subjected to experimental tests. The results showed water absorption, apparent porosity, bulk density, compressive strength and thermal conductivity of 25.6%–46.7%, 43.5%–75%, 1.45g/cm3 –1.9g/cm3, 0.7MPa–9.7MPa and 0.11W/m.K–0.53W/m.K respectively. The mineralogical properties of the sintered samples were obtained using XRD. The results indicated a viable material for use in thermal insulation of residential buildings.

Impact of natural and artificial ageing on the properties of multilayer external wall thermal insulation systems

Multilayer external wall thermal insulation systems are widely used in new constructions and for the retrofitting of building façades. Despite the increasing use as constructive solution, significant anomalies have been frequently identified on these systems only few years after their application, raising questions on their long-term durability. This paper focuses on the effects of one-year natural ageing and artificial ageing through hygrothermal cycles (heat/rain and heat/cold) on the water performance (capillary water absorption and drying kinetics), bio-susceptibility (mould development) and surface properties (colour, gloss, and roughness) of four multilayer external wall thermal insulation systems (three ETICS and a thermal rendering system). Results showed a significant loss of surface hydrophobicity after ageing. Considering the 24 h water absorption results, an increase up to 73% and 432% was obtained for the naturally and artificially aged systems, respectively, and when compared to the reference unaged systems. The drying kinetics was affected by ageing, with increases of the drying resistance ranging between 47% and 122% after artificial ageing. Traces of mould growth were observed on the artificially aged systems; however, no growth was detected on either the unaged or the one-year naturally aged systems. Substantial colour change for all systems after ageing was observed, confirming aesthetic alteration. Results contribute towards the development of implemented artificial ageing protocols, as well as for the delivery of multilayer thermal systems with enhanced performance and durability.

Evaluating the properties of cellular ceramics prepared with a granite dust and plantain (Musa paradisiaca) peel powder for external wall thermal insulation of buildings

The viability of preparing cellular ceramics suitable for external wall insulation of buildings was investigated using granite dust, ball clay, plantain peels, sodium silicate, and sodium hydroxide. The predetermined compositions of the raw materials were mixed homogeneously and then subjected to uniaxial pressing at 10 MPa. The formulated samples were oven-dried and sintered in a gas kiln at 850 °C for 3 h. The obtained cellular ceramics were then subjected to standard property tests. The results revealed water absorption of 19.5-41.7%, bulk density of 1.39-1.86 g/cm3, apparent porosity of 36.4-66.7%, thermal conductivity of 0.09-0.62 W/(m.K), and compressive strength of 0.9-18.4 MPa. From the results, the optimum sample of the cellular ceramics prepared is a potential thermal insulation material for load-bearing applications such as walling systems in buildings, where not only low thermal conductivity but also high mechanical strength is required.

Effects of Climate Change on Thermal Comfort and Energy Demand in a Single-Family House in Poland

In regions with temperate climates, the thermal insulation of buildings is increased to reduce the need for heating. It might significantly reduce human thermal comfort in the summer period. The problem can increase with global warming. The aim of the paper is to analyze the heating and cooling demand, as well as thermal comfort in a single-family house located in Poland for three climate scenarios (typical, real, and future weather data) and for two types of thermal insulation of external walls. In the study, two ways of cooling the building were taken into account: using split air conditioners and using fresh airflow provided through the opening of windows. The open area and the temperatures for opening windows have been optimized using a two-criteria function. The energy simulation was carried out in EnergyPlus 9.4 software. The multi-zone model was validated on the basis of the temperature measurement. The results showed that there will be a problem with ensuring thermal comfort in the future, especially in well-insulated buildings. The energy demand for cooling will be greater than the demand for heating. The use of passive cooling is a good solution for residential buildings in these regions, and the number of discomfort hours is small (max 5%).

Risk of Using Capillary Active Interior Insulation in a Cold Climate

The retrofitting of cultural heritage buildings for energy efficiency often requires the internal thermal insulation of external walls. Most of the in situ studies of capillary active interior insulation were performed in mild oceanic climate regions, and they showed an excellent performance. However, as a large part of Central–Eastern Europe belongs to a continental climate with cold winters and long periods of temperatures below the freezing temperature, the applicability of the capillary active interior insulation in cold climate was studied. The hydrothermal behaviour of the three walls was determined—each consists of one of three different interior insulations—and the original wall is made of historic regular solid bricks. Two interior thermal insulations were capillary active (aerated cellular concrete, calcium silicate) and one vapour-tight (glass foam). A hot box–cold box experiment and a steady-state model were used to demonstrate an increase in the original wall mass due to the water condensation only when the capillary active interior insulation is used. The combination of the water condensation and the low sub-zero temperature may lead to a risk of freeze–thaw damage to the original wall. The numerical simulation of the water vapour condensation for the considered walls for the Slovenian town Bled with sub-zero average winter temperatures was performed to obtain the whole temperature and moisture profile. It showed good agreement between an experimentally and numerically obtained amount of water condensation. The capillary active interior insulation proved to be unsuitable for improving the thermal insulation of buildings in cold continental climate, and only a vapour-tight system can be recommended.

Construction Technology and Measures of Building External Wall Thermal Insulation

Construction Technology and Measures of Building External Wall Thermal Insulation

Improving the energy efficiency of existing residential buildings by applying passive and cost-effective solutions in the Hot and humid region of Iran

This paper aims to investigate the improvement of the energy efficiency of typical apartment buildings in the hot and humid region of Iran by applying passive and cost-effective solutions. For this purpose, a residential building, that reflects the current typology, is selected in Bushehr, Iran, and its annual energy consumption is explored using electric and gas bills. Then, a primary and calibrated model of the building is made using a real occupancy schedule and hourly weather data of Bushehr in Design Builder Software to simulate its energy performance. Considering the architectural design of the baseline model and using passive solutions (including low-E glazing, thermal insulation of external walls, roof and ceilings, and pre-heating of domestic hot water), a developed model is made. The simulation results indicate that the annual carbon dioxide emission and energy consumption of the developed model is reduced by 18.7% and 20%, respectively. These passive solutions can be used to improve the energy efficiency of existing buildings to achieve low Carbon buildings and neighborhoods in this part of Iran. This study also proposed a new reference for the annual energy consumption of low-energy houses in the hot and humid area of Iran and the Persian Gulf region (75-76 kWh/m2/Year). Moreover, the economic analysis in this study demonstrates that the above-mentioned passive solutions will be cost-effective if the government subsidies for the residential buildings’ energy use are eliminated in this region.

Technical and Economic Analysis of External Wall Thermal Insulation for Nearly Zero Energy Buildings Based on Life Cycle Cost

The outer protective structure of nearly zero Energy building generally has better thermal insulation performance. With the increase of the thickness of the external wall insulation, the energy conservation gains decrease. This paper studies the economics of the life cycle cost of the external wall insulation of nearly zero energy buildings in different climate zones. Considering solar radiation and nocturnal radiation, an explicit one-dimensional unsteady heat conduction model is established by using the finite difference method, and the temperature of each point inside the wall at various times within 8760 hours of the year is calculated, thereby calculating the annual heat transfer amount per unit wall area. Considering the construction cost, annual operating cost, and discount rate, calculate the cost of the life cycle of the insulation material under different thicknesses in each climate zone. The best economic thickness of each insulation material in each climate zone is obtained.

Measured and Simulated Energy Use in a Secondary School Building in Sweden—A Case Study of Validation, Airing, and Occupancy Behaviour

In this case study, the energy performance of a secondary school building from the 1960s in Gävle, Sweden, was modelled in the building energy simulation (BES) tool IDA ICE version 4.8 prior to major renovation planning. The objectives of the study were to validate the BES model during both occupied and unoccupied periods, investigate how to model airing and varying occupancy behaviour, and finally investigate energy use to identify potential energy-efficiency measures. The BES model was validated by using field measurements and evidence-based input. Thermal bridges, infiltration, mechanical ventilation, domestic hot water circulation losses, and space heating power were calculated and measured. A backcasting method was developed to model heat losses due to airing, opening windows and doors, and other occupancy behaviour through regression analysis between daily heat power and outdoor temperature. Validation results show good agreement: 3.4% discrepancy between space heating measurements and simulations during an unoccupied week. Corresponding monthly discrepancy varied between 5.5% and 10.6% during three months with occupants. Annual simulation indicates that the best potential renovation measures are changing to efficient windows, improved envelope airtightness, new controls of the HVAC system, and increased external wall thermal insulation.

Analysis of new inorganic exterior insulation materials and thermal energy storage

In order to reduce the energy efficiency of the construction industry and improve the building safety, in this research, a new type of inorganic insulation material ? vitreous bead insulation mortar is studied and its properties are analyzed. Quantitative method is used to analyze the influence of glass bead mixing amount, cellulose ether mixing amount and redispersible emulsion powder mixing amount on the consistency, water retention rate, dry density, softening coefficient and compressive strength of glass bead insulation mortar. The effect of different raw materials allocation on the thermal conductivity of vitrified microbeads thermal insulation mortar is explored. The results show that the performance of insulation mortar decreases significantly with the increase of glass bubbles. With the increase of cellulose ether content, the consistency and compressive strength of insulation mortar first increased and then decreased, the water retention rate increased significantly, but the dry density decreased significantly. With the increase of the content of redispersible emulsion powder, the consistency and compressive strength of insulation mortar first increased and then decreased, but the dry density decreased gradually. Glass bubbles and fly ash parameters are the main factors that affect the thermal conductivity of thermal insulation mortar, and their thermal conductivity decreases with the increase of the proportion of air-entraining agent. As a result, the performance of vitreous microbeads thermal insulation mortar will change to a certain extent with the different proportion of raw materials, which provides data support for the preparation and application of inorganic external wall thermal insulation materials.

Towards the EU Emission Targets of 2050: Cost-Effective Emission Reduction in Finnish Detached Houses

To mitigate the effects of climate change, the European Union calls for major carbon emission reductions in the building sector through a deep renovation of the existing building stock. This study examines the cost-effective energy retrofit measures in Finnish detached houses. The Finnish detached house building stock was divided into four age classes according to the building code in effect at the time of their construction. Multi-objective optimization with a genetic algorithm was used to minimize the life cycle cost and CO2 emissions in each building type for five different main heating systems (district heating, wood/oil boiler, direct electric heating, and ground-source heat pump) by improving the building envelope and systems. Cost-effective emission reductions were possible with all heating systems, but especially with ground-source heat pumps. Replacing oil boilers with ground-source heat pumps (GSHPs), emissions could be reduced by 79% to 92% across all the studied detached houses and investment levels. With all the other heating systems, emission reductions of 20% to 75% were possible. The most cost-effective individual renovation measures were the installation of air-to-air heat pumps for auxiliary heating and improving the thermal insulation of external walls.

A technical and economic analysis of the thermal modernization of historic buildings using an innovative thermal insulating paint

Due to the need for making the thermal modernization of buildings of historical value, where the Conservation Officer often does not approve the thermal insulation of the building’s facade with a traditional method using expanded polystyrene (EPS), an innovative paint has been proposed to be used, which can substitute for an EPS layer for the thermal insulation of buildings where everything that is the most beautiful is often situated on the building’s external facade. The article analyzes two different thermal modernization methods: the traditional method and the one using an innovative thermal insulating paint. During selecting the material, the main aspects were: material strength and durability, workmanship, the execution cost of a sample project, and the behaviour of materials during operation. All advantages and disadvantages of either of the external wall thermal insulation technologies are indicated. Cost calculation figures for the project under consideration carried out using the above-mentioned technologies have also been examined. It has been found that the technology using the innovative thermal insulating paint is fairly expensive and the obtained coefficients of heat transfer through the partition are not competitive compared to the traditional method using expanded polystyrene. However, by using the innovative technology for historic buildings, we are able to improve the aesthetic appearance of the facade and, at the same time, the thermal properties of the partition during carrying out a single project, while not spoiling the historical look of the building.

Technical Study on the Rock Wool/Polyurethane Composite Insulation Board and Its External Insulation System for Ultra-low Energy Consumption Buildings

Ultra-low energy consumption buildings refer to the buildings which adapt to the climate characteristics and natural conditions, use the envelope structure with high thermal insulation and air tightness performance as well as efficient fresh air heat recovery technology to minimize the heating and cooling demand of buildings, and make full use of renewable energy to provide comfortable indoor environment with less energy consumption. As a key part of the ultra-low energy consumption building technology system, the external wall heat transfer coefficient K value is much higher than the external wall heat transfer coefficient required by the current ordinary energy-saving buildings in China. In order to achieve the thermal insulation performance required by the ultra-low energy consumption buildings, higher requirements are put forward for the thermal insulation materials and external thermal insulation system of building envelope. In this research, a new type of thermal insulation material for external wall of buildings which combines rigid polyurethane and rock wool is developed, and its application technology in ultra-low energy consumption building external wall thermal insulation system is also studied.

Increasing efficiency of atriums in hot, arid zones

This research evaluated the efficiency of Atrium in hot, arid regions and investigated the parameters influencing the total energy consumption of an existing shopping mall in Dubai, UAE using the IES-VE energy modeling software. The parameters tested included: Roof profile, Roof ventilation, Number of floors, glazing's Light to Solar Gain ratio (LSG) and the Thermal insulation of the building envelope. The impact of using light sensors was also studied. The light sensors and the roof's thermal insulation resulted in the highest reduction of the atrium's energy, 8.5% and 7.5%, respectively. Increasing the number of floors reduced the energy consumption by 5% per unit area. The roof profile, external wall's thermal insulation and height of the atrium resulted in similar energy reductions of 3.5% each. The external glazing's LSG reduced the energy consumption by 3.25% while the roof ventilation resulted in a reduction of 1.3%. The internal glazing's LSG did not affect the atrium's total energy consumption. An optimal combination of the parameters studies resulted in an energy reduction of about 20%. Thus, this paper presents the optimal design configuration to reduce the energy consumption of an atrium located in a hot and arid climate.

Energy Life Cycle Analysis of a Residential Building with the Help of BIM in Different Climates of Iran

With energy resource scarcity and energy crisis in the world, energy efficiency has become a subject of great importance. In warm and humid climates along with cold and mountainous ones, annual energy consumption is too high to achieve desirable living conditions in built environments, and hence energy efficiency measures and practices in such buildings is of utmost priority. Given the direct relationship of amount energy consumption and comfort level of occupants in residential buildings, energy saving and energy efficiency are of increasing importance specifically in the residential sector. In this study, a combination of building information modeling (BIM) and building performance modeling (BPM) is applied to identify appropriate dimensions and building materials to reduce energy in the lifecycle of a building. To perform this modeling, we evaluated various software applications employed in different studies and after identifying their advantages and disadvantages, finally Autodesk Revit and Autodesk Ecotect were chosen. Moreover, suitable building materials and optimum sizes are computed corresponding to different weather conditions and climates in Iran. In another part of this study, the breakdown of energy consumption in the commercial and residential areas in Iran is examined. Given the 38% share of space heating in total building energy consumption, the essential role of thermal insulation of external walls is emphasized. The effect of insulating in this region is calculated and marked applying simulation of energy consumption. Utilizing a suitable insulation system, can save 35% in lifecycle energy consumption.

USE OF MONOLITHIC FOAM CONCRETE IN ENCLOSING STRUCTURES OF BUILDINGS AND STRUCTURES WITH VARIABLE THERMAL CONDITIONS

This article considers the features of the use of monolithic foam concrete as a heat-insulating layer in the building enveloping structures of buildings operated under intermitt ent heating conditions. To assess the eff ectiveness of the use of monolithic foam concrete in building enveloping structures, a thermal engineering calculation of the outer wall, insulated with the use of monolithic foam concrete, was carried out. Based on the calculations carried out by the authors, graphs of the dependence of the heating time of multilayered enclosing structures on the thickness of the heat-insulating layer and the reduced resistance to heat transfer of the structure were obtained. The optimum range of thicknesses and densities of monolithic foam concrete for thermal insulation of external walls of buildings, operated in conditions of intermitt ent heating, is off ered. This calculation also showed that the use of foam concrete as a heater from the inside of the outer wall can reduce the load on the foundation of the building.