Enhancing building energy efficiency using locally available insulation materials: experimental study on a double brick wall in hot climates

In response to increasing global temperatures and energy demands, optimizing buildings’ energy efficiency, particularly in hot climates, is an urgent challenge. While current research often relies on conventional energy estimation methods, there has been a decrease in the efforts dedicated to leveraging AI-based methodologies as technology advances. This implies a dearth of multiparameter examinations in AI-driven extreme case studies. For this reason, this study aimed to enhance the energy performance of residential buildings in the hot climates of Dubai and Riyadh by integrating Building Information Modeling (BIM) and Machine Learning (ML). Detailed BIM models of a typical residential villa in these regions were created using Revit, incorporating conventional, modern, and green building envelopes (BEs). These models served as the basis for energy simulations conducted with Green Building Studio (GBS) and Insight, focusing on crucial building features such as floor area, external and internal walls, windows, flooring, roofing, building orientation, infiltration, daylighting, and more. To predict Energy Use Intensity (EUI), four ML algorithms, namely, Gradient Boosting Machine (GBM), Random Forest (RF), Support Vector Machine (SVM), and Lasso Regression (LR), were employed. GBM consistently outperformed the others, demonstrating superior prediction accuracy with an R2 of 0.989. This indicates that the model explains 99% of the variance in EUI, highlighting its effectiveness in capturing the relationships between building features and energy consumption. Feature importance analysis (FIA) revealed that roofs (29% in Dubai scenarios (DS) and 40% in Riyadh scenarios (RS)), external walls (19% in DS and 29% in RS), and windows (15% in DS and 9% in RS) have the most impact on energy consumption. Additionally, the study explored the potential for energy optimization, such as cavity green walls and green roofs in RS and double brick walls with VIP insulation and green roofs in DS. The findings of the paper should be interpreted in light of certain limitations but they underscore the effectiveness of combining BIM and ML for sustainable building design, offering actionable insights for enhancing energy efficiency in hot climates.

The reduction of thermal gains in summer and heat loss in winter is ensured through the enhancement of thermal insulation and the thermal inertia of building envelopes. This study aims to exploit local materials from the Saharan region of Algeria, particularly from the Ouargla region, to construct building envelopes with high thermal resistance and inertia at minimal cost. The objective is to evaluate the current insulation methods in Algeria, which primarily use an air gap between two walls, and compare them with local insulating materials such as palm fibers, Drinn, and sheep wool, specifically for hot and arid regions. An experimental setup was designed, comprising two walls: an outer wall with a thickness of 15 cm and an inner wall with a thickness of 10 cm, with a 5 cm air gap in between, resulting in a total multilayer wall thickness of 30 cm. In this experimental study, palm fibers, Drinn, and sheep wool were inserted into the 5 cm gap between the two walls, replacing the conventional air gap. The results demonstrated an improvement in the thermal resistance of the multilayer wall with Drinn, sheep wool, and palm fibers compared to a conventional multilayer wall with an air gap. This improvement was reflected in the reduction of overall heat flux during the 10-hour experiment. The reductions in heat flux for Drinn, sheep wool, and palm fibers were 54.80%, 54.22%, and 25.99%, respectively. Sheep wool and Drinn provided nearly the same reduction in overall heat flux, but due to the higher cost of sheep wool, Drinn emerges as the best insulating material in terms of the insulation efficiency-to-cost ratio.

Enhancing building energy efficiency, insulation materials should be evaluated considering not only their fire resistance and high mechanical strength but also their low thermal conductivity (λ). In this context, the aim of the paper is to investigate the influence of different insulation materials on the λ value of the hollow prototype. This research, a vertical hollow block (prototype) with dimensions of 300 × 296.5x100 mm was constructed. The λ value of this prototype was determined using the Heat Flux Meter (HFM) measurement method in the absence of any insulating material. Subsequently, various insulating materials were placed in the identified hollows of the prototype. Various fillers such as Expanded Polystyrene (EPS), Extruded Polystyrene (XPS), Polyurethane (PUR), Glass Fiber (GW), Rock Wool (RW), Perlite (PLT), Mineral-Based Insulation Material (MLT), Vacuum Insulation Panel (VIP) and Vermiculite (VMC) were used to fill the hollows of the prototype. The effect of these insulation materials on the λ of the prototype was determined by experimental methods. In addition, two different numerical analysis programs (COMSOL and Ansys) were used to calculate the λ of the prototype with different insulation materials. The calculated results and test data of the prototype filled with insulation material were compared with the results of the prototype without any insulation material. In conclusion, the VIP insulated prototype exhibited approximately 4.5 times higher thermal insulation performance compared to the uninsulated prototype. Additionally, in terms of thermal resistance and insulation thickness, the VIP insulated prototype was followed by the PUR insulated prototype.

Thermal performance assessment of double hollow brick walls filled with hemp concrete insulation material through computational fluid dynamics analysis and dynamic thermal simulations

Heat gain and loss through the building envelope is affected by some features such as geometry and orientation, materials’ properties, construction type, and its interface with the outdoor environment. Thus, decisions on envelope design are contained by the objective, whether to advance or limit heat gain or loss, which pertains to the climatic conditions of the construction site. The purpose of this article is to probe the potency of using unventilated air-gapped facades for thermal insulation in hot climates. It is expected to gain positive results regarding the capability of air gap as a thermal insulation in walls of buildings, consequently, reducing the cost of thermal insulation materials and the cost of energy consumed as well. Three different profiles of building facades were selected: a controlled facade with no insulation material, a facade with an air gap as a substitute to the thermal insulation material, and a facade with a polystyrene layer of thermal insulation. The methodology of work depended on building three models in a simulation software for the examined building. Design-Builder Simulation software was repeatedly run to estimate the quantities of energy consumption associated with the usage of the proposed facades through multiple analysis processes. The resulting annual average, annual cooling, and annual heating energy consumption were compared. So that the effectiveness of an air gap as a thermal insulator could be examined. The results showed that unventilated air-gapped facade profiles had a limited efficiency in thermal insulation in hot-humid areas. They showed greater efficiency in reducing heating loads than cooling loads. Reduction efficiency values were twofold more in the winter season than in the summer season. Thus, the role of air-gapped facades as thermal insulators might be more efficient in areas where heating seasons are longer than cooling seasons.

In last two decades, energy consumption worldwide has increased by more than 30%. The limited thermal conductivity of thermal insulation materials is currently receiving significant attention in hot-weather countries where temperatures reach high levels. This leads to a significant decrease in the demand for energy in HVAC systems and reduces the negative effects on the environment. The purpose of current study is to define the optimum construction techniques for buildings to enable energy savings while occupying minimal space. This research dedicated on the role of wall and roof materials in the energy efficiency of a building by exploring different options, including variations in materials and construction methods. The study employed mathematical calculations to determine the U-value of wall and roof insulating materials. The results indicated that cavity walls with insulation material and cavity roofs with an air gap and insulation material are optimal solutions for improving energy efficiency in buildings. This study recommended considering long-term energy savings to substantiate the effectiveness of these materials in conserving energy for buildings.

Decarbonizing buildings is a pressing challenge in sustainable architecture, particularly in hot climates where cooling energy demand is high. Natural and locally available insulation materials, such as sheep wool fiber, can enhance thermal comfort, reduce energy consumption, and lower greenhouse gas emissions. This study evaluates the performance of sheep wool insulation compared to conventional alternatives across hot dry and hot humid climatic zones in Egypt. Using dynamic simulation with climate data from eight representative cities, the analysis considered two building orientations to assess thermal and environmental performance. The research methodology employs simulation tests. A model residential house from Egypt's social housing project (Ministry of Housing, Utilities & Urban Communities) was selected for a one-year simulation experiment using DesignBuilder V7.3.0.029. Climate data from eight cities across various Egyptian climate zones were utilized, with the simulation model tested in two primary orientations for comparison. Results show that sheep wool insulation reduced the thermal comfort index (PMV ET) by about 10%, lowered cooling energy demand by an average of 16%, and decreased CO2 emissions by up to 12%. The greatest improvements were observed in hot dry zones and with northwest building orientation. These findings highlight sheep wool insulation as a viable, eco-friendly solution for enhancing building energy efficiency in hot-climate regions. Incorporating such natural materials into building codes and design practices could support national sustainability targets and contribute to global climate action efforts.

The insulation materials are used to reduce heat loss to/from the ducts with additional investment. This study introduces an air gap between insulation and duct surface to reduce the quantity of insulation. It uses lifecycle cost (LCC) analysis to determine the economic benefits of the air gap, considering four insulation materials for insulating the duct and natural gas as an energy source for chiller operation. The preliminary data regarding design and operating parameters were obtained from a renowned pharmaceutical company. The duct's annual energy loss was estimated for given operation hours in a year using the preliminary data and ambient conditions. The estimated energy loss through the duct was fed in LCC analysis to determine the impact of the air gap on optimum insulation thickness (OIT) corresponding to the minimum LCC and payback period. Results revealed that OIT thickness for a duct with an air gap was lower than insulated duct without an air gap, resulting in maximum cost savings within a shorter payback period. Among different insulation materials, insulated duct with expanded polystyrene was investigated as cost-effective insulation material with maximum cost savings of USD (508.8-766.8)/m/year and a payback period of 1.15-1.17years. On the contrary, the air gap was the most effective in terms of cost savings for the ducts insulated with rock wool. In conclusion, an air gap is a cost-effective design approach for duct applications.

Investigation of the thermal behavior of the natural insulation materials for low temperature regions

The article presents the results of the analysis of the investigated external walls of residential buildings with a screen and an air gap in a dry hot climate. The preferred distance between the wall and the screen was set equal to 30–40 cm. With these thicknesses of ventilated air layers, the air temperatures at the wall surfaces behind the screen did not differ from the outside air temperature. An air gap is formed in the process offorming by metal inserts by hollow formers, which are removed after the concrete has hardened. The production of such panels requires special molding equipment of the factory technological lines for the production of external wall panels.

As the voltage level of the grid continuously rises, more and more new insulating materials with better performance are put into use. Nevertheless, air gaps often appear in insulating materials due to poor material quality, structural design flaws, etc. High-field-strength air gaps will produce partial discharge or even breakdown, resulting in electrical equipment failure. In addition, during operation, organic insulating materials are simultaneously exposed to high temperatures, mechanical stress, electrical stress, and moisture. Consequently, aging is inevitable. The aging of insulation materials is the root cause of the reduced insulation properties of the degradation of the insulation properties of electrical equipment in long-term operation. In order to improve the safety performance of power equipment and assure the safety of power grids, the detection and identification of internal structural defects and aging states of insulating materials have always been hot issues in related fields. However, structural defects inside the insulation materials used in power equipment, which are tiny (microns to millimeters), are exceedingly challenging to detect. While there are various destructive methods for detecting the aging status, non-destructive in-line inspection methods are still less commonly reported. In recent years, some scholars have begun to try to use terahertz spectroscopy to detect insulating materials. Numerous scholars have discovered that terahertz spectroscopy can not only detect structural defects inside insulating materials but can also detect non-destructive testing on the degree of material aging and even the type of material, which has excellent engineering value and promotion prospects. In order to help relevant researchers understand the application of this emerging technology in the field of insulating materials, this paper reviews the basic principles of terahertz detection and its applications in air gap detection, moisture detection, and aging analysis of insulating materials. Existing problems and future development directions are discussed.

Enhancing building energy efficiency and thermal performance with PCM-Integrated brick walls: A comprehensive review

Many brick buildings in Sweden today face a large need for renovation measures to prolong their service life and make other uses possible. Conventional thermal insulation materials, such as fibre glass and EPS, demand a thick layer of insulation to reach the energy targets. Super insulation materials, such as vacuum insulation panels (VIP) and aerogel blankets (AB), are thermal insulation components with a 3-10 times higher thermal resistance than conventional insulation materials. In this study, the effect of interior insulation using super insulation materials is investigated, using experiences from a case study in a brick wall from the 1800s. Earlier research has shown that interior insulation decreases the drying-out capacity of an exterior wall and increases the risk for freeze-thaw damages in brick walls. The case study building is an industrial building from 1896 with 470 mm homogeneous brick masonry walls insulated with both aerogel insulation and with vacuum insulation panels. Six heat flux sensors were installed in the wall and used to evaluate the thermal resistance of the wall with and without insulation. The initial measurements showed that the rate of water flow in the bricks is approximately three times higher than that in modern bricks. The average calculated U-value was reduced by 70% for the AB and 81% for the VIP layers, while measurements at the three occasions gave a reduction of 72-83% for the AB and 72-84% for the VIP layers, i.e. in the same order of magnitude.

The objective of this paper is to study a new double-wall steel insulation silo with multiple bolted joints for grain storage, which is designed to improve the insulation effect and mechanical behavior of the traditional silo structure. The silo employs the planar thin-walled steel plate as the internal wall, and the continuous ladder-shaped profiled plate as the external wall. The cavity between the internal and external walls is filled with insulation material. The silo utilizes specifically designed bolt connections to connect the internal and external walls. This paper carefully studied the structural behavior of the silo and the results indicate that the horizontal pressure from the grains is resisted by the internal wall under tension, and that the vertical friction force is mainly carried by both the external and internal walls. The stability of the internal wall is effectively provided by the external wall. The selection of connection model between the internal and external walls has a significant impact on the structural performance of the silo. To make the optimal selection, further verification and experimental studies are needed.

PurposeThis paper investigates thermal mass performance (TMP) in hot climates. The impact of using precast concrete (PC) as a core envelope with different insulation materials has been studied. The aim is to find the effect of building mass with different weights on indoor energy consumption, specifically cooling load in hot climates.Design/methodology/approachThis research adopted a case study and simulation methods to find out the efficiency of different mass performances in hot and humid climate conditions. Different scenarios of light, moderate and heavyweight mass using PC have been developed and simulated. The impact of these scenarios on indoor cooling load has been investigated using the integrated environment solution-virtual environment (IES-VE) software.FindingsThe results showed that adopting a moderate weight mass of two PC sheets and a cavity layer in between can reduce indoor air temperature by 1.17 °C; however, this type of mass may increase the cooling demand. On the other hand, it has been proven that adopting a heavyweight mass for building envelopes and increasing the insulation material has a significant impact on reducing the cooling load. Using a PC Sandwich panel and increasing the insulation material layers for external walls and thickness by 50 mm will reduce the cooling load by 15.8%. Therefore, the heavyweight mass is more efficient compared to lightweight and moderate mass in hot, humid climate areas such as the UAE, in spite of the positive indoor TMP that can be provided by the lightweight mass in reducing the indoor air temperature in the summer season.Originality/valueThis research contributes to the thermal mass concept as one of these strategies that have recently been adopted to optimize the thermal performance of buildings and developments. Efficient TMP can have a massive impact on reducing energy consumption. However, less work has investigated TMP in hot and humid climate conditions. Furthermore, the impact of the PC on indoor thermal performance within hot climate areas has not been studied yet. The findings of this study on TMP in the summer season can be generated in all hot climate zones, and investigating the TMP in other seasons can be extended in future studies.