Thermal Performance Assessment of External Wall Construction for Energy-Efficient Buildings

Abstract

Building envelope such as external walls are still constructed from poor materials which results in higher heating and cooling loads thereby raising energy bills. Improving building energy efficiency with advanced technologies is being sought. In this context, a numerical study was conducted to solve the coupled heat transfers through a standard wall structure used in Libyan residential buildings. Different techniques were compared to reduce the thermal transmittance of the traditional wall structure for saving energy including the application of radiant shield, low-e coating, insulating filling and external insulation. The numerical results revealed that the thermal radiation inside the cavities of hollow block is important and accounts for 21% of total heat transfer, while conductive and convective heat transfer contributes by 65% and 14% from the total, respectively. The obtained thermal transmittance value of the common wall structure was considered as high as 2.33 W/m 2 •K due to lower resistance of wall elements. The adoption of 50 mm layer of expanded polystyrene insulation (EPS) to the exterior wall showed the best thermal performance with a reduction of thermal transmittance by 45%. On the other hand, filling the interior of cavities with EPS resulted in a 37% reduction of thermal transmittance compared to 20% of using 3 mm aluminum foil as a radiant barrier in the middle of the cavities. The last case was less effective with a reduction of almost 10% when a commercial coating of 0.4 surface emissivity was applied to the interior of cavities.

A Comparative Analysis of Traditional and New Construction Methods for External Wall Insulation in Jiangning, Nanjing, China

“…Several studies have explored the optimization of thermal insulation thickness for buildings in diverse climates [22] , the use of external thermal insulation composite systems with materials such as Styrofoam and mineral wool in new constructions [7]and the benefits of external insulation methods in enhancing energy efficiency and reducing life-cycle costs [23].Traditional external insulation composite systems usually entail attaching insulation materials to walls using binders or anchoring parts, followed by the application of protective and decorative layers [24]. In contrast, more recent methods, such as using thermal insulation blocks, have demonstrated significant reductions in heat transfer and energy consumption in residential buildings [5]Comparative analyses have also been conducted to decrease the thermal transmittance in traditional wall structures by employing techniques like radiant shields, low-e coatings, and insulating fillings [25].Moreover, research has emphasized the advantages of incorporating innovative materials, such as MgO-based boards, in construction to promote sustainability and energy efficiency [26]This includes benefits such as improved energy storage, enhanced comfort, and increased resistance to fire. Moreover, studies have examined the influence of insulation materials on building energy efficiency by comparing traditional options with cuttingmaterials, such as aerogel and vacuum insulation panels [3].In addition, research on the thermal performance of various wall constructions, featuring straw bales, bio-based materials, and rammed earth, has demonstrated their ability to provide effective thermal insulation and enhance hygrothermal comfort [14]; [4]; [27].Furthermore, studies have delved into optimizing insulation thickness through real-time measurements and examined the influence of factors, such as surface reflectivity, on insulation strategies for buildings in diverse climates [12]; [28].In summary, the field of external wall insulation methods encompasses a diverse range of studies that examine both traditional and contemporary construction techniques, assess the thermal performance of various materials, and aim to improve energy efficiency in buildings.…”

Thermal conductivity improvement in a green building with Nano insulations using machine learning methods

“…The important factors in the field of reducing energy consumption in buildings are climate conditions and insulation thickness. The optimal thickness of the advanced seals and insulations based on the climate conditions of the cities are considered as a great concern for many researchers (Ertürk and Keçebaş, 2021;Kon et al, 2021;Alfarawi et al, 2022;;Aktemur et al, 2021). The results of the studies proved that energy saving through the insulations method can create effective influences on the constructions industries (Gustavsson and Piccardo, 2022;Aydin and Biyikoğlu, 2021).…”