Thermal resistance of masonry walls: a literature review on influence factors, evaluation, and improvement

Abstract

Increasing the thermal resistance of masonry wall systems is one of the effective ways to reduce energy consumption in the operation of masonry buildings. This increase is also demanded by newer, more stringent energy codes. However, the effective thermal resistance ( R-value) of masonry walls is affected by many factors, such as thermal bridging, which occurs in places where highly conductive structural components penetrate insulating materials. Thermal bridging is common when connecting masonry veneers to structural backup walls. Furthermore, quick and precise methods for estimating the R-value are needed for thermal design improvements and code-compliance calculations. This study presents a comprehensive literature review on key factors that influence the overall thermal performance of masonry walls, methods to effectively estimate and measure R-values, and improvements in thermal design. In addition to identifying the main technical and practical challenges and the corresponding progress made on each front, key design considerations, such as code compliance, material properties, insulation types, and location, as well as special ties and shelf angles types, are also discussed. This study summarizes critical information and recommendations that will help improve the thermal design of masonry walls, hence reducing the energy consumption of buildings.

Hygrothermal performance of a brick wall with interior insulation in cold climate: Vapour open versus vapour tight approach

“…To erect energy efficient, moisture safe and thermally comfortable buildings the modern masonry structures offer a wide variety of solutions – a review of which is presented by Ismaiel et al (2021). However, the need for a thermal upgrade also affects existing buildings where the inherently safer exterior insulation may not be desirable or possible.…”

Selection of Exterior Wall System and MCDM Derived Decision

“…This type of wall is characterised by highly rated system solutions in terms of construction, but may have limited availability on the local market depending on the manufacturer and the availability of skilled labour (Table 3). Extremely good thermal characteristics (Ismaiel et al, 2021), but also high price (Figure 7), are some of the distinctive characteristics of this system. The exterior wall system designated as "S2", presented in Figure 8, is an exterior wall system whose core material is made of concrete-core polystyrene or extruded polystyrene blocks filled with concrete, as a very good and precise system solution in terms of construction.…”

“…It does not have a wide range of applications, due to smaller design ranges available, however its thermal performances are high (Figure 8). (Ismaiel et al, 2021) The exterior wall system designated as "S3", presented in Figure 9, is the system whose core material is made of clay. The exterior wall system S3 could be observed through its vertical cross section: interior plaster -1cm, thermally improved ceramic block -25cm, thermal insulation (XPS) -10cm and façade acrylic plaster as the outer layer -0.5cm.…”

“…It has improved thermal properties (Fioretti & Principi, 2014) due to the geometry of the horizontal cross section of the block, lambda value presented in Figure 8, but due to their dimensions the blocks tend to be heavy, and thus, difficult to handle, and processed later. They do offer good availability on local market, there is qualified labour, but like all walls in this group, they do not have sufficiently good thermal characteristics (Caruana et al, 2017), and during the design phase and the actual execution of work, thermal bridges and linear transmission losses are common (Ismaiel et al, 2021). 3.4 THE EXTERIOR WALL SYSTEM S4 (system belonging to the group of ceramic / structural clay products)…”

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

“…There are many studies on using some efficient technologies and sustainable materials to improve energy performance of building envelope (namely, the external wall). Accuracy depends on the adopted approach to calculate the effective thermal conductance/transmittance (U-value) including the use of simplified analytical approach, detailed numerical simulation or experiment (Ismaiel et al, 2021). Bodalal (2010) numerically investigated the impact of building envelope construction materials on the thermal performance of residential buildings in Benghazi-Libya using three scenarios.…”