Search Results (18)

Lightweight steel-framing (LSF) systems have become increasingly prominent in modern construction due to their structural efficiency, design flexibility, and sustainability. However, traditional facade materials such as stone are often cost-prohibitive, and brick veneers—despite their popularity—pose seismic performance concerns. This study introduces an innovative porcelain sheathing system for cold-formed steel (CFS) shear walls. Porcelain has no veins thus it offers integrated and reliable strength unlike granite. Four full-scale CFS shear walls incorporating screwed porcelain sheathing (SPS) were tested under combined cyclic lateral and constant gravity loading. The experimental program investigated key seismic characteristics, including lateral stiffness and strength, deformation capacity, failure modes, and energy dissipation, to calculate the system response modification factor (R). The test results showed that configurations with horizontal sheathing, double mid-studs, and three blocking rows improved performance, achieving up to 21.1 kN lateral resistance and 2.5% drift capacity. The average R-factor was 4.2, which exceeds the current design code values (AISI S213: R = 3; AS/NZS 4600: R = 2), suggesting the enhanced seismic resilience of the SPS-CFS system. This study also proposes design improvements to reduce the risk of brittle failure and enhance inelastic behavior. In addition, the results inform discussions on permissible building heights and contribute to the advancement of CFS design codes for seismic regions. Full article

The accurate evaluation of the thermal performance of building envelope components (e.g., facade walls) is crucial for the reliable evaluation of their energy efficiency. There are several methods available to quantify their thermal resistance, such as analytical formulations (e.g., ISO 6946 simplified calculation method), numerical simulations (e.g., using finite element method), experimental measurements under lab-controlled conditions or in situ. Regarding measurements, when using the heat flow meter (HFM) method, very often, the measured value is based on surface conditions (e.g., temperature and heat flux), achieving in this way the so-called surface-to-surface or conductive thermal resistance ($R_{cond}$). When the building components are made of homogeneous layers, their $R_{cond}$ values are constant, regardless of their internal and external surface boundary conditions. However, whenever this element is composed of inhomogeneous layers, such as in lightweight steel-framed (LSF) walls, their $R_{cond}$ values are no longer constant, depending on their thermal surface resistance. In the literature, such systematic research into how these $R_{cond}$ values vary is not available. In this study, the values of four LSF walls were computed, with different levels of thermal conductivity inhomogeneity, making use of four finite elements’ numerical simulation tools. Six external thermal surface resistances ($R_{\mathrm{s}\mathrm{e}}$) were modelled, ranging from 0.00 up to 0.20 m²·K/W. The average temperature of the partition LSF walls is 15 °C, while for the facade LSF walls it is 10 °C. It was found that the accuracy values of all evaluated numerical software are very high and similar, the $R_{cond}$ values being nearly constant for walls with homogeneous layers, as expected. However, the variation in the $R_{cond}$ value depends on the level of inhomogeneity in the LSF wall layers, increasing up to 8%, i.e., +0.123 m²·K/W, for the evaluated $R_{\mathrm{s}\mathrm{e}}$ values. Full article

In order to maintain the quality of construction for nearly zero energy buildings and to reduce the pressure on construction workers with the addition of the need for faster and simpler structures, the use of cavity-insulated LSF (lightweight steel frame) panels is increasing. Requirements for performance quality, quality of life, and low energy consumption have led to the need for closer examination of heat transfer through building elements. Due to the impact on increased heat losses, thermal bridges can cause structural damage due to the increased risk of water vapor condensation on the interior surface. In this paper, numerical heat transfer analysis with the optimization of thermal bridges for LSF cavity insulated walls was made in order to reduce the overall transmission heat losses. The effects of different cavity insulation materials (mineral wool and polyurethane foam) on overall heat transferred through the building elements were analyzed. Additionally, in order to reduce the effect of thermal bridges caused by the steel frame structure, the PVC spacers between the steel and sheathing panels are introduced into calculation models. Lastly, additional layers of insulation were added on the internal and external sides of the LFS panels in order to minimize the effect of thermal bridges and maximize air tightness. Combinations of all three setups were made for wall–window, ceiling–wall, wall–floor joints for the numerical calculation. For each setup, the temperature distribution and overall heat transferred through the building elements were calculated. Different thermal bridge designs have a significant influence on the overall heat transfer, and by choosing the optimal design, the transmission heat losses can be reduced by up to 67%. Full article

The thermal performance of lightweight steel framed (LSF) facade walls depends on many factors, such as the steel studs, the batt insulation, the external thermal insulation composite systems (ETICS), and the sheathing layers. Moreover, the high thermal conductivity of steel could negatively affect their thermal performance due to the consequent thermal bridge effect. Furthermore, in LSF walls, the batt insulation is usually bridged by the steel studs. Thus, some analytical calculation procedures defined in standards (e.g., ISO 6946) are not valid, further complicating their thermal performance quantification. In this research, a parametric study to evaluate the thermal performance of facade LSF walls is presented. Seven relevant parameters are assessed, most of them related to the use of thermal break strips (TBS) and ETICS. The 2D numerical models used to predict the conductive $R$-values were experimentally validated, and their precision was successfully verified. As earlier found in a previous research work for partition LSF walls, it is also more effective for facades to increase the TBS thickness rather than their width, with the $R$-value increments being slightly smaller for facade LSF walls. These features were more pronounced for double TBS and for the smaller stud spacing (400 mm). The major thermal performance improvements were found when increasing the ETICS insulation thickness and decreasing their thermal conductivity. Full article

Thermal bridges are a very relevant issue for lightweight steel-framed (LSF) construction systems given the high thermal conductivity of steel, which can negatively compromise their thermal behaviour, reduce their durability, and decrease the building energy efficiency. Several thermal bridge mitigation strategies exist, including the attachment of thermal break strips (TBS) to the steel studs’ flanges as one of the most widely employed techniques. In this research, the relevance of TBS to the thermal performance improvement of load-bearing LSF partition walls was assessed by performing a parametric study, making use of a validated 2D numerical model. A sensitivity analysis was performed for five different key parameters, and their importance was evaluated. The assessed parameters included the number of TBS and their thickness, width, and thermal conductivity, as well as the vertical steel stud spacing. We found that these parameters were all relevant. Moreover, regardless of the TBS thermal conductivity, it is always worth increasing their thickness. However, the increase in the TBS width does not always lead to increased thermal resistance; a thermal performance reduction was noted when increasing the width of the TBS at higher thermal conductivities. Therefore, it was concluded that it is more efficient to increase TBS thickness than their width. Full article

The strategic issue faced by the Ministry of Public Works and Housing, Republic of Indonesia (PUPR) is the large housing backlog, especially in the urban areas. Low-income communities earning less than 2 USD/day are found as the most vulnerable to lack of access to affordable housing. This experiment aims to find an alternative solution on building construction material in accordance with the Ministry of Public Housing regulation No. 11 of 2011 about affordable housing guidelines. The experiment was carried out on an LSF to compare four different wall cladding materials. The building area was 36 m² and the total wall cladding area was 95 m². The wall cladding materials used were metal sheet, lightweight concrete brick, gypsum reinforced cement (GRC) board, and unplasticized polyvinyl chloride (uPVC) fiber. The experiment collected data on purchases of materials to develop the S-curve and measure construction progress. Then, the work unit price analysis (WUPA) approach was carried out to simulate the labor coefficient of construction speed and its comparison to the material costs of the four wall cladding materials. The experiment on this 36 m² house found that metal sheet is the most efficient material, which took 22.7 h to cover a 95 m² wall. Later, it was followed by uPVC fiber with 46.6 h, GRC board with 59.7 h, and finally lightweight con-bricks with 85.7 h. Apparently, the metal sheet not only presented the most efficient construction time, but also provided the lowest construction cost with 115.960 IDR/m² (8.24 USD/m²). It was followed by uPVC fiber at 133.37 IDR/m² (9.48 USD/m²); GRC board at 146.91 IDR/m² (10.44 USD/m²) and finally lightweight con-bricks at 156.88 IDR/m² (11.15 USD/m²). Through WUPA, this study also found that efficient workmanship (construction speed) of the labor greatly affects construction costs. Full article

Thermal bridges may have a significant prejudicial impact on the thermal behavior and energy efficiency of buildings. Given the high thermal conductivity of steel, in Lightweight Steel Framed (LSF) buildings, this detrimental effect could be even greater. The use of thermal break (TB) strips is one of the most broadly implemented thermal bridge mitigation technics. In a previous study, the performance of TB strips in partition LSF walls was evaluated. However, a search of the literature found no similar experimental campaigns for facade LSF walls, which are even more relevant for a building’s overall energy efficiency since they are in direct contact with the external environmental conditions. In this article the thermal performance of ten facade LSF wall configurations were measured, using the heat flow meter (HFM) method. These measurements were compared to numerical simulation predictions, exhibiting excellent similarity and, consequently, high reliability. One reference wall, three TB strip locations in the steel stud flanges and three TB strip materials were assessed. The outer and inner TB strips showed quite similar thermal performances, but with slightly higher thermal resistance for outer TB strips (around +1%). Furthermore, the TB strips were clearly less efficient in facade LSF walls when compared to their thermal performance improvement in load-bearing partition LSF walls. Full article

This paper proposes an improvement of the conventional Lightweight Steel Frame (LSF) wall structure suitable for the design of high-performance modular buildings. A mobile module, named MUZA, is used as a case study building to analyse the performance of such LSF structures in terms of their thermal bridging effect on the U-value of the opaque envelope elements, linear heat losses at junctions, and moisture condensation risk, as well as thermal bridging effect on the overall energy performance of the building. The study included an additional climate- and orientation-dependent analysis that examined the performance of MUZA under various conditions. The main conclusion is that the steel studs increase the U-value from 28.4% to 41.6% compared to cases without the studs, which consequently increases transmission losses through opaque elements. Thanks to the continuous covering of the metal studs with thermal insulation, the thermal bridges at the element junctions are minimized, and in almost all cases, the Ψ-values are well below 0.1 W/(m·K) and are free from moisture condensation. The overall impact of thermal bridges on heating energy demand is significant, while the impact on cooling energy is less pronounced. The designed module with the proposed LSF wall structure can meet the Croatian requirements for Nearly Zero-Energy Buildings (NZEB), but the shading devices and photovoltaics orientation must be optimized depending on the climatic conditions and the orientation of the large transparent openings. MUZA can be a promising solution for post-disaster housing, providing better indoor environmental quality, healthy living conditions, and low energy bills for the affected people. In addition, it can also be used for permanent housing when a fast and robust modular construction is required which is also energy efficient and sustainable. Full article

The thermal performance of Lightweight Steel Framed (LSF) walls could be strongly compromised due to steel’s high thermal conductivity and their related thermal bridges. In this paper, the performance of bio-based (pine wood) and recycled (rubber–cork composite) Thermal Break Strip (TBS) materials, to mitigate the thermal bridge effect originated by steel profiles in LSF partition walls, is evaluated. This assessment was achieved by measurements under controlled laboratory conditions and by predictions using some numerical simulation models. Regarding the measurements, two climatic chambers (cold and hot) were used to impose a nearly constant temperature difference (around 35 °C), between the LSF partition test samples’ surfaces. To measure the overall surface-to-surface thermal resistance (R-value) of the evaluated LSF wall configurations, the Heat Flow Meter (HFM) method was used. Moreover, the measured values were compared with the calculations by 2D (THERM models) and 3D (ANSYS models) numerical simulations, exhibiting an excellent agreement (less than ±2% difference). Three TBS locations and three materials are evaluated, with their thermal performance improvement compared with a reference interior partition LSF wall, having no TBS. The top performance was accomplished by the aerogel super-insulating TBS material. The bio-based material (pine wood) and the recycled rubber–cork composite present quite similar results, with a slight advantage for the pine wood TBSs, given their higher thickness. Considering the TBS location, the inner and outer side present comparable performances. When using TBSs on both sides of steel profile flanges, there is a relevant thermal performance improvement, as expected. The thickness of the TBS also presents a noteworthy influence on the LSF partition thermal resistance. Full article

Light steel frame (LSF) building systems offer high structural resilience, lower costs due to fast prefabrication, and high ability to recycle and reuse. The main goal of this paper was to provide state-of-the-art main components for such systems with the intention to be implemented for use in nearly-zero energy buildings (NZEBs). A brief historical outline of the development of LSF systems was given, and the key parameters affecting the design and use of LSF systems were discussed. The influence of the individual components of the LSF system (steel studs, sheathing boards, and insulation materials) was then thoroughly discussed in light of relevant research on energy efficiency and other important properties (such as sound protection and fire resistance). Web of Science and Scopus databases were used for this purpose, using relevant key words: LSF, energy efficiency, sheathing boards, steel studs, insulation, etc. Several research gaps were identified that could be used for development and future research on new LSF systems. Finally, based on the analysis of each component, an innovative LSF composite wall panel was proposed which will be the subject of the authors’ future research. Conducted preliminary analysis showed low thermal transmittance of the system and indicates the path of its further research. Full article

A variety of mathematical models are available to estimate the thermal performance of buildings. Nevertheless, mathematical models predict the thermal performance of buildings that might differ from the actual performance. The hot box is a widely-used test apparatus to assess the actual thermal performance of various building envelope components (walls, roofs, windows) in the laboratory. This paper presents the process of designing, constructing, and calibrating a unique small-scale hot box apparatus. Despite its smaller metering area (1.0 m × 1.0 m), this apparatus met the key requirements (below ±0.25 °C fluctuations in chambers’ air temperature, and below 2.0% variation from the point-to-point temperature in reference to the temperature difference across the specimen) as prescribed in the ASTM C1363 and ISO 8990 standards. The walls of this apparatus are uniquely constructed using vacuum insulation panels or VIPs. The efficient and novel use of VIPs and workmanship during the construction of the apparatus are demonstrated through the temperature stability within the chambers. The achieved range of temperature steadiness below ±0.05 °C and point-to-point temperature variation below 1.0% of the temperature difference across the specimen allow for this apparatus to be considered unique among the calibrated hot box categories reported in the literature. In addition, having an affordable, simple-to-operate, and high-accuracy facility offers a great opportunity for researchers and practitioners to investigate new ideas and solutions. The apparatus was calibrated using two extruded polystyrene foam (XPS) specimens with thicknesses of 2″ and 4″. The calibration exercise indicates small differences between results obtained numerically, theoretically, and experimentally (below 3.0%). Ultimately, the apparatus was employed to measure the thermal properties of a specimen representing a lightweight steel framing (LSF) wall system, which is commonly used in cold climates. The results obtained experimentally were then compared to the ones estimated numerically using a 3D finite element modelling tool. The difference between the results obtained by both methods was below 9.0%. Full article

Typically, reinforced concrete and brick masonry construction is the most common construction system of the majority of the southern European residential building stock. However, the lightweight steel framing (LSF) construction system has been progressively assuming a relevant position in the residential sector. Since LSF is not the traditional construction system, the indoor thermal environment of these buildings has not been widely studied and discussed considering the southern European climate context. The low thermal inertia of this construction system is commonly pointed to as a possible weakness in warmer climates. The present work aims to address this research gap by evaluating and comparing the LSF and masonry construction systems in terms of the indoor thermal environment focusing on the level of thermal inertia. The considered methodology lies in a long-term experimental campaign based on the construction and monitoring of two identical experimental test cells, differing only in the construction system. The test cells are in the central region of Portugal. The monitoring period elapsed over an entire year. Dynamic simulations are also carried out with a model experimentally validated to consider a wider range of climatic conditions. It is shown that internally insulating the ground floor has an impact on the indoor thermal environment of the LSF test cell by accentuating the indoor air temperature fluctuations and magnitude of the extreme peak values. However, the results also reveal that the faster and closer response to the outdoor conditions may be beneficial for LSF buildings during the heating season. Full article

Lightweight Steel Frames (LSF) in building construction are becoming more popular due to their fast, clean, and flexible constructability. Typical LSF wall panels are made of cold-formed and thin-walled steel lipped channel studs with plasterboard linings. Due to the high thermal conductivity of steel, these LSF components must be well engineered and covered against unintended thermal bridges. Therefore, it is essential to investigate the heat transfer of the LSF wall of different configurations and reduce heat loss through walls by lowering the thermal transmittance, which would ultimately minimise the energy consumption in buildings. The effect of novel thermal insulation material, Vacuum Insulation Panels (VIP), their position on the LSF wall configuration, and Oriented Strand Board (OSB) and plasterboard’s effect on the thermal transmittance of LSF walls were investigated through numerical analysis. A total of 56 wall configurations and 112 finite element models were analysed and compared with the minimum U-value requirements of UK building regulations. Numerical model results exhibited that using plasterboards instead of OSB has no considerable effect on the U-value of the LSF walls. However, 77% (4 times) of U-value reduction was exhibited by introducing the 20 mm VIP. Moreover, the position of the VIP to the U-value of LSF was negligible. Based on the results, optimum LSF wall configurations were proposed by highlighting the construction methods. Additionally, this study, through literature, seeks to identify other areas in which additional research can be conducted to achieve the desired thermal efficiency of buildings using LSF wall systems. Full article

The reduction of unwanted heat losses across the buildings’ envelope is very relevant to increase energy efficiency and achieve the decarbonization goals for the building stock. Two major heat transfer mechanisms across the building envelope are conduction and radiation, being this last one very important whenever there is an air cavity. In this work, the use of aerogel thermal break (TB) strips and aluminium reflective (AR) foils are experimentally assessed to evaluate the thermal performance improvement of double-pane lightweight steel-framed (LSF) walls. The face-to-face thermal resistances were measured under laboratory-controlled conditions for sixteen LSF wall configurations. The reliability of the measurements was double-checked making use of a homogeneous XPS single panel, as well as several non-homogeneous double-pane LSF walls. The measurements allowed us to conclude that the effectiveness of the AR foil is greater than the aerogel TB strips. In fact, using an AR foil inside the air cavity of double-pane LSF walls is much more effective than using aerogel TB strips along the steel flange, since only one AR foil (inner or outer) provides a similar thermal resistance increase than two aerogel TB strips, i.e., around +0.47 m²∙K/W (+19%). However, the use of two AR foils, instead of a single one, is not effective, since the relative thermal resistance increase is only about +0.04 m²∙K/W (+2%). Full article

One strategy to increase energy efficiency of buildings could be the reduction of undesirable heat losses by mitigating the heat transfer mechanisms across the building envelope. The use of thermal insulation is the simplest and most straightforward way to promote thermal resistance of building elements by reducing the heat transfer by conduction. However, whenever there is an air cavity, radiation heat transfer could be also very relevant. The use of thermal reflective insulation materials inside the air gaps of building elements is likewise an effective way to increase thermal resistance without increasing weight and wall thickness. Some additional advantages are its low-cost and easy installation. In this work, the performance of a thermal reflective insulation system, constituted by an aluminium foil placed inside an air cavity between a double pane lightweight steel framed (LSF) partition, is experimentally evaluated for different air gap thicknesses, ranging from 0 mm up to 50 mm, with a step increment of 10 mm. We found a maximum thermal resistance improvement of the double pane LSF walls due to the reflective foil of around +0.529 m²∙°C/W (+21%). The measurements of the $R$-values were compared with predictions provided by simplified models (CEN and NFRC 100). Both models were able to predict with reasonable accuracy (around ±5%) the thermal behaviour of the air cavities within the evaluated double pane LSF walls. Full article