Cavity Insulation Research Articles

Fire performance of superabsorbent polymers protected full-scale cold-formed steel wall lined with plasterboards

Superabsorbent polymers (SAPs) have shown promise in enhancing the fire resistance of steel structures because of their exceptional absorbency and water retention capabilities. This study innovatively applies SAP insulation to cold-formed steel (CFS) walls with gypsum (GP) boards to improve fire performance. One full-scale CFS wall underwent axial compression testing at ambient temperature, and four full-scale fire experiments were conducted on CFS walls with load ratios of 0.27 and 0.85. All specimens were sheathed with double layers of GP boards, and rock wool served as the cavity insulation, with SAP insulation material applied to the cavity of wall studs. Additionally, a novel finite element model was developed to simulate the fluid-heat interaction within a furnace-CFS wall. The simulation results showed that SAP insulation material significantly changes the fire-induced failure mode in wall studs at a 0.27 load ratio, transitioning from hot flange (HF) local buckling to local buckling of the whole stud section. The inclusion of SAP insulation material absorbs heat, effectively delaying the rise in wall stud temperature. This property significantly enhances the structural performance of CFS walls during fire exposure. With SAP insulation material, the fire resistance time of the CFS walls increased by over 66 min compared to non-SAP insulation material counterparts. Moreover, increasing the stud web depth and reducing the HF width-to-thickness ratio can enhance the fire performance of CFS walls. The HF critical failure temperature of specimen S2 with an HF width-to-thickness ratio of 80 was 783 °C, 150 °C higher than that of specimen P2 with an HF width-to-thickness ratio of 67. Additionally, the adverse effect of screws on the fire performance of the CFS wall was localized. After 120 min of fire exposure, the temperature on the ambient side, which was severely influenced by the screws, was 360 to 370 °C.

Design and characterization of geopolymer foams reinforced with Miscanthus x giganteus fibres

This paper presents the results of the optimisation and characterization of Miscanthus fibre reinforced geopolymer foams based on fly ash and represents an important step forward in the development of a sustainable and environmentally friendly insulation material. Miscanthus belongs to a promising group of renewable raw materials with favourable thermal insulation properties. Design of experiment (DoE) were used to optimize the thermal conductivity and compressive strength of Miscanthus x giganteus reinforced geopolymer foams. In addition, the samples was analyzed using X-ray diffraction (XRD), Field emission scanning electron microscopy (SEM) and Fourier-Transform Infrared Spectroscopy (FTIR). Mixtures with a low thermal conductivity of 0.056 W (m K)−1 and a porosity of 79 vol% achieved a compressive strength of only 0.02 MPa. In comparison, mixtures with a thermal conductivity of 0.087 W (m K)−1 and a porosity of 58 vol% achieved a compressive strength of 0.45 MPa. Based on the determined parameters especially due to the low compressive strength, an application as cavity insulation or insulation between rafters is possible.

Fire performance enhancement of cold-formed steel walls: experimental and numerical study

Cavity-insulated cold-formed steel (CFS) walls, with gypsum plasterboard (GP) on both sides, are widely used in the construction industry. However, their fire performance is compromised by the faster rise in the temperature of the hot flange (HF), which is influenced by cavity insulation and board joints. This study aims to optimize cavity insulation configuration to enhance fire performance. Two mid-scale, non-load-bearing fire experiments on CFS walls were conducted, employing double-layered GP boards and rock wool insulation, under ISO834 time-temperature fire conditions. Meanwhile, a finite element model of physical space fluid-heat coupling of furnace-CFS walls considering joints with time was developed to reveal joint mechanisms and configurations. The results showed that non-insulated stud CFS walls had slower HF temperature rise and similar insulation compared to insulated counterparts, delaying HF temperature reach to 537 °C by 14 min. The base-layer joints had the least adverse impact on the HF temperature rise than overlapped joints and face-layer joints. The HF temperatures for various joint configurations reached 537 °C at different times: 57 min for the face layer, 62 min for the base layer, and 49 min for overlapped joints. Considering the construction cost-effectiveness, it was found that adding steel strips (the same width as the flange) at the joint position could significantly decelerate the HF temperature rise. In 60 min, the HF temperature in the model with additional steel strips dropped by 94 °C lower than in the 10 mm overlapped joint model. Finally, based on finite element results, design equations were proposed for predicting HF temperature variation over time across joint types.

Trampolines and insulation and data, Oh My!

This presentation will discuss sound and vibration data gathered for two separate and unrelated acoustical consultations. The first is a consultation for an adventure park facility (trampolines, arcade games, ball pits, etc.) planned on the upper level of an existing mall; acoustical concerns included vibration from jumping on trampolines and noise from amplified music to adjacent tenant spaces. The second is a comprehensive set of sound level reduction measurements in accordance with ASTM E336 / ASTM E2235, as well as ASTC calculations in accordance with ASTM E413; these results facilitated an investigation of the effect of complete versus partial cavity insulation within partitions.

Numerical modelling and investigation of CFS built-up stud walls in fire

Cold-formed steel (CFS) stud walls with the studs made of BC (built-up back-to-back CFS channel) and NC (built-up nested CFS channel) members are likely to be utilised in many applications in CFS building structures. However, the knowledge and understanding related to the thermal and structural behaviour of these improved CFS stud walls under fire exposure and their FRLs (fire resistance levels) are still limited. Although standard fire tests of real-sized walls could show the behaviour and FRL of some BC and NC stud walls, their results are limited because of their high cost and time-consuming nature, and are applicable to only the tested configurations. In this study, thermal and sequentially coupled structural finite element models were established. The validation of these models was achieved using the standard fire test results of real-sized BC, NC and channel stud walls. Later, parametric investigations based on the established models were undertaken to investigate the behaviour and FRLs of load-bearing BC, NC and channel stud walls with or without cavity insulation under varying load ratios. The outcomes from these investigations clarified the superiority of cavity insulated NC stud walls. Details of this study and its outcomes are presented in this paper.

Optimization of Thermal Bridges Effect of Composite Lightweight Panels with Integrated Steel Load-Bearing Structure

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%.

Predicting the behaviour of external steel walls under bushfire radiant heat conditions

External walls of the buildings possess the highest surface area and significantly contribute to the buildings’ bushfire resilience. Therefore, this study is aimed at advancing the understanding the behaviour of the external light steel framed walls exposed to bushfires, in particular the heat transfer across the walls. It presents a detailed numerical study where suitable numerical models were developed to simulate two series of experiments conducted under indoor and outdoor conditions and validated using the experimental results. The study was then extended to predict the heat transfer of light steel framed wall systems under different bushfire conditions for buildings in the bushfire flame zone (BAL-FZ) and the highest radiant heat exposure zone (BAL-40). The results showed (a) the importance of using steel cladding in the external walls, (b) the effect of different cavity insulation, and (c) the importance of selecting the suitable wall boards for different bushfire conditions. Based on the modelling results, it recommends suitable zone-specific wall systems to reduce cost and material use, and acceptable design load ratios for the construction of the selected external light steel framed walls in two critical regions in the bushland urban interface.

Fire performance of gypsum-sheathed cold-formed steel walls with rectangular section studs

This study conducted axial compression experiment of one full-scale CFS wall at ambient temperature and four full-scale fire experiments of CFS walls with two initial load ratios of 0.27 and 0.85. Specimens were sheathed with double layers of gypsum plasterboard, rock wool was the cavity insulation and the wall studs had rectangular cross sections. A finite element model was used to optimize the arrangement of rock wool cavity insulation for the CFS walls. The results showed that the failure mode changed from local buckling of the hot flange under a load ratio of 0.27 to local buckling of the whole stud section under a load ratio of 0.85. The fire resistance time of the specimen without rock wool insulation in the stud cavity was 7 min longer than that of the specimen with rock wool insulation. This was attributed to the thermal radiation effect of the stud cavities, which delayed the increase in hot flange temperature and improved the fire resistance time of the CFS walls. Thus, for CFS walls with rock wool-insulated cavities, the stud cavity configuration was more reasonable without than with rock wool insulation. When the axial thermal expansion load was considered, the load on the wall studs increased by a maximum of 43.3 kN per stud. In addition, for CFS walls with low load ratios of 0.27, the wall studs near the face-layer board joints tended to buckle first.

Design and 3D printing of porous cavity insulation structure for ultra‐high electrical withstanding capability

AbstractVacuum‐dielectric interface is the most vulnerable part of vacuum insulation systems where surface electrical breakdown is prone to happen, hence severely restricts the development of advanced electro‐vacuum devices with large capacity and its miniaturisation. Generally, a direct and effective way to improve vacuum surface insulation is to alleviate the initiation and development of multipactor phenomena. Inspired by this approach, the authors report a 3D‐printed insulation structure designed with a millimetre‐scale surface cavity covered by periodic through‐pore array via stereolithography, exhibiting remarkable multipactor suppression and flashover threshold improvement, well outperforming the conventional flashover mitigation strategies. Experiments and simulations demonstrate that electrons in the multipactor region pass through‐pores and are unlikely to escape from the cavity, hence no longer participate in the above‐surface multipactor process, and eventually improve flashover threshold. The proposed approach provides new inspiration for the design of advanced insulators featuring ultra‐high electrical withstanding capability and brings up new insight into pertinent industrial applications.

Full-scale tests of load-bearing LSF walls made of built-up CFS channel sections under fire conditions

Built-up cold-formed steel (CFS) studs, such as back-to-back channels (BC) and nested channels (NC) are used in light gauge steel framed (LSF) wall systems instead of the conventional channel studs for improving their load-bearing capacity. However, the knowledge and understanding of their behaviour under fire conditions is limited. In this study, the behaviour of load-bearing LSF walls made of BC and NC studs under fire conditions was investigated using four full-scale standard fire tests. The obtained fire test results were evaluated in terms of both thermal and structural behavioural characteristics and fire resistance level (FRL), and were used in the comparison with those for conventional LSF walls made of single channel studs. The test results showed that (1) without cavity insulation, the thermal and structural behavioural characteristics of the LSF walls made of BC and NC studs are very similar to those of LSF walls made of channel studs, and their FRLs can be taken as the same for the same load ratio (2) LSF walls made of BC and NC studs with two layers of 16 mm thick gypsum plasterboards on each side and without cavity insulation have an FRL of 120 min for a load ratio of 0.4, and (3) the use of cavity insulation reduces the FRL of LSF walls made of NC studs. This paper presents the details of this research study and its outcomes.

Hygrothermal performance optimization of lightweight steel-framed wall assemblies in hot–humid regions using orthogonal experimental design and a validated simulation model

As a layered construction, lightweight steel-framed (LSF) wall assemblies are applicable to different climates and used worldwide. Due to ill-informed construction and material designs, moisture-related durability problems occur, especially in hot–humid areas. Here, a hygrothermal simulation model of typical LSF wall assemblies was validated, and the influences of six construction layers (each with three sets of parameters) on the overall properties and performance were investigated via orthogonal experimental design (OED). Each layer exhibited various impact trends and contribution ratios at different positions. To reduce moisture risks, LSF wall assemblies should generally prevent the infiltration of outdoor moisture as much as possible while strengthening the inward drying capacity. The optimal configuration should comprise multiple water and vapour barriers with a ventilated layer, external insulation, permeable cavity insulation and interior sheathing board with a finish. Finally, this optimization method comprising the hygrothermal simulation and OED techniques could be applied to the hygrothermal performance of LSF wall assemblies under certain climatic conditions.

Fire Propagation Characteristics and Fire Risks of Polyurethanes: Effects of Material Type (Foam & Board) and Added Flame Retardant

Polyurethane material is used as an interior finish and wall cavity insulation. Flame-retardant products may be used for ignition, flame diffusion, and heat-release blocking. A large-scale test was conducted to understand the flame propagation characteristics of polyurethane with the addition of a flame retardant. The fire propagation properties and fire risks of four commonly used polyurethane materials were examined using three tests. Specifically, ignition properties, flame propagation behavior, and flashover occurrence were probed using full-scale tests, while heat release and fire characteristics were examined using cone calorimeter tests, and the toxicity of gaseous combustion products was assessed using gas toxicity tests. PIR F and PIR B, which contained flame retardants, featured slow flame propagation and a long-lasting residual flame, and PIR F released HCl and Br2 on combustion. Full-scale tests revealed that although external flame propagation was always accompanied by flashover, irrespective of whether the flame retardant was present, a delay or blockage of energy transfer to the inside was observed for flame-retardant-containing specimens. Apart from checking the safety at the material level, the importance of identifying the actual fire characteristics through a full-scale test was confirmed.

Fire performance of lightweight concrete-filled LSF wall panels

Light Gauge Steel Frame (LSF) wall panels with cold-formed thin-walled steel-Lipped Channel Sections (LCS) and plasterboard linings are increasingly used in the construction industry due to their lightweight and constructability characteristics. However, due to the high thermal conductivity of the LCS, rapid heat transfer is observed in LSF walls, causing negative impacts to the fire performance of the LSF wall elements. Cavity insulation is one of the practical solutions used in the industry to improve the fire performance of LSF walls. Insulation materials such as rockwool, glass fibre, cellulose fibre, ceramic fibre are commonly used as cavity insulation materials in LSF walls. A novel approach in LSF walls is the introduction of lightweight concrete filling as a cavity filler. The effect of lightweight concrete filling on the fire performance of LSF walls was analysed with the numerical investigation in this study. Fire performance of conventional LSF walls with 12.5 mm and 15 mm single and double plasterboard with Autoclaved Aerated Concrete (AAC) with 600 kg/m3 density, Foam Concrete (FC) with 650 kg/m3 density and FC with 1000 kg/m3 density lightweight concrete fillings were compared with LSF walls without cavity insulation and rockwool insulation under standard and hydrocarbon fire conditions. It was observed promising improvement in insulation and load-bearing fire ratings in LSF walls with lightweight concrete filling. Among lightweight concrete materials considered, FC with 1000 kg/m3 density has exhibited the best fire performance. LSF walls performance could be enhanced with lightweight concrete fillings depending on the application with improved fire performance.

Finite element analysis of lightweight concrete-filled LSF walls exposed to realistic design fire

PurposeLight-Gauge Steel Frame (LSF) structures are popular in building construction due to their lightweight, easy erecting and constructability characteristics. However, due to steel lipped channel sections negative fire performance, cavity insulation materials are utilized in the LSF configuration to enhance its fire performance. The applicability of lightweight concrete filling as cavity insulation in LSF and its effect on the fire performance of LSF are investigated under realistic design fire exposure, and results are compared with standard fire exposure.Design/methodology/approachA Finite Element model (FEM) was developed to simulate the fire performance of Light Gauge Steel Frame (LSF) walls exposed to realistic design fires. The model was developed utilising Abaqus subroutine to incorporate temperature-dependent properties of the material based on the heating and cooling phases of the realistic design fire temperature. The developed model was validated with the available experimental results and incorporated into a parametric study to evaluate the fire performance of conventional LSF walls compared to LSF walls with lightweight concrete filling under standard and realistic fire exposures.FindingsNovel FEM was developed incorporating temperature and phase (heating and cooling) dependent material properties in simulating the fire performance of structures exposed to realistic design fires. The validated FEM was utilised in the parametric study, and results exhibited that the LSF walls with lightweight concrete have shown better fire performance under insulation and load-bearing criteria in Eurocode parametric fire exposure. Foamed Concrete (FC) of 1,000 kg/m3 density showed best fire performance among lightweight concrete filling, followed by FC of 650 kg/m3 and Autoclaved Aerated Concrete (AAC) 600 kg/m3.Research limitations/implicationsThe developed FEM is capable of investigating the insulation and load-bearing fire ratings of LSF walls. However, with the availability of the elevated temperature mechanical properties of the LSF wall, materials developed model could be further extended to simulate the complete fire behaviour.Practical implicationsLSF structures are popular in building construction due to their lightweight, easy erecting and constructability characteristics. However, due to steel-lipped channel sections negative fire performance, cavity insulation materials are utilised in the LSF configuration to enhance its fire performance. The lightweight concrete filling in LSF is a novel idea that could be practically implemented in the construction, which would enhance both fire performance and the mechanical performance of LSF walls.Originality/valueLimited studies have investigated the fire performance of structural elements exposed to realistic design fires. Numerical models developed in those studies have considered a similar approach as models developed to simulate standard fire exposure. However, due to the heating phase and the cooling phase of the realistic design fires, the numerical model should incorporate both temperature and phase (heating and cooling phase) dependent properties, which was incorporated in this study and validated with the experimental results. Further lightweight concrete filling in LSF is a novel technique in which fire performance was investigated in this study.

Improving fire resistance and energy performance of fast buildings made of hollow polypropylene blocks

Polypropylene (PP) lightweight blocks have been recently developed for fast, easy and affordable way of residential and administrative building constructions. Although; PP blocks are characterized by many competitive advantages over traditional brick masonry, they lack of fire resistance owing to their low melting temperature. Therefore this study presents a technical cost-effective solution for improving the fire resistance rating (FRR) of the exposed PP walls to meet the requirements of the international building and international fire codes for providing optimal fire protection for occupants. A fire protective cladding system consists mainly of cold-formed steel framing lined with gypsum plasterboards with cavity insulation has been proposed to attain adequate FRR of exposed PP walls. Fire resistance standard test has been conducted on a representative test assembly to evaluate the FRR of the new composite wall. The contribution of the newly developed cladding to the energy consumption performance of a PP building model as compared to the traditional bricks/blocks has been assessed by using DesignBuilder energy simulation software. FRR of an hour (1-h) has been attained based on verifying structural integrity and thermal insulation of the protected PP wall. Up to an hour of fire exposure, the maximum temperature recorded for the unexposed PP wall surface was 69 °C this confirm the enhanced thermal insulation of the composite wall. The utilization of PP blocks in buildings has reduced the annual energy consumption by about 13 and 33.6% as compared to conventional clay and cement bricks respectively. The cladding system has provided additional considerable reduction in the energy consumption rate of PP blocks.

Novel conventional and modular LSF wall panels with improved fire performance

Fire performance of Light-gauge Steel Frame (LSF) constructions is being extensively investigated recently, due to the critical behaviour of cold-formed steel structures at elevated temperatures. Among the many design parameters involved with LSF constructions, the effect of cavity insulation inside LSF walls at different ratios on the Fire Resistance Level (FRL) has not been addressed yet. Hence, Finite Element Models (FEMs) were developed for the LSF walls to simulate the full-scale fire tests conducted applying the standard fire temperatures, where the Finite Element Analyses (FEA) results were very well agreeing with the experimental results. Thereafter, the validated FEMs were extended to study the fire performance of the conventional and modular LSF wall systems with different cavity insulation ratios, where 0.4 cavity insulation ratio was found to be most efficient when structural FRL is of concern while producing satisfactory energy performance at reduced material costs. To calculate the structural FRLs of conventional and modular, single and double plasterboard layers sheathed LSF walls, 4 empirical models have been proposed where more than 97% accuracy was achieved. Moreover, incorporating back blocking panels and discontinuous insulation options, several novel conventional and modular LSF walls have been proposed with up-to 70% improvement in structural FRL.

Fire resistance of external LSF walls with corrugated steel cladding

This paper presents the details of full-scale standard fire tests of external light-gauge steel-framed (LSF) walls with corrugated steel cladding exposed to fire on the external side. Corrugated steel cladding of 0.42mm thickness is generally used in roof and wall systems of buildings. In this study, it is used as the wall cladding of external LSF walls and as a lightweight cladding replacement to the combustible aluminium composite panels. A detailed investigation was undertaken to evaluate and understand the fire and energy performance of corrugated steel clad external LSF walls, which included (a) thermal property tests of two different types of Earthwool insulation (glass fibre insulation) used in wall systems, (b) full-scale (3m×3m) load bearing standard fire tests of two external LSF wall systems – first with cavity insulation and the second with external insulation and (c) THERM modelling of the tested walls. Steel cladding prevented direct exposure of fire on plasterboards and hence delayed the temperature rise and increased the failure time. Overlaps along the vertical edges of steel cladding played a critical role as gaps formed during the tests. The two external LSF wall systems achieved fire resistance levels (FRLs) in excess of two hours (122min and 158min) with improvements greater than 40% due to the addition of thin steel cladding. Replacing cavity insulation with external insulation improved the FRL by about 30% and also its effectiveness in terms of energy efficiency.

Production and Physical-Mechanical Characterization of Peat Moss (Sphagnum) Insulation Panels.

Peat moss (sphagnum) is a commonly used sealant, fill, and insulation material in the past. During the efforts to rewet drained moors due to ecological considerations, the technical use of peat moss (sphagnum farming) again became the focus of attention. In the framework of this investigation, insulation panels consisting of peat moss, bound with urea formaldehyde, were produced. Panels manufactured in a wet process and mats bound with textiles were also fabricated. The specimens’ thermal conductivity, water vapor diffusion resistance, modulus of rupture, modulus of elasticity, internal bond, compression resistance, water absorption, and thickness swelling were measured. Physical–mechanical properties were adequate with the resin-bound panels, but not with wet process panels. Moss mats had good characteristics for cavity insulation purposes. The thermal conductivity of the moss panels and mats was found to be lowest with a density of 50 kg/m3, accounting for 0.04 W/m·K. The results show that peat moss is a promising resource for production insulation panels, because their thermal conductivity and mechanical stability are comparable to other insulation materials.

Energy Performance of 3D-Printed Concrete Walls: A Numerical Study

Three-dimensional-printed concrete (3DPC), which is also termed as digital fabrication of concrete, offers potential development towards a sustainable built environment. This novel technique clearly reveals its development towards construction application with various global achievements, including structures such as bridges, houses, office buildings, and emergency shelters. However, despite the enormous efforts of academia and industry in the recent past, the application of the 3DPC method is still challenging, as existing knowledge about its performance is limited. The construction industry and building sectors have a significant share of the total energy consumed globally, and building thermal efficiency has become one of the main driving forces within the industry. Hence, it is important to study the thermal energy performance of the structures developed using the innovative 3DPC technique. Thermal characterization of walls is fundamental for the assessment of the energy performance, and thermal insulation plays an important role in performance enhancements. Therefore, in this study, different wall configurations were examined, and the conclusions were drawn based on their relative energy performance. The thermal performance of 32 different 3DPC wall configurations with and without cavity insulation were traced using validated finite element models by measuring the thermal transmittance value (U-value). Our study found that the considered 3DPC cavity walls had a low energy performance, as the U-values did not satisfy the standard regulations. Thus, their performance was improved with cavity insulation. The simulation resulted in a minimum thermal transmittance value of 0.34 W/m2·K. Additionally, a suitable equation was proposed to find the U-values of 100 mm-thick cavity wall panels with different configurations. Furthermore, this study highlights the importance of analytical and experimental solutions as an outline for further research

Energy performance of fire rated LSF walls under UK climate conditions

Light-gauge Steel Frame (LSF) systems, one of the emerging building practices can be susceptible for catastrophic failure in fire accidents and less energy efficient due to the high thermal conductance of Cold Formed (CF) steel elements and resulting thermal bridging effect. Apart from independent investigations and optimization on LSF walls against fire and energy performance, it is vital to build-up knowledge on energy performance of fire rated LSF walls. Therefore, a series of fire rated conventional and modular LSF wall panels, which covers a wide range of industrial practices in European countries, have been investigated for their thermal transmittance, U-Value in the present study. Firstly, Finite Element Models (FEM) for three LSF wall panels were developed and validated against previous results. Subsequently, these models were extended to analyse the U-Values of the parametric specimens. The results show that, the concepts of back-blocking panels and discontinuous insulation options account for only slight improvements of U-Value (3–5%). Moreover, the variation of U-Value with respect to the cavity insulation ratio is found to be quite interesting, that adding cavity insulation at very low Insulation Ratios (IR) like 0.2 to 0.4, a 40%–60% reduction in the U-Value is obtained while further increase in IR results in less than 10% U-Value reduction. Therefore, 0.2 to 0.4 IR is proposed for conventional and modular LSF walls for appreciable energy performance avoiding unnecessary compensation in terms of costs, weight of the structure and structural fire performance.