Search Results (31)

The United Kingdom’s (UK) retrofit revolution is at a crossroads and the efficacy of retrofit interventions is not solely a function of insulation thickness. To truly slash emissions and lift households out of fuel poverty, we must solve the persistent problem of thermal bridging (TB), i.e., the hidden flaws that cause heat to escape, dampness to form, and well-intentioned retrofits to fail. This review moves beyond basic principles to spotlight the emerging tools and transformative strategies to make a difference. We explore the role of advanced modelling techniques, including finite element analysis (FEA), in pinpointing thermal and moisture-related risks, and how emerging materials like vacuum-insulated panels (VIPs) offer high-performance solutions in tight spaces. Crucially, we demonstrate how an integrated fabric-first approach, guided by standards like PAS 2035, is essential to manage moisture, ensure durability, and deliver the comfortable, low-energy homes the UK desperately needs. Therefore, achieving net-zero targets is critically dependent on the systematic upgrade of the building envelope, with the mitigation of TB representing a fundamental prerequisite. The EnerPHit approach applies a rigorous fabric-first methodology to eliminate TB and significantly reduce the building’s overall heat demand. This reduction enables the use of a compact heating system that can be efficiently powered by renewable energy sources, such as solar photovoltaic (PV). Moreover, this review employs a systematic literature synthesis to critically evaluate the integration of TB mitigation within the PAS 2035 framework, identifying key technical interdependencies and research gaps in whole-house retrofit methodology. This article provides a comprehensive review of established FEA modelling methodologies, rather than presenting results from original simulations. Full article

Although vacuum insulated panels (VIPs) are known for their exceptional thermal insulation capabilities, their service life is limited due to an increase in internal gas pressure and material aging. In this study, an innovative monitoring system incorporating embedded sensors was developed to estimate the lifespan of VIPs in real time. A test panel was specifically selected to degrade its thermal conductivity over a shortened timeframe to facilitate validation and optimize the experimental duration. Hourly pressure and temperature data collected from the sensors embedded within the panel were analyzed using established pressure–thermal conductivity (λ) relationships from the literature. Based on the time-dependent λ values, a machine learning model employing a random forest regressor was trained to predict the panel’s lifetime. The model demonstrated high accuracy with R² = 0.9999 and RMSE = 0.0017 mW/mK. During the test period, the panel maintained acceptable performance, and the model projected that the critical thermal conductivity threshold of 8.0 mW/mK would be reached at day 66.9. This approach enables continuous, in situ field monitoring of VIP service life without the need for laboratory infrastructure and offers a scalable and practical solution for assessing long-term energy efficiency. Full article

The long-term reliability of vacuum insulation panels (VIPs) is constrained by the barrier film degradation caused by micro-cracks during the flanging process. However, the correlation mechanism between process parameters and microleakage remains unclear. This study systematically investigates the impact of the number of flanging cycles on the barrier properties and insulation failure of aluminum foil composite film (AF) and metallized polyester film (MF). Accelerated aging tests revealed that the water vapor transmission rate (WVTR) of MF surged by 340% after five flanging cycles, while its oxygen transmission rate (OTR) increased by 22%. In contrast, AF exhibited significantly increased gas permeability due to brittle fracture of its aluminum layer. Thermal conductivity measurements demonstrated that VIPs subjected to ≥5 flanging cycles experienced a thermal conductivity increase of 5.22 mW/(m·K) after 30 days of aging, representing a 7.1-fold rise compared to unbent samples. MF primarily failed through interfacial delamination, whereas AF failed predominantly via aluminum layer fracture. This divergence stems from the substantial difference in mechanical properties between the metal and the polymer substrate. The study proposes optimizing the flanging process (≤3 bending cycles) and establishes a micro-crack propagation prediction model using X-ray computed tomography (CT). These findings provide crucial theoretical and technical foundations for enhancing VIP manufacturing precision and extending service life, holding significant practical value for energy-saving applications in construction and cryogenic fields. Full article

Building facade insulation technologies have evolved from primitive thermal barriers to high-performance, multifunctional systems that enhance energy efficiency and indoor comfort. Historical insulation methods, such as thick masonry walls and timber-based construction, have gradually been replaced by advanced materials and innovative facade designs. Studies indicate that a significant proportion of a building’s heat loss occurs through its external walls and windows, highlighting the need for effective insulation strategies. The development of double-skin facades (D-SFSs), adaptive facades (AFs), and green facades has enabled substantial reductions in heating and cooling energy demands. Materials such as vacuum insulation panels (VIPs), aerogels, and phase change materials (PCMs) have demonstrated superior thermal resistance, contributing to improved thermal regulation and reduced carbon emissions. Green facades offer additional benefits by lowering surface temperatures and mitigating urban heat island effects, while D-SF configurations can reduce cooling loads by over 20% in warm climates. Despite these advancements, challenges remain regarding the initial investment costs, durability, and material sustainability. The future of facade insulation technologies is expected to focus on bio-based and recyclable insulation materials, enhanced thermal performance, and climate-responsive facade designs. This study provides a comprehensive review of historical and modern facade insulation technologies, examining their impact on energy efficiency, sustainability, and future trends in architectural design. Full article

The ever-increasing requirements in the field of energy efficiency of buildings imply the necessity of using an ever-increasing amount of insulation in building structures. However, together with the requirements of the new EPBD directive EU/2024/1275, it is also necessary to monitor the carbon footprint of individual materials incorporated into the building structure. The aim of the research work is to substitute primary raw materials used for the production of vacuum insulation panels (VIPs) with secondary cellulose fibers produced by recycling newsprint. Five recipes were proposed to verify the substitution effect for individual key raw materials of core insulation for VIPs. Key (primarily thermal insulation) properties were determined on laboratory-produced samples, and it was found that the proposed hybrid core insulations with secondary cellulose fibers from recycled newsprint exhibit very favorable properties and could be used for the production of VIPs used in building structures. Full article

Vacuum insulation panels (VIPs) have emerged as a cutting-edge strategy for achieving superior thermal insulation across a wide range of applications, including refrigerators, cold-chain transportation and building envelopes. The key factor for the exceptional performance of VIPs is maintaining an ultralow pressure environment within the panels, which is crucial for minimizing heat transfer. However, the presence of non-condensable gases can compromise the vacuum state, leading to a reduced insulation effectiveness during a panel’s service life. This review offers a comprehensive analysis of getter materials used in VIPs, focusing on their fundamental properties, types, integration techniques and performance characteristics, further emphasizing the challenges and potential directions for the development of getter materials. Overall, this review intends to provide novel insights into the development of getter materials for use in VIPs, offering essential viewpoints to aid future studies on this topic. Full article

Vacuum insulation panels (VIPs) with cavities can be used in many applications, but their thermal bridge effect can be pronounced. In order to investigate the thermal bridge effect of VIPs with cavities, a numerical model was used for an analysis of the thermal bridge effect. The occurrence of the thermal bridge effect was investigated in nine groups of VIPs with different sizes and shapes of cavities. The results were experimentally verified. The results show that the effective heat transfer coefficient of VIPs decreases by 1.9% with an increase in the number of cavity sides, and the thermal bridge effect is much smaller with a larger number of cavity sides. The authors also found that an increase in the radius of the cavity tangent circle resulted in a more pronounced thermal bridge effect, with the effective thermal conductivity of the VIP increasing by 11.4%. In addition, the results obtained from the numerical analysis were verified by a simulation using COMSOL software (version 6.1). This study provides a reference for the variation rule of the thermal bridge effect in VIPs and reveals the numerical laws between the different parameters when the thermal bridge effect occurs. Full article

Prefabricated temporary buildings are a promising solution for post-disaster scenarios for their modularity, sustainability and transportation advantages. However, their low thermal mass building envelope shows a fast response to heat flux excitations. This leads to the risk of not meeting the occupant comfort and HVAC energy-saving requirements. The literature shows different measures implementable in opaque surfaces, like vacuum insulation panels (VIPs), phase change materials (PCMs) and switchable coatings, and in transparent surfaces (switchable glazing) to mitigate thermal issues, like overheating, while preserving the limited available internal space. This paper investigates the energy and overheating performance of the mentioned interventions by using building performance simulation tools to assess their effectiveness. The optimization also looks at the transportation flexibility of each intervention to better support the decision maker for manufacturing innovative temporary units. The most energy-efficient measures turn to be VIPs as a better energy solution for winter and PCMs as a better thermal comfort solution for summer. Full article

In this study, a comparative life cycle assessment of three different products with reusable and single-use packaging for fresh food distribution was conducted. For the reusable packaging, one utilized a vacuum insulation panel (VIP) box made of recycled polyethylene terephthalate (r-PET), while the other employed expanded polyethylene (EPE). For comparison, a disposable box made of widely used expanded polystyrene (EPS) was selected. We analyzed the environmental impacts of production, transportation, reprocessing (reused boxes), and disposal in 18 impact categories. As a result of analyzing the actual reuse of 300 rounds of fresh food, the cumulative global warming potential (GWP) values of the VIP and EPE box were 136.58 kg carbon dioxide (CO₂) eq and 281.72 kg CO₂ eq, respectively, 87% and 74% lower than those of the EPS box. Additionally, the GWP values were the same as those of the EPS boxes when the VIP and EPE boxes were reused 7 and 12 times, respectively. The best-case scenario was revealed when the reusable packaging with the r-PET VIP was compared with the EPE and EPS boxes. In conclusion, reusable packaging is expected to contribute to the reduction in the environmental burden and better suit global environmental requirements for sustainable food distribution and related industries. In addition, our findings can inform policy and industry decisions to promote more sustainable practices in the food industry, contributing to the advancement of sustainability in this field. Full article

International standards for vacuum insulation panels (VIPs) include an accelerated test method and a minimum quality standard for evaluating their long-term thermal performance after 25 years. The accelerated test method consists of various tests according to the characteristics of the core material and requires six months (180 days) at minimum. Herein, we propose an accelerated method for determining the long-term thermal performance of fumed-silica VIPs by shortening the required time and simplifying the procedure. Highly accelerated conditions (80 °C and 70% Relative humidity (RH)) were set for the evaluation method, using the maximum temperature (80 °C) cited in international standards and compared with the accelerated test method under accelerated conditions (50 °C and 70% RH). The inner-pressure increase rate of the VIP samples after conditioning for approximately 70 days was similar to that after conditioning for 180 days under highly accelerated and accelerated conditions, respectively. In addition, the estimated long-term thermal conductivities of the fumed-silica VIP were derived as 0.0076 and 0.0054 W/m·K under highly accelerated and accelerated conditions, respectively. These accelerated methods can be used to produce fumed-silica VIPs with similar long-term thermal conductivities. Therefore, the accelerated test method for long-term thermal performance using the highly accelerated conditions can be evaluated using a test that involves conditioning the sample for approximately 70 days under 80 °C and 70% RH. Full article

Policymakers regularly implement stricter building energy-efficiency codes towards curtailing building energy use. Inevitably, super-insulating materials such as Vacuum Insulation Panels (VIPs) are essential to satisfy such codes. VIPs have been applied to buildings for over two decades now, with many lessons learned. Generally, the thermal conductivity values of VIPs often reported in the literature are the center-of-panel thermal conductivity (λ_cop) and effective thermal conductivity (λ_eff), factoring thermal bridges. However, there are other indexes, such as λ_90/90 (declared value in the 90% percentile with a confidence of 90%) and λ_{cop,90/90,aged} (factoring aging), that increase consistently and reliably in the declared thermal conductivity value for VIPs. These indexes are scarcely computed and hardly reported. The main aim of this study was to examine the different declared thermal conductivity values of VIP-based guidelines, such as draft ISO DIS 16478, and evaluate their implications on annual building energy consumption. The main study constitutes four parts: (1) experimental evaluation of the thermal properties of pristine and aged VIP samples, (2) computation of thermal conductivity indexes, (3) numerical investigation of thermal conductivity indexes based on a reference building, and (4) related building energy implications. The mean λ_cop for 10 VIP samples was 0.0042 W/(mK) and increased to 0.0073 W/(mK) for ${\lambda }_{90/90}$, bridge, aged. Results show a significant bearing on building energy performance of as much as 2.1 GJ. Full article

Vacuum Insulation Panels (VIPs) provide significant adiabatic performance for heat/cooling systems to reduce energy consumption. The application of fibrous porous material (FPM) as the ideal core of VIPs has gained global attention in recent decades. The microstructure and physical properties of FPMs, filled as novel VIPs’ core material, and holding superior thermal performance, affected effective thermal conductivity (ETC) greatly. Aiming to deeply understand heat transfer mechanisms, a holistic simulation method that combined with a developed 3D FPM structure generation method and a D3Q15-Lattice Boltzmann method (LBM) is proposed to simulate the heat transfer in FPM and to illuminate the influence factors of ETC on the microstructure of FPM in a vacuum. The improved and modified mesoscopic 3D fibrous random micro-structure generation approach involved five structural parameters: generation probability of nucleus growth, fiber length, diameter, coincidence rate, and orientation angle. The calculation model of ETC is established, and the discrete velocity, distribution, evolution, and boundary conditions of D3Q15-LBM are invested in detail. The model is validated with influences of different microstructure parameters. It indicated that FPM with finer diameter, smaller average pore size, and bigger orientation angle easily gain the lower ETC in a vacuum. The ETC was also affected by the orientation angles of fibers. The more the heat transfer direction is inconsistent with the length direction of the fiber, the better the adiabatic performance is. The reliability of the model is verified by comparison, and this work is a reference to optimize the fibrous core of VIPs. Full article

This study is devoted to the possibility of using advanced insulation materials, such as Vacuum Insulation Panels (VIP), in the insulation and reconstruction of buildings, in connection with the green elements that are installed on the facade in the case of the use of external thermal insulation composite systems (ETICS). The use of VIP as part of the insulation system will result in a significant reduction in the required thickness of the insulation layer. In turn, the reduced overall thickness of the system will allow for easier direct anchoring of the elements of the green facade through the insulating layer to the base of the structure. The research carried out proves that, by using VIP in the insulation system (with a VIP thickness of 30 mm in combination with 20 mm of extruded polystyrene XPS), the thermal insulation properties can be significantly improved and, thus, the thickness of the insulation system can be reduced to 1/3 of the thickness of conventional insulation (while achieving the same thermal resistance), thereby enabling the anchoring of green elements on the surface of such an insulation system. Full article

Most of today’s buildings will still be in use in 2050 and upgrades should therefore contribute to reducing energy consumption and carbon footprint. This paper addresses a challenge for upgrading of basement exterior walls of single-family dwellings, where ordinary retrofit insulation can lead to the basement wall protruding from the existing outer wall. For some, this will be an aesthetic barrier for an energy upgrade (an “ugly” solution). Superinsulation may solve this challenge without compromising the energy performance. This study analyses energy, cost and carbon footprint, to identify under which conditions upgrading with vacuum insulation panels (VIP) can be a preferred solution. Three alternatives are analysed in a parametric model: ordinary upgrade with XPS (the aesthetically “ugly”), upgrade with VIP above ground and XPS below ground (the aesthetically “good”), and iii) no upgrade (the “bad”, as it does not contribute to reducing energy consumption). Results show that using VIP and XPS to perform energy upgrade of a basement exterior wall may lead to an aesthetically more pleasing solution than with only XPS, but that it will lead to higher carbon footprint and higher costs. The least favourable option is to install a drainage system without doing an energy upgrade, which will have negative impact for energy use, carbon footprint and life cycle cost. 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