As thermal energy storage (TES) technologies gain more significance in the global energy market, there is an increasing demand to improve their energy efficiency and, more importantly, reduce their ...costs. In this article, two different methods for insulating TES systems that are either incorporated inside residential buildings or buried underground in direct vicinity of the building are reviewed and discussed. Boundary conditions are storage volumes in the range 10 – 1000 m3 and storage temperatures up to 90 °C. The first method involves the application of thermal insulation materials on the outside of the storage. Thermophysical properties and costs of conventional materials (such as mineral wools and organic foams) are compared against those of state-of-the-art products such as vacuum insulation panels and aerogels. A parametric comparative analysis is conducted to evaluate the combined costs of thermal insulation and living space occupied by the thermal insulation for TES systems integrated inside buildings. It is shown, for example, that the use of vacuum insulation panels becomes advantageous when the economic value of saving living space outweighs the extra cost of the insulation itself. The second method discussed is the so-called evacuated powders, in which the insulation is realized by creating an evacuated double-wall powder-containing envelope around the storage. The theoretical foundations of this method are discussed and the properties of commonly used powders – such as expanded perlite and fumed silica – are provided. Reference costs of double-wall vacuum-insulated TES tanks are provided and the use of evacuated powders is compared against the application of conventional insulation materials.
•Thermal insulation is aspect in the optimization of thermal energy storage (TES) systems integrated inside buildings.•Properties, characteristics, and reference costs are presented for insulation materials suitable for TES up to 90 °C.•State-of-the-art thermal insulation materials can lead to significant space and cost savings in seasonal TES systems.•Double-wall vacuum insulated tanks can be buried underground, eliminating the need for valuable space inside buildings.
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•A novel methodology for payback analysis of vacuum insulation panels was proposed.•The methodology considers the variation of techno-economic parameters with time.•Space heating energy and emission ...savings were calculated.•Longer lifespan vacuum insulation panel achieved a shorter payback period.•Fumed silica VIPs are economically viable for adoption into non-domestic buildings.
The potential savings in space heating energy from the installation of Fumed Silica (FS) and Glass Fibre (GF) Vacuum Insulation Panels (VIPs) were compared to conventional expanded polystyrene (EPS) insulation for three different non-domestic buildings situated in London (UK). A discounted payback period analysis was used to determine the time taken for the capital cost of installing the insulation to be recovered. VIP materials were ranked using cost and density indexes. The methodology of the Payback analysis carried out considered the time dependency of VIP thermal performance, fuel prices and rental income from buildings. These calculations show that VIP insulation reduced the annual space heating energy demand and carbon dioxide (CO2) emissions by approximately 10.2%, 41.3% and 26.7% for a six storey office building, a two floor retail unit building and a four storey office building respectively. FS VIPs had the shortest payback period among the insulation materials studied, ranging from 2.5years to 17years, depending upon the rental income of the building. For GF VIPs the calculated payback period was considerably longer and in the case of the typical 4 storey office building studied its cost could not be recovered over the life time of the building. For EPS insulation the calculated payback period was longer than its useful life time for all three buildings. FS VIPs were found to be economically viable for installation onto non-domestic buildings in high rental value locations assuming a lifespan of up to 60years.
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The study provides an overview of the research focus on vacuum insulation panels (VIPs). Scientific literature published between 1960 and 2022 is identified, and a database covering 423 documents is ...amassed. In the first phase, research documents were categorised into three groups: product, other and buildings. In the second phase, data about the studied building applications and research topics were extracted and quantitatively evaluated. In the last phase, the studies evaluating VIPs' environmental and economic implications in buildings were analysed in detail. The study results show an increasing publication trend on VIPs, with almost 90% of the literature published from 2010 onwards. Building applications are the dominant research subject, representing 56% of identified documents. A detailed analysis of life cycle studies pointed to a consensus that in building applications, fumed silica VIPs exert a higher environmental impact and costs than conventional insulation materials if the comparison is based on an equivalent thermal transmittance value. However, several studies showed reasonable payback and environmental neutrality periods for retrofitting scenarios. Benefits could also be achieved if insulation layer thickness is limited. External wall insulation represents the vast majority of the applications analysed. Studies further showed that VIPs in external wall applications could be economically viable compared to conventional insulation if added useable floor space is considered. The characteristics of life cycle studies were analysed, research gaps and possibilities were identified, and research recommendations for environmental and economic studies of VIPs were provided.
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•Research highlights and trends for past research on VIPs are presented.•56% of studies evaluate building applications, 87% documents published after 2009.•Detailed analysis of LCA and LCC studies and multiple findings highlighted.•Recommendations for future life cycle studies of VIPs presented.•A database file of amassed documents generated and made publicly available.
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Renewable energy systems are key technologies towards realizing reduced carbon footprint and sustainable architecture. Building integrated photovoltaics (BIPV) are renewable energy ...systems that function as integral building envelope components and simultaneously produce electricity. Not only is it essential to install BIPV for energy rebates, incentives or to cut down dependence on grid, but it is equally important that BIPV satisfies relevant building energy codes. Thus, thin high-performance insulation is needed to meet strict codes. Of all kinds of insulation materials presently available, vacuum insulation panel (VIP) has the highest thermal resistance per unit thickness. Therefore, VIP is a viable solution as an insulator for BIPV. In this study, the thermal characteristics and electrical performance of a hybrid BIPV module combined with VIP was investigated. The study is largely based on experiments carried out in a test building facility and supplemented with essential numerical simulations using Physibel BISCO/TRISCO building physics software. Data analysis was carried out for winter season. Results indicated that temperature at the back of the hybrid BIPV module (directly in contact with indoor air) was about 4 °C warmer than the heating setpoint temperature, which is advantageous for winter season. The maximum electrical efficiency was estimated to be 12.3 %. Compared to manufacturer specified electrical efficiency of 15 %, the peak efficiency realized is somewhat acceptable, factoring losses and winter weather conditions. Integrating BIPV and VIP yields an overall hybrid product that is compact and portable, and thermally more efficient from a building envelope perspective. As far as the authors know, this study is the first covering BIPV combined with VIP as a unitized module. Finally, current challenges and future research opportunities are explored.
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Vacuum insulation panels (VIPs) are regarded as one of the most promising high performance thermal insulation solutions on the market today. Thermal performances three to six times better than ...still-air are achieved by applying a vacuum to an encapsulated micro-porous material, resulting in a great potential for combining the reduction of energy consumption in buildings with slim constructions. However, thermal bridging due to the panel envelope and degradation of thermal performance through time occurs with current technology. Furthermore, VIPs cannot be cut on site and the panels are fragile towards damaging. These effects have to be taken into account for building applications as they may diminish the overall usability and thermal performance.
This paper is as far as the authors know the first comprehensive review on VIPs. Properties, requirements and possibilities of foil encapsulated VIPs for building applications are studied based on available literature, emphasizing thermal bridging and degradation through time. An extension is made towards gas-filled panels and aerogels, showing that other high performance thermal insulation solutions do exist. Combining the technology of these solutions and others may lead to a new leap forward. Feasible paths beyond VIPs are investigated and possibilities such as vacuum insulation materials (VIMs) and nano insulation materials (NIMs) are proposed.
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•An unconventional VIP, labeled cavity-core matrix VIP (CCM-VIP) was investigated.•CCM-VIP was composed of glass fiber core encapsulated in Al foil envelope.•Surface cavities on CCM-VIP formed ...interlocking topology with adjacent mortar.•Bond strength for optimized CCM-VIP increased by about 50% magnitude.•The equivalent thermal conductivity for optimized CCM-VIP was 4.8mW/(mK).
Energy efficiency of buildings can be improved by implementing strategies to develop the building envelope components. Thermal insulation of buildings has become vital, to attenuate energy demands for space heating and cooling. Presently vacuum insulation panel (VIP) is regarded as a high performance thermal insulation material. VIP enables efficient insulation solutions in systems such as refrigerators, controlled thermal packages and buildings. For building applications, it is imperative to minimize material defects and to ensure thermal comfort. However, these panels typically use spacers that cause a significant thermal bridge and undesirable gas permeation through spacer hole seal area. This study introduces an unconventional VIP, labeled as cavity-core matrix VIP; solving the aforementioned technical issue related to VIP application in buildings. The cavity-core matrix VIP was composed of glass fiber core material, and laminated aluminum foil envelope material. Owing to interlocking surface topology, bond strength increased by nearly 50% magnitude; considering the limitations specified. The estimated equivalent thermal conductivity of the optimized cavity-core matrix VIP was about 4.8mW/(mK). The preparation processes, thermo-physical properties and challenges of cavity-core matrix VIP were discussed. The concept and exposition examined will enable building engineers and manufacturers to create thermally well performing and structurally adapted VIPs.
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•Affordable and adaptable VIP based internal and external retrofitting solutions.•Implementation of VIP based integral retrofitting solutions in two tertiary buildings.•Space heating energy saving ...analysis before and after VIP based retrofit.•Envelope heat loss coefficient reduction analysis before and after retrofitting.
Vacuum insulation panels (VIPs) represent a huge opportunity to achieve nearly zero energy buildings, especially in the retrofitting of existing buildings. VIPs can be applied in conjunction with façade cladding elements, considerably reducing the heat losses or gains from the building by means of very slim wall construction systems or retrofit solutions. However, the fact that VIPs cannot be cut on-site, can be easily damaged during their handling, installation and use and have an envelope that can cause thermal bridging in the junction between panels or when combined with other materials, has hindered their penetration in the construction market.
This paper presents two innovative façade retrofitting solutions, a rear ventilated façade and a stud mounted internal solution, that have tackled all these issues and provide thermal transmittances of 0.28 and 0.14 W/m2 K in relatively slim insulation systems of 10 cm widths. Solutions have been installed on the entire façade of two existing buildings located in Bilbao (Spain) and Malmö (Sweden) subjected to an integral rehabilitation process, covering 2100 m2. Buildings energy use have been monitored before and after the renovation, showing energy cuts of around 35% from pre-intervention status.
This paper presents the lessons learnt during the design and installation process of the vacuum insulation integrating solutions in the façade of two existing buildings and the thermal performance results achieved after their retrofitting.
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Structural insulation panels (SIPs) are considered promising building products that achieve the low-energy goal, and its potential energy performance can be further improved by combining it with a ...vacuum insulation panel (VIP) in cold climates. The aim of this study is to determine the optimal SIP with VIP (VIP–SIP) thickness and to minimize the energy cost. We conduct a VIP-SIP thickness optimization and cost analysis for five cold sub-regions using P1-P2 methods. First, we develop an energy model using the building energy simulation software OpenStudio considering the VIP aging effect, and the accuracy of this model is validated using field test data. Results indicate that as climates become colder from Cold area B to Severe Cold area A, the optimal VIP thickness increases from 3.5 mm to 31 mm, whereas the optimal PU thickness decreases from 66.875 mm to 174.2 mm. In addition, the total cost saving rate increases from 40.5% to 47.9%, and the discounted payback period decreases from 12.59 years to 8.98 years, indicating improved economic feasibility. Furthermore, the influence of the P1 value and VIP price on the optimal thickness and total cost are also discussed. The findings of this study confirm the economic feasibility of combining SIP with VIP in cold areas, and provide feasible parameters for the design of low-energy buildings in cold areas of China.
•Thickness optimization using - methods for double-layer VIP-SIP wall is conducted.•Aging effect of VIP and PU in OpenStudio energy simulation is concerned.•Optimal VIP-SIP wall tends to use thicker VIP and thinner PU in colder regions.•VIP-SIP has good financial feasibility in cold regions.•P1 value and VIP price influence the optimal thickness and total cost greatly.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•A guarded hot plate apparatus utilizing a Peltier module was proposed and developed.•Effective thermal conductivity of a vacuum insulation panel was precisely measured.•Contributions of conduction ...and radiation in a vacuum insulation panel were examined.
In this paper, a guarded hot plate (GHP) apparatus utilizing a Peltier module is proposed and developed to precisely measure the thermal conductivity of insulation material. The Peltier module is used to detect a temperature difference with high sensitivity and to precisely measure heat flux. To develop the GHP apparatus, a two-dimensional axisymmetric heat conduction analysis and calibration experiments of thermistors and Peltier module were conducted. In addition, to assess the reliability of the developed apparatus, thermal conductivity measurements for a high-density glass wool and vacuum insulation panel (VIP) were conducted. Based on the results, the expanded uncertainties of the measurements were estimated. Therefore, the apparatus was found to be reliable for conducting precise thermal conductivity measurements not only for conventional insulation materials but also for a VIP.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
► Vacuum Insulation Panels (VIP), a high thermal resistance building insulation. ► Review of research into VIPs for building applications. ► High cost and uncertainty of service life are two barriers ...for VIP use in buildings. ► SiO
2/SiN
x coated PET laminate- candidate for high barrier VIP envelope. ► The optimum combination of VIP core and envelope yet to be determined.
Demand for energy efficient buildings has increased drastically in recent years and this trend will continue in the future. Insulating building elements will play a key role in meeting this demand by reducing heat losses through the building fabric. Due to their higher thermal resistance, Vacuum Insulation Panels (VIPs) would be a more energy efficient alternative to conventional building insulation materials. Thus, efforts to develop VIPs with characteristics suitable for applications to new and existing buildings are underway. This paper provides a review of important contemporary developments towards producing VIPs using various materials such as glass fibre, foams, perlite and fibre/powder composites. The limitations of the materials currently used to fabricate VIPs have not been emphasised in detail in previous review papers published. Selection criteria, methods to measure important properties of VIPs and analytical and numerical models presented in the past have been detailed. Limitations of currently employed design tools along with potential future materials such as Nano/microcellular foams and SiO
x
/SiN
x
coatings for use in VIPs are also described.
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