• Energy Research

Abstract This review paper gives the latest state of the art communicated during the 11th International Vacuum Insulation Symposium IVIS2013 and beyond. Although the largest application of the Vacuum insulation panels (VIPs) concerns the refrigeration industry (60%) and transport boxes (30%) and only a tiny amount is used in the building industry (10%), the number of scientific publications dealing with VIPs with regard to the latter dominate since more than a decade. The main topics addressed therein are the aging of the VIP as a whole as well as the role of the components, under different long term hygrothermal stress conditions. There is a clear expansion of VIP applications in buildings from primarily German speaking countries, toward Europe, and then to overseas. Recent years have witnessed an increasing confidence in this product among researchers and practitioners interested in energy efficient buildings worldwide.

Abstract This review paper gives the latest state of the art communicated during the 11th International Vacuum Insulation Symposium IVIS2013 and beyond. Although the largest application of the Vacuum insulation panels (VIPs) concerns the refrigeration industry (60%) and transport boxes (30%) and only a tiny amount is used in the building industry (10%), the number of scientific publications dealing with VIPs with regard to the latter dominate since more than a decade. The main topics addressed therein are the aging of the VIP as a whole as well as the role of the components, under different long term hygrothermal stress conditions. There is a clear expansion of VIP applications in buildings from primarily German speaking countries, toward Europe, and then to overseas. Recent years have witnessed an increasing confidence in this product among researchers and practitioners interested in energy efficient buildings worldwide.

Abstract Vacuum insulation panels (VIP) are considered as high-performance thermal insulation products in the building industry where their spread has continuously increased a decade since. The authors believe that this trend will continue and even strengthen in future. Subsequently, they are willing to emphasize that addressing quality issues from production to installation is essential in avoiding costly pitfalls. The present study analyses the reasons for the deterioration of some specific VIP panels encapsulated in expanded polystyrene and applied to a facade in an urban area. The reason for failure in this case can be attributed to a systematic failure in the metallization process i.e. to a failure in quality assurance and not as assumed in most cases to the vulnerability of the VIP envelope. The shortcomings of the investigated facade are discussed based on both on-site and laboratory investigations to avoid similar quality flaw in VIP containing constructions. The aim is to prevent unfavorable publicity for this high-tech product with a promising applicability in retrofitting the considerable number of existing old buildings worldwide.

Abstract Vacuum insulation panels (VIP) are considered as high-performance thermal insulation products in the building industry where their spread has continuously increased a decade since. The authors believe that this trend will continue and even strengthen in future. Subsequently, they are willing to emphasize that addressing quality issues from production to installation is essential in avoiding costly pitfalls. The present study analyses the reasons for the deterioration of some specific VIP panels encapsulated in expanded polystyrene and applied to a facade in an urban area. The reason for failure in this case can be attributed to a systematic failure in the metallization process i.e. to a failure in quality assurance and not as assumed in most cases to the vulnerability of the VIP envelope. The shortcomings of the investigated facade are discussed based on both on-site and laboratory investigations to avoid similar quality flaw in VIP containing constructions. The aim is to prevent unfavorable publicity for this high-tech product with a promising applicability in retrofitting the considerable number of existing old buildings worldwide.

The vacuum insulation panel (VIP) is a high performance thermal insulation component recently introduced into building technology. Its high thermal resistivity provides new solutions for slim but still energy efficient building envelopes. One of the key issues for building application is to minimize failure in service and to ensure a service life in the order of several decades under typical stress conditions especially thermal and hygric effects. However, little experience exists up to now on the long-term properties and the durability of VIPs. This article describes aging mechanisms and reports experimental results for different temperature and humidity induced deteriorations. A functional representation of the measured data at steady state conditions is introduced. For specific VIP applications the internal pressure increase is calculated on the basis of a dynamic thermal model. End-of-life criteria and respective service life estimates are discussed as well.

The vacuum insulation panel (VIP) is a high performance thermal insulation component recently introduced into building technology. Its high thermal resistivity provides new solutions for slim but still energy efficient building envelopes. One of the key issues for building application is to minimize failure in service and to ensure a service life in the order of several decades under typical stress conditions especially thermal and hygric effects. However, little experience exists up to now on the long-term properties and the durability of VIPs. This article describes aging mechanisms and reports experimental results for different temperature and humidity induced deteriorations. A functional representation of the measured data at steady state conditions is introduced. For specific VIP applications the internal pressure increase is calculated on the basis of a dynamic thermal model. End-of-life criteria and respective service life estimates are discussed as well.

Abstract The prediction of the long term performance of VIPs remains challenging. To improve the forecast, the evaluation of VIPs aged for very long periods can help significantly. This study reports the characterization method which was implemented on VIPs after an artificial aging of 10 years in the laboratory, at room temperature in two different relative humidities: quite low and high (23 °C at 33 and 80 %RH). The aim is to evaluate the aging of the fumed silica core thanks to the detailed study of the hygrothermal and structural evolutions of the core material. The evaluation reveals that the silica core has been partly aged at high relative humidity (80 %RH), as highlighted by: (i) the moisture content at equilibrium which is not so high as the moisture content that could be reached by short-term additional aging of the sole silica at high humidity levels, (ii) the evolution of the specific area (decrease of only several percents). For the VIP aged at relatively high humidity, the water sorption isotherm indicates that the moisture content inside the VIP corresponds to a humidity level of 44 %: in comparison with the permeation at the beginning of the accelerated aging, the WVTR decreased approximately by a factor 2 (humidity gradient from 80 to 44 %). Furthermore, thanks to the follow-up on the weight and internal pressure of the VIPs, the permeances of the barrier laminate to water vapor and air are also estimated.

Abstract The prediction of the long term performance of VIPs remains challenging. To improve the forecast, the evaluation of VIPs aged for very long periods can help significantly. This study reports the characterization method which was implemented on VIPs after an artificial aging of 10 years in the laboratory, at room temperature in two different relative humidities: quite low and high (23 °C at 33 and 80 %RH). The aim is to evaluate the aging of the fumed silica core thanks to the detailed study of the hygrothermal and structural evolutions of the core material. The evaluation reveals that the silica core has been partly aged at high relative humidity (80 %RH), as highlighted by: (i) the moisture content at equilibrium which is not so high as the moisture content that could be reached by short-term additional aging of the sole silica at high humidity levels, (ii) the evolution of the specific area (decrease of only several percents). For the VIP aged at relatively high humidity, the water sorption isotherm indicates that the moisture content inside the VIP corresponds to a humidity level of 44 %: in comparison with the permeation at the beginning of the accelerated aging, the WVTR decreased approximately by a factor 2 (humidity gradient from 80 to 44 %). Furthermore, thanks to the follow-up on the weight and internal pressure of the VIPs, the permeances of the barrier laminate to water vapor and air are also estimated.

Retrofitting the residential building stock poses a major challenge for the European building sector in the coming years. It is also crucial to achieve the decarbonisation goals set by the EU's Energy Roadmap 2050. The EASEE research project, funded by the European Commission, addressed this issue by developing a holistic approach to envelope retrofitting. This paper presents an innovative technical solution developed within this research project: a lightweight, aerogel-based wallpaper that can be easily installed on the inner side of perimeter walls. The system is composed of an aerogel-impregnated textile layer, forming the insulating core, and a fabric finishing that can be easily installed and replaced thanks to a bespoke tensioning device. The development of the system is explained starting from the identification of the challenges related to the application of an insulating layer to the internal face of an existing wall. These include building physics, as well as operational aspects to reduce disturbances of users. The insulating layer, based on a textile mat impregnated with aerogel, was tested and characterised at laboratory scale to ensure its high thermal performances and its permeability to water vapour. The fabric finishing system was also designed to provide the possibility of easy tensioning and disassembly for cleaning or replacement. An innovative device, based on plastic zips, was developed and patented within the project. As part of the process, specific studies were developed about cold bridges, thermal capacity and environmental impact of the system. The wallpaper was finally tested and monitored to assess its in-situ thermal performance and the assembly procedure on a building at Politecnico di Milano. International High-Performance Built Environment Conference – A Sustainable Built Environment Conference 2016 Series (SBE16), iHBE 2016 Procedia Engineering, 180