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Vacuum insulation in buildings: Means to prolong service life
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
2006 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

Vacuum insulation panels, VIPs, constitute a new insulation material, 6 to 8 times better than traditional insulation materials, which utilizes the positive influence vacuum has on the thermal properties of certain materials. A VIP is a composite with a flat core enclosed by an envelope preventing the core to fill with gas. The vacuum in the core is vital to reach thermal conductivities down to 0,0035 W/(m K), if the vacuum is lost the panel has reached the end of its service life time. Metal sheets would the preferred material to create an impermeable envelope but would creates a large thermal bridge at the edges of a panel when it folds over the edges of the panel.

A serpentine edge has been proposed in order to deal with this large thermal bridge. This serpentine edge has been evaluated first as a numeric model in software and then by measuring on a prototype edge element in a hot and cold plate instrument. Measured temperatures were used to validate the numerical model. Results show that a serpentine edge can greatly reduce the thermal bridge if designed correctly.

Another direction taken in the development of the VIP barrier is to use very thin metal layers, metallization layer or coating, incorporated into multi layered polymer composite film. This creates barrier films with very good barrier properties and only small thermal bridges. The modeling of gas flux through films with more than one coating has only just started. Existing models for flux through multi coated films all assume that flux is only taking place through defects in the coating layers, that all defects are of the same size and that all defects are positioned in square lattices. The model discussed herein use the same assumption of flux through pinholes only but it does take defect sizes and positions into account. Barrier film, from a regular vacuum insulation panel, with double coatings has been evaluated in light microscopy to characterize the defects in each of the coatings. The data found have been fed into the model and the results comply well with reported permeabilities of similar barrier films.

Place, publisher, year, edition, pages
Stockholm: KTH , 2006. , x, 43 p.
Series
Meddelande. Institutionen för byggvetenskap, ISSN 1651-5563 ; 198
Keyword [en]
vacuum insulation, thermal bridge, serpentine edge, coated film
National Category
Building Technologies
Identifiers
URN: urn:nbn:se:kth:diva-4149ISBN: 91-7178-470-5 (print)OAI: oai:DiVA.org:kth-4149DiVA: diva2:10925
Presentation
2006-11-02, Fyslab, KTH, Brinellvägen 34, Stockholm, 11:00
Opponent
Supervisors
Note
QC 20101125Available from: 2003-10-18 Created: 2003-10-18 Last updated: 2010-11-25Bibliographically approved
List of papers
1. Edge loss minimization in vacuum insulation panels
Open this publication in new window or tab >>Edge loss minimization in vacuum insulation panels
2005 (English)In: Proceedings of the 7th symposium on Building Physics in the Nordic Countries, Reykjavík, 2005Conference paper, Published paper (Refereed)
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-6255 (URN)
Conference
7th symposium on Building Physics in the Nordic Countries - Reykjavík, June 2005
Note
QC 20101125. Uppdaterad från Manuskript till Konferensbidrag (20101125).Available from: 2003-10-18 Created: 2003-10-18 Last updated: 2012-02-28Bibliographically approved
2. Edge loss minimization in vacuum insulation panels: Model verification
Open this publication in new window or tab >>Edge loss minimization in vacuum insulation panels: Model verification
2006 (English)In: Research In Building Physics And Building Engineering / [ed] Fazio P, Ge H, Rao J, Desmarais G, London, England: TAYLOR & FRANCIS LTD , 2006, 251-256 p.Conference paper, Published paper (Refereed)
Abstract [en]

Vacuum insulation panels have, by design, a thermal bridge at each of the edges of the panel. This paper presents continued work on an edge design that minimizes this effect, a serpentine edge. Numerical modeling as well as laboratory measurements has been done. Results presented here show that this serpentine edge have the potential to reduce the thermal bridge around the edges of a traditional vacuum panel alternatively enable designs with metal foil or thin metal sheet barriers which would allow other core such as glass fibers, open cell polyurethane instead of commonly used fumed silica. Fumed silica or aerogel that have pore-sizes in the nano region might not need stainless steel barriers to reach technical lifetimes of several decades but can still benefit from a sturdier shell. A welded stainless steel envelope helps to create a panel that will withstand handling and other loads in a construction.

Place, publisher, year, edition, pages
London, England: TAYLOR & FRANCIS LTD, 2006
Series
Proceedings and Monographs in Engineering, Water and Earth Sciences
Keyword
Bridges, Buildings, Colloids, Electron emission, Engineering research, Glass fibers, Inert gas welding, Metal foil, Polymers, Serpentine, Sheet metal, Silica, Silicate minerals, Stainless steel, Steel, Steel corrosion, Steel metallurgy, Two phase flow, Vacuum
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-6256 (URN)000242847800033 ()2-s2.0-56249135581 (Scopus ID)0-415-41675-2 (ISBN)
Conference
3rd International Building Physics Conference Concordia Univ, Montreal, CANADA, AUG 27-31, 2006
Note

QC 20141117

Available from: 2003-10-18 Created: 2003-10-18 Last updated: 2014-11-17Bibliographically approved
3. Integrating vacuum insulation panels in building constructions: an integral perspective
Open this publication in new window or tab >>Integrating vacuum insulation panels in building constructions: an integral perspective
2007 (English)In: Journal of Construction Innovation, ISSN 1471-4175, Vol. 7, no 1, 38-53 p.Article in journal (Refereed) Published
Abstract [en]

Purpose – Although vacuum insulation panels (VIPs) are thermal insulators that combine high thermal performance with limited thickness, application in the building sector is still rare due to lack of scientific knowledge on the behaviour of these panels applied in building constructions.This paper, therefore, seeks to give an overview of the requirements for and the behaviour of VIPs integrated into building components and constructions. Moreover, the interaction between different requirements on and properties of these integrated components are discussed in detail, since a desired high quality of the finished product demands an integral approach regarding all properties and requirements, especially during the design phase. Therefore, the importance of an integral design approach to application of VIPs is shown and emphasized in this paper. Design/methodology/approach – To achieve this objective, the legally and technically required properties of VIPs and especially their interrelationships have been studied, resulting in a relationship diagram. Based on these investigations of thermal- , service life- and structural-properties have been selected to be studied more elaborately using experimental set-up for structural testing and simulation software for thermal and hygrothermal testing. Findings – Two relationships between requirements or properties were found to be of principal importance for the design of fac¸ade components in which VIPs are integrated. First, thermal performance requirements strongly interact with structural performance, principally through the edge spacer of this fac¸ade component. A high thermal performance requires minimization of the thermal edge effect, in most cases reducing the structural performance of the entire panel. Second, an important relationship between thermal performance and service life has been recognised. The operating phenomenon mainly governing this interaction is thermal conductivity aging. Originality/value – Most research in the field of vacuum insulation until now has been directed towards gaining knowledge on specific properties of the product, especially on thermal and hygrothermal properties. The relationships and interactions between these properties and the structural behaviour, however, have been neglected. This paper, therefore, addresses the need for an integral design (and study) approach for the application of VIPs in architectural constructions.

Keyword
Vacuum devices, Integration, Building specifications, Thermal efficiency, Structural design
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-6257 (URN)10.1108/14714170710721287 (DOI)
Note
QC 20101125. Uppdaterad från Accepted till Published (20101125).Available from: 2003-10-18 Created: 2003-10-18 Last updated: 2012-02-28Bibliographically approved
4. A hybrid model for diffusion through barrier films with multiple coatings
Open this publication in new window or tab >>A hybrid model for diffusion through barrier films with multiple coatings
2010 (English)In: Journal of Building Physics, ISSN 1744-2591, Vol. 34, no 4, 351-381 p.Article in journal (Refereed) Published
Abstract [en]

The amount of gas that penetrates the barrier of a vacuum insulation panels is directly linked to the service life of that panel. Therefore, to model and predict vacuum insulation panel service life, it is necessary to model the diffusion through its barriers. Best barriers on the market today are composites of multiple polymer layers with two or more inorganic coatings. It is accepted that the main part of diffusion, in such films, takes place through defects in the coating layers, but there are only a limited number of numerical models for this geometry with more than one coating. In this article, a hybrid model is presented that models gas permeation through film geometry with two coatings on a polymer substrate. Numerical calculations are combined with analytical ones to create a model that does take individual defect sizes as well as actual defect positions into account. Resulting oxygen transmission values calculated with this model have been compared to available manufacturer data with good agreement.

Keyword
diffusion, coated film, defect driven, multi coated, metalized polymer film
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-6258 (URN)10.1177/1744259110388264 (DOI)000289277500003 ()
Note
QC 20101125. Uppdaterad från Submitted till Published (20101125).Available from: 2003-10-18 Created: 2003-10-18 Last updated: 2012-02-28Bibliographically approved

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