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Advances in Thermal Insulation: Vacuum Insulation Panels and Thermal Efficiency to Reduce Energy Usage in Buildings
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

We are coming to realize that there is an urgent need to reduce energy usage in buildings and it has to be done in a sustainable way. This thesis focuses on the performance of the building envelope; more precisely thermal performance of walls and super insulation material in the form of vacuum insulation. However, the building envelope is just one part of the whole building system, and super insulators have one major flaw: they are easily adversely affected by other problems in the built environment. 

Vacuum Insulation Panels are one fresh addition to the arsenal of insulation materials available to the building industry. They are composite material with a core and an enclosure which, as a composite, can reach thermal conductivities as low as 0.004 W/(mK). However, the exceptional performance relies on the barrier material preventing gas permeation, maintaining a near vacuum into the core and a minimized thermal bridge effect from the wrapping of barrier material round the edge of a panel.

A serpentine edge is proposed to decrease the heat loss at the edge. Modeling and testing shows a reduction of 60% if a reasonable serpentine edge is used. A diffusion model of permeation through multilayered barrier films with metallization coatings was developed to predict ultimate service life. The model combines numerical calculations with analytical field theory allowing for more precise determination than current models. The results using the proposed model indicate that it is possible to manufacture panels with lifetimes exceeding 50 years with existing manufacturing.

Switching from the component scale to the building scale; an approach of integrated testing and modeling is proposed. Four wall types have been tested in a large range of environments with the aim to assess the hygrothermal nature and significance of thermal bridges and air leakages. The test procedure was also examined as a means for a more representative performance indicator than R-value (in USA). The procedure incorporates specific steps exposing the wall to different climate conditions, ranging from cold and dry to hot and humid, with and without a pressure gradient. This study showed that air infiltration alone might decrease the thermal resistance of a residential wall by 15%, more for industrial walls.

Results from the research underpin a discussion concerning the importance of a holistic approach to building design if we are to meet the challenge of energy savings and sustainability. Thermal insulation efficiency is a main concept used throughout, and since it measures utilization it is a partial measure of sustainability. It is therefore proposed as a necessary design parameter in addition to a performance indicator when designing building envelopes. The thermal insulation efficiency ranges from below 50% for a wood stud wall poorly designed with incorporated VIP, while an optimized design with VIP placed in an uninterrupted external layer shows an efficiency of 99%, almost perfect. Thermal insulation efficiency reflects the measured wall performance full scale test, thus indicating efficiency under varied environmental loads: heat, moisture and pressure.

The building design must be as a system, integrating all the subsystems together to function in concert. New design methodologies must be created along with new, more reliable and comprehensive measuring, testing and integrating procedures. New super insulators are capable of reducing energy usage below zero energy in buildings. It would be a shame to waste them by not taking care of the rest of the system. This thesis details the steps that went into this study and shows how this can be done.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. , xiv, 126 p.
Series
Meddelande. Institutionen för byggvetenskap, ISSN 1651-5536
Keyword [en]
Vacuum insulation panels, VIP, serpentine edge, thermal bridge, composite film, gas diffusion, defect dominated, holistic approach, building enclosure, integrated testing and modeling, energy equivalent, field performance, air flow, thermal insulation efficiency
National Category
Building Technologies
Identifiers
URN: urn:nbn:se:kth:diva-90745ISBN: 978-91-7501-261-2 (print)OAI: oai:DiVA.org:kth-90745DiVA: diva2:506266
Public defence
2012-03-16, F3, Lindstedtsvägen 26, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
QC 20120228Available from: 2012-02-28 Created: 2012-02-28 Last updated: 2012-02-28Bibliographically 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. 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
4. 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
5. Integrated Methodology for Evaluation of Energy Performance of the Building Enclosures - Part I: Test Program Development
Open this publication in new window or tab >>Integrated Methodology for Evaluation of Energy Performance of the Building Enclosures - Part I: Test Program Development
2008 (English)In: Journal of Building Physics, ISSN 1744-2591, E-ISSN 1744-2583, Vol. 32, no 1, 33-48 p.Article in journal (Refereed) Published
Abstract [en]

As a result of increased concern with energy consumption in the industrial world, it is only natural to look towards the building sector to seek significant improvements to meet expectations of the society. After all, the building sector consumes more energy than the transportation sector. Yet, the procedures that are used to define the thermal performance of, for example a wall, are typically based on the tests performed on dry materials, without consideration of air and moisture movements. In other words, these tests represent arbitrary rating conditions because we know that the energy performance of materials and building assemblies are affected by moisture and air flows. It is believed that to improve their energy performance one must have more precise means of evaluation of their field performance that would also include the consideration of air and moisture transfer conditions. In the first part of this article a background for the evaluation of thermal performance by traditional testing with calibrated boxes shows that use of these tests is limited. The average heat flow that they measure is sufficient to rate the wall assemblies but insufficient to calculate its thermal performance under field conditions. To include the effect of climate on thermal performance one must use computer models that are capable of simultaneous calculations of heat, air, and moisture transfer. Effectively, to characterize energy performance of the building enclosure one must simultaneously use assembly testing and modeling, i.e., an integrated methodology. In the second part of the article, this integrated testing and modeling methodology is applied to a few selected residential and commercial walls to highlight the magnitude of air flow effects on the steady-state thermal resistance. The integrated methodology proposed by Syracuse University includes several otheraspects of  hygrothermal performance evaluations. Those aspects will be addressed in later parts of this article series.

Place, publisher, year, edition, pages
Los Angeles, London, New Delhi and Singapore: Sage Publications, 2008
Keyword
energy efficiency, heat losses and gains, low energy housing, thermal performance, heat, air and moisture transfer.
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-65777 (URN)10.1177/1744259108093316 (DOI)000257641000004 ()
Note
QC 20120220Available from: 2012-01-25 Created: 2012-01-25 Last updated: 2017-12-08Bibliographically approved
6. Integrated Methodology for Evaluation of Energy Performance of Building Enclosures – Part II: Examples of Application to Residential Walls
Open this publication in new window or tab >>Integrated Methodology for Evaluation of Energy Performance of Building Enclosures – Part II: Examples of Application to Residential Walls
2008 (English)In: Journal of Building Physics, ISSN 1744-2591, E-ISSN 1744-2583, Vol. 32, no 1, 49-65 p.Article in journal (Refereed) Published
Abstract [en]

It is often forgotten that the building sector consumes more energy than the transportation sector. To meet expectations and needs of our society, onemust seek significant improvements in the efficient use of energy for this purpose. In many instances our normal approach based on conventional testing methods isnot comprehensive enough. For instance, the thermal performance of a wall is defined by tests performed on dry materials, without considering the air andmoisture movements. The energy performance of materials and building assemblies is affected by moisture and air flows. The authors believe that a more precise meansof evaluation of the thermal performance of assemblies must be used to guide us in developing construction practices that lead to better performance. This shouldinclude consideration of air and moisture transfer under field conditions.The previous part of this study describes the limitations of conventional thermal resistance testing using calibrated hot boxes and explains that the effect of climate onthermal performance must also involve use of computer models that are capable of simultaneous calculations of heat, air, and moisture (HAM) transfer.In this study, the integrated testing and modeling methodology proposed is applied to a few selected residential walls to highlight the magnitude of air floweffects compared with steady-state thermal resistance without air flows. Effectively, to characterize energy performance of the building enclosure, one must use an integratedmethodology that uses both testing and modeling. The study represents a first step in this direction.

Place, publisher, year, edition, pages
Los Angeles, London, New Delhi and Singapore: Sage Publications, 2008
Keyword
energy efficiency, heat losses and gains, low energy housing, thermal performance, heat, air and moisture transfer.
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-65782 (URN)10.1177/1744259108093317 (DOI)000257641000005 ()
Note
QC 20120126Available from: 2012-01-25 Created: 2012-01-25 Last updated: 2017-12-08Bibliographically approved
7. Integrated methodology for evaluation of energy performance of the building enclosures: part 3 — uncertainty in thermal measurements
Open this publication in new window or tab >>Integrated methodology for evaluation of energy performance of the building enclosures: part 3 — uncertainty in thermal measurements
2011 (English)In: Journal of Building Physics, ISSN 1744-2591, E-ISSN 1744-2583, Vol. 35, no 1, 83-96 p.Article in journal (Refereed) Published
Abstract [en]

Thermal performance of building enclosure is typically based on laboratory tests performed on dry materials without consideration of air and moisture movement through the assembly. To address the field performance of the assembly, however, one must combine measurements and hygrothermal modeling. Hygrothermal models are necessary to include effects of climate and in particular the effects of moisture movement on thermal performance. Full-scale testing is necessary to relate findings of the models to actual construction details. The first paper in this series (Bomberg and Thorsell, 2008) introduced a test program that starting with benchmarking of the R-value of the tested wall in standard conditions, examined the effects of air flow on its thermal performance. This test program does not use the average R-values of the wall as it is in the ASTM testing, but measures local thermal resistance in selected places and calculates the average R-values. The second paper in this series (Thorsell and Bomberg, 2008) applied this integrated testing and modeling approach to selected wood framed residential walls, identifying the magnitude of air flow effects on steady-state thermal resistance, as well as demonstrating that the thermal performance of the top of the wall differs from that at the bottom. It also showed a systematic and time dependent shift in thermal performance caused by moisture movement. In this, third paper in the series, we present measurements performed on metal frame walls that introduce additional sources of uncertainty in the experimental results. We end with a discussion on the need of improvements to testing procedures for evaluation of energy performance of building enclosures.

Place, publisher, year, edition, pages
Los Angeles, London, New Delhi and Singapore: Sage Publications, 2011
Keyword
full-scale testing, air flow, thermal performance, local measurements, metal frame
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-65785 (URN)10.1177/1744259111404381 (DOI)000292288100004 ()
Note
QC 20120126Available from: 2012-01-25 Created: 2012-01-25 Last updated: 2017-12-08Bibliographically approved

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