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Vacuum Insulation Panels (VIPs): An Historic Opportunity for the Building Construction Industry

May 15, 2014

WHAT IS A VACUUM INSULATION
PANEL (VIP)?
The construction of VIPs is based on the
principle of vacuum technology, invented by
British scientist James Dewar in 1892. VIPs
are made with open porous core materials
enclosed in an impermeable gas barrier
(Figure 1) and have three major components:
1) open porous core material that
imparts mechanical strength and thermal
insulating capacity, 2) gas barrier/
facer foil that provides the
air- and vapor-tight enclosure
for the core material, and 3) getter
and desiccant inside the core
material that help extend the
service life by adsorbing residual
or permeating atmospheric gases
or water vapor in the barrier
enclosure.
BACKGROUND AND
SIGNIFICANCE
Reduction of energy consumption
in every aspect of our
daily lives is considered to be
the key to tackling the issues
related to global warming and
its adverse effects on the environment.
Buildings consume up
to 40% of our total national
energy requirements, and thermal
insulation is a key component
that determines the energy
efficiency of the built environment.
Recent upgrades of energy
codes (e.g., NECB 2011, IECC
2012, and ASHRAE 2013) have
recommended higher levels of
insulation in building envelopes.
However, addition of more traditional insulation
in new or existing roofs and walls
is impractical for various reasons such as
very thick layers of insulation increasing the
thickness of the building envelopes beyond
current practices, loss of usable space, etc.
(Mukhopadhyaya et al., 2011). These issues
have provided a fresh impetus to the search
for high-performance thermal insulation for
building envelope construction.
Among the various nonconventional
insulations being introduced to the construction
industry as the next-generation
thermal insulation, VIPs appear to be one
of the most promising insulation materials
with the highest thermal insulating capacity
(up to ten times more thermally efficient
than conventional thermal insulation materials;
see Figure 2). In North America and
throughout the world, the potential to apply
A u g u s t 2 0 1 4 I n t e r f a c e • 1 1
Figure 1 – Vacuum insulation panel (left) and schematic construction of VIP (right).
Figure 2 – R-value of VIP compared with other insulation materials.
1 2 • I n t e r f a c e A u g u s t 2 0 1 4
VIPs in building envelope construction is
enormous, and VIPs can play a major role
in existing and new buildings to meet
the higher insulation requirements of the
newly introduced energy codes. However,
the acceptance of VIPs in the construction
industry is critically dependent on cost,
long-term performance, and availability of
best-practice guidelines.
The expensive core material (e.g., precipitated
silica or fumed silica) is one of the
main reasons behind the higher
cost of VIPs, which offer a satisfactory
long-term service life in
building envelope applications.
To overcome this cost barrier to
mass application of VIPs in the
building industry, researchers at
the National Research Council of
Canada – Construction Portfolio
(NRC Construction) have developed
a low-cost, fiber-powder
composite core material for VIP
(Mukhopadhyaya et al., 2008,
2014). Similar ongoing efforts have
been reported around the world
to introduce glass fiber and other
innovative core materials for VIPs
(Dia et al., 2014; Alam et al., 2014).
The long-term performance of
VIP is governed by two distinct
phenomena (Figure 3): 1) aging and
2) durability. Aging is considered to
be a natural phenomenon for VIPs,
but unknowns are the nature and
rate of aging. On the other hand,
durability is an issue that is related to manufacturing,
quality control, handling, and
maintenance of VIPs.
Finally, development of best-practice
guidelines is one of the most important
steps for creating broader market access
for VIPs in the building construction
industry. Several real-life examples of VIPinsulated
building envelope systems are
provided in literature (Binz et al., 2005;
Mukhopadhyaya, 2011; Brunner and Ghazi
Wakili, 2013); however, development of
technical best-practice guidelines is still a
work in progress at best.
The following paragraphs introduce readers
to the construction of VIPs, heat transfer
fundamentals related to their performance,
advantages and challenges, and observations
from two real-life field constructions.
The authors hope that dissemination
of the technology behind VIPs and their performance
record will stimulate the construction
industry in general and the roofing
community in particular to exploit the
historic opportunity arising from the newly
introduced building energy codes and to
integrate VIPs in the mass construction market
of North America and the rest of the world.
FUNDAMENTALS OF HIGHER
R-VALUE OF VIP
A few eyebrows may be raised over
the high R-value of VIPs, which can reach
R-60/in. or higher. Considering the fact
that the most efficient foam insulation is
about R-6/in., and the most efficient aerogel-
based thermal insulation has about
R-10/in. thermal resistance, it is important
to understand the fundamentals of heat
transfer mechanisms that make the much
higher R-value of VIP a credible reality.
There are three basic heat transfer
mechanisms that control the insulating
capacity of conventional thermal insulation
materials. These are: 1) conduction (solid
Figure 3 – Aging and degradation of VIPs.
Figure 4 – Heat transfer mechanisms through insulation materials.
conduction and air conduction), 2) convection,
and 3) radiation. It should be noted
that air conduction of heat transfer happens
in still air due to random movement of air
particles and collisions among them. The
solid conduction and radiation components
are functionally related to the density of the
insulation materials (Figure 4), and preventing
air movement through air space inside
the insulation can eliminate the convective
heat flow phenomenon almost entirely.
However, air conduction is an independent
component and offers a significant opportunity
to develop high-performance thermal
insulation materials by effectively reducing
this component.
REDUCING AIR CONDUCTION IN
THERMAL INSULATION
The reduction of thermal conduction
through air (i.e., air conduction) can be
done in three ways:
1. Replacing the air with a gas that has
a thermal conductivity less than that
of air
2. Reducing the pore size in insulation
materials to nanoscale
3. Reducing the air pressure inside the
insulation material
The first approach listed herein is the
key for development of closed-cell foam
insulation where gaseous blowing agents
with thermal conductivity lower than air
replace the air inside the closed cells.
The increase of thermal resistance with
the decrease of effective pore size of the insulation
material is a well-known physical phenomenon,
particularly for nano-pore-structured
insulation materials (e.g., aerogel).
In the third approach—reducing the
air pressure inside the insulation material
to increase the thermal resistance—the air
pressure inside the open porous structure
of an insulating material is brought very
close to zero (Figure 4), and the resulting
insulation product is a VIP.
APPLICATION OF VIPS IN BUILDING
ENVELOPE CONSTRUCTION:
ADVANTAGES AND CHALLENGES
VIPs offers a number of advantages and
challenges for application in the construction
industry.
Advantages
1. Higher thermal resistivity than any
known thermal insulation used in
the construction industry (Figure 1)
2. Reduced thickness of building
envelopes/components, providing
increased indoor space and optimization
of land use
3. Constitutive materials may be recycled
after the service life.
Challenges
1. VIPS are more expensive than traditional
thermal insulations used
for building envelope construction,
but are becoming more economically
attractive as a result of improved
research efforts, automation of manufacturing
processes, and increased
volume of production.
2. Aging of VIPs due to slow permeation
of gases/water vapor through gas
barriers, and/or off-gassing of core
material can be very slow, but is an
undeniable reality. Hence, it is very
important for designers and engineers
to know the long-term thermal
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performance of VIPs.
3. Durability (or more
specifically, the handling
of VIPs on the
construction site) is
a significant concern,
considering the fact
that any damage in
the vacuum system
(even a small pinhole)
will destroy the thermal
insulating capacity
of VIPs.
4. In general, VIPs have
a highly conductive
gas barrier/foil facer,
and VIPs are currently
available in sizes
that are much smaller
than traditional thermal
insulation boards
(e.g., rigid foam or high-density
mineral fiberboard). Thermal bridge
effect at edges in a VIP system is a
justifiable technical concern.
5. As VIPs cannot be drilled or cut on
the construction site, unlike traditional
insulation materials, special
design considerations must be
developed to deal with penetrations
through roofs and walls. VIPs with
predetermined holes are available at
a higher price.
However, significant progress has been
made to address these issues globally, and
initiatives are in progress to mitigate the
challenges associated with the application
of VIPs in the construction industry (Binz et
al., 2005; Mukhopadhyaya, 2011; Brunner
and Ghazi Wakili, 2013).
EXAMPLES OF FIELD APPLICATIONS
VIPs in Walls (Ottawa, Ontario)
VIPs were installed in a purpose-built
test hut (Figure 5) at the NRC1 Construction
campus in Ottawa. The indoor environment
of the test hut was controlled, and exterior
weather data were monitored. The VIPs were
installed on an east-facing wall of the test
hut. In the test area of the existing wall,
three 1150-mm x 750-mm x 12-mm (45-in.
x 30-in. x 0.5-in.) VIPs were installed in an
edge-overlapped formation (Figure 6). The
test area was equipped with temperature,
heat flux, and humidity sensors to gather
both external and internal data (Figure 6).
The performance of VIPs installed in the
test hut wall has been monitored since the
winter of 2009-2010. The recorded thermal
1 4 • I n t e r f a c e A u g u s t 2 0 1 4
Figure 5 – NRC test
hut, Ottawa, Ontario,
Canada.
Figure 6 – Construction details of VIPs in wall (Ottawa, Ontario, Canada).
performance of VIPs under dynamic temperature
conditions is shown as a function
of time in Figure 7. In general, there appears
to be no evident significant thermal performance
degradation of VIPs during four
years of field exposure. The monitoring of
thermal performance of VIPs installed in the
test hut will continue.
Performance of VIPs on a Roof
(Ottawa, Ontario)
The in-service low-slope roof was a
15-year-old built-up system on an NRC
office building (Figure 8) undergoing reroofing
with the new-generation rigid roofing
system (Molleti et al., 2011). The crosssectional
layout of this new roof comprised
a concrete deck, vapor barrier, 75-mm
(3-in.) rigid polyisocyanurate (also known
as polyiso or iso) insulation, 6-mm (0.25-in.)
asphalt cover board, modified-bituminous
membrane base sheet, and a modifiedbituminous
membrane cap sheet (Figure 9).
This was a mod-bit roofing system, and all
the roofing components are integrated with
solvent-based roofing adhesive. A 1.2-m x
2.4-m (48-in. x 96-in.) iso-VIP composite was
installed, replacing one of the 75-mm (3-in.)
iso boards. The 75-mm-thick, adhesivebonded
composite VIP comprised two layers
of 12-mm- (0.5-in.-) thick 450-mm x 560-
mm (18-in. x 22-in.) VIP, staggered to minimize
the effects of thermal bridging, sandwiched
between two layers of 25-mm- (1-in.-)
Figure 8 – Reroofed NRC office building.
Figure 7 – Thermal performance of VIP during a typical winter month in 2010, 2011, 2012,
and 2014.
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Figure 10 shows the performance of
VIPs in a week of February 2011, 2012, and
2013, respectively. These data clearly indicate
that thermal performance of VIP has
not gone down in any significant way over
the three years of real-life field exposure in
a roof construction.
SUMMARY
The information and discussion presented
in this paper can be summarized as
follows:
• Based on sound principles of the
basic physics of heat transfer, it is
realistic to expect five to ten times
higher R-value/in. from VIPs than
from traditional thermal insulation
materials used in building envelope
construction.
• Use of VIPs in energy-efficient building
envelope construction is a real
1 6 • I n t e r f a c e A u g u s t 2 0 1 4
Figure 9 – Construction details: VIPs in roof (Ottawa, Ontario, Canada).
Figure 10 – Thermal performance of VIPs during a typical winter week in 2011, 2012, and
2013.
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possibility and an attractive proposition
for the roofing industry.
• Recent upgrades of building energy
codes in North America offer an historic
opportunity for the construction
industry to integrate VIPs in
building envelope construction.
• Available field performance evaluation
results provide encouraging
indicators for the long-term thermal
performance of VIPs in both roof and
wall constructions.
• Application of VIPs as highly efficient
thermal insulation in building envelope
construction is advantageous
(e.g., higher thermal resistance,
reduced thickness of building components,
recyclable, etc.) and challenging
(cost, aging, durability, thermal
bridge, etc.) at the same time.
• Researchers across the world, including
those from the National Research
Council of Canada, are working with
construction industry stakeholders
to exploit the advantages and
addressing the challenges.
REFERENCES
1. M. Alam, H. Singh, S. Brunner,
and C. Naziris, “Experimental
Characterisation and Evaluation
of the Thermo-Physical Properties
of Expanded Perlite-Fumed Silica
Composite for Effective Vacuum
Insulation Panel (VIP) Core,” Energy
and Buildings, Vol. 69, February
2014, pp. 442–450.
2. ANSI/ASHRAE/IES Standard 90.1-
2013, Energy Standard for Buildings
Except Low-Rise Residential Buildings,
ASHRAE, Atlanta, GA.
3. A. Binz, A. Moosmann, G. Steinke,
U. Schonhardt, F. Fregnan, H.
Simmler, S. Brunner, K. Ghazi
Wakili, R. Bundi, U. Heinemann, H.
Schwab, H. Cauberg, M. Tenpierik,
G. Johannesson, and T. Thorsell,
“Vacuum Insulation in the Building
Sector – Systems and Applications
(Subtask B)” IEA/ECBCS Annex 39,
2005, pp. 1-134.
4. X. Dia, Y. Gao, C. Bao, and S. Ma,
“Thermal Insulation Property and
Service Life of Vacuum Insulation
Panels With Glass Fiber Chopped
Strand as Core Materials,” Energy
and Buildings, Vol. 73, April 2014,
pp. 176–183.
5. S. Brunner and K. Ghazi Wakili
(editors), Proceedings of 11th International
Vacuum Insulation Symposium
(IVIS-XI), Dübendorf, Switzerland,
2013, pp. 1-124.
6. International Energy Conservation
Code (IECC), 2012, International
Code Council (ICC), Lenexa, KS, U.S.
7. S. Molleti, P. Mukhopadhyaya, A.
Baskaran, P. Beaulieu, and G. Sherrer,
“Application of Vacuum Insulation
Panels in Low-Sloped Commercial
Roofing Systems,” Proceedings of the
10th International Vacuum Insulation
Symposium (IVIS-X), 2011, p. 10,
Ottawa, ON, Canada.
8. P. Mukhopadhyaya (editor), “Vacuum
Insulation Panels: Advances in
Applications,” Proceedings of 10th
International Vacuum Insulation
Symposium (IVIS-X), Ottawa, ON,
Canada, 2011, pp. 1-218.
9. P. Mukhopadhyaya, K. Kumaran, F.
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A u g u s t 2 0 1 4 I n t e r f a c e • 1 7
Ping, and N. Normandin, “Use of
Vacuum Insulation Panel in Building
Envelope Construction: Advantages
and Challenges,” Proceedings of the
13th Canadian Conference on Building
Science and Technology (Winnipeg,
Manitoba, 2011-05-10), pp. 1-10.
10. P. Mukhopadhyaya, K. Kumaran, N.
Normandin, D. van Reenen, and J.
Lackey, “High Performance Vacuum
Insulation Panel: Development of
Alternative Core Materials,” ASCE
Journal of Cold Regions Engineering,
Vol. 22, No. 4, December 2008.
11. P. Mukhopadhyaya, D. van Reenen,
and N. Normandin, “Performance
of Vacuum Insulation Panel
Constructed with Fiber-Powder
Composite as Core Material,”
ASTM STP 1574, pp. 1-10, April
2014, ASTM International, West
Conshohocken, PA, U.S.
12. National Energy Code of Canada for
Buildings (NECB), 2011, National
Research Council of Canada,
Ottawa, Ontario, Canada.
13. H. Simmler, S. Brunner, U.
Heinemann, H. Schwab, K.
Kumaran, P. Mukhopadhyaya, D.
Quénard, H. Sallée, K. Noller, E.
Kücükpinar-Niarchos, C. Stramm,
M. Tenpierik, H. Cauberg, and M.
Erb, “Study on VIP Components and
Panels for Service Life Prediction
of VIP in Building Applications,”
Subtask A, IEA/ECBCS Annex 39,
2005, pp. 1-157.
FOOTNOTE
1) National Research Council of
Canada, Ottawa, ON, Canada
1 8 • I n t e r f a c e A u g u s t 2 0 1 4
Phalguni Mukhopadhyaya
is a
senior research
officer at the National
Research
Council of Canada.
His research interests
are in energy
and moisture performance
of building
materials and
envelope systems.
At present, he is
working on next-generation thermal insulation
materials (VIPs, Aerogel, Bio-foam, etc.)
and systems and their integration in the
construction industry. Mukhopadhyaya has
authored or coauthored about 150 technical
publications and reports, coedited two ASTM
selected technical papers (STPs 1495 and
1519), and edited one conference’s proceedings
(see http://www.ivis2011.org).
Phalguni
Mukhopadhyaya
Sudhakar Molleti
is a research officer
at the National
Research Council
of Canada. His
work focuses on
the wind-induced
effects on lowsloped
roofing
systems. He is
currently working
on the wind performance
of vegetated roof assemblies, energy
and durability of PV integrated roofs, and
application of vacuum insulation panels in
roofing systems. Molleti is a member of the
ASTM D08 and CRCA Technical Committees.
He received his PhD in engineering from the
University of Ottawa (Canada).
Sudhakar Molleti
David van Reenen
has been a technical
officer at the
National Research
Council of Canada
for the past 14
years. During this
time he has been
involved in numerous
research projects
involving high
performance and
conventional insulations, building materials,
laboratory experiments, field exposures,
life-cycle analyses, and hygrothermal simulations.
David received his bachelor’s degree
in civil engineering from the University of
Waterloo (Canada) and his master of science
degree in building performance from the
Chalmers University (Sweden).
David van Reenen
Gil Hancock Mende, of Doylestown, PA, died June 14, 2014, at
the age of 80. Though few members of RCI knew him, Gil Mende’s
contributions to RCI have been considerable. Gil has been an extremely
gifted and conscientious proofreader of Interface and RCItems since
2007. In 2008, he researched and wrote RCI’s Silver Anniversary
Report, reviewing the first 25 years of our association’s history.
Working for RCI was the last stint in a long and varied professional
career that included teaching in the U.S., Venezuela, Angola,
Afghanistan, Norway, Spain, and the Netherlands, as well as positions
as a newspaper reporter, computer programmer, monument salesman,
technical writer, teacher of English as a second language, and Braille
transcriber for both text and music.
Gil Mende with RCI Director of Publications Kris Ammerman at the 2009
RCI convention in Dallas, Texas.
Gil Mende 1933-2014