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Measuring the characteristics of thermal insulation materials
Thermal insulation materials and
applications
1
Mineral fibres
© Claude-A. Roulet, Apples, 2015 2
• Fibres made out of melted glass, ceramic or rock, manufactured by centrifugation spinning.
• Fiberglass from recycled glass
• Rock wool from artificial lava or basalt
• Pure silica and aluminosilicates for high temperatures
• Coated with a resin or needled to make mats and plates
Examples of mineral fibres
© Claude-A. Roulet, Apples, 2015 3
Properties of mineral fibres
• Excellent resistance to fire
• Good thermal insulation
• Sound absorption qualities.
• High durability
• Resistant to rot, mould and vermin
• Permeable to air and water vapour
• Absorb water by immersion but drip and dry easily.
© Claude-A. Roulet, Apples, 2015 4
Lightweight glass fibres mat
© Claude-A. Roulet, Apples, 2015 5
Dense mineral fibres plates
© Claude-A. Roulet, Apples, 2015 6
Ceramic insulation
© Claude-A. Roulet, Apples, 2015 7
Organic fibres
© Claude-A. Roulet, Apples, 2015 8
• Wool, cotton, cellulose, straw, fibres from hemp plant, rice hulls, coco nut or durian
• Marginal market, growing
• Sensitive to moisture, pests, mould and fire
• Absorbs water
Organic fibres
© Claude-A. Roulet, Apples, 2015 9
Cellulose Hemp fibres
Wool
Mineral foams: glass foam
© Claude-A. Roulet, Apples, 2015 10
Baking at high temperature a mixture of fine glass powder with a bit of carbon powder.
Good resistance to compression but fragile
Totally tight to water and water vapour
Fireproof, service up to 450°C
Resistant to solvents and acids
Resists to rot, mould and vermin.
Expensive
Foamglass
© Claude-A. Roulet, Apples, 2015 11
Vermiculite
• Expanded mica, lamellar structure
• Filler for high temperature uses up to 1400 °C
• Hygroscopic (absorbs moisture),
• Very durable, and resistant to acids and alkalis
• Expensive
© Claude-A. Roulet, Apples, 2015 12
Vermiculite
13 © Claude-A. Roulet, Apples, 2015
Perlite
• Perlite is natural expanded lava
• Filler for high temperature uses up to 850 °C
• Non combustible
• Hygroscopic (absorbs moisture), but hydrophobic when mixed with bitumen
• Very durable, and resistant to rot, mould and vermin
• Cheap
© Claude-A. Roulet, Apples, 2015 14
Perlite
© Claude-A. Roulet, Apples, 2015 15
Autoclaved aerated concrete
© Claude-A. Roulet, Apples, 2015 16
(AAC), also known as autoclaved cellular concrete (ACC), autoclaved lightweight concrete (ALC)
Cement mortar with aluminium powder, autoclaved
Poor thermal insulation (0.16 < κ <0.21)
Fair mechanical strength
Lightweight building components, roofs, walls
Absorbs water and is very sensitive to frost when
wet
Autoclaved aerated concrete
© Claude-A. Roulet, Apples, 2015 17
Organic foams Expanded polystyrene EPS
General use
Poor resistance to water
Mechanical strength sufficient in most cases
Cheap
© Claude-A. Roulet, Apples, 2015 18
Extruded polystyrene XPS
Inverted roofs
Underground, drained insulation
Fair resistance to weather and water
Good mechanical strength
More expensive than EPS
Polystyrene foam resist to mould and rot, but can be destroyed by rodents or insects.
It does not resist to solvents and temperatures exceeding 80 °
Organic foams
© Claude-A. Roulet, Apples, 2015 19
Polyurethane
Good mechanical strength
Low κ
No resistance to weather and UV and sunlight
On site spraying or injection possible
Urea-formaldehyde
On site injectable foam
No resistance to water but resists rotting
No mechanical strength
Gives off formaldehyde when hardening
Mousses organiques
© Claude-A. Roulet, Apples, 2015 20
Applications of PUR foam
© Claude-A. Roulet, Apples, 2015 21
Woody materials
© Claude-A. Roulet, Apples, 2015 22
Wood fibre and straw
© Claude-A. Roulet, Apples, 2015 23
Cork
© Claude-A. Roulet, Apples, 2015 24
• Good mechanical strength
• May rot when wet for long
• Fair resistance to fire
Super-insulating materials
© Claude-A. Roulet, Apples, 2015 25
Space
© Claude-A. Roulet, Apples, 2015 26
• There is neither convection nor conduction in vacuum
• Only radiation remains
• A reflecting suit ensures a nearly perfect thermal insulation .
The Dewar container
© Claude-A. Roulet, Apples, 2015 27
• The vacuum between the double wall suppresses convection and conduction
• Reflecting metallised walls strongly reduce radiation
• Only conduction at the neck remains.
Vacuum insulation
© Claude-A. Roulet, Apples, 2015 28
Resists to atmospheric pressure (10 t/m²)
Support
material
Airtight
packing
Getter, er
dessiccant
Avoids air to fill the voids in the support material
Keeps a good vacuum despite degassing
Thermal conductivity and pressure
© Claude-A. Roulet, Apples, 2015 29
Vacuum insulation
© Claude-A. Roulet, Apples, 2015 30
© Claude-A. Roulet, Apples, 2015 31
© Claude-A. Roulet, Apples, 2015 32 www.mtsc.unt.edu/faculty/reidy/materials_synt
Silica nanogel
© Claude-A. Roulet, Apples, 2015 33 http://www.boingboing.net/200602061740.jpg
Nanogel products
© Claude-A. Roulet, Apples, 2015 34
Heavy gases
© Claude-A. Roulet, Apples, 2015 35
• Thermal conductivity of locked gases decreases with the molecular mass
• Ar, Kr, Xe, Freons, SF6 are used in:
– Incandescent lamps
– Double and triple glass panes
– Some foams (e.g. PUR)
Thin reflecting mats
© Claude-A. Roulet, Apples, 2015 36
Fibres Reflecting foil(s) Air gap
Thin reflecting mats
© Claude-A. Roulet, Apples, 2015 37
Attention to scammers,
miracles are rare !
Minimum thickness for U 0.40 W/m2K
© Claude-A. Roulet, Apples, 2015 38
8 c m
E P S
1 0 c m C e l l u l o s e
7.5 cm
X P S
6 c m P U R
1 c m
Vacuum fibre glas
m i n . 20 c m
Thermal, porosified brick
9 c m Foam glas
© Christoph Sibold, 2007
© Claude-A. Roulet, Apples, 2015 39
Caracteristics of
insulating materials
Insula
ting p
ow
er
Density
Fire r
ésis
tance
Wate
r vapour
diffu
sio
n
Resis
tance t
o w
ate
r
Com
pre
ssio
n
str
ength
Tra
ction s
trength
Heat re
sis
tance
Absorp
tion
of
vib
rations
Absorp
tion o
f
aerial nois
e
Cost
at giv
en
insula
tion
Gre
y e
nerg
y
Light mineral wool + - - ++ - - 0 - - - - + ++ $ - -
Dense mineral wool ++ + ++ - - 0 0 - ++ ++ + $ 0
Hemp fiber 0 - - 0 - - - - 0 - - 0 ++ $ - -
Wood fibers 0 ++ 0 - - - - + - - + + ++ $$ -
Wood straw -cement - ++ + - - - - + 0 + 0 + $$ -
Cellulose flakes + - - 0 - - - - - - - 0 ++ $ - -
Cork + ++ + + - + 0 ++ + - $$ - -
Glass foam + + ++ ++ ++ ++ ++ ++ - - - $$$ 0
Cellular concrete - - ++ ++ - - ++ + ++ - - - $$$ 0
PUR ++ - 0 - 0 + + ++ - - - $ ++
EPS + - - + + 0 + + 0 - - - $$$ -
Graphited EPS ++ - - + + 0 + + 0 - - - $ -
XPS ++ 0 + ++ + + ++ 0 - - - $ +
Silica aerogel +++ - - + - - ++ - - - + ++ - - $$$$ +++
Applications
© Claude-A. Roulet, Apples, 2015 40
Internal or external thermal insulation? Steady state, cold climate
© Claude-A. Roulet, Apples, 2015 41
Heavy
building
fabric
Heat flow
Wat
er v
apo
ur
con
den
sati
on
may
occ
urr
her
e
Heat flow
Heat flow
External Internal Distributed
Internal or external thermal insulation? Steady state, hot, sunny climate
© Claude-A. Roulet, Apples, 2015 42
Heat flow
Heat flow
Heat flow
External Internal Distributed
Internal or external thermal insulation? Variable outdoor temperature
© Claude-A. Roulet, Apples, 2015 43
External Internal Distributed
External insulation Advantages
increases the time constant;
stabilizes the temperature;
store excess heat or recover stored heat;
suppresses most thermal bridges;
in cold climates, completely suppress the risk of water vapour condensation inside the building element.
Inconveniences application from outside;
increases the time required to change the internal temperature.
In air-conditioned buildings located in warm and humid climate, may increase the risk of water vapour condensation inside the building element
© Claude-A. Roulet, Apples, 2015 44
Internal insulation Advantages
application from inside;
decreases the time required to change the internal temperature;
In air-conditioned buildings located in warm and humid climate, decreases the risk of water vapour condensation inside the building element.
Inconveniences thermal bridges
in heated buildings located in cold climate, may increase the risk of water vapour condensation inside the building element;
decreases the time constant of the building;
building structure exposed to external variations
© Claude-A. Roulet, Apples, 2015 45
Distributed insulation Advantages
simple construction: a single material is used;
regular distribution of the temperature in the wall;
relatively high internal thermal inertia
no condensation problem if permeable finishing.
Inconveniences limited insulation, or
very thick components.
building structure exposed to external variations
© Claude-A. Roulet, Apples, 2015 46
Thermal insulation in the building envelope
© Claude-A. Roulet, Apples, 2015 47
Homogeneous walls
– massive wood
– porosified clay brick,
– aerated concrete
– compressed straw
– adobe
Roof decks
© Claude-A. Roulet, Apples, 2015 48
Without protection
With protection
Inverted roof
Green roofs
49 © Claude-A. Roulet, Apples, 2015
Ventilated walls and roofs
© Claude-A. Roulet, Apples, 2015 50
External insulation, protected with tiles or cladding
Ventilation removes moisture
Inté
rieu
r
Exté
rieu
r
Inté
rieu
r
Ext
érie
ur
Deck temperature
© Claude-A. Roulet, Apples, 2015 51
Inté
rieu
r
Ext
érie
ur
Floor slabs
External insulation
© Claude-A. Roulet, Apples, 2015 52
Interior
Exterior
Interior
Exterior
Internal insulation
Insulation of walls
© Claude-A. Roulet, Apples, 2015 53
EIFS
ETHICS
Internal
insulation
INdoors
Double
wall
Outd
oors
Lightweight
panel
External Insulation and Finishing Systems (EIFS or ETICS)
© Claude-A. Roulet, Apples, 2015 54
Fixation
Insulation
Cement
Mesh
Finishing
© Claude-A. Roulet, Apples, 2015 55
EIFS-ETHICS
© Claude-A. Roulet, Apples, 2015 56
External insulation
• No thermal bridge
• High thermal innertia
• Good protection of the structure
• No internal condensation.
• Use only proven systems
• DIY is dangerous
• Poor shock resistance.
Advantages Cautions
Transparent insulation
© Claude-A. Roulet, Apples, 2015 57
• Solar radiation heats the wall behind the insulation layer.
• Most heat goes inside
• The wall becomes a solar collector
• For cold climates only!
Rayonnement
Heat gains
Pertes
Abso
rbin
g c
oating
© Claude-A. Roulet, Apples, 2015 58
© Claude-A. Roulet, Apples, 2015 59
Applications
Material
Hom
ogeneous
walls
Com
mon f
lat ro
of
Invert
ed r
oof
Ventila
ted
insula
tion
Betw
een w
alls
Inje
cte
d
Flo
ors
Pre
fabricate
d
panels
EIF
S
Fire p
rote
ction
Acoustic
absorp
tion
Isola
tion
to s
hock
nois
e
Light mineral fibre
Dense mineral fibre
Organic fibres
Wood
Wood fibres
Cellulose fibres
Cork
Glass foam
Aerated concrete
PUR, PIR
PS expanded
PS extruded
Urea Formaldehyde
60 © Claude-A. Roulet, Apples, 2015
Optimal thickness
Optimal
thickness
© Claude-A. Roulet, Apples, 2015 61
Effects on comfort Thermal inertia
Outdoors
Indoors
Heat storage
Damping of temperature
variations
Practical effects: cold climate
• Paramount for thermal comfort
• Reduces heating cost
• Internal mass allows using free solar gains through windows
• Heating cost may be reduced by a factor 4.
© Claude-A. Roulet, Apples, 2015 62
Practical effects: hot climates A necessary complement to solar protection
BEEP guidelines: 50-60% reduction in cooling energy by:
• Use of light colours
• Fixed and movable external window shades
• U-values of walls < 0.5 W/m²K
• Double glazing
• Optimise natural ventilation and
• Airtight envelope
• Over-deck insulation
© Claude-A. Roulet, Apples, 2015 63