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INSULATION MATERIALS
Fibreglass
This is a widely
used and common form of insulation. On the positive side, fibreglass
is a very good insulator and some brands are now using recycled
glass. On the negative side it requires allot of energy to produce
and the manufacturing process can result in harmful emissions of
fluorides, chlorine and volatile organic compounds. It is non-biodegradable
and emits toxic fumes when burnt. It can cause irritation to the
skin, eyes and throat and there are also some concerns though as
yet unproven that it may be carcinogenic. Fibreglass has a natural
resistance to rot and is reasonably durable.
Insulation performance:
K Value is 0.033 W/m.k - 0.040 W/m.k
Mineral Wool is often also referred to as 'Rock Wool' (a leading
brand) and is actually made up of a mix of recycled steel slag and
basalt rock. The proportions are usually at least 75% steel slag
and 25% basalt rock, but in some cases virtually 100% steel slag
is used. Like fibreglass, mineral wools are recyclable and have
the added advantage of being fireproof. However, they also share
many of the failings of fibreglass, being non-biodegradable, causing
irritation to skin, eyes & throat, and also the potential (as
yet unproven) threat of being a carcinogen. Mineral wools are very
durable and have a natural resistance to rot, but again compression
and moisture ingress will reduce their effectiveness over time.
Mineral wools also emit toxic fumes when burnt.
Insulation performance: K Value - 0.033 W/m.k - 0.040 W/m.k
Environmentally friendly insulation materials:
Wool is a naturally renewable resource and an ideal insulating material
with a similar thermal performance to mineral wool and fibreglass,
but without the environmental or health concerns. It does however
have one downside - it is more expensive. Wool is a natural material,
is fully biodegradable and recyclable, uses very little energy in
its production into insulation bats (pads) and is naturally resistant
to insects and decay. Even better, wool is completely safe to install,
is sound absorbent, inherently moisture tolerant (without losing
thermal efficiency) and also has the ability to soak-up and neutralise
harmful toxins such as nitrogen oxide. With its hygroscopic qualities
wool is particularly appropriate for timber framed buildings, but
if you are prepared to pay a little extra for your insulation it
will give eco-friendly, safe insulation that will last the lifetime
of your home plus a range of other benefits to any loft (or indeed
wall) irrespective of construction type.
Insulation performance: K Value - 0.037 W/m.k - 0.040 W/m.k
Physical properties of Sheep wool insulation:
- Density 22.5
kg/m³
- Vapour Resistivity
7.00 MNs/g
- Vapour Diffusion
Resistance Factor (ref. air) µ 1.0
- Water Absorption
(@100% RH) 40%
- Sound absorbing
properties- sheep wool insulation is effective in reducing the
transmission of airborne and impact sound through the building
envelope.
Fire Resistance
Sheep wool insulation
has greater fire resistance than cellulose or cellular plastic insulates:
it does not burn but melts away from an ignition point and self
extinguishes. The inert, naturally occurring mineral enhances the
natural fire resistance to comply with AS 1530.3-1989 (spread of
Fire) ignitability. Ignition point 560c
Resistance to
decay
Prolonged exposure
to water or sunlight will cause the wool to degrade, in common with
any organic material. Treatment of the wool with an inert, naturally
occurring material helps prevent attack from rodents, moulds and
fungus. when installed Sheep wool insulation will retain its loft
and thermal performance for the life of the building.
Recycled Newspaper
is another great insulator with similar thermal performance to the
above and strong environmental credentials. Like wool it is fully
biodegradable and recyclable (if kept dry) and the production process
requires little energy to produce the bats. It is also completely
safe to install and is less expensive than wool. Some users have
reported problems with mould (although this does appear to be in
exceptional cases) and moisture ingress is likely to reduce its
thermal performance. It usually contains some additives for fire
resistance and a fungicide as well as 'binders' to prevent compression.
Insulation performance: K value - 0.038 W/m.k - 0.040 W/m.k
Hemp is a third eco-friendly insulation alternative, and like both
wool and recycled newspaper is a non-hazardous fibre and therefore
completely safe to install. Furthermore it is fully biodegradable
(you can even add it to your compost pile at the end of its useful
life) and made from a renewable carbon-neutral resource. It has
natural resistance to insect attack and the production process requires
low levels of energy. Thermally it is equally as impressive as wool
and shares some of the same hygroscopic properties. The high density
of hemp insulation typically (35kg/cu.m) also gives it excellent
acoustic properties. Like wool insulation bats it does contain 15%
polyester fibre to retain lift and stability and also has non-reacting
salt additives to provide fire resistance. Unfortunately another
attribute it shares will wool insulation is that it is more expensive
than conventional insulation materials. The use of hemp particularly
with a hemp lime combination is such that the captured carbon is
retained within the fabric of the building. Capable of locking up
around 110kg of CO2 per m3 of wall.
Insulation performance: K values - 0.039 W/m.k - 0.043 W/m.k
- Capable of
locking up CO2 within the wall construction
- Offers a
highly sustainable and fast track method of construction
- High thermal,
insulations and air tightness properties
- Enough hemp
to produce one house can be grown in just 14 weeks in one hectare
of land.
All images copyright © Eco Build Property 2008
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