Insulation Using Organic Materials
Introduction
Unlike more traditional forms of insulation, such as fibreglass and mineral wool, organic materials require very little energy to manufacture, which means that their impact on the environment is incredibly low. In fact when used as an insulator, the energy saved can have an incredibly postive impact to the environment, which in todays environmentally conscious climate is becoming increasingly more relevant. They are also almost always non-toxic making them safe to handle and thus easier to install.
These materials are often rated by their embodied energy, or the degree of energy conservation as an insulator vs. the energy used in their manufacture. The lower the embodied energy the greater the positive effect to the environment.
The two most popular materials are Sheeps Wool and Celluose due to their incredibly low level of embodied energy, however many more products exists from cork through to hemp and straw. All of these products can be make effective insulators, however their application can be limited by the depth of material needed to provide adequate insulation.
Sheeps wool batts & rolls
Sheeps wool can make an excellent loft insulator due to it's core organic properties. It's breathable which allows it to absorb moisture, this greatly helps reduce condesation in winter, and in summer the moisture is released as the material warms, which can help cool a property.
Wool is also non-flammable, and when used as an insulator it is treated with a fire-proofing agent to increase it's fire withstanding abilities. This property allows it to meet British Standards regulations on fire spread.
- Renewable source
- Low embodied energy
- Safe to handle, making installation easy
- Life expectancy of 50 years or more
- Fire resistant
- Incredably durable
- Naturaly resistant to decay and fungal attack
- Can be argued that wool demand increases methane production
- Organophospates in sheep dips have been linked to illnesses in farmers
Cellulose Batts & loose-fill
This form of insulation is made from cellulose fibres extracted from 100% recycled newspapers. This application puts to good use a material which would ordinarily be buried in a landfill site.
To meet modern fire safety standards the cellulose fibres are treated with inorganic salts, a fungicide is also usually added to further increase resistance. The only true downside is the poor strength of the material, cellulose is a great insulator so long as it lies undisturbed.
- Low embodied energy
- Non-toxic, non-irritant
- Recyclable if kept dry
- Biodegradable
- Safe to handle and install
- Durable so long as kept away from moisture
- Requires venting due to the release of formaldehyde gas from decomposition of newspaper ink
- Can still be susceptable to mould attack
- Strength and resistance to compression is very low
Flax batts & rolls
This form of linen is becoming increasingly popular as an insulator. Be aware though that if imported from the continent the embodied energy rating isn't as low as if it is home produced. As with cellulose, insect and fire repellants are added to increase resistance.
- Low embodied energy
- Recyclable
- Safe to handle and install
- High natural content
- Biodegradable
- Some products may contain plastic binding agents
- Embodied energy increases if imported
Hemp batts
A perfect use for this multi-functional material. Hemp is usually imported into the UK from Germany thus embodied energy count is slightly higher. As with other materials of this type hemp batts contain a fire retardency additive however, due to it's natural resistance to insect attack, a fungicide is not required.
- Low embodied energy
- Recyclable
- Renewable resource
- Safe to handle and install
- High natural content
- Biodegradable
- Naturally resistant to insect attack
- Contains polyester matting (~15%)
- Imported into the UK, increasing embodied energy count
- Currently very expensive
Cork board
With similar insulating properties to hemp and flax, cork boards can make a very useful alternative to fibre glass. Naturally resistant to decay and fungal attack, cork is also resistant to compression making it ideal for flat roof applications. Cork is usually imported into the UK from Portugal, thus increasing it's embodied energy count.
- Very low embodied energy - assuming minimum transportation
- Safe to handle and install
- Recyclable
- Renewable resource
- Biodegradable
- Naturally resistant to insect and fungal attack
- Can give off a small amount of formaldehyde gas
Straw
Strawboards are a classic example of a medieval method for insulation which is becoming increasingly popular again due to it's clear organic nature. With an incredibly low embodied energy count straw may seem an obvious choice, however with the amount needed to act as an insulator it is incredibly heavy which can limit it applications some what.
Straw is also susceptable to fungal attack, this can be reduced though by treating with boron.
- Very low embodied energy - assuming minimum transportation
- Recyclable
- Renewable resource
- Biodegradable
- 100% natural content
- Usually imported to UK which increases embodied energy
- Susceptable to fungal decay unless boron treated
- Very heavy
- Requires specialist installation
- Needs to be kept dry to avoid swelling
Further information and useful links
- Find a Insulation Installer near you
- National Insulation Association
- Energy Savings Trust (est.org.uk)
- Cavity Insulation Guarantee Agency (ciga.co.uk)
- Party Wall Guidance (rics.org)
- Impact of the Party Wall Act 1996 (communities.gov.uk)
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