Insulation derived from organic sources
 |
Cellulose insulation |
 |
Cork insulation |
 |
Wood wool insulation |
 |
Wet-formed wood fibre board insulation |
 |
Hemp insulation |
 |
Hempcrete |
 |
Flax insulation |
 |
Sheeps wool insulation |
Cellulose insulation
Cellulose insulation is made from recycled newspaper. The material is usually treated with a mixture of borax and boric acid to provide fire resistance as well as to repel insects and fungi. The insulation is suitable for use between rafters and joists and timber 'breathing' wall construction. Cellulose insulation is available in a loose format for pouring and dry or damp spraying as well as in slab format for fitting within metal or timber frames.
 |
The cellulose component typically (around 80% of the total) contains over 90% post-consumer recycled material. |
|
Manufactured from renewable resources. |
|
Reusable if kept dry |
|
Recyclable |
|
Sequesters CO2 during tree growth. |
|
Very low embodied energy. |
|
Hygroscopic – provides a degree of humidity control. |
 |
Newsprint production can produce hazardous waste1 |
|
Contains boron-based flame retardant and biocide (approx. 20% of total content) |
|
Possible odour and formaldehyde off-gassing from printing inks – though containable through use of vapour control membranes |
|
Possible risk associated with the inhalation of paper dust during installation |
|
Mould has been known to be an issue in exceptional circumstancess. |
|
Thermal conductivity can be increased by compaction or settlement. 5 |
|
Borates will leach if they are exposed to permanent or intermittent wetting such that the insulation remains damp to the touch for protracted periods. 6 |
Thermal conductivity
Typical: 0.038 W/m°C - 0.040 W/m°C
Density
Typical density of loose-fill insulation: 32 kg/m3
Embodied energy cradle to gate
Varied eg:
- 16.64 MJ/kg (cradle to grave) 7
- 7.6 MJ/kg (LHV for a major Swiss producer) 2
- 4.9 MJ/kg (for UK product) 8
Cork insulation
Cork insulation is made from cork bark that is harvested from the tree every 25 years. Cork granules are expanded and then formed into blocks, using the natural resin, through high temperature and pressure. The most common applications for cork insulation are in flat roofs and insulated render systems, both of which take advantage of cork’s dimensional stability and resistance to compression.
|
Manufactured from renewable resources (subject to management) |
|
Reusable if not adhesive or render-coated |
|
Recyclable as loose fill |
|
Can be used in energy recovery |
|
Cork forests support indigenous wildlife (but detailed research of impacts on biodiversity is still lacking) |
|
Cork production helps to sustain communities in poorer agricultural areas |
|
Sequesters CO2 during tree growth |
|
Waterproof |
|
Naturally resistant to insect and rodent attack (except wasps) |
|
Resistant to compression |
|
Dimensionally stable |
|
Cork dust may be a health issue – avoid inhalation |
Thermal conductivity
Typical: 0.038 - 0.050 W/m°K
Density
Typical density: 105 - 120 kg/m3
Embodied energy cradle to gate
Varied eg: 26 MJ/kg (LHV one major producer in Portugal using continuous and batch processes) 2
Wood wool insulation
Wood wool insulation is made from forestry thinnings and saw mill residue. Binding is provided by polyolefin fibres and the fire retardant is usually ammonium phospate. Wood fibre insulation is used in breathing wall construction, ventilated pitched roofs and in ceilings and floors.
|
Typically contains high percentage of pre-consumer waste material |
|
Manufactured mainly from renewable resources |
|
Reusable if in a suitable condition |
|
Recyclable |
|
Compostable or can be used in energy recovery |
|
Sequesters CO2 during tree growth |
|
Hygroscopic – provides a degree of humidity control |
|
Contains non-renewable material (polyester binder). |
|
Contains an ammonium phosphate based fire retardant |
|
Thermal conductivity can be increased by compaction and moisture. 5 |
|
Relatively untested |
Thermal conductivity
Typical: 0.038 W/m°K 20
Density
Typical density: 50 kg/m3 20
Embodied energy cradle to gate
10.8 MJ/kg 21
Wet-formed wood fibre insulation board
Wet-formed wood fibre board insulation is made from largely pre-consumer waste wood from saw mills. The wood is reduced to chips and then soaked in water before being pressed and dried without additional bonding agents. For sarking applications, latex is added to provide water-proofing properties. Wood fibre board insulation is typically used in breathing wall construction as well as in roofs as insulated sarking.
|
Typically contains high percentage of pre-consumer waste material |
|
Manufactured from renewable resources |
|
Reusable if in a suitable condition |
|
Recyclable |
|
Compostable or can be used in energy recovery |
|
Sequesters CO2 during tree growth |
|
Hygroscopic – provides a degree of humidity control |
|
High embodied energy |
|
Usually imported from the continent which adds to embodied energy |
Thermal conductivity
Typical: 0.038 – 0.050 W/m°K
Density
Typical density: 160 - 240 kg/m3
Embodied energy cradle to gate
17 MJ/kg (sarking: 13MJ/kg) 8
Hemp insulation
Hemp insulation slabs are made from hemp or hemp mixed with either recycled cotton fibres or wood fibres, bound with a polyester binder and treated for fire resistance. Hemp insulation is used in breathing wall construction, ventilated pitched roofs and in ceilings and floors.
|
Hemp is a renewable material. |
|
Some products contain recycled material. |
|
Compostable or can be used in energy recovery. |
|
Reusable if in a suitable condition. |
|
Recyclable |
|
Sequesters CO2 during plant growth. |
|
Hygroscopic – provides a degree of humidity control. |
|
Contains non-renewable material (polyester binder). |
|
Production of fertilisers contributes to global warming. |
|
Use of pesticides in crop production. |
|
Contains an ammonium phosphate based fire retardant. |
|
Usually imported from the continent (though some material can be grown in the UK) which adds to embodied energy. |
|
Thermal conductivity can be increased by compaction and moisture 5 |
|
Borates will leach if they are exposed to permanent or intermittent wetting such that the insulation remains damp to the touch for protracted periods 6 |
|
Relatively untested |
Thermal conductivity
Typical: 0.38 - 0.040 W/m°K
Density
Typical density: 40 kg/m3
Embodied energy cradle to gate
Various: between 10.5 and 33 MJ/kg LHV dependant on binder type used and scale of production 3
Hempcrete
Hempcrete, first developed in France and now manufactured by Lime Technology Ltd as Tradical products in the UK, is a precast, insitu cast or sprayed mixture of lime, cement and hemp insulation.
|
Hemp is a renewable material. |
|
Vapour permeable |
|
Hemp sequesters CO2 during plant growth. |
|
Hygroscopic – provides a degree of humidity control through ‘moisture mass’ |
|
Thermal mass |
|
Use of cement contributes to global warming |
|
Production of fertilisers contributes to global warming. |
|
Use of pesticides in crop production. |
|
Drying time |
|
Relatively untested |
Thermal conductivity
Typical: 0.070 W/m°K 9
Density
Typical density: 220 - 330 kg/m3
Embodied energy cradle to gate
Trade figures unavailable but estimates in the region of 2 – 5 MJ/kg LHV are expected dependant on ratios of materials used and scale of production 3
Flax insulation
Flax insulation slabs are made from flax with a polyester binder and treated for fire resistance. Flax insulation is used in breathing wall construction, ventilated pitched roofs and in ceilings and floors.
|
Flax is a renewable material |
|
The flax used in insulation is a by-product of the linen industry – though not strictly waste, insulation flax fibres are of a much lower economic value than linen flax fibres |
|
Reusable if in a suitable condition |
|
Recyclable |
|
Compostable (though presence of boron salts might be of concern) or can be used in energy recovery. |
|
Sequesters CO2 during plant growth |
|
Space efficiency |
|
Hygroscopic – provides a degree of humidity control |
|
Contains non-renewable material (polyester binder) |
|
Production of fertilisers contributes to global warming |
|
Use of pesticides in crop production |
|
Contains boron-based flame retardant and biocide |
|
Usually imported from the continent which adds to embodied energy |
|
Thermal conductivity can be increased by compaction and moisture 5 |
|
Borates will leach if they are exposed to permanent or intermittent wetting such that the insulation remains damp to the touch for protracted periods 6 |
|
Relatively untested |
Thermal conductivity
Typical: 0.038 – 0.040 W/m°K
Density
Typical density: 30 - 35 kg/m3
Embodied energy cradle to gate
Various figures:
- between 11 and 30 MJ/kg LHV dependant on binder type used and scale of production 3
- 39.5 MJ/kg 1
Sheeps wool insulation
Sheep’s wool slabs and rolls are made from wool with a polyester binder and treated for fire and insect resistance. Wool is suitable for use as insulation between rafters, joists and timber studs in timber ‘breathing’ wall construction. Sheep’s wool has excellent hygroscopic properties that help to moderate temperatures throughout the seasons.
|
Sheep’s wool is a waste product from renewable sources |
|
Wool sequesters CO2 during animal growth |
|
Hygroscopic – provides a degree of humidity control |
|
Can absorb moisture without loss of thermal efficiency |
|
Reusable if in a suitable condition |
|
Recyclable |
|
Contains non-renewable material (polyester binder) |
|
Contains boron-based flame retardant and biocide |
|
Imported wool adds to embodied energy |
|
The possible use of pesticides in imported wool |
|
Thermal conductivity can be increased by compaction 5 |
Thermal conductivity
Typical: 0.039 W/m°K
Density
Typical density: 25 kg/m3
Embodied energy cradle to gate
Various figures:
- 20.9 MJ/kg 6;
- 12 – 36.8 MJ/kg dependent on the use of waste wool and scale of production. 3
Other types of insulation
 |
Mineral insulation |
 |
Oil-derived insulation |
References
1 'A Comparative Life Cycle Assessment of Building Insulation Products made of Stone Wool, Paper Wool and Flax'; Anders Schmidt et al, 2004 (an industry-sponsored report)
2 Ecoinvent, 2007 supplied by Dr Andrew Norton, Renuables
3 Dr Andrew Norton, Renuables
4 'Life Cycle Assessments of Natural Fibre Insulation Materials'; Murphy & Norton, 2008
5 'Insulation for Sustainability - A Guide', XCO2 Conisbee, 2003 (an industry-sponsored report)
6 Mark Lynn, Second Nature
7 'Cellulose Fibre Insulation', Eurima, 2004 (an industry-sponsored report)
8 BRE Environmental Profile
9 Lime Technology Ltd. Tradical
20 Steico
21 'Inventory of Carbon & Energy (ICE)' - 1.6a, Hammond & Jones, 2008
Insulation products on GreenSpec
Disclaimer
GreenSpec accepts no responsibility or liability for any damages or costs of any type arising out of or in any way connected with your use of this web site. Data and information is provided for information purposes only, and is not intended for trading purposes. Neither GreenSpec nor any of its partners shall be liable for any errors in the content, or for any actions taken in reliance thereon.
