Mineral insulation
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Rock mineral wool insulation |
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Glass mineral wool insulation |
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Cellular or foamed glass insulation |
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Aerogel insulation |
Rock mineral wool insulation
Rock mineral wool is made from quarried diabase rock and recycled steel slag. The insulation is produced in a variety of densities according to format and function. Varying densities result in varying levels of thermal conductivity. Applications include masonry cavity walls, timber frame walls, roof rafter insulation, loft and suspended floor insulation.
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Can include around 23% of secondary industrial waste 4 |
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Some brands include recycled mineral wool |
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Reusable if in a suitable condition |
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Some companies have initiated ‘take-back’ schemes |
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Recyclable |
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Inherently non-combustible and resistant to rot |
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A formaldehyde-free binder is available in some brands |
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Quarrying of material can result in land-degradation |
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Production emissions include carbon monoxide, formaldehyde and phenol. The release of these emissions is reduced through use of an afterburner 4. UK emissions are within legally defined limits |
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Though mineral wool is no longer classified as a skin irritant, exposure can cause temporary irritation |
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Thermal conductivity can be increased by either compaction or wetting 5 |
Thermal conductivity
Typical: 0.031 – 0.040 W/m°K
Density
Typical density: 24 - 40 kg/m3
Embodied energy cradle to gate
Various figures:
- 16.8 MJ/kg (cradle to grave) 10
- 15.7 MJ/kg 11
- 22.4 MJ/kg (Flumroc AG, Switzerland) 2
Glass mineral wool insulation
Glass wool insulation is manufactured in a similar way to rock wool, though the raw materials are different as well as the melting process. Glass wool is made from silica sand, recycled glass, limestone and soda ash. The insulation is produced in a variety of densities according to format and function. Varying densities result in varying levels of thermal conductivity. Applications include masonry cavity walls, timber frame walls, roof rafter insulation, loft and suspended floor insulation.
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Typically includes 30 – 60% of post consumer waste 4 |
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A formaldehyde-free binder is available in some brands. |
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Reusable if in a suitable condition. |
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Recyclable. |
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Relatively low-density of material in use reduces overall environmental impact. |
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IInherently non-combustible and resistant to rot. |
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Quarrying of raw materials can cause landscape degradation. |
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Emissions associated with the manufacture of glass wool - mostly in energy generation. UK emissions are within legally defined limits |
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Can include boron to improve moisture tolerance 4 |
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Thermal conductivity can be increased by either compaction or wetting 5 |
Thermal conductivity
Typical: 0.031 – 0.040 W/m°K
Density
Typical density: 16 - 24 kg/m3
Embodied energy cradle to gate
Various figures: example of 49.6 MJ/kg (for glass wool mat produced by Isover SA, Switzerland) 2
Cellular or foamed glass insulation
Foamed glass insulation is made from crushed glass that is mixed with carbon and heated to 1000ºC. The heat causes the carbon to oxidise to form the characteristic bubbles. Foamed glass has a relatively high compressive strength which, combined with its water and vapour resistance, makes the insulation slab suitable for flat roofing in high-load situations such as retaining walls, car parks and green roofs. Other applications include thermal breaks, wall and floor insulation.
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Contains post-consumer glass waste – typically circa, 60%. |
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Can be crushed and recycled. |
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Relatively high compressive strength. |
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Water and vapour impermeable with glued joints. |
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Dimensional stability. |
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Inherently resistance to fire and rot. |
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Thermal mass. |
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Quarrying of raw materials can cause landscape degradation. |
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Emissions associated with the manufacturing of glass. |
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Bitumen content complicates disposal12 |
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Poor flow rate for baths. |
Thermal conductivity
Typical: 0.037 – 0.048 W/m°K
Density
Typical density: 100 - 120 kg/m3
Embodied energy cradle to gate
Various figures: example of 26 MJ/kg (for foam glass produced in Belgium)
Aerogel insulation
Aerogel is a lightweight, low-density material made from silica and air. Relatively new on the market, aerogel blankets are beginning to appear as a component in laminate panels bonded to boards including plasterboard, wood fibre reinforced gypsum board, plywood, and chipboard. The panels are distinguished by their outstanding insulation properties.
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Relatively high compressive strength |
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Water impermeable |
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Inherently resistance to fire and rot |
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Reusable if in suitable condition |
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Though used in other industries for a number of years, it is still relatively untested in the construction industry |
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Quarrying of raw materials can cause landscape degradation |
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Expensive |
Thermal conductivity
Typical: 0.013 W/m°K 13
Density
Typical density: 180 kg/m3
Embodied energy cradle to gate
53 MJ/kg 14
Other types of insulation
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Plant / animal derived insulation |
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Oil-derived insulation |
References
2 Ecoinvent, 2007 supplied by 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)
8 BRE Environmental Profile
11 ETH-ESU, Zurich, Switzerland
12 'The Ecology of Building Materials', Bjorn Berge, 1992 & 2000
13 Proctor Group
14 Aspen Aerogels
Insulation products on GreenSpec
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