Building insulation materials 3: Mineral

Rock mineral wool insulation
Glass mineral wool insulation
Cellular or foamed glass insulation
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.

Pro Can include around 23% of secondary industrial waste (4)
Pro Theoretically reusable if in suitable condition
Pro Theoretically recyclable
Pro Inherently non-combustible and resistant to rot
Pro A brand of formaldehyde-free rock wool is apparently available in China, but not yet seen in the UK.
Con Quarrying of material can result in land-degradation
Con 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
Con Only formaldehyde-bound brands available in the UK.
Con Though mineral wool is no longer classified as a skin irritant, exposure can cause temporary irritation
Con Thermal conductivity can be increased by either compaction or wetting (5)
Con High embodied energy
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

More: Thermal properties of insulation.....


 

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.

Pro Typically includes 30 – 60% of post consumer waste glass (cullet) (4)
Pro A formaldehyde-free binder brand is available in the UK
Pro Reusable if in a suitable condition, but there are no current 'take back' schemes
Pro Theoretically recyclable
Pro Relatively low-density of material in use reduces overall environmental impact
Pro Inherently non-combustible and resistant to rot
Con Quarrying of raw materials can cause landscape degradation
Con Emissions associated with the manufacture of glass wool - mostly in energy generation. UK emissions are within legally defined limits
Con High embodied energy
Con Can include boron to improve moisture tolerance (4)
Con Thermal conductivity can be increased by either compaction or wetting (5)
Embodied energy cradle to gate

Various figures: example of 49.6 MJ/kg (for glass wool mat produced by Isover SA, Switzerland) 2

More: Thermal properties of insulation.....

 

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.

Pro Contains post-consumer glass waste (cullet) – typically circa, 60%
Pro Theoretically can be recycled
Pro Relatively high compressive strength make it appropriate for inclusion in structural environments (e.g. walls, slabs)
Pro Water and vapour impermeable with glued joints
Pro Dimensional stability
Pro Inherently resistance to fire and rot
Pro Small degree of thermal mass
Con Quarrying of raw materials can cause landscape degradation
Con Emissions associated with the manufacturing of glass
Con Bitumen content complicates disposal (12)
Embodied energy cradle to gate

Various figures: example of 26 MJ/kg (for foam glass produced in Belgium)

More: Thermal properties of insulation.....

 

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.

Pro Relatively high compressive strength
Pro Water impermeable
Pro Inherently resistance to fire and rot
Pro Reusable if in suitable condition
Con Though used in other industries for a number of years, it is still relatively untested in the construction industry
Con Quarrying of raw materials can cause landscape degradation
Con Expensive
Embodied energy cradle to gate

53 MJ/kg 14

More: Thermal properties of insulation.....

 

Other insulation material types

Plant / animal derived insulation

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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