Oil-derived insulation
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Expanded Polystyrene (EPS) insulation |
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Extruded Polystyrene (XPS) insulation |
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Rigid polyurethane (PUR/PIR) insulation |
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Phenolic foam insulation |
Expanded Polystyrene (EPS) insulation
Expanded Polystyrene insulation is made from small beads of polystyrene mixed with a pentane as the blowing agent. Heating expands the beads. EPS boards are produced by putting the beads into moulds and heated further to fuse the beads together. Typical applications of EPS boarding are in walls, roofs and floors. Polystyrene beads are frequently used as cavity fill in masonry walls.
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Recyclable through grinding down and adding to new sheeting. |
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Reusable if in suitable condition. |
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Fairly high compressive strength |
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Water impermeable. |
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Inherently resistant to rot and vermin |
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Derived from petrochemicals – causing resource depletion and pollution risks from oil and plastics production. |
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Styrene and other hydrocarbons are emitted as part of the production process. UK emissions are within legally defined limits |
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HBCD, used as a fire retardant, is regarded as hazardous 15 |
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High embodied energy |
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The finished product can have some unstable residues of monomers of styrene which may outgas. 16 |
Thermal conductivity
Typical: 0.032 – 0.040 W/m°K 5
Density
Typical density: 15 - 35 kg/m3
Embodied energy cradle to gate
Various figures: example of 108 MJ/kg (for EPS Average of 2 Swiss factories) 2
Extruded Polystyrene (XPS) insulation
Extruded Polystyrene (XPS) is made by mixing polystyrene with a blowing agent under pressure and the resulting fluid forced through a die. As it emerges from the die it expands into a foam, is shaped, cooled and trimmed to dimension. XPS is slightly stronger than EPS, and although it is used in many of the same applications as EPS, it is particularly suitable for use below ground or where extra loading and/or impacts might be anticipated.
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Recyclable through crushing and adding to new sheeting |
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Reusable if in suitable condition |
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High compressive strength |
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Water impermeable |
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Inherently resistant to rot and vermin |
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In Europe, most blowing agents are zero ozone depletion (ODP) blowing agents |
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Derived from petrochemicals – causing resource depletion and pollution risks from oil and plastics production |
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Styrene and other hydrocarbons are emitted as part of the production process. UK emissions are within legally defined limits |
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HBCD, used as a fire retardant, is regarded as hazardous 15 |
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Can also release small amounts of chlorofluorocarbons 16 |
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The finished product can have some unstable residues of monomers of styrene which may outgas. 16 |
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Relatively high embodied energy |
Thermal conductivity
Typical: 0.028 – 0.036 W/m°K 5
Density
Typical density: 30 kg/m3
Embodied energy cradle to gate
Various figures: example of 95 MJ/kg (for XPS, calculated by Ecoinvent using data from leading factories in Germany and USA) 3
Rigid polyurethane (PUR/PIR) insulation
Polyurethane (PUR), a closed-cell plastic, is formed by reacting two monomers in the presence of a blowing agent catalyst (polymerisation). Polyisocyanurate foam (PIR) is essentially an improvement on polyurethane where there is a slight difference in the constituents and where the reaction is conducted at higher temperatures. PIR is more fire-resistant and has a slightly higher R value. Applications include wall, floor and roof insulation. Polyurethane is also popular in laminate form in SIPS and as an insulation backing to rigid boarding such as plasterboard.
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Recyclable through grinding down and adding to new sheeting |
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Reusable if in suitable condition |
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High compressive strength |
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Water impermeable |
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Inherently resistant to rot and vermin |
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In Europe, most blowing agents are zero ozone depletion (ODP) blowing agents |
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Derived from petrochemicals – causing resource depletion and pollution risks from oil and plastics production |
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The production process produces a number of emissions to air and water and hazardous wastes as defined by EU Directive 91/689/EEC 17. UK emissions are within legally defined limits |
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Relatively high embodied energy |
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Shrinking of panels leading to gaps in the insulation layer, can reduce insulation effectiveness. Jointing of panels (eg tongue & groove) and multiple layers can reduce the problem |
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Insulation performance can be reduced over the first 3 years due to gas exchange from the cells. This reduction of performance is usually included in the manufacturers declared value of thermal conductivity |
Thermal conductivity
Typical: 0.022 – 0.028 W/m°K 5
Density
Typical density: 30 - 40 kg/m3
Embodied energy cradle to gate
101 MJ/kg 17
Phenolic foam insulation
Phenolic foam insulation is made by combining phenol-formaldehyde resin with a foaming agent. When hardener is added to the mix and rapidly stirred, the exothermic reaction of the resin, together with the action of the foaming agent, causes foaming of the resin. This is followed by rapid setting of the foamed material. Though more usually employed in building services applications, phenolic foam panels are suitable as insulation for roofs, walls and floors. Phenolic foam is also popular in laminate form as an insulation backing to rigid boarding such as plasterboard.
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Reusable if in suitable condition |
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Inherently flame resistant |
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High compressive strength |
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High thermal performance |
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Moisture resistant |
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In Europe, most blowing agents are zero ozone depletion (ODP) blowing agents |
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Not readily recyclable |
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Produced from phenol formaldehyde - a toxic petrochemical derivative 19 |
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Shrinking of panels leading to gaps in the insulation layer can reduce insulation effectiveness. Jointing of panels (eg tongue & groove) and multiple layers can reduce the problem. |
Other types of insulation
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Plant / animal derived insulation |
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Mineral insulation |
References
2 Ecoinvent, 2007 supplied by Dr Andrew Norton, Renuables
3 Dr Andrew Norton, Renuables
5 'Insulation for Sustainability - A Guide', XCO2 Conisbee, 2003 (an industry-sponsored report)
15 DEFRA & CSF www.defra.gov.uk/environment/chemicals/csf/advice/hbcd.htm
16 SEDA: www.seda2.org/dfcrb/append.htm
17 'Polyurethane Rigid Foam', I Boustead, PlasticsEurope (an industry-sponsored report)
19 'Formaldehyde Found in Building Materials', Healthy Building Network, 2008
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