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Choosing between insulation materials

The following guidelines aim to help you to choose the right insulation materials for your needs, and suggest what to take into account regarding environmental impact. There are basically three different types of insulation material:

Organic – derived from natural vegetation and renewable resources and reclaimable on demolition: for example cork (slabs, tile and granular fill), expanded rubber (pipe sections etc.), wood fibre (insulation board), hemp (loose fill), hemp/lime (rigid construction), sheep’s wool (felted quilt), heraflax (felted quilt), woodwool (rigid slabs), cellulose (loose fill in shredded paper pellet form).

Inorganic – derived from naturally occurring minerals, non-renewable but from mostly plentiful sources, and reclaimable on demolition: for example mineral fibres (rockwool and fibreglass quilt or loose fill), perlite and vermiculite (loose fill, aggregate for concrete), aerated concrete blocks, foamed glass (glass in cellular form).

Fossil organic – mainly plastics derived by the chemical industry from fossil fuel sources, difficult to reclaim upon demolition, and polluting in production: for example expanded polystyrene (‘bead board’ – usually white), extruded expanded polystyrene (semi-rigid, smooth-skinned closed cell boards, usually tinted), polyurethane foam (closed cell semi-rigid boards and foam fill), urea- and phenol- formaldehyde foam, polyisocyanurate foam.

In order of preference, the best choices are insulation made from organic materials from renewable sources and recycled materials (eg cellulose fibre insulation made from recycled newspaper), followed by non-renewable but plentiful inorganic materials, and then those from fossil fuel sources.

The table below compares the embodied energy (energy required for manufacture) of various insulating materials.

Type of insulation

Embodied energy – kWh/m3

Plastic insulation


Foamed glass insulation


Mineral fibre insulation


Cellulose insulation


Sheep’s wool insulation


Sources: CAT; Green Building Bible; Environmental Science Handbook; Pittsburgh Corning; Timber Trade Federation; CIRIA; GreenPro.

However, bear in mind that the embodied energy is marginal for a product like insulation, which can be expected to last the life of the property, and is saving energy all the time it is in use. For this reason, producers of plastic based insulation, such as Kingspan, argue that their products are better, as they are longer lasting, being less prone to damage by water or pests than more natural materials.

Also, remember to look for the U-value when buying insulation material as an indication of the thermal efficiency of the material – a smaller U-value is better as it means less heat loss.

An important issue related to choosing fossil organic insulation is the environmental impact of any blowing agents used during manufacture. Check that they have been blown with pentane rather than ozone depleting or greenhouse gases (HCFCs or HFCs).

Also remember that it is better to insulate with any material than not insulate at all.


The following selection of suppliers provides a flavour of the range of products available.

  • Cork Industry Federation - Trade association for the cork industry. Members include insulation manufacturers.
  • Ecomerchant Ltd   - Supplies sustainable building materials to trade and the general public, including cellulose, wool and wood fibre insulation materials.
  • Warmcel insulation, made from recycled newspaper. Also makes pre-insulated (with Warmcel) structural wall panels and the Soundcel (thermal and acoustic) Floor System.
  • Kingspan Insulation Ltd - ‘Zero Ozone Depletion Potential Products’, including insulation.
  • Limetec - Makes hemp/lime mortars and products.
  • Thermafleece - Manufacturer of Thermafleece insulation, made from British sheep’s wool
  • Natural Building Technologies - Supplies green building products, including woodfibre board insulation.
  • Rockwool Ltd -  Manufactures Rockwool (mineral wool) insulation, including rockfibre cavity wall insulation.
  • ecological Building Systems - UK suppliers of pro clima vapour control, roofing and wall membranes, and wood-based climate boards.