Frequently asked questions
This section provides short replies to some frequently asked questions. More detailed information can be found in other sections of this site.
What is polyurethane?
The term ‘polyurethane insulation’ covers the family of insulation materials based on PUR (polyurethane) or PIR (polyisocyanurate). Polyurethane is derived from a chemical reaction of a diisocyanate with a polyol. Once this reaction has occurred, a substance is created that is safe and extremely versatile. It can have a number of diverse properties (resilience, flexibility, rigidity), depending on the choice of combined substances.
Can we afford to use fossil fuels for the production of thermal insulation?
Many power stations burn fossil fuels to generate electricity. In the case of polyurethane insulation, crude oil is used to save energy for fifty years or more. Over its life time, a polyurethane insulation board will save over 100 times the energy required for its production. In other words, the amount of energy used to produce the polyurethane insulation for one house is subsequently saved in less than one year thanks to the insulation provided.
Polyurethane insulation accounts for less than 0.04 % of the world’s annual crude oil consumption.
At the end of its life, the energy contained in polyurethane insulation can be recovered by waste to energy plants which further improves the overall energy balance.
Are recycled or renewable materials used for polyurethane insulation production?
Yes. One of the main raw materials, the polyols, can be made from different plant-based substances, such as castor oil, soya oil, glycerol and sucrose, or recycled PET materials. Their share in the total product can already attain as much as 20 % today. Further increases can be expected over the next years.
Can polyurethane insulation products be recycled?
Yes, uncontaminated polyurethane insulation can be recycled. Production waste is usually transformed into other products. For example, highly resistant construction boards can be formed from grinded PU waste through an adhesive pressing process.
Thanks to its durability, undamaged insulation panels can also be re-used in another application.
However, recycling may not always be the most environmentally sound choice for end-of-life polyurethane insulation. It may involve long trasport ways, require a great deal of energy or the product may be contaminated after a decades-long use face. In those cases, energy recovery may be the best solution. In the EU, this is achieved through waste-to-energy plants, which filter pollutants and generate heat and electricity as a result of the combustion process.
Does polyurethane have high energy content?
No. One kilogramme of polyurethane insulation contains about 72 MJ1. This is more than mineral wool or wood fibre, but less than polystyrene. However, one should never use weight as a measurement unit. Polyurethane has a very low thermal conductivity and is extremely light weight. Hence, for the same end-use application (for example a flat roof), the weight of other materials may be six to ten times that of polyurethane and their total energy content will also be significantly higher.
1 Hammond, G and Jones, C (2008) Inventory of Carbon and Energy (ICE) Version 1.6a
Are polyurethane insulation products dangerous?
Absolutely not. Substantial research has shown polyurethane insulation to be safe and inert. No specific health and safety requirements apply to the installation of polyurethane insulation or to its in-use phase over its whole life cycle.
PU insulation products have one of the lowest indoor air emission levels of all insulation products on the market today. Hence, in countries where levels for the emission of dangerous substances exist, PU insulation (PUR and PIR) achieves the best class.
It should be noted that the installation of spray foam should always be performed by qualified contractors.
Does the low breathability of polyurethane cause condensation and mould in buildings?
No. The concept of low and zero energy buildings clearly requires the building envelop to be air tight to avoid uncontrollable air exchange with the outside. Condensation can indeed occur in the insulation layer of walls if a material with low vapour resistance is used. PU will not be affected.
Futhermore, even in the worst case scenario (0.5 air changes an hour), ventilation accounts for 95 % of the vapour transfer from a house with breathable walls. Bulk air-exchange (intended ventilation plus air-leakage) is at least 19 times more important than breathability in controlling air-borne moisture, surface condensation, mould growth, dust mites and consequent health problems. More details here
Is polyurethane insulation expensive?
No. Whilst one kilogramme of polyurethane would be more expensive than certain other products, the picture changes when you look at the amount of money needed to achieve a certain insulation value for your building or building element (roof, wall, etc.). Polyurethane is extremely efficient and hence the insulation layer is thin. This increases revenues from rent or sale in the case of internal lining. Moreover, no major design adjustments are required in the case of low energy buildings which can drive cost significantly up. Thinner walls mean smaller window boards, shorter studs and smaller roofs. Thanks to its low weight, polyurethane insulation will need less fixing devices and the building structure may be lighter in a number of cases. Finally, polyurethane insulation will not settle, guarantees a high mechanical resistance on flat roofs and is unaffected by moisture and air flow. This increases product durability and reduces maintenance costs. All this adds up to a very cost-competitive product.
Where can I find polyurethane insulation products?
Most polyurethane insulation products are sold directly to qualified installers to ensure highest quality in workmanship and hence maximum savings. To help your installer find the right product, we recommend that you go to the website section Where to buy PU.