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Do you know about PU and its Global Warming Potential?

As you are all aware the pace of Global Warming is increasing due to growing population and the continuing requirement for fossil fuels. A better understanding of what contributes to Global Warming has put all aspects of life under the microscope including the components that make SIP which are generally OSB/PU (polyurethane) or OSB/EPS (polystyrene).

PU is used in lots of applications from car interiors, upholsterer, paints, sponges to the soles of your feet. PU can provide materials that vary in density, stiffness and hardness. Some chemical compositions of the PU formulations can be harmful to the environment with large GWP.

What is GWP?

GWP, Global Warming Potential, is a measure of how much heat trapping potential a substance has in comparison to Carbon dioxide CO2, which has a GWP of 1. PU is manufactured by combining 2 liquids, polyol and isocyanate, and injected with a blowing agent which controls the chemical reaction and induces foaming. It is the blowing agent that has the GWP. The first generation of blowing agent Hydrofluorocarbons HFC had GWP >2500 so 1kg of HFC would equal 2500kg of CO2. Thankfully each generation of blowing agent has seen significant reductions in GWP and HFC as a blowing agent with a GWP > 150 are banned in the UK. The good news is PU technology is constantly advancing and in the last decade there have been alternative blowing agents developed. Newly developed PU are 4th generation.

Blowing Agents.

The most commonly used blowing agents in SIP manufacture are:-

  • Pentane

    • Pentane has a low GWP of <5. It is used in both PU and EPS manufacture. Pentane assists in providing one of the lowest lamda values, which in simple terms is a very good insulate.

  • Water Blown

    • Water Blown has a GWP of 0 however it is not as good an insulate with a higher lamda value than blown Pentane.

  • HFO

    • The New ERA of blowing agent HFO stands for Hydrofluoroolefin. HFO has zero ODP ozone depletion potential, low GWP <1 and lower lamda value than Pentane there for a better insulate.

As far as we are aware, no SIP manufacturer (PU/EPS) are using high GWP blowing agent, and PU technology is under continual development creating better greener insulates. It is also worth pointing out that each blowing agent has varying characteristics in manufacturing, dimensional stability, adhesion. So when considering SIP and GWP you know what questions to ask.

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