Foam Blowing Agent

High quality high performance insulation improves energy efficiency primarily by reducing heat transfer. For building insulation, it reduces heat loss or heat gain which improves occupant comfort and can lower energy costs.  For cold and chilled storage and transport, it reduces heat gain and helps maintain good temperature control.

The currently most widely used HFCs were back then shown to be non-flammable and of low toxicity. Their environmental impact was fully characterized. When HFC-134a was introduced, no other industrial product had been so extensively tested. HFCs are hydrocarbons containing fluorine atoms that give them their exceptional properties. Their common names consist of the abbreviation HFC (hydrofluorocarbon),a number and some letters which reveal the exact molecular structure. For more details, reference is made to the EFCTC Learn about … (H)(C)FC and HFO Nomenclature – basic principles.

In “Buildings & Climate Change: A Summary for Decision-makers UNEP’s Sustainable Buildings & Climate Initiative (SBCI)”, it is stated that not only do buildings use about 40% of global energy for heating and cooling, but in addition, that they emit approximately one third of all greenhouse gas (GHG) emissions. Therefore, increased building insulation offers great potential for achieving significant GHG emission reductions, in developed and developing countries.[Report of the Technology and Economic Assessment Panel, June 2016, Volume 1, Progress Report]

There are a wide range of insulating materials but closed-cell foam insulation has several advantages as it:

  • Preserving food and medicines in refrigeration appliances.
  • Providing comfortable and safe living via air-conditioning in offices, houses hospitals, and shops.
  • Saving energy as blowing agent for high performance thermal insulation foams.

Foam Blowing Agent

The foam blowing agent is selected to provide a closed-cell structure which minimizes heat transfer, in part due to the properties of the foam blowing agent, which is retained within the foam essentially for the lifetime of the foam’s use. The blowing agent used can be a liquid or a gas that is dissolved in the foam precursors and expands to form the foam once it is injected or sprayed and the foaming reaction begins. Traditionally, HFC foam blowing agents have been widely used due to their suitable boiling points and overall performance. The foam blowing agent and foam matrix, which may be bonded to impermeable metal facings, are selected to minimize migration of the blowing agent out of the foam which increases its thermal conductivity. Most importantly, HFCs provide very good insulating properties to the foam and are non-flammable which is ideal for spray polyurethane foam insulation.

Due to their high global warming potential, Regulation 517/2014 has use bans for some HFCs in insulation foams:

Foams that contain HFCs with GWP of 150 or more except when required to meet national safety standards

  • Extruded polystyrene (XPS): 1 January 2020
  • Other foams: 1 January 2023

Alternative blowing agents, such as hydro-fluoro-olefins (HFOs) , with very-low GWPs, are being introduced as a replacement for HFCs while retaining similar technical and insulation performance.   Non-flammable HFO blowing agents have a GWP as low as one, which is equivalent to carbon dioxide.

 

For the first time, the emergence of HFOs seems to be offering a level of performance which not only allows the replacement of blowing agents with high-GWPs such as HFCs, but also has the potential to replace some elements of the hydrocarbon and CO2-blown sectors, based primarily on improved thermal properties. This is particularly the case in the PU Appliance sector. In practice, blends of HFOs with other blowing agents are likely to be favoured.

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