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The Importance of Refrigerants in Heat Pump Selection

We are increasingly seeing heat pumps being specified to provide heating and cooling to new buildings and this is something we expect to continue. The forthcoming changes to Part L of the Building Regulations will incentivise this further by reducing the carbon intensity of electricity from the grid (mirroring the changes in generation we have witnessed in the last few years).


Specifiers, purchasers and operators need to be savvier when it comes to heat pumps. Regulations limiting the use of certain refrigerants have come into place in the last few years and will continue to tighten in the coming years. Poor management (i.e. selection and replacement) of these could easily lead to operators being stung by long term costs and retrofitting complexities.

WSP’s recent White Paper on Heat Pumps (which can be found here) spoke at length about the benefits of heat pumps for heating and cooling of buildings in terms of operating costs and carbon savings. While these are all true, one element touched on was the role of refrigerants within these units.

Key issues with the use of refrigerants

Single-split heat pumps typically use a hydrofluorocarbon (HFC) refrigerant such as R410A and contain a charge of between 1-5kg, while larger multi-split systems may have a charge up to 50kg (typically for systems over 250kW). The most common fluids used in heat pumps are HFCs which have a global warming potential (GWP) over 1,000 times that of CO2 (R410A has a GWP which is 2,088 times that of CO2).

When equipment is taken out of service, HFC refrigerants are typically cleaned and re-sold. Some of the refrigerant can however be released into the atmosphere (via pipework leaks during the operational life of the product); a feature which many carbon saving calculations fail to acknowledge. Once these losses are taken into account, carbon savings can often be found to not materialise.

Some heat pump systems are also more prone to leaks than others, which exacerbates this issue. Whilst literature suggests that for systems within the EU, heat pumps have a leakage rate of 3-5%, typically this is only part of the story. Quite often systems that do leak, will leak catastrophically, releasing large quantities of refrigerants into the atmosphere in one go.

In the last few years the EU has introduced a new regulation on the use of fluorinated greenhouse gases (F-gases) like HFCs, perfluorocarbons (PFCs) and sulphur hexafluoride (SF6). This includes the limiting of F-gases that can be sold in the EU and the outright banning of certain gasses which have the worst GWP. This has already led to a sharp increase in the cost of certain refrigerants which have limited availability.

Our Advice

In order to be Future Ready specifiers should take into account the potential impact of these regulations for both new and retrofitted systems. If you are working on a project which involves the use of high GWP refrigerants it is worth taking a moment to consider the long term ramification, and if alternatives may be better suited and can be used to guard against future costs.

One option to reduce the issue is careful specification of products. Water-based systems (such as air to water heat pumps rather than traditional split units) may be selected. While these also contain refrigerant, it is hermetically sealed (completely airtight) within the compressor (through the creation of permanent connections by welding or brazing) and factory tested. As no refrigerant is used within the heat distribution system (water is used instead) the volume of refrigerant in the system is minimal and the risk of leakage is greatly reduced.

Another solution may be to consider systems which utilise low GWP refrigerants; though these may not necessarily be a like for like replacement for traditional refrigerants.

In order to future-proof installations, building services professionals need to be aware of and act on these upcoming changes and the general shift in policy. The long term trend in Europe is a move away from high GWP refrigerants; these are being limited on the market and we have seen them becoming increasingly costly. There are solutions already available on the market, but they need careful consideration to get the best result.

This blog was written by Sabbir Sidat, Principal Consultant of Energy, Waste and Sustainable Places. For more information, contact sabbir.sidat@wsp.com