How refrigerants work in heat pumps and what their environmental impacts are

Heat pumps have become increasingly popular over the last few years as a heating and cooling system, but many are unaware that these systems rely on refrigerants to operate. In this article we explain how refrigerants work in heat pumps and what their environmental impacts are.

Thanks to their energy-saving and efficiency features, heat pumps are not only an innovative system for heating, cooling and producing domestic hot water, they are also a key element in the European Union’s strategy to combat climate change. Yes, because, as everyone knows, the primary goal of the European Green Deal is for all EU countries to achieve climate neutrality by 2050.

 

Decarbonisation

Europe is regulating the use of refrigerants with the primary goal of achieving decarbonisation in the near future. Decarbonisation, which is an essential ally in heat pumps, is a milestone since the extraction of energy from the ground, air or groundwater needed for their operation results in a total absence of fuel gas use.

 

The energy efficiency of heat pumps

As energy-related products, heat pumps fall within the scope of application of the European Parliament Directive no. 2009/125/EC of 21 October 2009, which regulates their eco-design and the definition of minimal eco-design specifications. A Directive that has given rise to numerous implementing regulations over the years, such as Regulation 813/2013 for single and combined heating systems, and that in 2021 alone saved more than 120 billion euros in energy. On the other hand, Directive 2010/30/EU of 19 May 2010 introduced energy labelling for energy-related products, including heat pumps, which indicates their consumption by means of an energy rating and certain other parameters.

 

The use of renewable energy

When talking about renewable energy, it is impossible not to refer to the so-called Renewable Energy Directive (2009/28/EC), a Directive focused on the development and distribution of clean energy in all sectors of the European economy, which has steadily expanded its targets over the years. After achieving the first target of producing at least 20% renewable energy by 2020, with consumption rising from 12.5% in 2010 to 21.8% in 2021, the European Commission has proposed to reach 40% by 2030. With RePowerEU, the plan launched in May 2022 in response to the emergence of energy market issues due to Russia’s invasion of Ukraine, the idea is to raise this percentage to 45%.
Moreover, with this initiative, EU countries have reduced their dependence on Russian fuels, saved about 20% energy and introduced a cap on gas and oil prices.

Heat pumps
and refrigerant

As already mentioned, heat pumps are a viable green alternative to the traditional boiler, since they “use” a naturally available source of thermal energy to transfer heat from a colder environment to a warmer one. An innovative technology that pollutes less and ensures significant savings on utility bills. Among the various components used in heat pumps, now increasingly popular in residential, commercial and industrial settings, there is one element that can potentially have a strong environmental impact and is essential for operation of the device: the refrigerant.

DIN EN 378-1 refers to refrigerant as a fluid used in a refrigeration system that enables heat transmission due to its physical properties. This is a process in which the refrigerant passes through a circuit consisting of a compressor (2), a condenser (3), a lamination valve (4) and an evaporator (1), changing from a liquid state to a gaseous state and vice versa.

Quite often the term “coolant” is improperly used as a synonym for refrigerant. The former, however, is not enough to ensure proper operation of a heat pump, as it only removes heat from an object when the outdoor environment temperature is lower. On the other hand, the refrigerant removes heat even when the environment temperature is warmer than that of the object to be cooled.

What are the characteristics and main types of refrigerants?

Clearly, all refrigerants are not the same. Indeed, there are substantial differences depending on their field of application. However, they have some characteristics in common, such as a very stable chemical structure and a high performance coefficient. Furthermore, most refrigerants have a low vapour volume, liquefy at low pressure and have a low boiling point.
Refrigerants can be divided into three main categories: pure organic fluids such as water and ammonia, hydrocarbons such as butane, isobutane, propane and propylene, and halogenated hydrocarbons, namely hydrofluorocarbons (HFCs), chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) and perfluorocarbons (PFCs). But which refrigerants are most commonly used in heat pumps? First of all, here are those that cannot be used. CFCs and HCFCs, for example, have been banned because they are considered to be amongst the main contributors to the destruction of the ozone layer. The current standard requires the use of HFCs in heat pumps and generally in air conditioning systems in buildings and vehicles.

Il Regolamento 517/2014 sugli F-Gas

The emission of fluorinated greenhouse gases, commonly referred to as F-Gases, into the environment produces significantly more warming than carbon dioxide. This is why the European Union is tightening its control on the types of refrigerant gases that can be used in heating and cooling devices. With the F-Gas Regulation 517/2014, published in 2014, a number of obligations were established that came into force gradually and will become effective by 2025. The goal? To reduce F-Gas emissions by 79% by 2030, compared to the average from 2009 to 2012. But what, specifically, are the limitations imposed by the Regulation? The first concrete actions concerned refrigeration systems for commercial use, such as cold counters and cold rooms in warehouses and supermarkets. In fact, at the beginning of 2020, the Regulation banned the use of HFC gases with a global warming potential (GWP, index denoting the harmfulness of gas in relation to the greenhouse effect) of 2,500 or more in this type of system. From 2022, the GWP must be less than 150.
Subsequently, the Regulation was also extended to cover equipment in industrial refrigeration plants with a capacity of more than 40 kW or more, where the use of gases with a GWP below 150 was banned from 1st January 2022, with the exception of the primary circuit of cascade systems where the refrigerant must have a GWP below 1,500. On the other hand, residential air conditioners with a gas charge of less than 3 kg, i.e. classic split systems, will only have to comply with a new regulation as of 2025, when refrigerant gases with a global warming potential of more than 750 may no longer be used in any new models.

How do you choose the right refrigerant?

While the primary criterion that results in choosing one refrigerant over another relates to its field of use (air conditioning, cooling, heat pump, etc.), there are many other elements to be taken into account that concern environmental and safety aspects, but also thermodynamic and economic issues.
In terms of safety, the two properties that characterise refrigerants are toxicity and flammability. For a more accurate overview and classification of risks, the American Society of Heating, Refrigerating and Air-Conditioning Engineering (ASHRAE) has identified two classes for the first property (A = low toxicity, B = high toxicity) and three classes for the second (1 = non-flammable, 2 = flammable, 3 = highly flammable). How about a few examples? Hydrocarbons such as refrigerant propane (R290) and butane (R600) are in class A3 as they are non-toxic but at the same time highly flammable, whereas most hydrofluorocarbons (HFCs) are in class A1.
Environmentally friendly refrigerants:
Clivet

From 2025, as mentioned above, new purchases will be required to choose air conditioners and heat pumps (with a gas charge of less than 3 kg) that use refrigerants with a GWP index of less than 750. Clivet adapted a while ago, using a refrigerant fluid with a lower GWP index than the mix most commonly used in the past, namely R-410A. This gas is R-32 which, although considered a new generation refrigerant, has already been in use for several years as a 50% component of the same R-410A mix. The new R-32, found in all of Clivet’s split heat pumps and packaged units, is in fact characterised by an ODP (Ozone Depletion Potential) of 0 and a GWP of 675 (about one third of that in R-410A gas, which averages 2088).

Find out more about Clivet heat pumps containing R-32 gas