Heat pumps are often presented as a more environmentally friendly heating solution than gas or oil. However, their environmental impact depends on many factors: system performance, outdoor temperature, installation quality, settings, electricity consumption, usage and refrigerant.
So, is a heat pump really environmentally friendly? To answer this question, we need to look at both sides of the issue: how the surrounding environment affects its performance, but also what impact the heat pump itself has on the environment.
The environment directly affects heat pump performance
An air-source heat pump — air-to-air or air-to-water — draws part of its energy from the outdoor air. The conditions in which it operates therefore have a direct impact on its efficiency.
Good to know
An air-to-air heat pump extracts heat from the outdoor air to warm the air inside the home directly. If it is reversible, it can also provide cooling. An air-to-water heat pump also uses energy from the outdoor air, but transfers the heat to the water circuit of the heating system.
Outdoor temperature: efficiency changes with the seasons
A heat pump's performance is measured in particular by its coefficient of performance, or COP. A COP of 3 means that the system delivers 3 kWh of heat for every 1 kWh of electricity consumed.
When the outdoor temperature drops, the heat pump has to work harder to extract the heat available in the air and maintain the desired indoor temperature. Its efficiency can therefore decrease.
In the United Kingdom, the government highlights that heat pumps are well suited to the country’s variable climate and can continue to operate even when temperatures fall below freezing. Cold weather therefore does not prevent them from working, although it can affect their efficiency.
However, weather conditions do not explain everything. The performance of the equipment itself, its sizing, the heat emitters used, its settings and the quality of the installation also affect its actual efficiency.
Wind, humidity, rain and snow: what impact do they really have?
An outdoor unit is designed to operate outside and withstand normal weather conditions. Rain or humidity are therefore not, in themselves, a problem for the system.
In winter, however, the combination of cold and humidity can encourage frost to form on the heat exchanger. The heat pump then automatically starts a defrost cycle, which is necessary for operation but may temporarily reduce efficiency.
And this is not only a winter issue. In summer, a reversible heat pump operates in reverse to extract heat from the home and release it outside. During very hot weather, cooling demand increases, meaning that outdoor conditions affect its operation throughout the year.
A well-planned installation limits the impact of the surrounding environment
The importance of choosing the right location
The performance of an outdoor unit also depends on its immediate surroundings. It must have enough space to draw in and discharge air efficiently, remain accessible for maintenance and comply with the clearances recommended by the manufacturer.
In particular, configurations that could encourage recirculation of discharged air should be avoided, as they would force the system to operate under less favourable conditions. The location should also take neighbouring properties and potential noise disturbance into account.
Maintaining good operating conditions is not only a technical consideration: if a heat pump has to consume more electricity to provide the same level of comfort, part of the intended energy benefit is lost. Any structure installed around the outdoor unit should therefore respect this principle.
Why protect the outdoor unit without restricting ventilation?
This question arises in particular when the aim is to protect the system or simply integrate it more discreetly into a façade, garden or terrace.
An air-to-air or air-to-water heat pump constantly exchanges large volumes of air with its surroundings. A cover that is too enclosed or incorrectly sized can therefore restrict this airflow or encourage recirculation of discharged air.
Key takeaway
Choosing a cover is not only about appearance. Its design must above all preserve the airflow required to maintain the heat pump's energy performance.
This principle applies whether you choose an aluminium air conditioner cover or a wooden air conditioner cover.
What is the real environmental impact of a heat pump?
Putting electricity consumption into perspective
A heat pump uses electricity, but it uses it to transfer heat rather than generate it directly. It can therefore deliver several kWh of heat for every 1 kWh of electricity consumed.
This difference in how they operate helps explain the gap compared with direct electric heating, which converts the electricity it consumes directly into heat. As an indication, the UK Energy Technology List uses a coefficient of performance of 3 for an electric heat pump in one of its examples: for every unit of electricity consumed, three units of heat are produced.
For a reversible heat pump, however, summer use must also be taken into account. Cooling a home during a heatwave provides real comfort, but inevitably results in additional electricity consumption.
Heat pumps: a much lower carbon footprint than fossil-fuel heating systems
Unlike a gas or oil boiler, a heat pump does not directly burn fossil fuels in the home. Its carbon footprint depends mainly on its efficiency and on how the electricity it uses is generated.
In the United Kingdom, the carbon impact varies significantly depending on the heating system used. Data published by the Energy Technology List make it possible to compare the emissions associated with producing the same amount of useful heat: heat pumps have lower emissions than direct electric heating, as well as gas and oil boilers.
These figures are based on the assumptions used by the Energy Technology List and are intended primarily to illustrate the differences between various heating technologies. Actual performance depends in particular on the efficiency of the equipment, the quality of its installation, how it is used and changes in the electricity mix.
A heat pump is therefore not “impact-free”. However, its energy efficiency can enable it to significantly reduce heating-related emissions when it replaces a system running directly on gas, oil or electricity.
Beyond these differences between heating systems, decarbonising heating is a major challenge in the United Kingdom: heating accounts for more than one third of the country’s carbon emissions and around half of UK natural gas demand.
A heat pump can reduce carbon emissions by up to 70% compared with a gas boiler. Source: UK Government.
Refrigerants: an important consideration
The environmental impact of a heat pump does not, however, depend solely on electricity consumption.
Its operation requires a refrigerant to transfer heat through the system. Some fluorinated refrigerants have a high global warming potential if they are released into the atmosphere.
In the United Kingdom, the use of fluorinated gases is also regulated in order to gradually reduce reliance on refrigerants with a high global warming potential. In Great Britain, the regulations notably provide for a progressive phase-down of HFCs and place restrictions on the use of certain refrigerants in air-conditioning systems and heat pumps. Ensuring the refrigerant circuit remains leak-tight, together with high-quality installation and regular maintenance, therefore remains essential.
Extending the life of a heat pump also helps reduce its environmental impact
The impact of a system is not limited to the energy it consumes during operation. Its manufacture, transport and replacement also require raw materials and energy.
Correctly sizing the heat pump, choosing an efficient system, optimising its settings, maintaining it properly and ensuring good operating conditions all help preserve its efficiency and prevent premature wear.
Key takeaway
A heat pump that remains efficient over time is also one whose overall environmental impact can be better controlled.
Best practices for combining performance, durability and environmental responsibility
A genuinely efficient heat pump ultimately relies on a combination of factors: equipment suited to the home's needs, a correctly sized installation, an appropriate location, optimised settings, sensible use in both winter and summer, regular maintenance and unobstructed airflow around the outdoor unit.
If you would also like to integrate the outdoor unit more discreetly into your exterior, always choose a solution specifically designed to respect its ventilation requirements. You can also find an air conditioner cover installer to support you with your project.
Ultimately, a heat pump does have an environmental impact, but its energy efficiency can enable it to achieve a significantly lower carbon footprint than fossil-fuel heating systems. However, its environmental performance depends heavily on the quality of its installation, how it is used and maintained, and the operating conditions of its outdoor unit.
FAQ: heat pumps and the environment
Is a heat pump really environmentally friendly?
A heat pump is not impact-free: it consumes electricity, requires raw materials and uses a refrigerant. However, its energy efficiency and the absence of direct fossil-fuel combustion can enable it to achieve a significantly lower carbon footprint than gas or oil heating. In the United Kingdom, the government estimates that a heat pump can reduce carbon emissions by up to 70% compared with a gas boiler.
Why does a heat pump's performance decrease in winter?
When the outdoor temperature drops, an air-source heat pump has to work harder to extract heat from the air. Its coefficient of performance can therefore decrease, even though modern systems are designed to operate at low temperatures.
Can rain or snow damage a heat pump?
Outdoor units are designed to withstand normal weather conditions. In cold, damp weather, frost can nevertheless form on the heat exchanger, in which case the unit automatically starts a defrost cycle.
Does a heat pump cover reduce performance?
A properly designed and sized cover should not reduce performance, provided that it preserves the required airflow and clearances around the unit. By contrast, an enclosure that is too closed can interfere with air circulation.
What is the carbon footprint of a heat pump?
It depends on the performance of the equipment, how it is used, the electricity it consumes, the refrigerant and its life cycle. In the United Kingdom, available data show that a heat pump can generate significantly lower emissions than a gas boiler, an oil boiler or direct electric heating. However, results vary depending on the installation and the assumptions used.
Are refrigerants polluting?
Some refrigerants have a high global warming potential if they leak. In Great Britain, regulations on fluorinated gases govern their use and provide for a gradual reduction in the use of the most climate-damaging HFCs.
Sources and references:
- UK Government — Heat pump investment roadmap: Leading the way to net zero. View the GOV.UK publication
- UK Government – Energy Technology List — Heat pumps: Air to Air, Water to Air, Air to Water, Water or Brine to Water Heat Pumps. View the Energy Technology List document
- UK Government — Fluorinated gases (F gases). View the GOV.UK guidance on F gases
