Heat Pumps: Cheaper and Greener than Gas Heating? A Guide
Heat pumps are likely to be found in many more houses over the next few years. Here’s a guide to exactly what heat pumps are, whether heat pumps are cheaper than gas heating and whether heat pumps are greener than gas heating.
What is a Heat Pump? How Does it Work?
A heat pump is an appliance that transfers heat from one environment to another environment creating a temperature difference in the process. In a home, heat pumps work to transfer heat between the outside of the house and the inside of the house.
A simple explanation of what a heat pump does is that it is similar to a refrigerator or air conditioning unit but operating in reverse.
Heat pumps use electrical energy to power a fan and compressor and move refrigerant fluid between the two environments transferring heat in the process. The heat generated can then be used to power a ducted air heating system. Or it can be used to supply radiators and provide domestic hot water in the usual way. This is known as an air-to-water system.
Heat pumps can be ground source heat pumps (known as GSHPs) that take heat from the ground or water source heat pumps. Heat pumps can also be air source heat pumps (ASHPs) that take heat from the air. Air source heat pumps are probably the most usual type at the moment.
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Amongst other grants and incentives for energy-saving measures, the Government has recently announced new grants to encourage the use of heat pumps. From April 2022 they will offer £5,000 grants for up to 90,000 homes to contribute towards the cost of installing heat pumps and other forms of low carbon heating.
Will Heat Pumps Replace Gas Heating?
The Government has announced plans to ban the installation of gas and oil-fired boilers in new build houses from 2025. Existing properties will still be able to use and replace existing gas boilers. There could however be a complete ban on all new gas boilers by 2035.
Are Heat Pumps Cheaper than Gas Heating?
When considering whether heat pumps are cheaper than gas heating it’s necessary to consider what heat pumps cost to buy and what heat pumps cost to run.
Are Heat Pumps Cheaper to Buy than Gas Heating?
Heat pumps are much more expensive to buy than gas heating typically.
Trade directory site Checkatrade say that air-to-water heat pump systems are the more expensive option and cost an average of £13,000 for supply and install. They say that a gas boiler supply and installation normally costs from £2,000-£4,000.
Heat pump systems may also need new radiators and a hot water cylinder in the house which adds to the cost.
Heat pumps also need a house to be well insulated in order to be effective. So the cost of any extra insulation that is needed may add to the cost.
Grants and other incentives that are available from the Government should help to reduce the cost of getting a heat pump installed but even taking this into account heat pumps are more expensive than gas boilers.
It is anticipated that as heat pumps become used more widely it will become cheaper to buy a heat pump.
Are Heat Pumps Cheaper to Run than Gas Heating?
It is sometimes thought that since heat pumps use free heat from the ground or air heat pumps will be cheap to run, but this is not strictly true. Heat pumps still use electricity to run.
So, whether a heat pump is cheaper to run than gas heating depends on the cost of the electricity used to power it.
Heat pumps are much more efficient than gas heating, however.
The Energy Saving Trust say that heat pumps are around 3-4 times more efficient than boilers because they give out a lot more heat than the electricity they use to run. They say that although electricity is a lot more expensive than gas or oil at the moment the higher efficiency means that the running costs often work out similar. They say that if you’re replacing an old and inefficient gas heating system your bills could go down dramatically.
They estimate that replacing an old G-rated gas boiler with an air source heat pump, for example, could save you up to £375 a year on your heating bills. This is based on an average-sized, four bedroom detached house.
Suppliers of heat pumps suggest that a heat pump will take 7 years to pay for itself when funded using Government incentives.
The Government is proposing to shift statutory levies away from electricity and onto gas in the coming years. This could make electricity cheaper and so make heat pumps cheaper to run.
How cheap a heat pump is to run will depend on how well insulated the property it is used in is. A heat pump in a very well insulated property will be cheaper to run than in a less well insulated property.
It is also important to consider the costs of maintenance and repairs when considering if a heat pump is cheaper than gas heating. Parts for heat pumps are more expensive than for gas boilers. Relatively few engineers are able to repair heat pumps so labour costs for heat pump repairs can be higher. It is anticipated that as heat pumps become more widespread repair and maintenance costs should fall.
Are Heat Pumps Greener than Gas Heating?
One of the arguments put forward for heat pumps is that they are greener than gas heating.
It is often thought that heat pumps are completely green since they utilise free heat from the air or ground. This is not entirely correct, however, as heat pumps require electricity to operate.
It is probably true to say that heat pumps are greener than gas boilers since they are much more efficient at converting the energy they consume into heat.
A report by comparison site Greenmatch says that boilers are typically only 85% efficient but heat pumps are typically 300% efficient.
Heat pumps are potentially greener than gas heating because they can make use of green, renewable electricity. Heat pumps can be fuelled by electricity generated by wind, water or solar power instead of by that generated from gas or coal. Gas boilers are not greener because they can only be fuelled by burning gas which emits carbon and is not renewable. So whether heat pumps are actually greener than gas also depends on how the electricity used to power them is generated.
It is really difficult to find concrete figures on how green are heat pumps. However, it is probably fair to say that heat pumps are potentially much greener than gas heating.
The same Greenmatch report says that gas boilers emit 4,540 kg/yr of CO2 per useful kWh but heat pumps typically emit 2,200 kg/yr of CO2 per useful kWh based on typical usage.
One more thing to bear in mind when considering the green credentials of heat pumps is that the refrigerant gas used in some of them can be hazardous. According to this report from industry experts, the most common fluids used in heat pumps are HFCs which have a global warming potential (GWP) of over 1,000 times that of CO2.