In our last post, we discussed the merits of hydrogen boilers to heat our homes and help reach the UK government's net-zero emissions target by 2050. However, hydrogen is not the only green energy contender. Today we explore the emergence of the heat pump!
What is a heat pump?
A heat pump is simply a device that transfers heat from one source to another. When it comes to our homes, we can use this heat exchange technology to cool our homes in the summer and heat them in the winter by creating a loop between the property and a ground/air source. Electricity is required is run these pumps, but the heat energy that enters the property is up to 4 times greater than the electricity input of the pump, making it far more efficient than a traditional boiler. Furthermore, if the electricity comes from a renewable source, the home can be considered carbon neutral. It is estimated that the UK will see 15 million heat pump installations in new homes by 2050.
Air source heat pumps
An air source heat pump draws in ambient air from outside, even when the air temperature is as low as -15°C. The units look similar to air conditioners and are placed outside a property, usually in the garden. Plenty of open space is required around it to allow sufficient air intake.
Ground source heat pumps
A ground source heat pump works on the same principle but takes its heat energy from the ground. With the suns radiation, the earth can maintain a temperature of around 10°C just a few metres below the surface - even in winter. The installation of these pumps is more involved than their air counterparts as the components have to be buried underground. Additionally, a large enough garden is required to accommodate the excavation. However, they are out of sight and very quiet due to their location.
How do they work?
Cold air is drawn from the air or ground into a refrigerant fluid. This passes through a compressor which increases its temperature, before being transported to the various circuits in the heating system such as radiators and underfloor heating. This circulation loop is bi-directional meaning it can also be used for cooling. It follows the same principle as as car radiator whereby the constant flow of fluid moves heat away from the engine and brings in cold ambient air. In our homes this cold air can be used for applications such as air conditioning.
How much do they cost?
Due to increased efficiency, heat pumps can significantly reduce energy bills, however one has to consider the higher installation costs. The good new is that as a efficient energy source, they are eligible for one of the governments green financial initiatives. Since 2014, The Domestic Renewable Heat Incentive (Domestic RHI) has been used to promote the use of renewable energy. Homeowners can receive quarterly payments for up to seven years based on the estimated amount of clean, green renewable heat that produced by their heating system. The scheme is currently open for applications until March 2022.
There are numerous factors that would influence the cost of installing any type of heat pump but the following figures are a rough guide based on a 250m² property.
Air pump Domestic RHI
£10,000 - £12,000 £8,400
Ground pump Domestic RHI
£15,000 – £20,000 £17,500
Compare this to a standard boiler installation of approximately, £1500 - £6000 including parts and labour. That said, it's worth noting that while boilers typically have a lifespan of 8 - 12 years, you can typically expect 15 - 25 years from heat pumps due to fewer moving parts. Moreover, they do not require the same frequency of servicing because the safety risks associated with gas are not present. However, one thing to bear in mind is that to reap the rewards heat pumps can offer, a home needs to be very well insulated. So if you have an old draughty house, factor that into the price as well.
Should I get one?
It depends... As a homeowner, you would have to consider numerous factors, the first one being space as this is a deal breaker. Assuming you have a large enough garden and in the case of ground pumps, space to dig, then then one can begin looking at other variables such as the specific heating/cooling applications in the house e.g. underfloor heating, radiators etc. The financial implications would have to be closely scrutinised, taking into account installation, modifications to the exiting house and or heating system and the length of time the property will be occupied in order to recoup the investment.