We know that households across the UK will need to adopt a low carbon alternative to traditional heating solutions such as oil, gas, coal or wood burning in the future.

Air source or geothermal ground source heat pumps are being touted as just such an alternative to help the UK reach its net zero carbon emissions targets by 2050.

That’s a long way off of course, but we do know that the UK government has committed to a ‘decisive shift’ away from fossil fuel burning, with the most popular forms of domestic gas boilers to be phased out by the mid-2030s.

The drive for efficiency is only likely to intensify following the Conference of the Parties (COP 26), attended by countries that signed the United Nations Framework Convention on Climate Change (UNFCCC).

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The 26th Conference of the Parties to be held in Glasgow this coming November is the most significant COP since the Paris Agreement was signed in 2015 as nations will be reviewing their emissions targets. Six years ago world leaders committed to an historic agreement to keep global mean temperature rises well below 2 degrees C, and to strive to limit the rise to 1.5 degrees C.

A difficult choice

As with the shift away for the internal combustion (IC) engines in cars and vans, there is much debate about which way to go, which systems will win out in the end: fully electric, hybrid, fuel cells, hydrogen etc.

We are talking about new and in many cases untried technologies, heat pumps, biomass and hydrogen and solar, so making a choice as to which horse to back, whether with transport or home heating, is going to be a real challenge for manufacturers and the rest of us in the near future.

The government’s December 2020 energy white paper, ‘Powering our net zero future’ states that new measures are definitely to be introduced soon to start switching home heating, at scale, to low-carbon alternatives.

It means that at some point in the future a low-carbon heating system, or an appliance that can be converted to use a clean fuel, will have to be installed in domestic properties. It is thought that at this stage, though technologies are developing, heating systems using heat pumps or hydrogen-ready boilers, or a combination (hybrid) system, are likely candidates to replace current natural gas and oil fired boilers in the future.

Although heat pump systems are a relatively new technology in the UK, they are not a new idea or application, having been used successfully in Scandinavia, Germany and other parts of Europe for many years, where there is an abundance of renewable electricity – namely hydro or wind turbine powered generators.

How does the Heat Pump work

A heat pump takes energy from either the outside air (air source) and the outside ground (geothermal ground source) and transfers it into heat (similar to a refrigerator in reverse) to be circulated around a heating and hot water system. Electricity is used to run the heat pump, principally a fan, compressor and circulating pumps to transfer energy from the heat source into the heating system.

This renewable source of heat (air or ground) is used to create warm air or water (for space and central heating) as well as hot water (for both central heating and domestic hot water supply) by utilising the small differences in temperature from the source to a fluid. This fluid passes through a compressor, increasing the temperature, and transfers that higher temperature heat to the heating and hot water circuits of the home.

What are the arguments for fitting a heat pump system?

Warning, this assumes that you have chosen a reliable system supplied by a reputable manufacturer and fitted by an experience installer. You need to do thorough research before making a decision as the technology’s use is still at an early stage in the UK.

The main advantages are:

  • Overall lower running costs than oil and gas boilers, even taking into account the extra electricity use
  • There should be less regular maintenance with a reliable system properly installed
  • No carbon monoxide risk
  • Meets Carbon Emissions standards
  • Can be used to provide cooling, acting like AC
  • The system should have a long life-span
  • It is eligible for the Domestic Renewable Heat Incentive (RHI)

What are the downsides to Heat Pumps?

There are some disadvantages to heat pumps, the primary one being the high initial investment required, but also a property needs to be very well insulated if the heat produced internally is to be adequate.

  • High upfront cost – typically between £6,000 to £20,000 depending on installation and property size
  • Requires a property with very good insulation
  • Difficult to install so an experience supplier and installer is a priority
  • Requires significant work and disturbance, particularly ground source which also require suitable ground space
  • There can be issues in very cold weather
  • Some questionable the overall sustainability and whether these systems are entirely carbon neutral
  • Planning permission may be required

So is a heat pump system suitable for a rental property?

These are personal views, so take this with a piece of salt! When we are talking about a new-build with current specification insulation and where the property is off the mains gas grid, then fitting a heat pump system for the long-term is the most viable of the heat pump options. It should save money in the long run, cut down on maintenance requirements, add to safety and fitting the system along with the build will ease installation work and will likely reduce the payback time.

Retro fitting a system in a well insulated home, where the alternative sources of heat are electricity, oil or LPG, will also mean that a heat pump system can give substantial savings. But careful due diligence will be needed to calculate the payback time and chose a suitable manufacturer and installer.

It is likely to be less advantageous to fit these systems when mains natural gas is available, certainly in the short-term, ie., up to 2035.

My own experience, of staying in a well insulated holiday lodge, heated by a Panasonic air source heat pump, during a cold spell, was that an air source system (deemed to be not quite as efficient as a ground source system) provided very adequate room heating and hot water.

1 COMMENT

  1. Aside from whether heat pumps do an adequate job and are suitable for retrofitting to older properties (both of which I dispute) the cost of fitting and the fact that they score so poorly on EPCs makes them a non starter for most rentals. Until the green subsidies heaped on our electricity bills are transferred to gas there is no chance of any electrical system gaining the EPC C that is being proposed for rentals.

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