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Will heat pumps keep us warm? The future of heat

Posted by Brychan Williams on 26 July 2019 at 4:36 pm

Part one

The Government’s advisor the Committee on Climate Change recommended back in March this year that gas heating should be banned in the UK for new homes as of 2025 to help meet climate change obligations. Currently gas is the primary source of heating for around 85% of UK homes. As is evident, currently homes within the UK rely heavily on gas for heating.

Therefore, what possible options are there available that can replace gas as the main source of heating within the UK? Further for those who want to change from their gas based systems, what can they do in order to reduce their carbon footprint?

Currently, it is difficult to see exactly what the future of heat will be within the UK. Of the options available, some systems are too expensive, some don’t suit particular households and other forms of systems such as a hydrogen based heating system aren’t fully developed or adequately means tested yet. What does appear likely, in line with the Government’s ‘Clean Growth Strategy’, that the future of heating will be largely electric based.

In part 1 of this blog we will look at air source heat pump and ground source heat pump systems and analyse the role that they could potentially play in the future of UK heating.

Air source heat pumps and ground source heat pumps

Heat pumps operate in a similar way to refrigerators in the sense that they capture heat from outside a property, either from the air, ground or nearby water and concentrate it for use inside.


  • Greener than gas: Heat pumps operate at efficiencies of around 250-400% depending on the type and season, which means for every unit of electricity used, 2.5-4 units of thermal energy is created. This energy is also created without releasing harmful gasses into the atmosphere locally; as long as the electricity used to run the system comes from a renewable source. In Q4 of 2018 the UK’s electricity mix was made up of 37.1% renewables, dramatically improving the ‘green’ benefits of heat pumps. The grid is set to become increasingly de-carbonised over the next few years and therefore these systems will only become more renewable over time.


  • Renewable Heat Incentive (RHI): The government offers financial support for qualifying heat pump systems. As of 2014 the government has put in place the RHI. It provides financial support for the domestic owner of heating system for seven years. This support comes in the form of quarterly payments over seven years. The amount you can earn depends on several different factors. You can estimate how much money you could receive through the RHI scheme by using the Department for Business, Energy and Industrial Strategy’s calculator. For air source heat pumps you could potentially receive up to £9,100 and for a ground source system you can receive up to £27,000.


  • Savings on fuel bills can be are significant: Ground Source heat pump systems are estimated to be around 26% cheaper than the savings that can be made with a new gas boiler (factoring in running costs). However, these savings are dependent on a number of factors therefore it is quite difficult to accurately calculate total savings and they are likely to be different for each household.


  • Low Maintenance: Once a year some details of the system need to be checked, while it is advisable to enter into a servicing contract some basic details could easily be checked by yourself. Installers should give you details about what to check and they will usually guarantee as part of an instalment guarantee that they will come round every 3-5 years to check the system.


  • Heat pumps are expensive to install but you can recover some of the capital costs through the RHI payments over 7 years. However, for those who are on low incomes or cannot afford to pay between £6,000- £18,000 to install these systems, they unfortunately won’t be an option.


  • Heat pumps rely very heavily on electricity to operate. If the electricity supplied to power heat pumps comes from conventional or ‘brown’ sources, this reduces the environmental benefits of a heat pump. However, they are a perfect fit to go alongside a solar electric panel system. If coupled together with sufficient solar PV, heat pumps could potentially make your home a zero net energy home during the summer. This can occur when your solar panel system is generating at optimum conditions.


  • During times of cold weather, heat pumps can experience some issues. Full heat efficiency cannot always be achieved during really cold weather and the back-up heating within the heat pump might be called into operation. Installations should be carried out only by contractors who are registered with the Micro-Generation Certification Scheme.


  • Heat pumps are not suitable for all types of buildings. They only really work well in well insulated homes free from draughts. Therefore, for energy inefficient homes these are generally not suitable.


  • Heat Pumps tend to work most efficiently when the hot water they produce for space heating is delivered at a lower temperature and over a consistent period of time. For this reason, it is important that occupants understand how to run and control their heating system to get the best performance. In addition, the heat distribution system must be carefully designed be it underfloor heating, special fan coil radiators or traditional radiators. Standard type radiators will invariably need to be oversized to take account of the lower water circulation temperatures.


We asked Paul Ciniglio owner of an Air Source Heat Pump in his ‘SuperHome’ about his experience. he said “I have been very pleased with my Air Source Heat Pump since I installed it in my home in 2009. My house is located off the gas network in a rural location so it was a very good fit with heat pump technology. I made sure that I upgraded the thermal performance of my existing home with new insulation and reducing unwanted air leakage before the installation. I have been very impressed with the reliability of my heat pump, it hasn’t failed me in a decade. My thermal comfort improved post retrofit and my heating and hot water running costs have been affordable.”

From all of the above, it looks like heat pumps could be the heating systems of the future. Making heat pumps the norm for new builds would lead to demand going up and the price going down. However, as 85% of households currently rely on gas for heating, substantial reinforcement of the national electricity grid would need to be undertaken to support the eletrical demand. Further, a lot of these households will not be energy efficient enough or adequately insulated for heat pump systems. It is also unlikely the majority of households will be able to afford the initial costs of these systems.

This leaves a gap however. How can we replace gas? Can we make heating more sustainable whilst at the same time make it affordable for consumers? These are questions that will need to be answered if the UK is set to meet its current target of becoming a net-zero carbon economy by 2050. The UK government has yet set out how it is going to achieve this and has not explained what will replace gas.

In part two of this blog series we will explore some of the other options.



If you have a question about anything in the above blog, please ask it in the comments section below.

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13 comments - read them below or add one


homefarmComment left on: 15 October 2019 at 4:51 pm

Our air source heat pump has been in operation for five months, over spring and summer, so it is a good time to review the performance and efficiency of our Caernarfon 18kW Eco Air Source Heat Pump (ASHP) from Global Energy Systems.

Most ASHP owners in the UK use Mitsubishi, Hitachi or Daiken ASHPs, so it should be interesting to see how a British manufactured ASHP, made for the British climate, will perform and compare.

As part of this video, I’ve addressed our coefficient of performance (COP), performance and efficiency, the control panel and settings for the ASHP, noise rating and some general thoughts.

I will do a follow up video in autumn and winter to provide a full performance and efficiency comparison. 

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Bean Beanland

Bean BeanlandComment left on: 19 September 2019 at 11:14 pm

@martinwinlow, do you have evidence of the "ridiculous over-inflated" heat pump installation prices caused by the RHI? I'm not sure that the profitability of most heat pump installers would support this theory. 

As for the benefit staying with the house if sold within the 7-year term of the Domestic RHI, the assumption is that the property value when sold is higher becuase it's energy efficient, so the original owner would walk away with that benefit.

Where I am equally excited, is with the arrival of phase-change thermal storage. This won't increase the efficiency of the heat pump, but it will allow heat pump owners to load shift operation into the night where variable tariffs will provide for low cost heat pump operation. This provides for a financial argument in favour of the electrification of heat even when displacing (heavily subsidised) natural gas.

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martinwinlowComment left on: 31 August 2019 at 2:46 pm

I hope one of future installments in this series will discuss 'phase-change thermal batteries'.  Again relying on the enthalpy of materials to gain a 3 or more times energy efficiency advantage over purely resistive heating (and ideally combined with some PV or other reneable micro-generation), these have the potential to completely take over from fossil-fueled space heating (and water heating, too).  Early days but some very compelling products are just coming to market now.  Eg

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martinwinlowComment left on: 31 August 2019 at 2:41 pm

Be careful with the RHI as, if you move house before the 7 years is up, the new owners are entitled to claim the benefit - which seems extremely daft to me.  I know that HMG will say the system works better that way but for a self-builder (as I was) the idea that you have to hang on to a new property for 7 years to recoup the (rediculously over-inflated) istallation costs of a heatpump will put lots of potential HP customers off - and for the very sort of buildings that most suit HPs!  

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Bean Beanland

Bean BeanlandComment left on: 31 August 2019 at 1:09 pm

@Jeff B. Do you have hard evidence that non-MCS certified installations are cheaper when of equal quality and equally policed? In any non-MCS world, there would be a quality free-for-all, is that what you are really advocating? I'm not suggesting that MCS if perfect yet, but the improvements made under the new ownership/management team are significant and there is much more to come, including really important training initiatives.

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Jeff B

Jeff BComment left on: 9 August 2019 at 11:12 pm

Bean Beanland - my last RHI payment will be in September 2021, so yes, too late anyway! Let's hope central government promotes some new incentives to persuade folk to swap to ASHP. I certainly could not afford one under the current MCS scheme (where the price is hiked up due to RHI) but I probably could if I could find a friendly non-MCS certified heating guy to install it for me!

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Bean Beanland

Bean BeanlandComment left on: 9 August 2019 at 10:35 am

Your statement that the installation of heat pumps only really works well following some sort of building upgrade and is likely to be inefficient in a draughty house is misleading. It completely contradicts the findings of the Delta-EE report, Technical Feasibility of Electric Heating in Rural Off-gas Grid Dwellings, from December 2018, which found that “based on average winter day temperatures, around 84% of homes can be electrified at their current level of insulation.”. Your comments also ignore the large installed base of (predominantly) ground-source heat pumps in Grade I & II Listed buildings.

Statements about radiator over-sizing can also be misleading. In an intermittant heating controls scenario (timer and thermostat) radiators are already over-sized to provide for acceptable heat up times. If installing a heat pump and migrating to an always on, weather compensated controls strategy, the existing over-sizing is frequently perfectly adequate. I've been retro-fitting heat pumps into existing and period dwellings for over ten years and the number of occasions when wholesale radiator replacement was required has been tiny.

It is correct to say that any requirement for higher flow tempertaures from heat pumps will reduce efficiency, but it should also be remembered that these higher flow temperatures will only be required for relatively short periods of the year. This is the benefit of weather compensated controls, which commentators frequently choose to ignore. The key is to design for the highest possible Seasonal Performance Factor (SPF) averaged over the year, rather than to concentrate on a low Coefficient of Performance (CoP) when the air temperature is very low.

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Bean Beanland

Bean BeanlandComment left on: 9 August 2019 at 10:15 am

@Jeff B. If your biomass RHI contract terminates after 31st March 2021, you would not be able to lodge any new application because the scheme closes to new applicants at midnight on 31st March 2021. Given that the Domestic RHI only started in March 2014, unless you were a very early adopter, I can't see you meeting this timeframe.

On another point, the basis for the Domestic RHI tariffs was to reward 20 years of low carbon heat generation, but to condense the payments into seven years becuase this is the average time that UK homehowners stay in one property. Therefore, it's unlikely that the public purse would want to reward you for another 20-years' worth of low carbon heat immediatly after the first seven years had elapsed.

report abuse from National Energy FoundationComment left on: 5 August 2019 at 12:02 pm

@Jeff B It still seems that you are inelligible because although the heating systems will not be running at the same time, you have already chosen to apply for the existing biomass system. Therefore a second system with a different comissioning date would not be eligible.

If you follow the link to multiple products you will find this information.


I hope this helps,


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Jeff B

Jeff BComment left on: 2 August 2019 at 3:47 pm

I should re-emphasise that I will wait until the current 7 year RHI payment schedule has come to an end.

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Jeff B

Jeff BComment left on: 1 August 2019 at 11:13 pm

Brychan - thank you for your response. I had a look at the "multiple products" link but I don't think any of the given scenarios are like my case, unless I have misread the guidance. I am not intending to have two systems running side by side. My intention is to stop using the wood pellet burner all together (maybe sell it or give it away) and get an ASHP as a replacement system.

report abuse from National Energy FoundationComment left on: 30 July 2019 at 9:46 am

@Jeff B

Sorry I did not get back to you sooner. I have been in touch with Ofgem and it seems you will be ineligible unfortunatley. Here is the response Irecieved:

"Thank you for your query regarding the Domestic Renewable Heat Incentive (RHI), I am sorry I did not reply sooner.

Please refer to Domestic Renewable Heat Incentive Frequently Asked Questions for Applicants, this document contains answers to FAQs for people intending to apply for the Domestic Renewable Heat Incentive.

11. Can I apply for more than one renewable heating system?

You can apply for one space heating system (including one that heats domestic hot water) and one solar thermal system supplying domestic hot water only. The rules are more complicated where you have more than one system installed at your property for space heating, or a heating installation that’s made up of multiple products. For further information on this, please see multiple products in our key terms.

Therefore, in the scenario below an additional application for the Domestic RHI Scheme for an Air Source Heat Pump would not be eligible.

I hope this has been helpful, however if you have any further queries please do not hesitate to contact us."

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Jeff B

Jeff BComment left on: 27 July 2019 at 10:25 pm

A question regarding RHI for heat pump installation. I am already receiving RHI payments for a biomass boiler. The 7 years will be up in 2021. If I then stop using the biomass system (which I am seriously thinking of doing) and install an ASHP can I claim a second round of RHI payments for this?

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