Site Prices Update
Last Updated28th June 2022
All calculations on this site are based on current fuel prices, they are checked regularly and calculations are automatically updated.
The costs calculated based on these fuel prices should be regarded as 'good estimates', given that fuel prices vary in different parts of the county and at different time of the year.
The calculations also have different levels of accuracy depending on the nature of the calculation. For example calculating the energy use of a known power output TV is very easy compared to calculating the effect on energy savings when insulating a cavity wall.
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At Confused About Energy we aim to provide practical, impartial advice on all aspects of energy usage, climate change and ways to save money on energy bills.
All calculations on this site are based on current fuel prices they are checked regularly are automatically updated and were last changed on:-
28th June 2022
The costs calculated based on these fuel prices should be regarded as 'good estimates', given that fuel prices vary in different parts of the county and at different time of the year.
The calculations also have different levels of accuracy depending on the nature of the calculation. For example calculating the energy use of a known power output TV is very easy compared to calculating the effect on energy savings when insulating a cavity wall.
Site Calculations
| Electricity | £0.271 per unit (1 kWh) |
| Economy Electricity | £0.094 per unit (1 kWh) |
| Gas | £0.072 per unit (1 kWh) |
| Domestic LPG | £0.122 per unit (1 kWh) |
| Heating Oil | £0.104 per unit (1 kWh) |
| UK Grid CO2 Emissions | 0.233 kg per kWh used |
The main units used in this site are in the table below, For a complete explanation of power and energy Read More.
| Unit | Name | Detail |
|---|---|---|
| W | Watt | Unit of Power |
| kW | Kilowatt | 1000 watts |
| kWh | Kilowatt hour | Measure of Energy |
| L | Litre | Measure of Volume |
Please use twitter to ask a question Message @@EnergyThinking
Heat pumps function by extracting heat from the ground the water or the air respectively and releasing that heat energy at a higher temperature within a building.
|
Cost: High
ROI: 2 to 61 Years (No RHI)
Skill: Specialist
Energy Saving: Medium
CO2e Saving: High
|
ROI is the time it takes to return the investment in fuel savings for an average gas heated 3 bed semi-detached house and assumes no government incentive schemes are used: Years
How easy this is to do: DIY-Easy : DIY-Skilled : Specialist
How much energy will be saved with this measure: Low : Medium : High
How much Carbon Dioxide emission will be saved with this measure: Low : Medium : High
What are they?
There are three main types, these are:-
- Ground Source Heat Pump (GSHP),
- Water Source Heat Pump (WSHP), and
- Air Source Heat Pump (ASHP)
They function by extracting heat from the ground the water or the air respectively and releasing that heat energy at a higher temperature within a building. All heat pumps consume energy usually in the form of electricity to operate the pump that is required to transfer the heat. They can supply all the heating you would require, and ground source systems are the most effective. To compare the performance of heat pump the term coefficient of performance is used (COP) and it described the ratio of heat movement to energy input. In the table below the Best Average COP is used. This a seasonal average, since air source and water source vary in performance with the temperature of the environment. For ground source the underground temperature is however remarkably constant all year.
It should also be noted that you will need a reasonable amount of land for an effective GSHP, unless you drill down, and for a water source heat pump a body of water is essential!
Energetically are they worth it?
According to manufacturer information heat pumps provide between 2.5 and 5 times the energy they consume(or they have a COP of between 2.5 to 5) and by energy consumption they usually mean energy in the form of electricity. Electrical power generation and distribution is covered in another article, however when trying to compare like for like and come to conclusions regarding total energy consumption, the inefficiency of power generation must be factored in, and it never is! So here are the main points:-
- 1kWh of electrical energy consumed by the pump should deliver 4kWh of heat energy, and it would have a COP of 4.
- For a gas fired power station for example 1kWh in your house requires about 2.2kWh of gas energy to generate it, so in reality 2.2kWh is required to deliver 4kWh of heat energy, so should the COP value really be 1.8?
You decide!
Financially are they worth it?
The answer to this question is depends. It simply depends on the form of heating you have currently, if you are mains gas heated this technology make no sense on financial grounds (without incentive schemes), since one unit of gas energy is three times cheaper than one unit of electrical energy; the system will take a lifetime to pay for itself; If your only source of alternative heating is electrically powered at the standard rate, then it could be well worth the investment and pay back in about 8 years, but most would use economy electricity in those circumstances.
Another valid point here is that if you are thinking heatpumps, you are likely to have a cheaper and perhaps greener source of electricity, The first table uses the standard rate of electricity to run the heat pump and the second table used the economy rate, so that you can see the difference at a glance.
What about CO2e emissions?
If you work down a column in the below tables and subtract the CO2 emissions from the CO2e saved emissions you will get the total CO2e emissions that you have prevented by installing a heat pump. It is substantial even though you are still using fossil fuel powered grid electricity.
Data tables
| Heat Pump Type | Ground Source | Water Source | Air Source |
|---|---|---|---|
| Best Average COP | 4 | 2.8 | 2.8 |
| Very Rough Equipment and Installation Cost | £12000 | £8000 | £6000 |
| Annual Electrical Energy Requirement to Run Pump (16,000kWh/COP) | £4000 | £5700 | £5700 |
| Cost of Standard Rate (0.271) Electrical Energy CO2e emissions |
£1084 (932kg) |
£1544.7 (1328.1kg) |
£1544.7 (1328.1kg) |
| Cost of "Replaced" Energy Gas Heated (90% efficient) CO2e emissions saved |
£1280 (3360kg) |
£1280 (3360kg) |
£1280 (3360kg) |
| Cost of "Replaced" Energy LPG Heated (90% efficient) CO2e emissions saved |
£2168.889 (3840kg) |
£2168.889 (3840kg) |
£2168.889 (3840kg) |
| Cost of "Replaced" Energy Electrically Heated CO2e emissions saved |
£4336 (3728kg) |
£4336 (3728kg) |
£4336 (3728kg) |
| Cost of "Replaced" Energy Economy Electrically Heated CO2e emissions saved |
£1504 (3728kg) |
£1504 (3728kg) |
£1504 (3728kg) |
| Payback Time Replacing Gas Heating | 61 Years | Never | Never |
| Payback Time Replacing LPG Heating | 11 Years | 13 Years | 10 Years |
| Payback Time Replacing Electrical Heating | 4 Years | 3 Years | 2 Years |
| Payback Time Replacing Economy Electrical Heating | 29 Years | -197 Years | -147 Years |
| Heat Pump Type | Ground Source | Water Source | Air Source |
|---|---|---|---|
| Best Average COP | 4 | 2.8 | 2.8 |
| Very Rough Equipment and Installation Cost | £12000 | £8000 | £6000 |
| Annual Electrical Energy Requirement to Run Pump (16,000kWh/COP) | £4000 | £5700 | £5700 |
| Cost of Economy Rate (0.094) Electrical Energy CO2e emissions |
£376 (932kg) |
£535.8 (1328.1kg) |
£535.8 (1328.1kg) |
| Cost of "Replaced" Energy Gas Heated (90% efficient) CO2e emissions saved |
£1280 (3360kg) |
£1280 (3360kg) |
£1280 (3360kg) |
| Cost of "Replaced" Energy LPG Heated (90% efficient) CO2e emissions saved |
£2168.889 (3840kg) |
£2168.889 (3840kg) |
£2168.889 (3840kg) |
| Cost of "Replaced" Energy Electrically Heated CO2e emissions saved |
£4336 (3728kg) |
£4336 (3728kg) |
£4336 (3728kg) |
| Cost of "Replaced" Energy Economy Electrically Heated CO2e emissions saved |
£1504 (3728kg) |
£1504 (3728kg) |
£1504 (3728kg) |
| Payback Time Replacing Gas Heating | 13 Years | 11 Years | 8 Years |
| Payback Time Replacing LPG Heating | 7 Years | 5 Years | 4 Years |
| Payback Time Replacing Electrical Heating | 3 Years | 2 Years | 2 Years |
| Payback Time Replacing Economy Electrical Heating | 11 Years | 8 Years | 6 Years |
The comment on "is it worth it to install a heat pump" are incorrect. in fact even withou the Renewable Heat Incentive it is still cheaper to run a correctly installed heat pump than a gas central heating system - main points gas is not a quarter the price of electricity your figures show it at one third. heat pumps can run at night using cheap rate electricity. A correctly installed water source heat pump will have a better cop than a grond source heat pump. The data table is also wrong - there is no adjustment for the gas or LPG efficiencies. please see our calculator at www.heatcollector.co.uk or call me on 01844 203895 for further details - mike ambrose
yup, thanks Gareth
and a good way to put it. All of that seems correct to me. It is the install cost that is the issue especially for gas as you point out.
One should also point out that if you use heat source you should also negociate an electricity price each year to get the best deal, since you will use a lot, savings are likely to be substantial and a better pay back picture than is portrayed above will materialise.
Hi Richard,
Your figures show, electricity emits 0.54 kg of CO2 per kWh. Oil emits 0.25 kg/kWh, LPG 0.21 and gas 0.19.
Heat pumps must manage SPFs of 1.0+, 2.2+, 2.5+ and 2.9+ to be greener than electricity, oil, LPG and gas respectively (actually less due to boiler inefficiencies). i.e. a heat pump with an SPF of 4.0 emits 28.5% less CO2 per kWh than even a natural gas boiler.
The best data on UK heat pump performance is DEFRA's latest field trial. It showed well installed, new Ground Source Heat Pumps achieve SPFs of around 3.8, making them cheaper to run than natural gas, but with extremely long (unsubsidied) paybacks. Air source (to water) pumps managed SPFs around 2.8 (some better), so were marginally more expensive than natural gas. Even for those that were better, payback vs gas is again very long.
No data on water source heat pumps to my knowledge.
Hi Mike
Can you share with us an actual case study to illustate your point and I will add it to the artice. I have never heard it claimed that replacing natural gas with a heat pump is rational [u]without the incentive[/u] so I would be very interested in some real data, including how one sensibly applies the use of off peak electricity within the mix when most of us turn our heating off.
[b]The renewable heat incentive makes an enormous difference, and this does make it financially viable.[/b]
At the time of writing the article it was closer to 4 times diffenent gas/electric prices, how times chanege. I have altered it to 3
Can you tell us the prices for fully installed systems now , because payback time is defined by this. Are your electricity and gas prices ex VAT? as they are very low against BEER figures.
I agree on efficency of boilers this is not factored into the table above. Modern boilers are beween 90 and 95% efficients, for those who wish to factor this into the sums. The calculations are however faily crude and intended to give people and idea of what is going on. The efficiency of a boiler is not as significant as the COP, I see you are quoting 4.3 (unless the boiler is ancient).
One thing I will never understand is why heat pumps are regarded as green renewable energy and eligible for the scheme at all. To me they generate more CO2 than burning gas in a boiler as they use grid electricity which is at best 80% fossil fuel supplied and converted at 30 to 40% efficiency. Views on this are also welcome.
Cheers
Richard
OK, I'm numerate, I CAN work it out for myself, but it would be nice to simply see the trade off of heat pumps against oil fired heating.
Surely the calculation should also consider the efficiency of and at what point in the replaced appliance lifecycle the change takes place. If you replace an inefficient oil boiler at the end of it's expected life span the the cost of replacing like for like (a new boiler) should be deducted from the cost of the heat pump, and the efficiency gains of a like for like replacement should be factored in to the pay back time.
re. oil, I can put oil in easily if useful on the heat pump page. The point was to just put a few indicative option in, to give people a feel for what they are doing to make sensible choices. There are lots of fuel types in use. re. not replacing an old boiler, you are correct of course, the cost should be deducted. So if you get a quote and you intend not to replace an old boiler, then yes use this number will be the total investment cost, I think this is a very useful point. And I will try to make the point clearer on the site, particularly true for GSHPs. re. relative efficiency gains, there it goes away from the spirit of simple digestible data, for example we could include heat pump life-cycle, relative maintenance costs (boiler, vs pump) and indeed if its better to invest the money in Greek bonds (I jest). How complicated should the comparison be, and at what point does it become over complicated is the problem here. Since every situation will be very different, it is difficult for a general site like this to cover all eventualities. cheers Richard
These claim COPs of over 5. Two of these 4.7kW units http://tinyurl.com/kj64dv7 (no connection - available elsewhere) to provide your space heating would cost only £1900 to buy and install. Existing/alternative system needed for hot water. Assume they only actually achieve 4.25 COP (20% below claimed 5.26) and that space heating is 75% of heating costs (common assumption). These would pay for themselves in 11 years vs gas, 3 years vs LPG and 1 year vs electricity. Incidentally, you need a COP of 2.4 to equal carbon emissions from using a gas boiler. This system would reduce space heating carbon emissions (assuming marginal electricity has the same carbon intensity as the average) by over 40%. A way to reduce carbon emissions vs gas boilers substantially without it being financially completely silly.
Good work on these instructions....helped me!
Putting Oil into the data table would be useful.
We've got air heat pumps here - for hot water and central heating wet radiators . We find that the radiators take a very long time to warm up compared to say a gas boilered central heating system. We also find the system regularly flushes itself with freezing cold water, thus cooling the hot water and radiators. And the Mitsubishi fans are noisy, especially when mounted next to the building - as vibration sound comes through the foundation, and where it's bolted to the wall.
Forgot to mention. The air flow forces cold air out of the system. If you have a small garden and the washing line is anywhere near in line with the fan - then your wet washing will be froozen like a board. Any plants in line with the air being forced out of the fan (which is through a wide angle) will be killed by frostbite.
More likley to be poor installation/commissioning. The outside unit should be installed on semi flexible feet and attached, if necessary, to the wall with a non rigid connection. Yes the flow temperature from a Heat Pump is lower than from a conventional boiler and this should have been made clear to you and factored in to the sizing calculation by your installer. Sometimes this means that some radiators may have to be increased in size and usually the pump is operated for longer periods than conventional high temperaturel fuel boilers. This increases effiiciency. Lastly, the initial setup of the flow controller is critical and if the installer has just left it at factory settings without taking into account your requirements it is unlikely to be working correctly.
Of course the radiators take longer to heat up than a gas boiler, thats why a heat pump is more efficient than a gas boiler, its like putting your foot on the accelerator pedal of a car, you shouldnt be switching it off at all they run on a constant trickle of heat controlled by your thermostat, and the rads sit at a constant temp.
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