Although Heat Pumps have been around quite a while, with the first one installed in this country in 1945, it is only with the recent moves towards Net Zero that their use is starting to become more wide spread. But are they really an important part of the drive towards a carbon neutral future?
With the rising cost of fuel, greater awareness of the environmental impact of fossil fuels along with the availability of Government grants more homeowners are starting to think about getting them installed. They basically pull free heating from the air so why would you not want one?!?
Except they don’t.
To understand whether a Heat Pump is a good idea for a home it is first worth thinking about how they produce heat. They work by evaporating a refrigerant into a gas, this is then compressed back to a liquid which generates heat. The heat is taken from the system, this cools the refrigerant and returns it to a liquid state and the cycle restarts. As the system uses the available external heat to evaporate the refrigerant (the refrigerant evaporates at a very low temperature so it does not matter if it is cold outside) this part of the process is does not require any additional energy. However, as the refrigerant needs to be pumped around the system and compressed it still needs an input of electrical energy. As a result, these systems are considered low carbon as opposed to carbon neutral.
This then raises the question of how efficient are they? The answer is they can be pretty good, depending on how the system is set up and used you can get between 1.5 and 4 kw of heat energy out for every 1 kw of electrical energy put in. Put more simply they can be up to 400% efficient. When you compare this to the 70% efficiency of older boilers or even 90% for a modern condensing boiler, they look pretty good.
Given that they can use up to 4 or even 5 time less fuel than conventional systems it is easy to see why they could play an important role in the move towards Net Zero.
So if they are that efficient they must be cheap to run?
Unfortunately, it is not that simple.
Reducing our carbon footprint and our environmental impact is important but with the cost of fuel we can’t ignore the economics.400% efficiency is really only achievable with a system installed within a new build property designed with this form of heating in mind so installing them at the time of construction makes a lot of sense. It is not the same with retrofitting a Heat Pump into existing properties, a lot will depend on the condition of that property including the existing pipework and radiators as well as the levels of insulation. Chances are the actual efficiency will be a lot less, if it is closer to 150% then you may find you end up spending more to heat the home.
Much of our electricity is generated using gas so what we pay for electricity is higher that what we pay for gas, around three times more on average. So here we need a quick bit of maths.
For a Heat Pump at 150% efficiency to generate 90 units of heat it takes 60 units of electricity
For a gas boiler at 90% efficiency to generate 90 units of heat it takes 100 units of gas
Electricity is 3 times the price of gas so producing that same level of heat with the Heat Pump would cost 80% more!
Obviously the real figures will depend on the actually efficiency of the Heat Pump compared to the boiler and whether the electricity is being generated by on site renewable sources but it does show that some careful thought is required before these systems are installed.
If you are buying a property and thinking about adding in a Heat Pump, then you first step should always be having a Home Buyers Survey or Building Survey carried out. Firstly, this is because there are many defects that can impact the energy efficiency of a property. Secondly your surveyor should also be giving you useful information about the efficiency of the current heating system along with information about the levels of insulation present.
If you book your survey with me, it will also include a lot of really helpful guidance and advice not just about energy efficiency but also many other issues around sustainability all of which can make a big difference to your environmental impact.
Get in touch here if you would like to book a survey.