Ground source heat pumps are growing in popularity as more people want to do the right thing for the environment. They are not necessarily the cheapest option, but look beyond the initial price tag and consider the longer-term savings before making your decision.
So, what do you need to consider?
Remember to include all the costs and savings
Cost is clearly an important question when you are looking at the different options for heating your home or commercial premises. Ground source heat pump costs can be deceptive because they require a larger upfront investment than some other forms of heating.
But don’t be too short-sighted in your calculations, because although the upfront costs can be considerable, ground source heat pumps often operate more efficiently than some of the other options available, which translates into savings down the road. Payback periods for ground source heat pumps can be as quick as 4 or 5 years.
How price sensitive are you?
Be clear from the beginning about how much contingency you have allowed in your heating budget. If you are very sensitive to increases in your budget, you could be exposing yourself to risk if there are complications with the ground works. Ground source heat pumps require pipework to be installed underground, and until the hole has been dug, there is no cheap and reliable way to establish exactly what is down there.
For example, bedrock could be very shallow, making it harder to excavate the trench for the pipes comprising the heat collection system (called the ground loop). Or in the case of a borehole, you might find yourself dealing with unstable ground conditions requiring more support for the borehole than was anticipated. Then there’s always the risk of encountering unexpected services such as sewer pipes or electricity cables, which can get in the way and, if you are unlucky it’s possible that these could be damaged, resulting in expensive remedial work. However, if you use a trustworthy contractor this shouldn’t be an issue.
At least with an air source heat pump, or even a conventional fossil fuel fired boiler, you will have a good idea how much it will cost to install. There are fewer variables that could cause difficulties and higher costs, which make them a safer option if your budget is constrained.
How “green” are you?
An important consideration that doesn’t get talked about very much is how committed you are to a heat pump system. If you are passionate about the technology itself or the benefits that it offers in terms of reduced environment impact, then you will probably be prepared to pay more compared to someone who is just interested in the savings that a heat pump system can offer.
Remember the grants that are available
The Renewable Heat Incentive (RHI) scheme is a government scheme that pays people for generating heat from renewable means. The scheme is run by Ofgem (the Office of Gas and Electricity Markets), which is a non-ministerial government department and an independent National Regulatory Authority. Ofgem protects the interests of gas and electricity consumers and pays those who generate heat under the RHI scheme using the Treasury’s funds.
The payment per kWhr for the generation of hot water and heat under the RHI depends on the size and specifics of the system being used. It will normally be a few pence per kWhr, which doesn’t sound like much, but you might be surprised to know that, over the course of the 20-year life of the payment, a typical system makes a profit, which brings me to my next point.
Don’t forget to factor in the savings over the lifetime of the system
A typical ground source heat pump system will last more than 20 years, which is plenty of time for the savings made on the running of the system compared with a combustion-based system to offset the installation costs. Look at the entire life cycle of the system to understand the overall savings or indeed profits that will be made by the system.
So how much will a ground source heat pump typically cost?
The answer is obviously, “it depends”, but as a general indication, the estimates given below should give you a rough idea. They are broken down into upfront and running costs.
Upfront prices for a 10kW system can range between £6,000 and £15,000. This price bracket doesn’t include the connection to the distribution system, which is obviously different for each building and location.
Again, running costs will vary according to a number of factors, the most obvious being the efficiency of the heat pump system. Efficiency is normally stated as the coefficient of performance (CoP). The CoP is simply the ratio of units of heat output to the units of electricity used to run the system.
Typically, most systems will have a CoP somewhere between 3 and 4. This is influenced by the difference in temperature between the heat source (the ground loop) and the heat sink (your heat emitters, such as radiators or underfloor heating).
The highest efficiencies will be achieved by low temperature applications such as underfloor heating, particularly if the climate is releatively mild, or if geothermal energy is producing high temperatures in the ground loop (e.g. a hot spring).
Conversely, heating hot water for use in showers, baths etc will result in lower efficiencies. Better efficiencies are always achieved by low temperature applications.
To give a rough guide, a system running at a CoP of 4 would result in 4kWh of heat being produced for each kWh of electricity used. So, assuming an electricity cost of 16p/kWh, such a system would cost 4p/kWh to run.
Add in the RHI savings that are available, and the savings increase even further.
The decision of whether a ground source heat pump is right for your budget or not is not straightforward, but it isn’t that complicated either. Just bear in mind the points above, be clear about your budget, the lifetime cost of the system (including both installation and running costs) and research the grant funding that is available through the RHI incentive scheme.
With those facts in mind, a calculator and a cup of coffee, you’ll be able to reach the right decision for your particular circumstances.