Brookforge swimming pool engineers

Geothermal & Ground Source Heat Pumps

3. Operating Cost



The price of electricity within the UK is very high compared to the cost of alternative fuels such as mains gas or heating oil. Despite the recent notable increases in the respective price of energy, this price relationship broadly still remains the case and the ground source heat pump obviously operates only on electricity.

By comparison :

Typical current price of mains gas : 2.73 p/kWh
Realistic boiler efficiency : 85 %
Price of heat produced for customer : 3.21 p/kWh

Typical current price of heating oil : 3.24 p/kWh
Realistic boiler efficiency : 75 %
Price of heat produced for customer : 4.32 p/kWh

Typical current price of electricity : 7.44 p/kWh
Efficiency of ground heat pump (3.5:1 COP) : 350 %
Price of heat produced for customer : 2.13 p/kWh

In respect of a ground heat pump, there may be some penalty involved through the need for higher pool hall ventilation rates etc, and so higher electricity consumption fan motors, but generally the operating costs would be less than an alternative fuel fired system, but perhaps not hugely less at today's energy prices.

With an indoor pool, much of the operating costs can relate to the dehumidification, heat recovery and ventilation requirements. By comparison, the actual air heating and water heating costs can be significantly less.

Operating costs and energy usage, whilst associated, are not the same thing and the ground source heat pump will invariably consume far less energy and be far less damaging to the environment than fuel fired alternatives. This obviously may be an important consideration for some customers.

In the foreseeable future, i.e. in 10 to 15 years time, the energy market and prices may be very different from today. It is probable that, for environmental reasons, the use of low energy solutions will continue to be heavily promoted through incentive and penalty and the availability and price of fossil fuel alternatives may continue to grow as issues.

In the long term, be it from nuclear or renewable sources, the method of energy distribution will invariably be through
electricity.Therefore, a system that utilises electrical energy over fossil fuel alternatives, looks a good long term bet today.

In addition, Energy Performance Certificates become compulsory in June 2007 as part of the 'home information pack' which house sellers will have to prepare. A ground source heat pump would improve overall scoring.

The announcement that new houses which are 'carbon neutral' will avoid stamp duty tax for a limited period of time is also relevant. On a large expensive house with an indoor swimming pool, stamp duty can be very significant.


The capital cost of a ground source heat pump installation, as opposed to a conventional fuel fired boiler system, is invariably very much higher, certainly on a like for like heat output basis.

At today's fuel prices, it is unlikely that an attractive pay-back period can truly be offered to the end customer but, as previously indicated, this is not the only consideration involved.

The ground pipes themselves should last at least 50 years, so there will be plenty of opportunity in the future to utilise this part of the installation works / cost.

There are also various grants already available, although some of these are means tested.


The actual heat outputs available / achievable from a ground source heat pump installation are generally significantly less than for a conventional fuel boiler. This is generally because of the high capital cost of the equipment per kW output and other practicalities such as electrical supply loadings and the requirement to space
multiple ground pipe circuits away from each other.

There is not the luxury / flexibility of the comparatively very high heat outputs that would be associated with fuel boilers.

Accordingly, there may be some limitations on the overall effect of the system, particularly in terms of a long initial warm-up period of the pool water from cold and the ability of the system to maintain the exact correct temperatures during cold weather.

However, the customer must appreciate that there may be some compromise in taking a 'green' approach to the heating of their swimming pool.

It is also possible to supplement the heat generated by the ground source heat pump with more conventional means, by installing direct electric in-line heaters or even fuel boilers as part of the central heating circuit. However, the central heating circuit temperature should still not be allowed to exceed the optimum temperature for the heat
pump operation.