About ground source heating
Ground source heating is probably the most dependable, reliable and cost-effective form of renewable energy that is accessible to domestic and small commercial users.
Wind turbines are notoriously expensive to install, and unless huge, (and hugely expensive) don’t produce much power. On a still day, they won’t work at all. Siting them can be problematic and planning permission is likely to be required. Installing a 20 metre mast in a domestic area is not likely to gain approval.
Photovoltaic cells convert daylight to produce relatively small amounts of power and won’t work at night time. They are extremely expensive to install. Any payback period is very long term. Planning permission would certainly be needed to install panels to any listed building.
Ground source heating works 24/7/365 regardless of weather conditions and it is highly unlikely that any planning permission will be needed. Although they need electricity to power the heat pump which is at the heart of the system, for each kilowatt-hour of electricity used, you get a return of up to 4 kilowatts of heat for your building.
Getting heat from the ground
For a heat pump to operate, it is necessary to install a heat collection system in the ground. There are two main ways to gain access to ground heat:
A horizontal system, involves digging a trench 1 or 2 metres deep, then burying pipes. A wide trench needs to be dug and coiled plastic pipe, coiled into ‘slinkies’ is buried. On average 10 metres of trench is needed for each kilowatt of power. This is likely to mean digging at least 100 metres of trench work – a considerable earthworks exercise.
A vertical system involves drilling one or sometimes more boreholes. Our compact drilling machine is set to work, and requires very little space to operate. When it departs and the installation is completed, there is little or nothing see! In a domestic situation, boreholes are often created beneath a front drive or in a garden.
The borehole drilling exercise is often completed within two days.
Why boreholes are the best source of ground heat
We’ll admit to being biased! However, you will see borehole systems bring major advantages:
Far less disruption: it eliminates the need to dig and re-cover massive trenches. Trenching is a major exercise. For most domestic properties and many commercial premises, the space is simply not available.
Far less mess: We drill using fluids rather than using compressed air, so that arisings from a borehole are contained and can be readily disposed of either on-site or carted away.
Better consistency and efficiency: Unlike trench systems, the underground temperature is consistent, and heat is extracted more efficiently.
Payback in relative few years
The cost of oil has risen steeply and is predicted to continue to rise. Of course, the price of oil and gas governs the cost of most forms of power including electricity generation.
The electricity used to power the heat pump is likely to produce 3 or 4 times its energy output from the ground source - the economies are clear. For each kilowatt hour (kWhr) of electricity powering the ground source heat installation, you can get a return of up to 4 kWhrs.
For many installations, ground source heat pumps are very competitive over their expected life when compared with oil, electricity and LPG. Unlike conventional boilers, once installed a ground source heat pump installation requires no regular maintenance.
As each installation is different and costs depend on variables such as site conditions and the amount of heat required, it is not possible to provide a pricelist for a complete heat pump installation. Obviously, it is best to design a property in the knowledge that ground source heating will be used.
However, the starting price including borehole and connection to your heating and hot water system can be from €12,000 plus VAT. So if your bill for heating oil is, say €3000 per year and rising, plus the cost of regular servicing of the boiler, the , the payback is predictable. As the price of fuel rises, your payback period will shorten. Government grants may be available, which will help reduce installation costs.
Boreholes for ground source heating
Closed loop HVAC systems are becoming increasingly important in the quest for improved energy savings and safety.
For optimum function, the quality of borehole construction is a key consideration. Our experience in drilling boreholes, with the emphasis on quality control and environmental care, will be a key factor in a fully successful outcome.
Borehole cooling and heat pumps extract the heat in the ground or water and transfer it to a building for space and water heating. To cool the building in hot weather, heat is returned to the ground or water.
In open loop systems, demanding too high a volume of water from a borehole can exhaust its supply. Otherwise, thermal breakthrough can occur, where the intake pulls warmed water back in. Then there are thermal plume migration issues too (an impact on other boreholes, or the surrounding environment.)
For open loop schemes and closed loop schemes over 50kw, specialist advice should be sought.
While existing buildings can often be successfully adapted to use ground source energy, the most efficient systems are designed into the building from the start. Liaison between building and systems designers, hydro-geologists and thermo-geologists will ensure that any risk factors are taken fully into account and eliminated.
Something for nothing is always appealing, and having paid for the installation, you’ll reap the benefit of low-priced heat for years to come.
What is a heat pump?
At the heart of a geothermal heating system is the heat pump. How does it work?
Think of it like a fridge, but in reverse. It takes the heat out of groundwater and concentrates it for use in the building. The opposite of a fridge which takes heat out of the appliance and dumps it into the air.