What are the disadvantages of ground source heat pumps?
A ground source heat pump take longer to install then air source heat pump or other heating systems because of the neeed to install the heat exchange loop in the ground. However, this is what enables a ground source heat pump to be more efficient at heating in winter - and more efficient at cooling in summer. It emits no CO2 on site, no NO2 and no other noxious gases because it doesn't employ combustion.
Can ground source heat pumps provide hot water?
Yes, a ground source heat pump can provide hot water as well as heating (and cooling).
How much do ground source heat pumps cost?
A ground source heat pump installation will cost more to install than a combustion boiler or an air source heat pump, but will be cheaper to run and last much longer.
How much water does a geothermal heat pump use?
A geothermal heat pump doesn't consume water: it extracts heat from the water that passes through it and returns the water to where it came from.
How much electricity does a geothermal heat pump use?
A geothermal heat pump uses a small amount of electricity to transfer a large amount of heat from the ground into a building. The heat transferred is typically 4 times the electricity used: it may be more in a well designed system, or less if the overall system is not well designed, not well installed or not well matched to the building being heated.
How long do geothermal systems last?
The ground loop heat exchanger should last for up to 100 years. The heat pump itself should last for around 25 years - ten years longer than a combustion boiler.
Does a ground source heat pump system primarily provide Heating or a Cooling?
A ground source heat pump can provide both heating and cooling. However, we need to know before the detailed design stage what you would like the system to provide: we need to know the heating loads and cooling loads expected in the building so that we can balance the system using Dynamic Thermal Modelling.
Will it be more expensive if we choose Cooling as well as Heating?
The system will cost marginally more if you choose Cooling too because the details required of the design for Cooling are more expensive. However, it is largely the same equipment that is used for both Heating and Cooling, so the extra cost is small.
Does this mean that a GSHP system will be less efficient at Heating if it is designed to provide Cooling as well?
No. It will also be more efficient at Heating, because the addition cost necessary to provide efficient Cooling is also helpful in increasing the efficiency of Heating.
Do we really need Cooling in the UK?
In order to reduce the cost of heating in winter we would recommend that your building is well insulated (whatever the heating system used). This additional insulation is likely to mean that your building may become too hot inside at the height of summer.
Many commercial buildings in the south of England with high passive heat gains from people, lighting, computers and sunshine have a need for cooling, even in the cooler months.
"We are reluctant to specify Cooling because it usually has a high running cost!"
It is true that air conditioning powered by electric chillers is expensive to run because it is based on the principle of "wasting" heat to the exterior. IHT is an alternative way of providing cooling that is in tune with nature. Please see Renewable Cooling and Natural Cooling.
Ground Source Heating and Cooling - Can these be provided together?
Yes. ICAX uses the mechanisms of Interseasonal Heat Transfer in reverse to provide Natural Cooling. The savings of providing Cooling (as opposed to using electric powered chillers for air conditioning) are even greater than the savings on providing heating (using gas boilers or oil burners).
What kinds of Renewable Energy are available?
The principal types of renewable energy available in Britain include:
Photovoltaic, wind turbines, combined heat and power, biomass, solar thermal and ground source heat pumps.
Each of these has strengths and weaknesses when considered individually: see Renewable Energy Options. However, the combination of solar thermal capture, solar thermal storage and heat pumps adds up to a practical solution that can make a real impact in reducing the carbon footprint of buildings. This renewable energy integration from ICAX is called Interseasonal Heat Transfer.
What is Solar Recharge?
Solar Recharge of the ground is the capture of solar energy in summer and storage of heat in ThermalBanks in the ground. ICAX uses a variety of solar thermal collectors to capture heat in the summer to heat up ThermalBanks. The coefficient of performance of ground source heat pumps in winter increases with the temperature available from Thermalbanks.
Is Underfloor heating a good idea?
Yes. Underfloor heating is an efficient method of distributing heat into a building to provide comfortable space heating (whether you use IHT or not). Lower temperatures (around 40°C) can be distributed over a larger area than the higher temperatures (around 70°C) needed for wall mounted radiators. Underfloor heating is invisible and clutter-free and radiates heat gently from ground level to avoid the convection and heat losses generated by wall mounted radiators. Underfloor heating makes a good match for distributing heat from a ground source heat pump – because a GSHP will deliver a higher coefficient of performance if a lower delivery temperature can be used.
The underfloor piping can also be used to extract heat from the building in summer by circulating cold water to provide "critical period cooling".
Are there alternatives to using underfloor heating?
Yes. ICAX has used fan coil units to distribute heat successfully within buildings. The same fan coil units can also be used to extract heat in summertime to provide cooling to the building efficiently. Heat from Interseasonal Heat Transfer can also be distributed within a building using TermoDeck. IHT can also provide heat - or cooling - to Air Handling Units if mechanical ventilation is the chosen route for your building.
What is Reusable Energy?
It is possible to reuse thermal energy: Interseasonal Heat Transfer captures surplus heat energy in summer, stores it in thermalbanks over the autumn for release to heat buildings in winter using a ground source heat pump.
Rechargeable Heat Battery
The ground can be used as a large Rechargeable Heat Battery. This allows for storage of solar energy from the time it is available in summer to the time it is needed for space heating in winter. Heat can be stored in a large volume of ground in a ThermalBank with very large capacity, a very long life and infinite capacity for re-use without degradation of performance.
What is "Free Cooling"?
"Free Cooling" is used to mean "heat dumping" from a building "source" to an external "sink" purely by means of circulating water to transport heat out of the building. "Critical period cooling" is the use of free cooling to cover brief times of high need for cooling – at a much cheaper price than full air conditioning.
What is The Merton Rule?
The Merton Rule states that: “All new non-residential development above a threshold of 1,000 square metres will be expected to incorporate renewable energy production equipment to provide at least 10% of predicted energy requirements.”
What is the "RHI"?
The UK government introduced the Renewable Heat Incentive for non-domestic buildings delivered over twenty years to recognise the benefit to the community of lower carbon emissions. In January 2013 DECC confirmed its intention to double the RHI tariff for ground source heat pumps for those applying for accreditation after 21 January 2013. DECC announced the increased rates for ground source heat pumps in December 2013 and these were enacted in May 2014.
See also: Glossary on Heat Pump terms
See also: Providing Sustainable Energy