What does ICAX stand for?
ICAX is an acronym for Interseasonal Collection And eXchange.
How do you pronounce "ICAX"?
As if it were written "ice-axe" or "içax".
How does ICAX manage to get such a high performance from a GSHP?
Interseasonal Heat Transfer is more than just a ground source heat pump. IHT is a complementary fusion of the most cost effective technologies in renewable technology based on a fundamental analysis of heat transfer in the ground. These renewable technologies can be harnessed by an Energy Management System to help save energy and balance the heating and cooling needs in buildings, without burning fossil fuels.
ICAX uses Asphalt Solar Collectors to capture heat in the summer months and boost the temperature of ThermalBanks so that heat can be extracted more easily – and more cheaply – for space heating in winter.
The high performance of a heat pump in an IHT system results from the way in which it is designed, installed and used. There are many detailed ways in which ICAX improves the performance of a heat pump to provide sustainable energy. The key is that the heat pump in an ICAX Skid starts with warmth from a ThermalBank instead of starting with a cold temperature from the ground.
Why does IHT use Asphalt Solar Collectors?
An Asphalt Solar Collector is a less expensive way to collect solar energy than using Solar Thermal Panels. ICAX invented Asphalt Solar Collectors to harvest heat from roads. Installing a pipe array beneath the surface of a road to collect heat gives a second function – heat collection – to existing building fabric – roads, car parks, or school playgrounds.
An ICAX Skid can also collect heat from roof mounted solar thermal panels and store the heat in ThermalBanks. Although flat plate collectors, and especially evacuated tube collectors, are a more expensive way to collect heat, they perform the useful function of being able to raise the temperature of water to higher levels. If these roof-mounted solar collectors are sized to generate sufficient heat in mild weather, they are likely to produce excess heat in hot weather. If the excess heat is not used there is a risk that these solar thermal panels will overheat and damage themselves. An ICAX Skid can collect the excess heat and store it in ThermalBanks for use as space heating in winter. This allows ICAX to provide Solar Assisted Ground Source Energy.
How did ICAX create ThermalBanks?
Previously GSHP installers used buried pipes to collect heat from the ground in winter by heat exchange. ICAX realised that a second function – heat storage to the ground in summer – could be added to existing building fabric – pipes in the ground – to boost the performance of heat collection in winter.
Why place ThermalBanks beneath the foundation of new buildings?
ICAX is giving a second function to existing building fabric. Every modern building must already plan insulation into the foundation of buildings (following Part L of the Building Regulations). The purpose of the Building Regulations is to prevent heat escaping down into the ground in winter. By placing the ThermalBank beneath the foundation ICAX is able to give a second function to the existing insulation – to stop heat rising in summer.
Before a building is constructed the ground must be exposed, prepared and levelled before the foundations are laid. This is the opportunity to lay down an array of pipes for the ThermalBank – at less cost than digging a dedicated trench to bury pipes for heat extraction.
Why not just use vertical boreholes to extract heat from the ground?
It is more expensive to drill vertical boreholes. Drilling rigs are expensive. Drilling a set of boreholes takes time. There are some uncertainties attached to drilling boreholes: the ground may be difficult to drill, the thermal properties of the ground may alter with depth, the level of the water table may introduce complications and a moving water course might allow your saved summer heat to escape before the winter.
Does ICAX ever use boreholes?
Yes! For retrofit of IHT to an existing building, where there is no access to lay a ThermalBank beneath the foundations, ICAX uses Borehole Thermal Energy Storage. ICAX has also used boreholes on new buildings where the main contractor requested that the ThermalBank should be outside the proposed building envelope. Boreholes would also be used where land space is limited.
Is IHT primarily a Heating system or a Cooling system?
IHT is an integrated system designed to 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 an IHT 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 government grants are available for Renewable Energy?
The UK has committed itself to meeting challenging EU binding targets on the reduction of CO2 by 2020. In order to meet these targets it has introduced a Clean Energy Cashback policy. This provides Feed-In Tariffs for those who generate on-site renewable electricity and Renewable Heat Incentives for those who generate on-site renewable heat.
Most households and organisations spend more on heat than on electricity. The Feed-In Tariffs for electricity are designed to provide a return of 5-8% on initial investment. The RHI for Renewable Heat is designed to provide a return of 12% on initial investment. The most practical method of providing space heating with renewable heat is now recognised to be to use Ground Source Energy. IHT uses Solar Thermal collection to store summer heat in Thermalbanks and double the performance of ground source heat pumps.
What is Interseasonal Heat Transfer?
Interseasonal Heat Transfer is a new form of on site renewable energy that combines the merits of solar thermal collection in summer with heat storage in ThermalBanks to double the efficiency and Coefficient of Performance of ground source heat pumps in winter.
Interseasonal Heat Transfer captures surplus heat from summer sunshine, stores it in ThermalBanks™ in the ground and releases it to heat buildings in winter.
Interseasonal Heat Transfer also captures cold on winter nights, stores this in ThermalBanks™ in the ground and releases it to cool buildings in summer.
An IHT system includes an Asphalt Solar Collector, a ThermalBank to store heat energy, a heat pump and a smart control system.
What is Intrabuilding Heat Transfer?
Intrabuilding Heat Transfer is the transfer of excess heat from hot rooms within a building to cold rooms needing space heating. ICAX is able to extract heat from IT fileserver rooms and transfer it to cold rooms by using the heat transfer mechanism in the ICAX Skid in conjunction with WR2 technology from Mitsubishi Electric.
Intrabuilding Heat Transfer saves energy by balancing the heating loads and cooling loads within a building. Where a building suffers an overall cooling need in summer, ICAX uses Interseasonal Heat Transfer to transfer the excess heat to a ThermalBank in the ground. Where an overall heating need exists in winter ICAX recovers the stored heat from the ThermalBank to heat the building in winter using the ICAX Skid which incorporates heat pumps.
Intrabuilding Heat Transfer is a major step towards balancing the heating loads within a building and achieving Zero Carbon Buildings.
Intrabuilding Heat Transfer was chosen by the London Borough of Merton for its new Acacia Intergenerational Centre: the new IGC achieves 46% on-site renewable energy.
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.”
The Merton Rule is named after Merton Council which adopted the first prescriptive planning policy that required new commercial buildings over 1,000 square metres to generate at least 10% of their energy using on site renewable energy. In 2008, the Government's Planning Policy Statement requires all UK local planning authorities to adopt a "Merton Rule" policy.
Why is Thermal Modelling important?
Thermal Modelling is critical to good design in any installation of a ground source heat pump. The sizing of the ground loop is key to the successful operation of the heat pump. Before sizing the ground loop correctly it is necessary to understand the qualities of the ground to be used as well as the expected heating loads and cooling loads of the building and these will be affected by the design of the building, its orientation to the sun, the activities in the building and the ventilation strategies. These are complex issues which need to be analysed in a thermal model to ensure that the system will meet the temperatures required in the building throughout the seasons of the year in a well balanced and sustainable way.
Why is Thermal Balance important?
Achieving Thermal Balance over the year is important in order to create a sustainable system. If a ground source heat pump is used to extract more heat in winter than the amount of heat replaced in summer, then there is a risk that the ground temperature will fall each year. As the ground temperature falls, the CoP of the heat pump falls and the cost of operating the heat pump will rise each year.
If the annual cooling load of a building is larger than the annual heating load then there is a risk that the ground temperature will rise year-by-year. As the ground temperature rises it becomes more expensive to use the ground as a heat sink for cooling.
For an Interseasonal Heat Transfer system ICAX uses Thermal Modelling to ensure that the heating loads and cooling loads are designed to be matched over the year. If a system becomes unmatched (because of unusual weather patterns, or change in use of the building from original intentions) then ICAX can re-balance the system by collecting more energy from its solar collectors in summer. Alternatively the collectors can be used to reject excess heat at night, or in wintertime. See Asphalt Heat Rejectors.
How do Solar Runways keep an airport runway surface ice-free?
Heathrow, and other UK airports, have been closed by snowfalls in recent years causing severe disruption to flights. While snow can be cleared with snow ploughs, it is difficult to shift ice once it has been allowed to freeze to the runway surface. It is not safe for aircraft to land on runways with ice as the brakes become ineffective. The problem extends to the taxiways and particularly the parking stands because it is difficult to clear snow and ice from a parking stand with an aircraft on it. Heathrow suffered sever disruption in the days leading up to Christmas in 2010 because ice was allowed to form on the parking stands.
Solar Runways can be installed to maintain the surface above freezing. Interseasonal Heat Transfer can be used to collect solar heat from an array of pipes embedded in the surface of the road in summer, store the heat in Thermalbanks until it is needed in winter. Heat can be transferred back through the same array of pipes in winter via computer controlled sensors to ensure that the surface is maintained above freezing.
What is the "RHI"?
The UK government introduced Phase One of the Renewable Heat Incentive in November 2011 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