The year of the ground- source heat pump?
The Government’s forthcoming announcement on new levels of RHI for ground-source heat-pump systems for heating and cooling will boost the market, explains Chris Davidson of GI Energy.
The alarming prediction that the UK will soon experience an energy ‘near-crisis’, as forecast by the outgoing head of Ofgem Alistair Buchanan, has pushed energy supply and use right to the top of the political agenda.
His dire warning of a ‘double squeeze’ of rising energy prices combined with a shortage of supply between 2015 and 2018 is already prompting businesses to think about how they can reduce their energy use.
Energy efficiency is now a top priority.
Against this background the use of ground-source heat-pump systems to heat and cool buildings is set to increase, especially as the stranglehold on the market caused by uncertainty over Government subsidies is about to be lifted.
Heating and cooling buildings is a major expense for most businesses, often second only to the cost of salaries, so it doesn’t make sense to rely on gas-fired heating if gas prices are going to go up steeply.
Tapping into the heat stored naturally underground is an extremely efficient way of heating a commercial building. For every kilowatt of electricity expended in running a ground-source heat-pump system for heating, 3 to 5 kW of heat is produced.
Ground-source heat-pump systems are even more efficient if cooling a building is required as well. Using the heat pumps in reverse, excess heat from the cooling can be re-directed underground to be stored until it is required again for heating. The coefficient of performance for cooling typically ranges from four to six.
These figures are not pie in the sky. Performance data gathered throughout 2012 for the Oxford Earth Sciences building at Oxford University, for example, shows a CoP of 3.6 for heating and 4.7 for cooling for its ground-source heat-pump system.
Another significant advantage is the reduction in carbon footprint that results from using less energy to run a building’s heating and cooling. This is an important consideration, which will only become more crucial in the future as environmental regulations multiply and get stricter.
Modern ground-source heat-pump systems can be controlled remotely by sophisticated units that continuously monitor the performance of a system and which can make intelligent decisions about how to optimise performance.
At Oxford Earth Sciences, the control unit is set to optimise carbon reduction and has been so successful that the ground-source heat-pump system has saved an extra 120 t of CO2 per year over and above expectations. This has been achieved despite the building requiring more heating and cooling than anticipated from the original designs.
At the simplest level, ground-source heat-pump systems comprise one or more heat pumps connected to a network of pipes buried underground that are filled with a water-based solution which extracts heat from the surrounding earth. The heat is used to run either radiators, hot water, underfloor heating or, most commonly, air handling units. Techniques now exist to drill boreholes directly under a new building during construction, so systems can be installed even on constricted urban sites.
Ground-source heat-pump systems have been installed in the UK in hospitals, universities, schools, supermarkets, commercial developments, housing associations, private homes and even a church. Landmark installations include One New Change in London, and Mansfield Hospital, which boasts Europe’s largest lake loop at over 10 MW. GI Energy alone has installed more than 200 MW of systems in the UK since 2000.
With all these advantages, why are not even more ground-source heat-pump systems being installed? I believe there will be soon.
In the early noughties, the technology was relatively new to the UK, but the market really took off in 2005 — doubling every year until the financial crash came along. Then followed uncertainty over Government green subsidies for ground-source heat-pumps.
When the Renewable Heat Incentive tariffs for commercial heating and cooling installations were introduced last year there was huge disappointment in the ground-source heat-pump industry. The tariffs appeared to be unintentionally biased towards other green technologies — primarily due to the poor quality market data used as a foundation for the scheme. This fact was acknowledge in the statement by Greg Barker, Minister of State for Climate Change, in January of this year.
The GSHP industry lobbied hard behind the scenes to change the Government’s mind — with some considerable success.
Greg Barker had the vision to see that ground-source heat-pump systems had a lot to contribute to the UK’s targets for carbon reduction, and he agreed the tariffs should be reviewed as a special case. An announcement is expected soon.
It is anticipated that the revised RHI tariffs will be far more generous — up to three times the previous level.
If DECC delivers, I believe that will be the incentive needed to kick-start investment in ground-source heat-pumps on a scale that will truly make a difference.
Chris Davidson is development director with GI Energy.
