Top of the class for energy performance

Two educational establishments have reached the top of the class for energy performance by using renewable ground source energy.

St John’s College, Oxford, and the new Ynysowen Community Primary School in South Wales, will reap major financial and environmental benefits from ground source heat pump technology from ENER-G.

The 280-pupil school, near Aberfan, and 500-student college are among a growing number of educational establishments using ground source heat pumps to harness solar energy absorbed by the earth as a cheap and reliable source of renewable energy.

By exploiting the relatively stable temperatures found under the earth’s surface, ground source heat pump systems are able to deliver heating and cooling at very high efficiencies.

A heat exchanger, comprising a network of polyethylene pipes, is buried under the ground to provide a means of transferring energy to or from the earth via a heat pump.

ENER-G’S heat pumps are available in a wide variety of styles and deliver heating or cooling to the building by various water or air distribution systems, including under floor heating, radiators, fan coils and ducted air systems.

The ground source system, due to become operational at the 500-student St John’s College this summer, is being installed in the new Kendrew Quadrangle development. It involves 48 boreholes and heat pumps with combined capacities of 146kW for heating and 115kW for cooling, installed under a contract with Oxfordshire-based building contractor Kingerlee Ltd. It is projected to achieve carbon savings of approximately 17 tonnes per annum, equivalent to the environmental benefit of 1700 trees.

Ynsowen’s ground source heating system involves 14 boreholes and a total heat pump capacity of 74kW installed under a contract with Llanelli-based building services company FP Hurley & Sons. Projected annual carbon savings of four tonnes are anticipated, which would equate to the environmental benefit of 400 trees.

The new school was designed by architects and landscape architects White Design and built by construction company Morgan Ashurst, with mechanical services installed by the Newport branch of FP Hurley. The school, which opened in April 2010, covers 2,000sq m and comprises 14 classrooms, an IT suite, library and assembly hall.

The proposed new renewable heat incentive (RHI) scheme increases the financial attraction of heat pump technology to many different organisations. It would guarantee significant subsidy payments and dramatically reduce the payback period for all organisations that install ground source heat pump technology. Under the RHI, a 200kW ENER-G ground source heat pump operating eight hours a day would create an annual incentive of approximately £18,000.

Similarly, ENER-G estimates that a 200kW air source pump, operating over a similar period in a comparable sized educational or commercial building, would lead to a financial gain of around £7,000 per year.

Heat pumps supply more energy than they consume by using a refrigeration cycle to absorb heat from the environment and raise it to a suitable level for heating buildings or providing hot water. The process can operate in a reverse cycle to provide cooling for buildings as well. Heat pump technologies can provide a 50% reduction in CO2 emissions compared to traditional technologies.

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