Kent’s Longfield Academy will harness the natural power of the sun and earth to give the academy full marks for renewable energy performance.
The new academy building for 1150 students, due to open in June 2011, is combining ground source heat pumps, which harness solar energy absorbed by the earth, with solar thermal technology to maximise renewable energy efficiency.
By working in tandem, these renewable technologies will supply heating and hot water to the academy, together with passive underfloor cooling in the summer months. This is projected to reduce the academy’s carbon dioxide (CO2) emissions from its heating system by up to 40%.
Both technologies are being supplied and installed by ENER-G as part of the sustainable design brief set by Carillion, who are main contractor on the project. Architect is Jestico + Whiles, with mechanical services provided by Halsion, who have commissioned the renewable energy contract.
The specialist science and arts academy is situated on the site of the former Axton Chase School in Longfield, Kent. It is expected to achieve a minimum ‘Very Good’ rating under BREEAM for schools, due to its use of renewable power sources, and extensive use of insulation to secure a thermal performance 15% beyond current standards.
ENER-G has installed 35 boreholes and is completing work on the plant room, to accommodate four ground source heat pumps with a combined capacity of 200kW. The company is installing a total of 22 solar thermal tubes, covering 44 sq metres of the academy’s flat roof.
“By combining these two technologies, the academy will dramatically increase its energy efficiency”, said Lee Marshall, Project Director for ENER-G Sustainable Technologies. “In the summer and spring months, any surplus solar energy not required for hot water will be diverted to the ground loop, where it can be stored to recharge the ground with heat during the colder winter months, thereby increasing the efficiency of the heat pumps”.
“The fusion of these two renewable technologies is used widely in countries such as the Germany, but is not so well developed in the UK, and Longfield will help to lead the way”, added Lee Marshall. “The education sector is, however, very active in using ground source heat pumps as a low cost, low carbon reliable source of renewable energy.”
“The move to the new building will begin a new exciting phase in our development towards an environmentally sustainable educational community. The new renewable technologies will complement the improvements students and staff have led that have enabled us to achieve the Eco School Green Flag status”, said Neil Willis, Principal at Longfield Academy
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.
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 also operate in a reverse cycle to provide cooling.
The government’s Renewable Heat Incentive (RHI) will guarantee subsidy payments over 20 years and dramatically reduce the payback period for organisations that install ground source heat pump and solar thermal technologies.
For further information contact ENER-G Sustainable Technologies on 01623 666340, www.energ.co.uk/heatpumps