Econic sinks 120 boreholes to harvest heat from the earth for Hellesdon Hospital

(17/08/2009)

Econic has commissioned a pair of 50 kW ground source heat pumps as part of a £9.4 million hospital development in East Anglia. The ground collector for the system is the largest installation of its type ever installed in the UK and the building sets a landmark for the National Health Service’s progress towards becoming carbon neutral by 2018.

The contract carried out during the construction of a new mental health unit at Hellesdon Hospital in Norwich involved Econic, together with its partner, Lankelma Green Energy, in sinking a total of 120 boreholes to harvest heat from the earth.

Arranged beneath what is now a car park and landscaped area, each of the collectors were sunk using an innovative method the partners have developed whereby metre long sections of steel pipe are pushed into the ground using hydraulic rams. Once the required depth is reached, the tubes are withdrawn leaving a closed end, 40 mm plastic pipe in position. A second, 25 mm diameter pipe is then inserted into the first to create a flow and return path for the heat transfer fluid, a mixture of water and antifreeze.

The 120 individual “pushes” are joined together using a network of pipes and manifolds. Finally a single pair of 90mm diameter flow and return pipes feed each of the Dimplex S1 50 heat pumps.

The energy gained from the ground is then raised by a factor of four through the refrigeration cycle of the two 50 kW heat pumps. The resulting higher temperature water is used to supply the under floor heating system in the new unit. A 40kW solar PV array on the roof produces electricity for the building, helping deliver an almost zero carbon heating system.

The trust’s Head of Estates and Facilities, Jonathan Stewart, commented: “Not only is this a state-of-the-art, purpose built facility, which will improve the way in which people experience psychiatric care, it also demonstrates the trust’s commitment to sustainability and renewable energy sources.”

The renewable energy heating system at Hellesdon Hospital was created with the help of funding from the Low Carbon Building Programme. Since the facility was finished earlier this year, other health trust’s and public bodies have been taking a keen interest in the technologies utilised, seeing the project as an exemplar for further progress in the field.

Related categories:  Environmental technologies for offices and commercial   Ground and air source heating   Solar power and photovoltaics