More than simply an historic house and garden, Bishop’s Palace is a splendid medieval Palace, which has been the home of the Bishops of Bath and Wells for 800 years. The Palace is surrounded by a stunning moat and it is from here that the renewable energy is sourced for the newly constructed visitor’s centre. Award winning renewable energy specialists, Ecovision are widely known for the innovative water source installation at Castle Howard in York. Many more ancient buildings have subsequently turned to the design expertise of Ecovision. A combination of ground, water and air source heat pumps coupled with solar power are now collectively radically reducing energy bills and carbon emissions nationwide.
Ecovision has designed and installed many closed loop water source systems but this was a more complex challenge, as it was not possible to drain the loop area prior to installation. Ecovision have designed a special system which includes an array of ground loops connected to loop support frames, an Ecovision diver then guided the loop array into the final position before lowering it under the water. The array sits on the moat bed but is lifted by weighting blocks which keeps it in position and holds the bottom of the loops 200 mm off the moat bed. This system can be applied to any building that has a water source close by, and the significant savings made at Castle Howard show that this is an extremely efficient way of reducing heating bills.
Neil Otter, Ecovision’s Operations Director commented,”We have installed many closed loop water source systems using the new loop layout strategy. Sometimes we have had the luxury of a dry surface to construct them, the challenge at Bishop’s Palace in the moving water was to get the loop set in exactly the right position by floating it from the launch area on the bank into the final sunken location. Calculations were made to ensure the loops, weighting blocks and frame would float into position and remain in position when filled and operational. It was a challenging part of the installation but with accurate planning it was plain sailing….”
The closed loop water source system comprises 6 x 100 metre coils headed into one larger flow and return which penetrates the moat wall adjacent to the plant room. The heat pump is the Dimplex SIH 20TE. The output of this heat pump is 22kW and can achieve a maximum flow temperature of 70º C. The heat pump will supply all of the heating and the hot water for the centre. Ecovision estimate the average temperature of the moat during the heating season to be approximately 7ºC.
The underfloor heating has been designed to operate effectively at the lowest possible flow temperatures. With this delta t across the system the average CoP of the heat pump system will be approximately 5.2. The system will be approximately 20% more efficient over the year than an equivalent ground source heat pump system.
The return from the Renewable Heat Incentive will be in the region of £1,700 per annum. The alternative conventional oil system would have cost approximately £2,900 per annum to heat the building. The heat pump will cost approx £1,200 per year to run. This gives an annual saving on heating costs of £1,700. Combined annual financial benefit is £3,400. The project received funding from the heritage lottery fund and Church Commissioners for England.