Having lived in a property heated by a ground source heat pump and underfloor heating in Canada, Dana Schell was keen to convince husband Paul to combine the two technologies with other renewable products in their eco-build project in Exmouth. As the technology had worked well in Canadian winters down to −20°C, Dana was certain that it would more than cope with Devon temperatures. Little did they know that the system would be tested as temperatures in the seaside town dropped as low as −8.5 in January this year.
The completed four-bed property integrates ecological technology including a grass roof, rainwater harvesting, high-performance glass, ground source heat pump and warm water underfloor heating.
‘Paul will be the first to admit he was apprehensive about integrating underfloor heating with a heat pump, but having experienced it for myself in Canada I knew it was worth fighting for. In fact, I even recruited the help of my mother to persuade Paul as she had also lived with a combined system and was able to confirm the economic savings and how the gentle warmth created by the underfloor heating is so easy to live with.’ When Paul agreed, Dana contacted Nu-Heat as the company could supply two of the main products needed.
The ground loops for the ground source heat pump were laid in trenches along the driveway with water-permeable paving set over the top. Initially the couple were going to have radiators on the first floor, until Nu-Heat suggested that underfloor heating would be as appropriate for the first floor as for the ground floor. Crucial to the design was advice given on suitable floor coverings and tog values.
The building is well insulated, although heat loss calculations had to take into account a large glass south facing wall. The resulting heat pump combined with underfloor heating system has proved Dana right, as she explains; ‘In our first winter with the combined heat pump and underfloor heating system we reduced our heating bill by 50% and have calculated that we will recoup what we invested even more quickly than we initially expected.’
Of the recent cold snap, Dana also commented that the system coped brilliantly with the freezing conditions; ‘The house remained really cosy, and the system didn’t once switch over to mains power.’
Dana and Paul will soon be starting work on their next eco-friendly property and are talking to Nu-Heat about integrating solar with heat pump and underfloor heating technology this time. Dana’s ambition, she says, is to be ‘bill-free!”
Confirmed data for the property: From September 2008 to September 2009, the energy savings from the heat pump was 21,160 kWh, and the Coefficient of Performance was 4.0 for the entire heating and domestic hot water demand. The cost of electricity to the heat pump over the 12 month period was £838 – the comparative cost of oil for this period would have been £1682. (Energy conversion factors in accordance with Defra/BERR guidelines).
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