The Government-funded Energy Saving Trust has produced a report on a field trial of heat pumps entitled Getting warmer. Mark Ellse has kindly provided a translation of the key findings from the executive summary into plain English.
1. “The performance values we monitored in the sample heat pumps varied widely; the best performing systems show that well-designed and installed heat pumps can operate well in the U.K.”
Translation: Most heat pumps operate poorly in the U.K. Rare exceptions are adequate but only if the systems themselves are well-designed, installed and operated.
2. “The sample of ground source heat pumps had slightly higher measured system efficiencies than the air source heat pumps. The ‘mid-range’ ground source system efficiencies were between 2.3 and 2.5, with the highest figures above 3.0.”
Translation: Ground and air source are equally unimpressive. Though ‘mid-range’ ground source system efficiencies were between 2.3 and 2.5, a third of the systems had efficiencies below 2.0, leading to inevitably high running costs.
3. “The system efficiency figures for the sample of ground source heat pumps were lower than those monitored in similar European field trials.”
Translation: Take no notice of cited efficiencies that are high. Real, measured efficiencies are much lower.