Perspectives on Heat Pumps
A publication by the Energy Saving Trust, The heat is on : phase 2 , provides a useful introduction to heat pumps [1]. Its focus is on the performance of heat pumps installed in UK homes during the years 2010 and 2013, both air-source and ground-source types. An earlier trial (phase 1) demonstrated poor performance in some installations, and remedial action was taken prior to phase 2. Several measures of heat pump efficiency - Seasonal Performance Factors - are discussed. For the phase 2 trials the metric SPFh4 was chosen; the calculation of this SPF includes “the electricity supplied to the heat pump, all fans or pumps and electricity delivered to any incorporated auxiliary or immersion heater”. 38 heat pumps were used in phase 2, with average SPFh4 figures of 2.45 for air- source heat pumps and 2.82 for ground-source heat pumps. However, the performance range was wide, with SPFh4 values from 2.0 to 3.6 for ASHPs, and 1.6 to 3.8 for GSHPs. Consequently several of the sites...