Study confirms heat pump efficacy
Technical data obtained from heat pumps at sites across the UK found that well-installed and operated heat pumps perform to a very high standard in UK homes.
This study, conducted between 2010 and 2013, follows on from the Phase 1 heat pump field trial begun in 2008. Phase 1 results showed wide variation, with the best-performing systems being those that were deemed to be properly designed and installed. As a result of Phase I, recommendations were made for achieving better performance from the technology.
For Phase II of the trial, 38 of the heat pumps from Phase I were selected for a range of interventions, from major (for example, re-sizing the heat pump) to minor (for example altering control parameters). Six new heat pumps sized and designed according to the new MCS MIS 3005 Issue 3.1 standards were also monitored.
The results of Phase II show that:
• There were significant improvements in performance at all but three of the sites which received major or medium interventions. Minor interventions had little effect on performance.
• 20 out of 21 ground-source heat pumps in the trial met or exceeded the performance criterion to be considered “renewable” under the EU Renewable Energy Sources Directive. The figure for air-source was 9 out of 15, on the basis that many of these heat pumps were installed before the new MCS standards came into force. Five of the six new air-source heat pumps installed and designed to these standards met the renewability criterion.
• DECC considers the most useful measure of performance for the householder to be SPFH4, weighted over both space and water heating. This is a comprehensive metric that takes account of all electricity used by the heating system including the auxiliary heater, domestic hot water immersion and building circulation pumps. According to this metric, the average performance was 2.82 for the ground-source heat pumps in the trial and 2.45 for the air source heat pumps in the trial.
Potential savings
According to the EST, homes best suited for heat pump installations could expect to earn savings and income of around £1350 a year on air source heat pumps and around £3000 a year on ground source heat pumps based on current Renewable Heat Incentive (RHI) payments. The domestic phase of the RHI is due to launch in April 2014 and will pay owners of air source heat pumps 7.3p/kWh and owners of ground source heat pumps 18.8p/kWh for they heat generated by their systems.
The Phase II study also included a survey of users’ experience with their heat pump systems. Eighty percent reported being satisfied with their heat pump’s performance, while over three quarters (77%) said they would recommend a heat pump to a friend, mainly because of its efficiency and running costs of the system.
“Based upon the results of the study, we are convinced that heat pumps can play a significant role in providing an effective heating solution for homes and reducing carbon emissions," says Jaryn Bradford, Senior Technical Manager at the Energy Saving Trust.
“From the study, it is clear that heat pumps are sensitive to design, commissioning and how the householder uses the system. However, the performance monitoring trials have provided early indications that the introduction of improved installation standards, amongst other things, will lead to improved performance.
“The interventions carried out during the study are an early indication of the successes that robust standards can achieve. If heat pumps were installed today under the current installer guidelines, alongside further customer guidance on operating the system, they would achieve even better performances than indicated in the study."
To view the Energy Saving’s Trust heat pump report – The heat is on: heat pump field trials phase 2 – visit http://www.energysavingtrust.org.uk/About-us/The-Foundation/Our-pioneering-research
