Tuesday, 15 February 2011

EST on Heat Pumps

Findings from Energy Saving Trust's eagerly awaited study.

Ground and air source heat pumps perform effectively, but must be installed and operated correctly. This is the verdict from the first phase of the most comprehensive field trial of the technologies undertaken in the UK.

The eagerly awaited study by Energy Saving Trust (EST) monitored technical performance and customer experience of 54 ground source heat pumps and 29 air source heat pumps in situ over the course of a year. The monitoring was carried out prior to the introduction of the Microgeneration Certification Scheme.


The trial found:

  • a number of heat pump installations performed very well, achieving an overall system efficiency rating of 3 and above, ie, for every unit of electricity put in there is an output of three units of heat.

  • the sample of ground source heat pumps had slightly higher measured system efficiencies than the air source heat pumps. The ‘mid-range' system efficiencies were between 2.3 and 2.5, with the highest figures reaching over 3.0.

  • control systems of the heat pumps were generally too complicated for householders to understand. Some found it difficult to control ambient room temperature.

  • often no single contractor was responsible for installation, which might involve a groundworks contractor, plumber, heat pump installer and electrician. This meant there was often no single point of responsibility or any liability for the eventual performance of the whole installation.


The study led EST to conclude:

  • heat pumps are sensitive to design, commissioning and use. The field trial covered a variety of early installations, many of which failed to correctly design and/or install the heat pump.

  • keep it simple. There were many system configurations monitored in the field trial. In most cases, the simplest designed systems performed with higher efficiencies.

  • the impact of domestic hot water production on system performance is unclear. Heat pumps can be designed to provide domestic hot water at appropriate temperatures, but more investigation is needed to determine the factors that have an impact on system efficiency.

  • heating controls for heat pump installations have to be comprehensively reviewed. There has been a failure to explain proper control requirements to both installers and heat pump customers.

  • responsibility for installation should be with one company, and ideally be contractually guaranteed to ensure consistency in after-sales service.

  • further study needs to be undertaken on an installation-by-installation basis, to record what has been done wrongly (or correctly), what could be done better, and what exactly should be done in the future.

Where next?

Simon Green, head of business development for the EST, said: "There is no doubt that the results are more varied than were expected, with results showing both high and low performing heat pumps.

"We are securing funding to extend the trial, with the objective of defining the reasons for variation in performance levels so that we can inform industry about good practice and advise householders on exactly what to look out for."

post by Melissa Downs ,

The PRESS now report

UK 'heat pumps' fail as green devices, finds study

This is the

Government plans to subsidise green heating are challenged today by the largest ever field study of "heat pump" devices in the UK, which reveals 80% perform so badly they would not qualify as renewableenergyunder proposed European standards.

The report, from the Energy Saving Trust, reveals the prevalence of badly installed heat pumps that are consequently under-performing. The controversial report could affect the government's plans to launch itsRenewable Heat Incentive (RHI) next April to pay householders for generating heat from such "green" ground and air source heat pumps. There are already fears the RHI could be a victim of spending cuts announced next month.

Unlike other sources of renewable energy, such as solar photovoltaic panels and wind turbines, heat pumps require a certain amount of electricity to create energy. They work like a refrigerator in reverse, using a coolant gas to transfer heat from outside air or soil into a building. Electricity is needed to pump and compress the gas, which also allows it to generate higher temperatures than those outside. Air source pumps typically look like oversized air-conditioning and are place outside homes, while ground source ones involve loops of plastic tubing laid underground. Theoretically they should generate more energy than they consume.

But the Trust's peer-reviewed study, the largest of its kind in the UK, found the 83 devices it monitored for a year were underperforming. About 87% didn't achieve a system efficiency of 3 which the Trust considers the level of a "well-performing" system (higher is better). And 80% failed to meet 2.6, the level being considered under the EU Renewable Energy Directive for classification as a renewable source of energy.

The Trust blamed the use of multiple contractors for fitting systems instead of a single contractor as used in Europe, wrongly sized systems, complicated controls and a lack of education for householders using them. However, the Trust said that for many of the 5 million people in the UK living off the gas grid and currently using energy sources such as oil to heat their homes, the heat pumps could offer carbon and energy bill savings.

Simon Green, head of Business Development for the Energy Saving Trust, said: "This trial shows that when installed and operated correctly, heat pump technologies will save significant amounts of CO2 in the UK, when replacing oil or traditional electric heating. But there is no doubt that the results are more varied than were expected, with results showing both high- and low-performing heat pumps."

The Heating and hot water council, whose members install such systems, said there are not currently enough installers capable of helping consumers choose the right products. Roger Webb, director at the HHIC, said: "Highlighting negative and positive results keeps all of us in the industry on our toes, so that we can work out ways that this vitally important heat pump technology can be realistically delivered. ."

A Decc spokesperson said: "The RHI is designed to encourage a switch using fossil fuels for heating to renewable technologies across all sectors, not just domestic. Heat pumps are just one of the technologies that the scheme would support. The majority of the renewable heat incentivised by the RHI will be produced by the commercial, public and industrial sectors.

"We know that domestic heat pumps have worked well in other countries, so we need to do more work to find out why they didn't perform as expected in EST's trials. For this reason, Decc, EST and industry intend to carry out a further year of monitoring to identify the factors that have caused poor performance of some of the heat pumps, and to determine whether performance can be improved."

Gaynor Hartnell, chief executive of the Renewable Energy Association, which represents renewable heat companies, said: "A properly installed and sized heat pump can deliver significant carbon savings, particularly in areas not served by the gas grid. Heat pumps are one of several technologies that can contribute to greening the UK's heat supply. These trials, while important, must not delay the introduction of the RHI in April next year."

Separately today, an analysis by the thinktank Institute for Public Policy Research suggested community buildings could earn around £100m a year from incentives for green electricity generation. The IPPR believes the UK's 280,000 pubs, village halls, community centres, churches, schools and pools could create the sizeable revenue streams by installing technologies such as solar panels and wind turbines and earning the government's feed-in-tariff, which launched in April. But the authors, who extrapolated analysis of 14 projects in British Gas's "Green Streets" scheme, acknowledged the one-off capital cost of such technologies would be around £1.2bn

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