Good Practice Case Study: Installation of ground source heat pumps in social housing homes Chy An Gweal, Penzance, Cornwall, UK

Website: www.completingtheloop.org.uk

Case Study (250 Kb PDF)

Summary

This project was the first in the UK to retrofit ground source heat pumps to a group of existing social housing homes, completed in July 2004. Fourteen bungalows were each fitted with Powergen "HeatPlant" heat pumps connected to vertical ground loops, providing affordable space heating (via radiator systems) and hot water with low carbon emissions. The project was carried out by Penwith Housing Association working in partnership with GeoScience (a UK national leader in GSHP technology which has now transferred its heat pump business to EarthEnergy Ltd), the utility company Powergen, the local authority Penwith District Council, and the Cornwall Sustainable Energy Partnership. The aim of the project was to demonstrate that ground source heat pumps could provide affordable space and water heating in existing homes in a rural area where there was no availability of mains gas. The project was funded by the Clear Skies programme, Penwith District Council and Penwith Housing Association. The success of the project has demonstrated that GSHP systems can work very well in this context. It has helped to stimulate the use of this renewable energy technology by a growing number of social housing providers in the UK.

Results

At Chy An Gweal itself the residents were happy with their new central heating systems. The project has served as living proof that ground source heat pumps can deliver space and hot water heating at an affordable cost, coupled with low CO₂ emissions. Shortly after completion the project won a South West Green Energy Award (Best Community Project 2004) and the 2004 National Home Improvement Council Award for "Innovative Approaches to Central Heating and Domestic Hot Water Installations". In 2006 the project was awarded the Building & Engineer Awards "Energy Efficient Project of the Year". These awards have done much to raise awareness of the technology. One of the most important outcomes of the project is that it has encouraged other social housing landlords to install ground source heat pumps. In the EST Innovation Programme funded project "Closing the Loop" the project partners are working to promote the use of ground source heat pumps in UK social housing. Further information can be found online at www.completingtheloop.org.uk. Under the Powergen HeatPlant programme (which includes both newbuild and retrofit projects) to date 25 housing associations and local authorities have GSHP installations either completed or in progress, and the total number of systems running or being installed is in the region of 700. In Cornwall these include two further Penwith HA projects, four projects for Cornwall Rural Housing Association, one for Coastline Housing, and a very substantial programme being carried out by Carrick Housing. The Carrick Housing project won the 2006 South West Green Energy Award for 'Best Housing Installation'.

Interest in ground source heat pump technology has increased dramatically following the recent high profile of climate change and associated new legislation. It is a field in which Cornwall can justifiably claim to lead the UK in terms of the expertise of businesses based in the county, the ground breaking projects that have taken place and the number of installed systems.

Comparison of Total Annual CO₂ Emissions - Chy an Gweal - 52m² - (Provided by Powergen - Jan 2007)

Fuel costs comparisons provided by Powergen

Annual Fuel Cost Comparison - Chy an Gweal - 52m² (Provided by Powergen - Jan 2007)

Lessons learned and repeatability

Before this project was carried out, in the UK ground source heat pumps were regarded as a renewable energy option for heating new dwellings but very few had been installed in existing homes. It was an important aim of the project to devise a means of retrofitting GSHPs in existing homes that would be readily replicable, as one of the greatest challenges in CO₂ reduction in the housing field is to reduce the emissions from the vast number of existing homes that do not have the possibility of benefiting from high efficiency gas boilers. The main problems that needed to be overcome to achieve this were not technical but cultural. There was no practical experience in the social housing sector of drilling boreholes in close proximity to occupied homes, and the viability of the technology to deliver reliable heating had not been proved. It was not known if this new application of the technology would be acceptable to the occupiers of the homes it was installed in. The project demonstrated that all of these challenges could be met successfully. Since the completion of the project a number of UK social housing providers have carried out similar projects, proving the potential for gshp€s to be fitted to a very large number of existing homes both in the UK and Europe. Specific lessons learned from the project include:

• Vertical boreholes work well for gshp ground collectors for homes with small gardens / external areas. With careful management the disruption traditionally associated with drilling boreholes can be reduced to a very acceptable level even for occupied homes.
• The costs of drilling boreholes can be reduced considerably if the installation is facilitated by an energy company or contractor who can procure drilling work in a significant volume. In the UK the Powergen 'HeatPlant' scheme has pioneered this approach.
• For small homes there are significant advantages in installing the heat pumps in external weatherproof enclosures.
• Despite the common association of ground source heat pumps with underfloor heating, they can work very well using a radiator system for internal heat distribution. This is much easier to install in an existing home. Where radiator systems are used it is essential to use high water content radiators unless a buffer vessel is used in the system.
• The heat pumps used in this project are designed to deliver domestic hot water in addition to space heating and to meet the full heating load of the home. Heat pumps which do not deliver domestic hot water or require supplementary flow boilers to augment the heating capacity can incur higher running costs and CO₂ emissions.
• Insulation levels in homes to be fitted with a GSHP should be increased to the highest practical level by means such as cavity fill of external cavity wall, top up roof insulation, replacement double or triple glazing and draughtproofing. The overall design heat losses of the home should not exceed the heating capacity of the heat pump
• There is a need for plumbing and heating engineers to familiarise themselves with the operating characteristics of GSHP systems, but once this has been done the plumbing and heating installation process for radiator systems involves no greater challenges than are normal for fossil fuel systems.
• There is a need for an expert installer, particularly for assessing the suitability of ground conditions at proposed sites and to design the ground loop correctly.

To find similar reports, click on a keyword below:
Architects/Architecture : Buildings : Decision Makers : ESCOs : Energy Efficiency : Engineering Organisations : Geothermal Energy : Heat Pumps : Heat/Heating : Households : Local Government : ManagEnergy : Property Owners : Refurbishment of Buildings : Regional Government : Renewable Energy Sources & Systems : Solar Thermal : Sustainable Communities : Utilities

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