Ground source heat pump systems can play a greater part in minimising carbon emissions, but improvements in design standards and training are critical, says Duncan Nicholson
Ground source heat pump (GSHP) systems should be at the forefront of the renewable strategy for the UK.
But the need for technical standards and designer training/competency has limited the uptake of the technology.
The GSHP industry in this country is in its infancy, although it is an accepted technology elsewhere.
The UK does not have a strong academic background in these systems and until recently few design guides were available.
The need is growing too - GSHP systems are included within the Renewable Heat Incentives (RHI) which came into effect at the end of September.
Until recently, the UK the industry has been led by the heat pump manufacturers and a few geothermal contractors.
The UK’s Ground Source Heat Pump Association (GSHPA) published a vertical borehole guide in September.
Work has also started on GSHPA thermal (energy) pile guide and a draft is planned for November 2011. This follows from the NHBC’s Guide NF21, published in February last year, which partly covered thermal (energy) piles for houses.
In addition, the Environment Agency issued a good practice guide for ground heating and cooling in May this year.
“The UK does not have a strong academic background in ground source heat pump systems”
A key driver to improving standards is the new revision to the Microgeneration Installation Standard: MIS 3005 (September 2011) edited by Gemserv with much input from the Department of Energy and Climate Change and industry.
This sets out the approval or certification of GSHP systems with tables developed specifically for the UK climate and ground conditions.
To meet these standards, training courses for GSHP system designers will be required.
In the UK, training courses are gradually being introduced through the Quality Credit Framework.
Currently these work at heat pump installer level and these need to be developed for domestic and then commercial design training.
So what can the geotechnical community do to help implement GSHP technology?
At the planning stage, the desk study could provide an interpretation of the geology to 150m depth based on the BGS mapping and free online Geoindex borehole log access.
Once on site, thermal conductivity testing can be carried out as part of the site investigation to provide information on ground temperature.
During the concept design stage, M&E engineers need to be involved for the best outcome and once the project reaches detailed design, there is an opportunity for geotechnical engineers to become more involved in the design but training is required.
Commissioning of the system could also provide important data but this is not currently being fed back into design.
Clients and academics have an important role in ensuring data is published.
- Duncan Nicholson is a director of Ove Arup & Partners and is also vice chairman of the GSHPA and a member of its technical committee.
The GSHPA is holding a one day technical seminar at Homerton College, Cambridge on 16 November 2011.
More details are available from www.gshp.org.uk