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Last updateTue, 21 May 2019 11am

Ground source heating for off-grid barn conversion

A stunning contemporary barn conversion located off-grid in South Norfolk is benefitting from energy efficient ground source heating from renewable heating experts, Finn Geotherm.

The four bedroom barn conversion in Hethersett was designed and built by homeowner Oliver Clarke. The property used the original 1980s steel framed sheep barn as the base with the new house built inside. Planning regulations required the appearance of the barn to remain as original as possible so Oliver designed and built bespoke exterior wooden shutters to go over each window and door. A large glass wall and bi-fold doors in the main living area provide stunning views over the fields and surrounding countryside. 

Oliver has also converted a second barn on the site to create a workshop for his carpentry business.

Located in rural South Norfolk, the barn is off-grid with no gas and mains water. When it came to heating, Oliver wanted a system which would be environmentally friendly but also self-sufficient and hassle free. Oliver explains: “Having had experience of air source in a previous property, I was keen to explore the opportunity for ground source to maximise the land available around our house. I had looked at other renewable heating options such as biomass but I wanted something that was going to require as little ongoing maintenance as possible.”

After a full site survey, Finn Geotherm specified and installed a single phase Lämpöässä VM14 ground source heat pump which incorporates a 480 litre thermal store. The new system, which is housed in the workshop, provides all the heating and hot water, harvesting the primary energy from a 700 metre ground array laid 1.2m underground in their garden. The ground loop had to be installed in white clay, which provided a slight additional challenge that Finn Geotherm easily overcame. Any grass, plants and foliage which are now grown above the ground array are not restricted as the low density and depth of the pipes mean they have no effect on the surface soil temperature and they take so little energy out of the soil per square metre.

A secondary return on the hot water ensures the system can deliver over 240 litres of hot water almost instantaneously anywhere in the house. Through a partner company, Finn Geotherm were also very involved in the design and installation of underfloor heating throughout. The heating is fully zoned to ensure rooms are maintained at Oliver’s preferred temperatures. The Lampoassa system is also connected to the internet which enables him to remotely control and monitor the heating. 

“I am really pleased with our ground source system,” said Oliver. “It’s energy efficient and works perfectly for our house. We just leave the heating on and we’re always warm enough without having to think about it. I installed a wood burning stove, more as a feature for the living room, but we don’t light it as there really isn’t any need. Finn Geotherm are the best contractors I have dealt with – all aspects of the system design and installation were easy and hassle-free.”

The installation is benefitting from the government’s seven-year Domestic Renewable Heat Incentive (RHI) scheme, a government financial incentive which rewards people tax free and index linked for opting for renewable heating. With this installation, RHI payments are more than five times the running costs. 

For more information on ground and air source heat pumps and details on Finn Geotherm, visit