Coastline Housing, Wheal Vyvyan

Ground Source Review: Coastline, Wheal Vyvyan.

Replacing inefficient night storage heaters with ground source heat pumps in twelve bungalows housing older residents in rural Cornwall; this five-time award-winning scheme is the first shared ground loop ground source heat network project undertaken by Coastline Housing and also the first of its kind in Cornwall.

Share Button

Ground Source Review: Coastline, Wheal Vyvyan



Coastline Housing was looking to replace inefficient night storage heaters in a group of bungalows situated off the gas grid. Coastline attended a seminar hosted by Kensa where they heard from fellow social landlord Trent & Dove Housing about their successful experience of installing ground source heat pumps into similar bungalows. This helped Coastline shape their opinion that ground source presented a credible and affordable heating and hot water option for tenants in off gas grid homes, and prompted them to undertake a trial in twelve bungalows housing older and vulnerable residents at Wheal Vyvyan in Constantine, Cornwall.

The project benefited from a combination of funding including the Non-Domestic Renewable Heat Incentive (RHI – this scheme has closed), an up-front grant from the Energy Companies Obligation (ECO) and new funding offered by DECC in the form of the Central Heating Fund (CHF). Coastline made a successful bid for the CHF money through Cornwall Council, which provided an attractive value for money opportunity when combined with the other funding streams. Therefore, it was a combination of Kensa’s successful case study portfolio and a funded proposal which led to Coastline taking this first project forward.


The project featured a micro district ground source heat network. This innovative system architecture, pioneered by Kensa, includes an individual ground source heat pump in each bungalow linked to a communal ground array. The Wheal Vyvyan estate had six communal boreholes drilled by local drilling contractor Aquasource to an average depth of 60m, feeding 12 individual 3kW Shoebox heat pumps. This communal approach reduced drilling costs and also made the project eligible for the Non-Domestic Renewable Heat Incentive (RHI – this scheme has closed), giving Coastline Housing the opportunity to receive quarterly payments from the Government for 20 years. It also ensured that each property can use their own preferred energy supplier and pay only for the heat they use, rather than more common district heating systems where it becomes necessary to meter for payment, which is more complicated for both the landlord and tenant. The system design is also exempt from Heating Metering and Billing regulations.

Shoebox Heat Pump with plugKensa specified a 3kW ‘Shoebox’ heat pump to be installed in every property; the innovative Shoebox model is the smallest and quietest ground source heat pump on the market. It is the product of choice in social housing properties, as there is no requirement for external plant rooms, unlike air source heat pumps, or ancillaries, such as oil tanks, to be sited. In the case of the Wheal Vyvyan estate the Shoebox units were neatly fitted in external stores previously used for coal, with additional shelving set up over the heat pump to provide a useful storage space for tenants.

The bungalows are occupied by older and vulnerable residents, who remained in their homes throughout the installations with work tailored to the individual circumstances of each tenant, for example fitting around carer visits. A high level of customer liaison was carried out by Kensa and Coastline Housing prior to the work commencing and tenants were kept informed throughout the installation process. Internal works on heating systems were provided by Coastline’s partner heating contractor Blue Flame and overseen by Kensa. The installations were carefully planned and carried out seamlessly over a six week period, which required dedicated and stringent project management. The drill rig was able to be positioned in a small area, minimising disruption during the drilling of the boreholes, and Kensa ensured any disturbed ground was fully restored.


Tenants have been very happy with their new ground source heat pumps, and Coastline will monitor their performance and tenant fuel bill savings as the weather turns colder in the autumn. On average tenants have each saved £188 per annum following the ground source heat pump installation compared to the previous electric economy 7 systems.

Resident Ms Osnebury commented:

“Very pleased on affordability – was approximately £30 per week now £12 per week – and I can stay nice and warm for that! I have never been happier. No damp problems now – all gone.”

Mr & Mrs Pellowe commented:

“The heating is fantastic! The old NSH weren’t working properly and no control and not consistent heat. Now we have the same temperature in every room and enjoy the constant temperature. All the damp smell which we had (e.g. musty smell in wardrobes) has completely gone. Running cost was £35 per week for 3 heaters with NSH. Now I reckon it to be £20-£25 per week so £10 saving for better comfort and consistent heating. It is perfect. Always plenty of hot water and good pressure. Previously couldn’t have the hot tap in kitchen running at same time as the bathroom or reduced to a trickle. It is a God send!”

Wendy has been in her property for 18 months and thinks that the ground source heat pump is a big improvement on the night storage heaters. She said:

Wendy_close upThe heat pump is much more economical, I noticed a difference straight away. I was often cold with the night stores, especially in the morning, but baking hot during the night. This is much better and  the hot water cylinder fits nicely in my attic, freeing up valuable cupboard space.”

Chris has lived at Wheal Vyvyan for nearly 8 years. He said:

Chris_close upThe night storage heaters were a waste of space, they didn’t stay warm. The heat pump heats up the house quickly and is easy to control using the themostat. They did a great job drilling the boreholes; I wasn’t sure how they would get into such small spaces, but even though the drill was large, you can hardly tell where they’ve been.”


Ralph Retallack, Energy Efficiency Manager at Coastline Housing said:

Ralph_close upThe properties on the Wheal Vyvyan estate had previously used night storage heater systems, which can be a very expensive way of heating a home. We are constantly seeking to reduce domestic fuel bills for our customers in line with our Affordable Warmth Strategy.”

Coastline Housing is the first housing association in Cornwall to install this type of micro ground source heat network system. It allows our tenants to retain control of their individual electric bills, which is more convenient for them and saves Coastline having to become involved in any billing. The system also qualifies for the Government’s Non-Domestic Renewable Heat Incentive (RHI – this scheme has closed) fund, which provides a welcome financial support for Coastline in the form of quarterly payments over the next 20 years. As we installed these first systems in the summer months, we do not yet have running cost data and full feedback from our customers. However, the experience of other social landlords that Kensa has worked with suggests that they should expect greater comfort and control of their heating, whilst at the same time benefit from constant levels of heat and significant savings on their fuel bills.”

I would strongly advise other social landlords to be open to this technology as an option. Ground source heat pumps are very low maintenance, there is simply not much to go wrong. The boreholes provide sufficient energy to meet each property’s full heating and hot water needs. The typical life expectancy of each heat pump unit is 20-25 years and the design life of the borehole is 100 years, so Coastline has invested in a renewable heating infrastructure that will keep its tenants warm for years to come. We were very impressed with the small size but high efficiencies of Kensa’s innovative Shoebox heat pumps, and they can easily be swapped out for refurbishment if needs be.”

From start to finish the project with Kensa has run extremely smoothly. They demonstrated very good knowledge in the area of social housing, where their experience of similar projects with Housing Associations, such as Trent & Dove Housing and Westward Housing, was evident.”

This was very much a ‘hands off’ project for Coastline once work commenced; we have been impressed with the level of care and consideration for our tenants needs; the swift and professional delivery of the physical work; and importantly the careful restoration of areas where the borehole drilling took place. As a reflection of this we are keen to progress a further project this year on a similar scale, which we have already scoped with Kensa should further CHF be made available to us. In addition, it has been great to be working with and supporting a fellow Cornish company!”

Simon Lomax, Managing Director of Kensa Heat Pumps said:

The project was supported by a grant from EDF and will provide Coastline Housing with a lucrative 20-year income stream from the Government’s Non Domestic Renewable Heat Incentive (RHI – this scheme has closed). There are a large number of rural social properties in Cornwall which cannot access the mains gas grid and these heat pump installations provide an excellent alternative to tenant and landlord alike.  We look forward to continuing our relationship with Coastline Housing in the future.

Due to the success of this project, Coastline is considering undertaking ground source installations on a larger scale to provide more energy efficient homes and lower bills for its customers, and is currently working with Kensa to scope out a second ground source heat pump project.

  • Winner: Best contribution towards the creation of a sustainable energy economy (Cornwall Sustainability Awards 2017)
  • Winner: Overall Winner (Cornwall Sustainability Awards 2017)
  • Winner: Best Renewable Energy Scheme (Regen SW Green Energy Awards 2016)
  • Winner: Sustainable Project of the Year (HVR Awards 2016)
  • Winner: Large Scale Project SW Region (Energy Efficiency & Retrofit Awards 2016)

Key Facts

  • x12 bungalows housing older residents
  • x11 Economy 7 electric heaters and x1 oil boiler replaced
  • x3 groups of 2 boreholes – each group serving 4 dwellings
  • An individual 3kW Shoebox heat pump housed in external enclosures next to the front door serving each dwelling
  • Non-Domestic Renewable Heat Incentive (RHI - this scheme has closed), Central Heating Fund (CHF) & ECO grant
  • New hot water cylinder and radiator systems
  • £188 saved on heating bills per annum

Related Content

News: Coastline & Kensa Deliver ‘Best Renewable Energy Scheme of the Year’

Cornish manufacturer Kensa Heat Pumps and Coastline Housing have received industry acclaim with an award for their recent renewable heating upgrade project in Constantine, the first of its kind in Cornwall.

News: Triple Win For Cornwall’s Coastline Housing & Kensa Partnership

Coastline Housing residents in Cornwall have benefitted from a triple award winning partnership in the form of renewable heating, using locally manufactured ground source heat pumps from Kensa Heat Pumps.