- Client: Athelhampton House and Gardens
- Location: Dorchester
- Technology: Solar PV, Battery Storage, Heat Pumps
- Partners: SPASE Architects
The Challenge:
Athelhampton House and Gardens is made up of a Grade 1 listed Tudor manor house dating from the 1400s, a reception building with catering and event facilities that also has listed status and a holiday rental cottage. The facilities are open to the public year-round and are a significant local employer.
The site is off the gas grid and has been heated with a mix of LPG and oil, it had a limited electricity supply resulting in frequent power cuts and as a result also had a large diesel generator.
The new owner had a vision to make the property operationally net carbon neutral and bring a historically significant building to a point where it was ready for the next 500 years without adding to global carbon emissions.
The clear objective of the owner was to get rid of all fossil fuel energy sources for all the buildings and operations on site.
The challenges were significant as there was a need for considerable generation on-site as well as plentiful renewable heating and an upgrade to the sites power supplies and connection to the grid.
Our approach to energy efficiency in historic buildings
The entire site is grade 1 listed. This meant that the normal “fabric first” approach to energy reduction was a challenge as options for retrofit insulation were limited.
Insulation was possible in 40% of the flooring using traditional insulation and 60% of the roof space with a mix of mineral wool and hemp insulation. This led to a technology-heavy set of solutions that were designed in detail to work around the sites many challenges.
We face a lot of negativity and incorrect information about renewable heating systems ability to heat anything other than modern, well insulated buildings. This project demonstrates that a building which would “typically” be considered impossible to convert to renewable heating is in fact both possible to convert – and run successfully.
As such, it works superbly as a flag-carrier to prove that if this project can be converted, so can any other! It will help to start to change the heating industries mindset of what is achievable with renewables and that will have a positive knock-on to more typical properties.
The solution: Renewables and Solar panels for listed buildings
The projects architects (whose offices are based on-site) contacted H2ecO who are located about 20 minutes away to see what could be done.
Many options were considered, modelled, and rejected, including River Water-source heat from the river that runs through the property, wind power, full ground source heating system with ground arrays, open and closed Boreholes etc.
Solar
Eventually, after planning discussions, an agreement was reached to allow for a 100kWp ground mounted array of Solar Panels in an attached meadow and a 25kWp array of Solar Panels in a service area. These were the maximum area of panels allowed after Planning and grid application limitations. The Grid connection was upgraded to 3 phase to allow for the renewable equipment to be connected and to improve the reliability of the local grid connection. The cost of this formed a significant part of the overall project cost but was considered as an investment in the long-term future of the site – and was needed to facilitate the various generation and heating technologies.
Battery storage
The generator was replaced with 3 x Tesla powerwall Battery storage systems and another 9 Tesla Powerwall’s were installed to allow time-shifting of the Solar PV energy and assist with grid balancing to help the National Grid decarbonise.
Heat Pumps
Heating was eventually managed with a large ground collector array in an adjacent three-acre meadow. This was connected to the holiday rental cottage which has its own GSHP from Kensa.
The “Coach House” reception and events building was across the river from the meadow, so the ground collector header pipes had to be run across the river to reach the new coach house plant room. This was achieved by directionally drilling under the river with attendant environment agency permitting and trenching through formal gardens. The coach house is now heated and has DHW provided by 3 x 15kW Kensa Ground Source Heat Pumps (GSHP’s).
The Manor House was a particularly difficult challenge as the property is solid stone, has stained glass windows and has construction elements dating back to the 1400s. It has a total heat loss of approximately 150kW. And in some locations older style radiators had to be retained, precluding the use of low temperature heatpumps.
As such, a higher temperature source of heat was required and after discussions with the planners, a bank of 10X Daikin High Temperature heatpumps was allowed in one location and another five in another location, 125 metres from the building they needed to heat.
This required the construction of a small new plant room and the installation of a long length of district heating pipe in a trench running through the formal gardens.
H2eco Athelhampton House ground source heat pump pipes
One of the key positive factors was these units exceptionally low noise output. In practice this has been borne out as the bank of 10 heatpumps, when running at full capacity, make less noise than the existing encased fountain pump they are located next to.
In both the coach house and the manor house, the plant room locations have been extremely challenging. Several external parties said it was impossible to fit the required equipment into the available spaces but by thinking 3 dimensionally, H2ecO and its partners have been able to achieve success.
The manor house has a domestic hot water demand for the recently renovated accommodation areas, which are available for rental for weddings and other events. 4 of the HHT heat pumps easily deliver the required heat to the 2 x 400 litre quad-coil DHW cylinders.
Interpretation panels are installed at the site so all of the visitors can learn about the project. The site attracts around 25,000 visitors per annum. The project is included in the official guidebook and staff are trained to talk to visitors about the project.
School groups who visit are told about and shown parts of the equipment and have the concept explained.
The Results
The first 12 months operational data show that the target energy reduction and carbon emissions are being achieved with all technologies working as expected.
Property owner, Mr Giles Keating said: “We knew from the start that our concept would be pushing the boundaries of what was possible and had already had feedback from some external parties that our plans were unrealistic.
“H2ecO along with SPASE were very good at taking our aims and proactively coming up with creative solutions to solve the many challenges – challenges which had put off other parties previously.”
If you have a listed property and are considering your renewable energy options, contact us to get a quote.
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Equipment Used
Daikin Equipment:
- 15 x Altherma 3 HHT heat pumps.
- 2 x sequence controllers and associated comms units in each heat pump.
Newark Copper:
- 1 x 500 litre buffer vessel.
- 1 x 300 litre buffer vessel.
- 2 x 400 litre Unvented quad-coil DHW cylinders.
Kensa Equipment:
- 1 x 13kW single phase EVO GSHP.
- 3 x 15kW 3 phase EVO GSHP.
- 2 x 150 litre buffer vessels.
- 3 x 400 litre DHW unvented cylinders.
- 600m of slinky ground collector, manifolds and header pipes.
Tesla Equipment:
- 12 x Tesla Powerwall Batteries.
Photovoltaic equipment.
- Solar Edge 3 phase Inverters totalling 95kWp.
- Solar Panels totalling 125kWp split as 100kWp and 25kWp arrays.
A letter from the Property owner, Mr Giles Keating.
Athelhampton House is now over 500 years old, and we have a vision for the development and preservation of this Grade 1 listed building and gardens that will ensure it has a successful future for the next 500 years of its life.
A very important part of that vision is to make the entire site carbon neutral in operation.
We started working on that idea several years ago and had progressed the basic concepts of generation, storage and heat generation to a point where we felt it was feasible with current technology. We recognised that we needed to involve external parties who were specialists in their fields to bring the project from a concept to reality.
SPASE Architects are a local architectural practice who are based on the Athelhampton site and who specialise in our type of older, more challenging buildings.
SPASE carried out a search for renewables specialists and H2ecO were selected. H2ecO took on the initial role of assessing the overall feasibility of our concept and working out how it could be physically achieved and delivered bringing their experience as installers and designers of all the required technologies.
We knew from the start that our concept would be pushing the boundaries of what was possible and had already had feedback from some external parties that our plans were unrealistic.
H2ecO along with SPASE were very good at taking our aims and proactively coming up with creative solutions to solve the many challenges – challenges which had put off other parties previously.
They took a fabric-first approach and added insulation where possible to reduce energy demands as much as possible, though there were significant limitations and challenges even with this due to the Grade 1 listed nature of the building and gardens, and our requirement to retain the historic nature of the building and its surroundings.
Once demand had been reduced as much as possible, H2ecO carried out an extensive series of investigations to see which of the available technologies could be used to achieve our aims. Many options were considered and rejected, and we were impressed by the way they were open to testing and modelling any available option to see if it could be made to work or be adapted to work in our situation.
The overall project required a Photovoltaic installation to generate renewable energy, and a large battery storage system to buffer the generation and demand. H2ecO did the initial designs for both – with a Tesla Powerwall multiple battery installation that required input from Tesla technical as it required their limits to be pushed due to the distances between components across the site. This was the largest powerwall installation in the UK at that time and the batteries were sourced from Tesla by H2ecO. Due to the overall scale of the entire project H2ecO then recommended a local specialist installer – normally a competitor of theirs – Empower Energy to do the physical installation work on both the batteries and 125kWp ground mount Solar installation, leaving H2ecO free to concentrate on the implementation of the heating solutions. Empower also managed the new National Grid three phase supply which was required to stabilise the grid supply to Athelhampton and allow the connection of the generation and storage.
For example, for the heating provision, Athelhampton has a beautiful river running through the property. As a result, a water source heating solution was initially considered but found to be impractical after extensive options were tested. The same applied to boreholes of various designs.
The final plans required a mix of heating technologies and locations to work around the physical constraints of the site and used an extensive ground source heating solution paired with an innovative use of high temperature air source heat pumps.
The overall plan was completed on a realistic timescale and deadlines relating to funding and grants were all achieved.
We received support from the Non-Domestic RHI and from Low Carbon Dorset.
We now use the installations to help educate groups of interested parties, both adults and local schoolchildren, on what can be done with renewables and have already converted people to the cause of decarbonising by showing them what is possible with commitment and the correct application of technology to help mitigate the climate change emergency. A building housing the larger indoor heat pump installation was modified to include a window to allow visitors to view the equipment from outside, and interpretative panels have been provided along with a description of the installation in the guidebook.
The greater coverage we can get for the project, the more it will help us to spread the message that renewables can be applied to any building if people are sufficiently committed to finding solutions and manufacturers are happy to work with each other and be flexible in how their equipment is used.
Yours
Giles Keating
Athelhampton House
DT2 7LG
