Case study: Gwylfan-y-Glaerwen, Llansteffan

A magnificent building housing cutting-edge and innovative use of renewable technologies, with stunning sea and estuary views set in eight acres of wild flower meadows with a large sunken walled garden, designed and owned by international fashion and textile artists, Charles and Patricia Lester.

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In the late 1990’s Charles and Patricia Lester bought an eight acre plot, part of a nine hole golf course, near the picturesque coastal village of Llansteffan in rural Carmarthenshire. Described as an “architecturally disadvantaged” building, the Lester’s wanted to turn the former unfinished concrete shell of a clubhouse building into a “palace by the sea” – but on a shoestring.

Neither had done anything like this before, but being designers they saw the old clubhouse shell as a blank canvas, which they have nurtured into a landmark project that is bold yet works in harmony with its surroundings thanks to the innovative application of several renewable technologies, including a Kensa heat pump.

Gwlyfan y Glaerwen

They initially employed an architect in an attempt to realise their vision, but the plans that were initially passed lacked the timeless quality and character that they wanted, so asked if they could re-design the house themselves. The planning officer was very supportive and not only guided the Lester’s but also made some excellent suggestions. The Lester’s worked on their dream home for over 10 years with a very limited budget, employing a small team of excellent Polish builders, using reclaimed materials wherever possible and carrying out a lot of the work themselves.

Consequently the home they created, which they have named ‘Gwylfan-y-Glaerwen’ (meaning ‘Watching Place of Bright Shining Water’), has a number of unique features including a library and reading room, studio space for the couple to work on their textile business, and an impressive tower allowing them to enjoy views of the nearby coastline and the unspoilt  rural landscape – because one has to “have a tower by the sea” says Patricia Lester!

Having autonomy over the build also allowed the Lester’s to add the finishing touches that make their home their own, including intricate glasswork created by their daughter, and hand-cast plaster arches in the conservatory.  The two conservatories are built out of reclaimed Bath stone – every block cut by Charles himself.  They designed the property not only for an interesting and comfortable home, but also so that they could create and film their own fashion shows and use the property as a location for film and television.

As well as being visually impressive, the house has also been designed to be as energy efficient as possible. Charles was originally a physicist specialising in ultrasonics in relation to textiles.  He designed his first solar heating system whilst in his teens 55 years ago. An innovator and inventor, he understands the benefits of renewable heating technologies and how they work scientifically. With the property being in a rural location with plenty of land, he was keen to use a ground source heat pump to cater for the property’s space heating requirement. In addition to this, Charles has also installed solar thermal panels, Solar PV, and passive solar, which pumps hot air from the conservatories into the house in winter.  He designed and installed a rainwater harvesting system.  All this with the  geothermal technology, makes the house nearly energy independent.  All the systems were designed to produce the maximum output possible at the equinoxes.  Excess heat in the summer  is stored.

 

 

Kensa specified a 16kW Twin Compact ground source heat pump for the project. Although capable of heating the whole house, the heat pump will rarely be needed to do so, as with support from Kensa, Charles cleverly integrated it with his solar technologies, effectively creating a ‘heat battery’ system that charges the ground with solar energy. He does this by procuring as much heat energy from the solar thermal as possible, which is initially used alongside the Solar PV to fulfil his domestic hot water requirement. Any leftover heat is then discharged into the ground via 400m of pipe laid underneath their wildflower meadow. The ground source heat pump then delivers space heating when needed by absorbing the heat stored in the ground via the straight pipe and two boreholes; this design ensures a warmer return temperature to the ground source heat pump and superior performance, equating to very low heating bills and high returns through the RHI.

The combination of boreholes and straight pipe as a ground array is unusual, but in the case of the Lesters it provided the optimum performance; the use of the ground as a ‘heat battery’ demanded a system design that would ensure all of the discharged heat into the ground was utilised to benefit the ground source heat pumps performance, so by using boreholes, which were drilled to depths of 880m, the borehole pipework along with the straight pipework in shallow trenches absorb all possible heat for the ground source heat pump to function super-efficiently.

Charles is passionate about renewable technologies and understands how to get the best efficiencies from the system he has designed. When the Lester’s bought the plot, the clubhouse building was effectively a concrete block with no insulation. Charles upgraded this to the highest possible specification, filling wall cavities with foam and Celcon blocks as the inner wall; covering walls with plasterboard backed with 25mm Celotex and foil.  He also added several air spaces between the layers of insulation in the roof, all of which improve the efficiency of the heat pump system.

He did a great deal of research about the benefits of underfloor heating and how well this type of heat emitter works with a ground source heat pump. Charles put the underfloor heating in himself across the whole house, which was no mean feat as 3km of pipework was required for the ground-floor alone as he designed the system to operate at 25°C to 30°C!  He also did all of the internal plumbing which was a complex undertaking as there were multiple heat outputs including the ground source heat pump. He is currently devising a system which will automatically divert heat around the house as and when it is needed.

As he did most of the work himself, Charles made use of Kensa’s MCS Umbrella scheme to make sure that the installation was properly accredited and therefore eligible for quarterly payments for the next seven years under the Government’s Domestic Renewable Heat Incentive (RHI) scheme. Since installing the renewable heating system, the Lester’s have received very small electricity bills for a property the size of Gwylfan-y-Glaerwen, and a generous sum in return through the RHI.

Charles initially approached two other international heat pump manufacturers to discuss his plans for integrating renewable technologies on site. However, the first seemed “baffled” by the system design that Charles was proposing and the second claimed COPs that were totally unrealistic.  Upon a recommendation he turned to Kensa to discuss how he could make his design a reality.

Charles said:

I loved the service I received from Kensa; they gave me lots of information and constant support which made a major difference during the installation process. I always got intelligent answers to the questions that I asked and I believe they went above and beyond in terms of the customer service that they offered to me.

If I was to offer advice to anyone thinking of installing a ground source heat pump, I would say don’t hesitate! It’s important to get advice from as many people as possible, but definitely talk to Kensa – they are experts and know what they’re doing. I would certainly recommend them.  I would also urge caution when relying on plumbers to do the design as they do not often have a full understanding of the technologies involved.

Expert’s Opinion:

Dr Matthew Trewhella, Project Manager (Kensa Heat Pumps)Dr. Matthew Trewhella, Kensa’s General Manager, provides his analysis of this interesting scheme:

“This project is a great example of complementary design. Normally a property of this size would consume very large amounts of energy. Incorporating high insulation, passive solar design and active solar thermal has dramatically reduced the demand for heat. Providing heating and hot water using a ground source heat pump is always a good idea but the energy reduction improvements mean the efficient heat pump is only used for heat that is absolutely necessary.

“This not only reduces the running costs but also decreases the initial investment – allowing Kensa to specify a smaller heat pump and smaller ground array. Even further improvements in efficiency are gained on this project by using excess solar thermal to recharge the ground array. In this case, this improves the system efficiency but in certain cases, it could be used to reduce the size and therefore capital cost of the ground array.

“There are other ways to recharge the ground array. As insulation levels increase, the demand for summer cooling is set to rise. A ground array can provide effectively free cooling whilst simultaneously recharging the ground array. Another exciting development is cooling of solar PV panels – solar PV operates more efficiently when it is cooler – by using a ground array to cool solar PV panels, we could improve ground source efficiency or decrease the size of the boreholes, lowering the capital costs.”

Key Facts

  • Luxury 800m² self-build home with 20 rooms set in 8 acres of Welsh coastal countryside
  • Ground source heat pump, solar thermal, Solar PV, passive solar generated hot air circulation from conservatories and rainwater harvesting
  • 16kW Kensa Twin Compact ground source heat pump for space heating
  • 400m horizontal ground loop and two boreholes in their own meadow
  • Solar system charges the ground as a 'heat battery' for the ground source heat pump
  • 10 year build project using Kensa’s MCS Umbrella scheme
  • Eligible for Domestic Renewable Heat Incentive (RHI)