Milestone House

Milestone House

Application: Private & Public Housing

Gordon & Lori Rautenbach recently retrofitted their 16th-century listed home in Bramley, Surrey, with renewable energy and heating systems, to create an energy-efficient, sustainable residence.

Their vision and achievement  resulted in a ‘Highly Commended’ award in the Domestic Ground Source Heat Pump category at the 2013 National Heat Pump Awards.

When Gordon and Lori first moved into the 400-year-old building – which had been extended in the 1960’s – all of the services, including heating to electricity, were in dire need of an upgrade. Gordon and Lori run an architectural practice, and they have an extensive understanding about sustainable buildings, and recognised that the extensive refurbishment that was required provided them with the opportunity to reduce the energy consumption of the property and to promote their long term environmental sustainability objectives.

“We understood, due to the age of the house, that Milestone was extremely energy inefficient and would need new heating and electrical systems anyway,” explained Gordon. “So we decided it would be worth the initial outlay to acquire innovative, energy-efficient systems, to make living in a larger house affordable in the long run.” Gordon and Lori were adamant that Milestone had the potential to become a self-sufficient home, even taking into account the inherent constraints of working with a listed building.

Two sixty metre bore holes were drilled in the garden behind the house to create a natural water supply from the aquifer. This water – pumped into the house at 8°C from one of the boreholes – then passes through a drip-tray equipped, heat exchanger (located  in the walk in pantry to keep food chilled), and returns the water to the other borehole at 4°C. The Danfoss ground-source heat pump, which  extracts 4°C of the water temperature,  and (with its compressor) boosts it up to the higher temperatures as needed for the  hot water and central heating via the Jaga dynamic radiators. A 4kW ground mounted photovoltaic system provides some of the electricity needed to drive the pumps and compressor.

To support their self-sustainable strategy, 21 Jaga Strada DBE radiators were installed throughout the property for  heat pump compatible, energy-efficient heating. 

The Strada DBE radiators, which feature Jaga’s Dynamic Boost Effect technology to provide an instant boost of heat when required, were selected by Gordon primarily for their extremely quiet fan noise. Reaching less than 35 dB(A) when on boost mode, the DBE unit fans are quieter than a domestic refrigerator. “This was absolutely imperative. While we wanted the heat boosting technology, it just wouldn’t have worked in such a quiet domestic situation if the fan noise was at all noticeable.”

Cementing Gordon and Lori’s decision to choose Jaga as their radiator manufacturer was the Strada DBE’s compact and unobtrusive design.

“The Strada radiators were ideal for blending with the interior decor,” said Gordon. “While we wanted energy-efficient heating that was compatible with our heat pumps, it was vitally important to us that the radiators provided a simple and elegant aesthetic that would not dominate our living environment. We also appreciate quality for its own sake as well as providing long term value for money.”

As well as using natural resources for the property’s water supply, Gordon and Lori have a photovoltaic (PV) solar panel system producing 4kW of electrical energy. Due to the Microgeneration Feed in Tariff (FIT), the solar panels not only provide the electricity needed to power appliances and the heat pump system, but generate tax free income for the owners, as well as feeding electricity back into the grid. With the introduction of the Renewable Heat Incentive (RHI) in April 2014, heating costs will be significantly reduced as well as providing further tax free income. “While the upfront costs of the ground source heat pump  and solar PV systems can seem expensive, our heating and electricity costs for the future will be very low, and we believe that we will  recoup our investment back within six to eight years,” said Gordon. “We also believe the expenditure will have added more value to the property than the cost – most prospective purchasers will be attracted by the very low running costs.”

Milestone is also equipped with a ducted heat recovery system as well as effective insulation. This, in conjunction with Jaga’s low-temperature radiators, means there is little heat loss during night cooling. “Because the Strada radiators are low-temperature units, their low mass makes them highly responsive and precisely controllable,” explained Gordon. “Turning a heating system on and off uses a lot more energy than people think when they are part of a heat pump system, so we have a large buffer tank, and we were adamant we wanted solutions and products that didn’t require this level of attention.”

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