Sewells Gatehouse

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Sewells Gatehouse
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Details

Address: Sewells Gatehouse, Barcombe, BN8 5FH
Owners: Jason and Mel Lundin
Type: Two storey detached chalet style
Built: 1985
Beds: 3/4
Walls: Timber frame with outer brick skin
Residents: 2 adults 2 children

Eco Features

Ground source heat pump (GSHP)
Underfloor heating
Triple glazing
Underfloor insulation
Solar PV (3.2 kWp)

Summary

Sewells Gatehouse was built in 1985 on the site two former tied farm cottages. It was built by Jason’s mother’s construction company to a ScandiaHus design, which at the time was cutting edge with high levels of insulation and triple glazing. Following construction, this was rented out continuously until very recently.

When Jason and his family decided to move in a couple of years ago, they felt it was time for a major upgrade to modern standards, with improved insulation, a ground source heat pump and solar PV panels on the roof to help balance the additional electric load. This replaced electric convector heating which was expensive and inefficient to run. Energy use is now nearly 50% below average and more than 60% lower than the former building.

The work took over a year and involved stripping out all flooring and plastered wall surfaces to gain access to the underlying structure. At the same time, the opportunity was taken to switch the kitchen from the south side, where it tended to overheat, to the north side, with its lovely views across the fields.

Energy efficiency measures

Heating and hot water

Heating is provided by a Bosch GSHP, coupled with a 300 litre thermal store, installed by ICE Energy, which supplies underfloor heating and hot water. This runs virtually continuously during the winter months giving gentle background
heat.

The heat is drawn from the ground via buried polythene coils, which radiate from the house in three branches, going under both the garden and beyond to the adjacent field. These cover 150m of looped 30mm pipe, buried 1.5/2m deep. Restoration of the surface was pretty simple, although the depth meant there was some settlement, which had to be corrected.

Insulation

The roof originally had 100mm of rockwool set between the rafters of the upstairs sloping ceiling. This has now received an additional layer of laminated foil insulation, cross battened and finished with plasterboard laminated with solid foam to prevent thermal bridging through the rafters. The dormer insulation was improved by replacing rockwool insulation in the cheeks with more efficient Celotex PIR foam.

These measures have dramatically improved insulation and cut roof heat loss by more than half. Walls were built as a frame of 120 x 30mm timber studs with 120mm rockwool between, clad externally in bituminised chip board with a 50mm cavity between it and the outer brick layer. This was a very well insulated solution, which has been improved further by replacing the plain inner plasterboard layer with plasterboard
laminated onto foam insulation, thereby eliminating any thermal bridging by the timber upstairs.  Downstairs he overboarded the existing inner fibreboard.

The original floor was suspended timber construction, with 100mm of fibre insulation between the joists. However, this had been disturbed and torn by successions of plumbers and electricians, meaning that heat loss was high. As Jason had decided on underfloor heating, he chose to replace the floor entirely with a solid floor of block and beam construction, covered with 80mm Celotex foam insulation and finished with a deep screed containing the underfloor heating pipes. The 28 year old triple glazed windows are still in good condition and were retained, as they are still performing well and exceed current building regulations, with u values of around only 1W/m2K.

Renewables and low carbon technology

The 3.2 kWp of Solar PV panels face south and produce around 3500 kWh of electricity per annum, which goes a long way toward matching the heat pump’s electric load. This was fitted by Randoll Solar. Heat pumps like this are eligible for the domestic Renewable Heat Incentive, which began in 2014. This gives a subsidy for seven years, based on the heat produced, and goes a long way to offset installation costs.

Lessons learned and future plans

Jason is keen on investigating the possibility of erecting a wind turbine to generate electricity, as this is an exposed site with high wind speeds in the winter. As a first step he is investigating putting up an anemometer for a period to confirm the wind resource.

Professionals

Building and groundworks: Neil Baker.

Solar PV: Randoll Solar.
Ground Source Heat Pump: Bosch Thermotechnic, installed by ICE Energy: www.iceenergy.co.uk

Gallery

Sewells Farm Cottage
Sewells Farm Cottage