Sunday, September 17, 2006

Mur Crusto eco-farm project, Llangybi

These are the basic plans we intend to put before the local council. I expect objections from them and will post further as things proceed. The idea is that if we can retrofit this cold, damp farmhouse to make it energy-efficient, something similar can be done with almost all the other poorly-insulated housing stock throughout Britain (or anywhere else where winters are cool, energy used to be cheap and insulation was ignored).
  1. To be energy autonomous: an example of low-energy living with carbon emissions cut to a small fraction of ‘normal,’ based on retrofits to existing buildings (difficult but no alternative) rather than new build (easy).
  2. To be sustainable: growing quality food without high energy inputs and without pollution

Development so far

  • Successful organic veg- and fruit-growing box scheme provides wholesome fresh food to local people (around 35 families), with zero ‘food miles’Sheep wool insulation in the walls of the conversion
  • Barn conversion to holiday eco-cottage completed in 2006 by ourselves and now successfully attracting regular visitors. Exceptional attention to insulation (see image, sheeps’ wool) and use of renewable electric power (from Ecotricity) means that this building has a SAP rating of 107 (max. possible is 120) and zero carbon footprint. Heating is electric underfloor and is only needed in the coldest weather. Top-up heating is by efficient log-burner supplied with wood from farm: carbon neutral. Double-glazed conservatory provides major solar gains for whole building.
  • Minimsed carbon emissions from Mur Crusto house by universal use of low energy bulbs, pipe lagging, insulation where possible and minimal use of central heating after installing new efficient boiler

Planned development

It is effectively impossible to insulate existing farmhouse because of its thick stone wall construction. It cannot be insulated on the inside because the rooms are already small and dark. Internal dry-lining would worsen this and require total interior demolition. , To be effective, external insulation cladding would require raising the entire roof and re-slating. Insulation in roof spaces already 300mm rock wool but much of the roof is inaccessible because of dormer window construction. Result: building is still a major source of carbon emissions from central heating oil with SAP probably below 30. It is also permanently cold. At present, we produce a minimum of 2.5 tonnes of CO2 per year with the oil-fired heating, run as little as possible. Main heat source is wood-burner (carbon-neutral) and well-insulated bodies. i.e. we wrap up well and try not to shiver when other people would just switch on the heating!

Windsave turbines
Solutions - in order of priority and dependant on our resources
1. Installation of double-glazed (e-glass) solar passive/semi-active heat collector/conservatory along south-facing front of house to cut down heat loss through walls and induct solar gains with controlled fans into house interior (using thermal mass of thick walls to store heat)
2. Installation of one or more Windsave 1kW turbines, grid-connected. Electricity savings such that one turbine should pay for itself in 5 years
3. micro CHP (combined heat and power, image right) installation instead of existing oil boiler. Savings of 1.5 tonnes/y of CO2 emissions normal for such installation
4. photovoltaic array, grid-connected, on south-facing and sloping roof of modern barn (consultants: Dulas Ltd, Machynlleth)

Final result
An energy-neutral sustainable farm, probably the first of its kind in Wales. Watch this space...

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