Earth Heart is a community of 22 people in 8 homes based on a large converted farm in Derbyshire set up in 1998 around home education. Although not initially concerned with eco-build, they have embraced the concept thoroughly during their upgrading of an old farm house and several outbuildings into dwellings.
There has been a focus on high levels of insulation and use of natural materials. They have a state-of-the-art wood chip boiler heating system, a bore hole as a water supply (though initially with problems) and a reed bed water treatment system. They grow much of their own food.
They have focused especially on a very robust approach to decision making which has worked well during the various phases of the building work.
Though not open to the public they have occasional weekends when you can tent there, meet the people and learn about the community. See more on the Diggers and Dreamers web site