And indeed for the most part, they follow through. Even the light fixtures are made from recycled plumbing. The exterior walls are made of one of shou-sugi-ban, a Japanese wood treatment where the wood is burned with a torch to create an exterior skin of black char. It lasts a long time and is actually fire resistant.
The heating system is very impressive: a pile of straw and manure with six hundred feet of pipe in it. This system was developed by French gardener Jean Pain in the 1970s. It delivers 150 degree hot water to the building, although they do not say how much.
About the only discordant note in the design is the use of Polyisocyanurate insulation. The designers write about their building and their choices:
We used local and wholesome materials, because we care about your health and the preservation of the environment. Back to purity. Back to simplicity.
Then they pick an insulation that is made from hydrocarbons, it uses hydrochlorofluorocarbon (HCFC) as a blowing agent, has trischloropropylphosphate (TCPP), a possible bioaccumulative toxin, as a flame retardant, and if it does catch on fire, "will produce dense, black, toxic smoke releasing carbon dioxide, carbon monoxide and possible traces of hydrogen cyanide, halogen acids and nitrogen."
But other than that, one can agree with the statement on the Elephant House website:
The end result of such effort is a home that has the power to change the lifestyle of its users. Streamlining daily tasks and functions with innovative design encourages the homeowner to integrate new ways of life that reflect a sustainable ethic.
See more on the project tumblr here.