Peat was used heavily, as well as animal dung and there was drift wood (not a stable source though, and mostly used for other endeavours). Also the fairly uniqu

Peat was used heavily, as well as animal dung and there was drift wood (not a stable source though, and mostly used for other endeavours). Also the fairly unique construction of the turf houses which had the animals living along side the humans, maximized the capture of body heat. Then again, life in Iceland was cold, dark and miserable for centuries all the while nature kept trying to kill everyone.