Hemp, part of the cannabis genus, is a great building material according to researchers in the UK. EcoWorldly has a good write-up on the hemp housing research.
Technically speaking, hemp is the common name for plants of the entire Cannabis genus, although the term is more typically used to refer only to strains of industrialized varieties which are not cultivated for drug use. Because industrialized hemp grows so quickly, requires almost no pesticides or herbicides, controls topsoil erosion and is a significant carbon sink, many environmentalists have been touting the plant as an eco-friendly miracle crop for decades. Furthermore, hemp can serve as a green-minded replacement for many other raw materials which arenâ€™t good for the environment, such as tree paper, plastics and certain clothing fibers. Hemp seeds are also edible, and hemp seed oils offer healthy alternatives to other cooking oils.