What makes a material green? Green materials are materials that are local and renewable. Local materials often are unique to the place and connect whatever people make with an area or region. Materials from the ground such as clay, sand and stone are green materials as they are found underfoot. Plant materials such as grasses, straw, wood and bamboo are also materials that have been used by humans since the beginning of building. They are for the most part renewable and grow quickly. Reclaimed materials are materials that can be reused in their existing form for new purposes. Recyclable materials are materials that can move from being waste material to being reused through reprocessing or re-purposing. Green materials today are defined as materials that are non-toxic. Non-toxic materials are materials that do not cause harm to the environment, to the users of the material or to the producers of the material.