Wood is the most widely used building material in the United States because of its efficiency, durable, and usefulness. One of the greatest attributes of wood is that it is a renewable resource, it has low carbon impact and low embodied energy. The amount of energy needed for producing wood products is much less than comparable products made from other materials. Carbon in wood remains stored until the wood deteriorates or is burned. Architects, product designers, material specifiers, and homeowners are increasingly asking for certified building products that are from sustainable resources. More than 50 different forest certification systems in the world represent nearly 700 million acres of forestland and 15,000 companies involved in producing certified products. In terms of forest acreage under certification, Forest Stewardship Council (FSC) and Sustainable Forestry Initiative (SFI) dominate in the United States.