Defining a product as "green" is not often straightforward since green building is a whole-systems approach to designing, constructing, operating and maintaining buildings. Often, a specific product is just one component of a larger system. To accurately assess the true greenness of a product, consideration must be given not only to particular environmental and health impacts of a product from its manufacturing, use, and disposal phases, but also to how the product is utilized within the larger system.
For a more detailed analysis of what constitutes a green product, see "Building Materials: What Makes a Product Green?" as featured by Environmental Building News.