How can some material types reduce more GHG emissions through recycling than source reduction?
In WARM, the recycling emission factors reflect the difference between making a product with virgin inputs and making a product with recycled raw material inputs. This means that the virgin inputs that would have been necessary to create the specific material are no longer required because this material is being recycled. In contrast, source reduction is assumed to displace the current mix of recycled and virgin raw material inputs used to manufacture a given material. This means that when a material is reduced (source reduction), the inputs needed to create this material come from both recycled content and virgin content. In cases where producing a material from 100 percent virgin materials is more GHG emissions intensive than to produce a material from recycled and virgin inputs, recycling a material is estimated to offset more GHG emissions than source reduction. Therefore, for some materials including aluminum, corrugated cardboard, newspaper, dimensional lumber, and medium-density
