Why can mixed materials (e.g. mixed organics, mixed plastics, mixed MSW) be “source reduced” in the alternative management scenario?
The mixed materials in WARM are composed of substrates of different material types on a percentage basis. This is to facilitate the comparison of waste streams that are unseparated. Source reduction of mixed material types is harder to conceptualize (how do you source reduce mixed MSW) and even harder to quantify. The mixed material emission factors reflect the mix of materials present in the US municipal solid waste stream, but information on the relative fractions of each material in the mixed categories would not necessarily be consistent with the proportions of the specific materials that are source reduced. Users interested in calculating benefits of source reduction will need some information on the quantities of individual material types that are being source reduced, then material-specific source reduction factors can be applied to those inputs and used to calculate the benefits. For mixed paper, the composition of each of the three mixed paper types (broad, office, and residen
