In Norway there are public reportin

In Norway there are public reporting systems for household waste, whereby municipalities report the quantities of waste they recycle, incinerate and landfill annually. Although source-sepa¬rated waste is reported by fraction, the data still do not provide en¬ough information with which to estimate the composition of household waste. In order to establish a reference scenario for waste composition with a sufficiently detailed aggregation level, we chose to combine the data reported by the municipalities of five cities (SSB, 2012b) with composition analyses from the same five cities (NORSAS, 2007; RiG and Asplan Viak, 2011; RKR, 2007). The reference waste composition used was therefore not a Norwe¬gian average, but represented an average of these five cities. The cities vary in size between 5000 and 170,000 inhabitants, and therefore represent small to large Norwegian cities. The waste frac¬tions were aggregated into nine main fractions and then an average of each fraction for the five cities was calculated (Table 1). This average waste composition is referred to as the reference scenario. In order to increase the level of detail, the 9 main fractions were then disaggregated into 18 fractions. The disaggregation was based on data available in the aforementioned composition surveys, a Norwegian report on the waste management system of Norway (Raadal et al., 2009) and the average waste composition for Danish households in 2005, found in EASEWASTE. Paper and cardboard was disaggregated into four fractions (newsprint 65%, paper and cardboard containers 13%, milk cartons 7% and other paper 15%); plastic was disaggregated into three fractions (soft plastic 50%, hard plastic 30% and non-recyclable plastic 20%); food was disaggregated into two fractions (vegetable food 76% and animal food 24%); glass was disaggregated into two fractions (recyclable glass 96% and non-recyclable glass 4%) and metals into three fractions (aluminium 10%, steel 70% and other metals 20%) We do not dis¬cuss the uncertainty within these fractions in this article. There are, however, differences between the data from the cities, the data from Denmark, and the report from the Norwegian system in terms of both the numbers of disaggregated fractions and the distribution between them. This is, however of little importance for the objec¬tive of this study.