In the second case (Case 2) the quantities recycled and inciner¬ated were kept constant. A variation in waste composition will in this case change the sorting efficiencies used in the calculations. This method is used for accounting LCA in existing systems when the waste composition and quantities of waste are known. Case 2 did not include uncertainty in how much waste is sorted or the quality of this waste. Changes in waste composition therefore only influenced the impact from the incinerator and the avoided impact from substituted energy. The functional unit, the system bound-aries and the technologies remained constant.