As chemical plants are becoming more and more tightly integrated, with extensive material and energy recycling, the need for improving their dynamic properties through process design modifications is increasing. However, this is not a trivial task since process integration usually also introduces a relatively complex relationship between properties of the individual units and the overall plant. In this paper, with designing buffer tanks for disturbance attenuation in tightly integrated plants as an example, we show that the structural location where the design modification is made in an integrated plant is a crucial decision with respect to their disturbance attenuation properties. A simple model based tool is derived which can be used to determine the optimal location and minimum buffer size for a given level of disturbance attenuation in an integrated plant.