Changeability is the capability of an organization to establish changes with a lasting effect. The possibility to correctly plan and create changeability of an organization already in the phase of plan-ning is an essential factor to be taken into account when considering changeable logistics systems. For this reason there is a need for conceptual change of established planning methods. In the context of discrete-event simulation, as an established planning method, the modular design of simulation models may be a first step to include changeability into model-based analysis. Against this background, This article discusses possibilities to build modular simulation models and shows how this modular design can be used in practice.