Safety critical embedded systems must be verified and optimized. Their production process, which includes both automatic code generation and middleware implementation, depends on the the target execution platform and must be adapted accordingly. In such a context, Model Driven Architecture provides several approaches to transform user models into programming code but these solutions lack of flexibility to address simultaneously the three issues of verification, optimization and adaptation. To overcome this limitation, we propose a method to structure the production process with design patterns for model transformations. Our approach allows to adapt the workflow of rule-based refinements according to the user input models, the targeted execution platform, and the analysis performed on intermediate transformed models.