Requirements are usually one of the main drivers for software architecture. Although current research acknowledges the opposite effects of design decisions on requirements engineering, it does not go beyond the general idea of their existence. The contribution of this paper lies in the explicit discussion of the effects of design decisions on requirements engineering. We define two types of design decisions and discuss their effect on requirements, and in particular on elicitation and prioritisation. Furthermore, we propose and demonstrate on an example two channels from architectural design to requirements that can be used to drive requirement elicitation and prioritization. This is the base for a new approach where also the results of the quantitative analysis of the effects of requirements on architecture are fed back into the requirements process.