Design does not emerge solely from individual creativity but from ongoing interactions between humans and their Umwelt—the subjective, meaning-structured world through which environments are perceived, interpreted, and acted upon. This article develops the concept of a Communicative Umwelt as a psychologically grounded framework for sustainable design, specifying it as a system of entities, signals, channels, and feedback mechanisms that shape creative processes, user acceptance, and longer-term market dynamics. By operationalizing Umwelt beyond metaphor, the paper connects perceptual and cognitive psychology with design practice and sustainability-oriented innovation. The framework is situated in relation to adjacent literatures, including ecological psychology, design semiotics, participatory and systemic design, and sustainability transitions, and is distinguished by its focus on psychological meaning-making and feedback-driven transformation. Rather than advancing universal market claims, the article proposes mechanism-oriented pathways and boundary conditions under which locally embedded, context-sensitive design practices may foster sustainable consumption patterns. Sustainability is thus reframed not as a technical constraint but as an emergent outcome of communicative interactions between humans, artifacts, and socio-ecological systems, offering a theoretically informed basis for future empirical and comparative research.