Usage–Existence Coherence: A Conceptual Framework for Aligning Product Use and Persistence

Abstract Contemporary sustainability frameworks increasingly address product lifetime through metrics of durability, reparability, recyclability, and life-cycle performance. While these approaches provide powerful tools to quantify impacts and optimise specific stages of a product’s trajectory, they rarely examine whether the continued existence of products remains coherent with how they are actually used and with what persists once use has ended. This article identifies a structural blind spot shared across dominant assessment frameworks: the implicit assumption that a product’s designed lifetime is, by default, appropriate to its real-world usage trajectory and post-use persistence. By reviewing life-cycle assessment methodologies, durability indices, end-of-life strategies, and circular economy approaches, the paper highlights a structural blind spot. Misalignments between design intention, effective use, and persistence are typically treated as isolated issues rather than as manifestations of a broader coherence problem. To address this gap, the article introduces the concept of Usage–Existence Coherence (UEC). UEC is defined as the degree of alignment between the intention that justifies the creation of a product, the way it is actually used over time, and the manner in which its existence persists, transforms, or resolves beyond use. Rather than proposing new indicators or optimisation targets, the framework offers a coherence-oriented analytical lens that operates alongside existing methodologies. By making coherence explicit, the UEC framework enables a reframing of product lifetime, under-utilisation, residual persistence, and responsibility across a product’s full existence. Its contribution lies in clarifying questions that remain implicit in current approaches, thereby opening new avenues for interpretation, design reflection, and future methodological development. Full text in attached PDF. This article is accompanied by an editorial presentation and discussion on Substack