Living-Ratio City: A Systems Framework for Urban Coherence and Environmental Exposure

This paper introduces Living-Ratio City as a bounded systems framework for examining how proportional characteristics of built environments may relate to non-invasive indicators of human physiological regulation. The work is presented as a hypothesis and methodological scaffold, not as an empirical validation study, optimisation model, or design prescription. It adopts a non-causal, observational approach and treats coherence as an inferred systems condition assessed through longitudinal patterns in heart-rate variability, sleep regularity, and affective stability. Environmental exposure is operationalised as a multivariate time-series encompassing acoustic variability, photic alignment, spatial density ratios, and green–built surface parity. A comparative Composite Coherence Index is defined for within-study analysis without diagnostic or universal claims. The paper is intended for researchers, architects, and urban planners exploring systems-based approaches to the built environment, environmental exposure, and human-scale urban coherence. It explicitly avoids prescriptive design rules, clinical interpretation, or policy recommendations.