Abstract This paper presents the Constraint–Relaxation Energy Model (CREM), a theoretical framework proposing that energy is an emergent consequence of imposing and relaxing constraints on an underlying phase space of possible states. Building on established principles from thermodynamics, information theory, and systems science, CREM reframes energy as the release of compressed geometric and informational relationships rather than a primitive substance. The model integrates feedback, coherence, and constraint geometry as necessary conditions for stable energy storage and release. Speculative extensions are explicitly delineated from established physics, positioning CREM as a unifying interpretive framework rather than a claim of new empirical phenomena. [2nd Paper] Abstract This paper extends the Constraint–Relaxation Energy Model (CREM) by (a) identifying the minimum new physics that would be required to move beyond currently known energy-constraint regimes, and (b) formalizing a Constraint Density Limit (CDL) analogous to established means such as energy density, stress–energy bounds, and information-theoretic limits. CREM frames energy as the release of compressed geometric and informational relationships generated by imposed constraints on a phase space of possible states. Building on thermodynamics, information theory, and Unified Consciousness Substrate Theory (UCST), this work distinguishes rigorously between established physics, speculative but coherent extensions, and currently unknown coupling mechanisms. The resulting framework preserves conservation laws while opening a principled research space for deeper substrate interactions without invoking free-energy or ontological violations.