Exergy-Based Personal Carbon Footprint Assessment as a Psychological Nudge Tool: A Conceptual Framework for Urban Mobility in Bangkok

Abstract Conventional carbon footprint calculators apply a linear multiplication of activity data by emission factors, yielding CO₂ equivalents that are cognitively distant from users' lived experience. This paper proposes an exergy-based thermodynamic framework — the **Planetary Thermodynamics Impact Engine (PTIE)** — as both a more physically complete model of energy dissipation and a psychologically proximate tool for behavioral change in urban mobility contexts. Drawing on the First and Second Laws of Thermodynamics, PTIE decomposes total energy input (Q_total) into useful work (W_useful, or exergy) and waste heat (Q_waste, or anergy), and calculates entropy generation (S_gen) for each mode of transport. We argue that Q_waste — expressed as megajoules of heat released into the urban environment per commute — constitutes a more immediately perceptible and emotionally salient variable than CO₂ kg for Bangkok residents, where urban heat island effects are a daily physical experience. The framework further identifies a structural alignment between thermodynamic efficiency of transport modes and documented psychological co-benefits: high-exergy activities (walking, cycling, electric transit) correspond to modes associated with reduced cortisol, increased endorphin release, and improved sleep quality in existing literature. We present the PTIE computational architecture, its thermodynamic parameter basis with full source declarations, a proposed pilot study protocol (n=30), and a research agenda for empirical validation. This paper establishes the conceptual and mathematical foundation; empirical results will be reported in a subsequent publication. Keywords: exergy, anergy, thermodynamics, carbon footprint, urban heat island, psychological nudge, urban mobility, Bangkok, behavioral change, entropy