SFA — Stationary Footprint Area introduces a new sustainability metric for Kenotomic Mobility: mobility governed by the reduction of unnecessary stationary burden. Modern mobility is evaluated mainly from the perspective of motion: speed, range, emissions, energy efficiency, autonomy, and aerodynamic performance. Yet vehicles also produce a second form of impact after arrival: the occupation of urban space while standing still. This paper defines Stationary Footprint Area (SFA) as the surface area occupied by a mobility system when not in active use. SFA is proposed as the applicative form of Kenos in mobility: a measurable criterion for reducing the residual spatial burden left behind by movement. The article develops the conceptual sequence: KENOTOMY → Kenotomic Mobility → Kenos / SFA → PARKING ZERO It argues that future mobility systems should be evaluated not only by how they move, but by what they leave behind after movement has ended. Cw measures the drag of motion. SFA measures the drag of rest. Keywords:Kenotomic Mobility; Stationary Footprint Area; SFA; PARKING ZERO; Discrete Mobility; urban mobility; parking footprint; sustainability metrics; mobility without parked mass; Kenotomy.
Gheorghe Teodorescu (Wed,) studied this question.