The One-Room Heat-Survival Pattern for an Elder in a Heat Wave: A Heat-Balance Model of the Cheapest Cooling Stack for One Survivable Room

SIMULATED, NOT MEASURED. A lumped-capacitance heat-balance model of one top-floor, west-facing room (4.0 x 3.5 x 2.6 m) under three multi-day heat-wave cases (dry, humid, warm nights) computes the cheapest stack of cooling measures - external shading, reflective surfaces, night purge ventilation, a room fan, evaporative cooling, and a smallest-size room air-conditioner - that holds the room at or below an adopted 27 C effective-temperature ceiling for a sedentary elder. External shading cuts peak window solar gain by 67% versus internal blinds (146 W vs 439 W). The dry case passes with passive measures plus evaporative cooling at $1.22 per survivable-room-day; the humid and warm-night cases have no passive solution in the model (best passive stacks miss the ceiling by 4.9 K and 6.9 K) and require the small air-conditioner, at $1.91 and $2.04 per survivable-room-day. All numbers are generated by the accompanying compute.py model described in the paper.