Insulation Material Loses Its Cooling-Energy Rationale Under SSP Climate Warming in a Hot-Humid Residential Building

Abstract

Insulation is specified in energy codes by R-value, on the assumption that once thermal resistance is fixed, material type has little independent effect on building energy performance. This study tests that assumption directly under future climate warming. Nine insulation materials (conventional, natural bio-based, and recycled) were simulated at equivalent R-values in a 16-unit hot-humid residential building in Austin, Texas, across a present-day baseline and four SSP-based future climate scenarios. Cooling energy converged statistically in four of five future scenarios, with inter-material spread collapsing from 17.4\% at TMY to 0.27\% at SSP1-2099. The SSP1-2050 exception establishes convergence as warming-magnitude-driven rather than time-driven. Heating differentiation persisted (CV 16–27\%) against a load share declining below 4\% by late century. Insulation material identity ceases to be a meaningful simulation variable for cooling optimization under mid- to late-century SSP forcing.