Statistical convergence of insulation material cooling performance under SSP-morphed climate scenarios: a multi-GCM EnergyPlus ensemble study for hot-humid residential buildings

Abstract

This study applies a multi-GCM EnergyPlus ensemble to test whether insulation material type remains a statistically distinguishable determinant of building cooling and heating energy under SSP-based future climate forcing. Nine materials (conventional, natural bio-based, and recycled) were simulated at equivalent R-values in a 16-unit CZ2A apartment building in Austin, Texas, using five-GCM morphed EPW files with urban heat island correction across TMY, SSP1-2050, SSP5-2050, SSP1-2099, and SSP5-2099. Inter-material differentiation was assessed using the coefficient of variation and Tukey’s HSD for daily energy distributions. 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.