Effects of Solar Irradiation Preprocessing and TMY Month Selection on Future Building Performance and Envelope Selection

Solar irradiation preprocessing can change both irradiation levels and the representative months selected for typical meteorological years (TMYs). This study evaluated the consequences for future building performance and envelope selection at four South Korean sites using observations from 2000 to 2024. Four weather conditions crossed raw and step-adjusted irradiation with two TMY month selections under identical climate-change signals. The main analysis combined 8000 EnergyPlus simulations of 125 envelope alternatives with normalized photovoltaic (PV) yield calculations. No changepoints were statistically significant after accounting for autocorrelation. With preprocessing assumptions fixed, reference-climate PV yield differences ranged from −6.25% to +2.61%. At reference equipment efficiencies, envelope rank correlations were at least 0.99696, and the maximum cross-weather selection penalty was 0.00631 kWh m−2 yr−1. However, 71 cases selected from combined gap-filling and adjustment realizations produced different optima in nine comparisons, with penalties up to 0.22460 kWh m−2 yr−1. Alternative moisture controls changed latent-load contrasts and heating–cooling cancellation. These results support reporting preprocessing, TMY selection and operating assumptions jointly, while distinguishing changes in predicted energy performance from their consequences for design selection. The findings quantify conditional sensitivity within the adopted apartment model; they do not demonstrate improved weather-data accuracy or establish performance under peak-load or overheating conditions.