Comparative analysis of building envelope thermal performance using OTTV, simulation, and validation

Abstract

This research analyses the thermal efficiency of building envelopes in two distinct climates: tropical Lampung, Indonesia, and temperate Busan, South Korea. Utilising university engineering edifices in both cities as case studies, we integrated overall thermal transfer value (OTTV) evaluations with thermal simulations and infrared thermography to analyse the thermal performance of these structures. Although both structures complied with local OTTV standards, recording values of 5.51-28.49 W/m2 in Lampung and 20.61-39.99 W/m2 in Busan, the findings indicated that OTTV measures alone inadequately reflect actual façade performance. Our models, corroborated by thermal imaging (correlation of ±2.0°C), indicated that horizontal louvres in Lampung reduced glass temperatures by 1–1.5°C; however, the high SHGC resulted in a maximum glass temperature of 33.6°C. Simultaneously, Busan’s well-insulated exterior maintained a consistent temperature of 24–29°C, even throughout a heatwave. The results indicate that while OTTV serves as a useful benchmark, it must be complemented by simulation and empirical data to fully comprehend performance. The research ultimately promotes climate-responsive norms that emphasise material selection, shading, and microclimates to better reflect real-world energy behaviour.