Towards Climate-Resilient Office Façades: Integrating PCM-Enhanced Glazing with Dynamic External Louvres Under Current and Future Hot–Arid Climates

Phase-change material (PCM) glazing and dynamic external shading are promoted as sustainable cooling measures, yet they act on the same solar load and are rarely assessed together under a mandatory energy code. This study aims to evaluate and compare the individual and combined performance of PCM glazing and adaptive external louvres in reducing cooling demand in a code-compliant office building under present and future hot–arid climates. The reference case is an SBC 601-compliant west-facing Riyadh office under present and 2080 weather. EnergyPlus was coupled with a calibrated one-dimensional enthalpy PCM model using a one-way coupling framework. The approach was verified against a fully bidirectional co-simulation (0.5–1.8%). Adaptive louvres cut annual cooling by 10.2% (71% of the west-glazing share). A matched no-latent control attributes only 0.5 of the 9.4 points saved by PCM glazing to latent storage: the code glazing optically starves the PCM. Their combination is sub-additive by 6.6 percentage points across 21 sensitivity variants. Melt and placement sweeps favour a 35 °C melt point and the outer pane. On thermal grounds, adaptive external louvres should be prioritised for code-compliant hot–arid buildings, while PCM glazing is most beneficial where higher solar gains allow latent heat utilisation, informing sustainable façade codes.