Cooling-dominated residential housing in hot-arid climates urgently requires facade solutions that reconcile architectural color with verifiable thermal-electrical efficiency. Current colored photovoltaics often suffer from thermal-induced efficiency penalties, limiting their broad adoption. This study addresses this barrier by evaluating a novel, constructible hybrid facade system that integrates colored building-integrated photovoltaics (BIPV), naturally ventilated cavities, and a 25 mm paraffin phase-change material (PCM) layer. The aim is to produce decision-quality evidence on how this specific configuration mitigates color-induced losses across thermal, electrical, and mechanical domains. The methodology couples a full-scale, multi-season experiment in Hail, Saudi Arabia, with a multiphysics simulation pipeline (OpenFOAM-Abaqus-EnergyPlus). This workflow is unified through Bayesian calibration against ISO/IEC 17025-traceable measurements to propagate measurement and parameter uncertainty into building-scale Key Performance Indicators (KPIs). Results demonstrate that, relative to a ventilated colored BIPV facade without PCM, the hybrid PV/T-PCM system reduces midday module temperature by 9.0 degrees C (95% Credible Interval: 7.1-10.9), recovers seasonal electrical yield by 7.4% (6.1-8.6), and lowers peak principal tensile strain at fixings by 31% (24-37). These facade-level improvements translate to calibrated building-scale benefits: annual cooling energy decreases by 10.8 kWh m(-2) yr(-1) (8.2-13.1), peak cooling demand drops by 12.6 W m(-2) (9.4-15.5), and occupied comfortexceedance hours fall by 19%. Collectively, these findings establish the proposed system as a scientifically verified pathway to neutralize color-induced penalties. This research contributes a validated design specification for hot-arid regions, proving that latent thermal buffering can deliver grid-relevant load reductions without compromising architectural aesthetics.