Experimental Investigation of Energy Performance in Double-Glazed Windows Utilizing Air and Phase Change Materials

Abstract

The growing emphasis on energy efficiency in buildings necessitates advancements in building envelope components, particularly windows, which significantly influence thermal comfort and energy consumption. This study experimentally evaluates the thermal performance of double-glazed windows incorporating paraffin wax phase change material (PCM) versus traditional air-filled cavities, aiming to enhance energy efficiency in buildings under varying solar radiation intensities. A modular insulated chamber (1 m³ PVC structure) with a double-glazed window opening was subjected to controlled radiant loads (500 and 1000 W/m²). Two 9mm-cavity configurations were tested: one filled with air and another with paraffin wax PCM (melting range: 56–58°C). Temperatures and heat flux were monitored using thermocouples and a data logger. PCM reduced cumulative heat transfer by 22% at 500 W/m² and 35% at 1000 W/m² compared to air. At 1000 W/m², PCM delayed peak thermal loads by 2.67 hours and reduced glass surface temperature gradients (ΔT) by 20.4%. Under 500 W/m², PCM increased peak heat flux by 15% due to solid-state conduction but still lowered cumulative energy transfer by 22% via thermal mass enhancement. PCM significantly improves thermal buffering and energy efficiency in double-glazed windows under high solar irradiance (≥1000 W/m²), reducing HVAC reliance. Optimal performance requires radiation sufficient to activate phase change (56–58°C), validating PCM’s suitability for high-solar regions.