Improving the thermal performance of roof through the integration of certain phase change materials for minimizing the heat transfer in buildings

• PCM sped early heating but stabilized faster; PCM2 cut temps 3.6%, PCM1 held heat longest, PCM2 exchanged heat fastest. • PCM2 (55°C) excelled in temp control & resistance; UPVC+PCM outperformed metal/tile roofs, showing broad application potential. • Field tests showed stable temps, peak cuts, longer cooling, better comfort, lower heat gain, and potential AC savings. Unplasticized Polyvinyl Chloride roofing systems through strategic Phase Change Material integration. The experimental design employed two distinct of Phase Change Material with melting points near 45 °C (referred as PCM1) and 55 °C (referred as PCM2). Standardized cubic test specimens measuring 60 cm × 60 cm × 60 cm were constructed to evaluate three configuration scenarios: Phase Change Material placement directly beneath the Unplasticized Polyvinyl Chloride roof, Phase Change Material sandwiching between the Unplasticized Polyvinyl Chloride roof and gypsum board substrate, and Phase Change Material positioning above the gypsum board layer. Controlled thermal testing was conducted at constant temperatures of 40 °C, 50 °C, and 60 °C, with each condition maintained for 240-minute durations using consistent heat sources. Results demonstrated optimal thermal performance when Phase Change Material was strategically positioned between the Unplasticized Polyvinyl Chloride roofing and gypsum board configuration. Comparative analysis between Phase Change Material formulations revealed Phase Change Material type 2′s superior heat transmission reduction capabilities, achieving temperature decreases of approximately 1.0 °C, 1.2 °C, and 1.3 °C ± 0.05 °C at the respective test temperatures compared to non-Phase Change Material type 2 integrated systems. Field validation over three days confirmed Phase Change Material type 2′s effectiveness, maintaining interior temperatures at 42.3 °C ± 0.05 °C, representing a 4.3 % reduction compared to conventional Unplasticized Polyvinyl Chloride roofing without Phase Change Material integration. Additionally, Phase Change Material type 2 installation exhibited extended heat flux time delays and reduced decrement factors, making it particularly suitable for residential roofing applications in Thailand’s tropical climate conditions.