In Iraq, solar radiation on building roofs can exceed 1100 W/m 2 , affecting indoor thermal comfort. This study aims to reduce the heat gain in buildings in hot climates. Thus, it introduces an experimental method to enhance roof thermal performance by integrating phase change material in aluminum pipes within a concrete slab, alongside water pipes linked to a geothermal source at a flow rate of 0.75 L/min. The phase change material used for the current experiments is paraffin with a melting point of 41 °C, which was encapsulated in aluminium pipes with dimensions of 2 cm × 4 cm and a length of 70 cm. Three roofs models were evaluated: a traditional roof (Model-1), one combining both PCM and geothermal elements (Model-2), and one with an embedded water pipe and geothermal source (Model-3). These models of roofs were placed on identical, dimensionally matched enclosures; each enclosure is 80 cm in length, 80 cm in width, and 100 cm in height. A comprehensive thermal, economic and environmental performance analysis was carried out. The results showed that the highest maximum inner surface temperature reduction was 57.7 % with the Model-2 compared to the measurements obtained from the traditional ceiling. Also, the effect of using phase change material pipes in a slab with a geothermal source was observed as offsetting the temperature by 9 % in the next cycle. Furthermore, reducing the heat gain in the Model-2 resulted in savings in electricity consumption costs and a reduction in CO 2 emissions of 0.23 USD /day and 1.83kg/day, respectively. These findings demonstrate that adding PCM to geothermal systems can improve ceiling performance considerably while providing both financial and environmental advantages.
Abed et al. (2026) studied this question.