Experimental Investigation of Phase‐Change Material‐Integrated Roofs for Peak Load Shifting in Extreme Hot Arid Climates: A Case Study of Baghdad

ABSTRACT

This work investigates the thermal performance of roof systems integrated with phase‐change materials (PCMs) to mitigate cooling loads under severe hyper‐arid climatic conditions. The primary objective is to evaluate the capacity of paraffin wax to enhance the thermal inertia of roofs and successfully shift cooling demands during peak solar hours. Dual custom‐built experimental test cells were deployed in Baghdad, Iraq, to conduct the field evaluations. To ensure a strict one‐dimensional (1D) downward heat flux through the roof and eliminate lateral thermal interference, the vertical walls of both cells were comprehensively insulated. The experimental data demonstrate that the PCM‐integrated roof effectively stabilized the indoor thermal environment, achieving a 40.5% reduction in the thermal load leveling rate (TLLR). Furthermore, a 3.3°C reduction in the peak indoor air temperature alongside a significant time lag of 4.5 h was recorded, thereby successfully shifting the cooling load to off‐peak periods. From an economic perspective, the system yielded an average daily electricity cost saving of 213.3 IQD and a carbon emission reduction of 1.73 kg of CO ₂ per day. Given a calculated payback period of 2.05 years, these findings conclusively demonstrate the technical viability and economic feasibility of the proposed PCM‐roof configuration for building energy efficiency in extreme desert environments.