The use of phase change material (PCM) as energy storage of cooling during the night-time to be retrieved during the daytime is one of the sustainable strategies for cooling buildings. Application of this strategy in hot climates is scarce, and the majority of published work has been conducted in moderate and continental climates. Therefore, in the present work, a modular PCM-air heat exchanger appropriate for buildings application in hot-arid regions has been investigated, utilising commercial paraffin-based RT28HC PCM modules. The thermal performance of the proposed system has been investigated under various operating conditions for different PCM modules arrangements. The results confirmed that a compact TES unit with narrow air flow channels has a better thermal performance, resulting in 10-14% reduction in the charging time, whilst this has a negligible impact on the comfort time during the discharging period. The results have shown that the proposed system is capable of operating satisfactorily under hot-arid climate conditions, and substantial energy savings are achievable. (C) 2019 Elsevier B.V. All rights reserved.