The use of phase change materials as energy storage of cooling during the night-time to be retrieved during the hot daytime is one of the sustainable strategies for cooling buildings. In the present work, a modular PCM-air heat exchanger appropriate for buildings application in hot-arid regions has been investigated experimentally 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 arrangement. The results confirmed that a compact design made of narrow PCM air flow channels has 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 design is capable of operating satisfactorily under the hot-arid climate conditions, and substantial energy savings are achievable.