Passive down-draught evaporative cooling: thermal modelling of an office building

Two simulation-based methods of predicting the dynamic thermal performance of non-domestic buildings in hot dry climates, conditioned by Passive Downdraught Evaporative Cooling (PDEC), have been evaluated. In the PDEC system analysed, microscopic droplets of water were evaporated in ambient air and the resulting cool dense air delivered passively, through controlled openings, to occupied areas. The first method predicts the annual hours of PDEC operation, the water usage and the frequency of occurrence of different internal temperatures. The second method, which requires a thermal model with an integrated airflow network, provides insight into the airflow control strategies. Both methods demonstrated that an office building, in Seville, would need support from a mechanical cooling system to remain comfortable. However, the predicted energy use and carbon dioxide production was just 25% of that for a conventional airconditioned building