The use of cooling in buildings is continuing to increase in Europe. This is raising concern that it will undermine the European Community’s drive toward reducing CO2 emissions. To counter this trend, there is increasing interest in evaporative cooling in general and passive downdraught evaporative cooling (PDEC) in particular. However, there are many locations in southern Europe where the relative humidity is sometimes too high for evaporative cooling to be viable. This in turn has led to the proposal for energy efficient hybrid cooling systems. This paper will present a case study of a hybrid downdraught cooling system within the new Malta Stock Exchange.