NEW: The Architecture & Engineering of Downdraught Cooling

NEW: The Architecture & Engineering of Downdraught Cooling

The Architecture & Engineering of Downdraught Cooling - A Design Source Book

Editor: Professor Brian Ford, Rosa Schiano-Phan, Elisabeth Francis

PHDC Press 2010

Downdraught cooling is an energy efficient alternative to conventional air-conditioning in buildings, and relies on the effect of gravity to create a downdraught, and thus circulate air from the source of cooling to the occupied zone within the building. The source of cooling may be either ‘passive’ or ‘active’, or a combination of the two, and hence the term ‘Passive & Hybrid Downdraught Cooling’ (PHDC).

PHDC has the potential, demonstrated through the successful operation of a number of buildings around the world over the last 15 years, to achieve very significant savings in electrical energy.  Fans, which may account for 25-35% of the electrical energy required in a conventional air-conditioned building, are avoided. In hot dry regions, energy savings can be further increased (by 5-10%) by evaporating water within the air-stream to create the downdraught, known as ‘Passive Downdraught Evaporative Cooling’ (PDEC).


A hybrid downdraught cooling system combines both ‘passive’ and ‘active’ downdraught cooling techniques. Such a system can then function in both hot and dry conditions (using PDEC) and warm and humid conditions (using chilled water cooling coils or de-humidifier), and is therefore applicable in many locations around the world, including the UK.