Design Considerations for Stack Effects in Hot and Arid Climates

Niall O'Sullivan
Regional Manager
Windtech Consultants Pty, London

The increasing number of high-rise developments globally requires a consideration of the buildings response to the local climatology. This consideration needs to be a whole of building approach whereby the interaction between the indoor and outdoor conditions are also considered.

The stack effect phenomenon is largely caused by the interaction between external and internal conditions for high-rise developments. This drives the internal movement of airflow within buildings due to the difference between inside and outside temperatures. While this occurs in all buildings around the world, the effect is most notable in tall buildings in extreme climates, where temperature differences, either hot or cold, are far greater. During the design process we need to consider how the outside can affect internal occupant comfort (including temperature and internal wind speeds), operational implications (such as lift door pressurisation, wind entry and mechanical ventilation performance) as well as potential health and safety issues (including control of air movement from smoking areas in some buildings and the downwards air movement of smoke during fire scenarios associated with reverse stack effect).

This presentation investigates the implications of stack effect in high-rise design on internal flow patterns (comfort conditions and smoke control), the effects on mechanical ventilation (cooling/heating) and pressurisation of entry doors, lift doors, the localised wind conditions and fa├žade air-tightness on the internal flow effects. Case studies will be presented for two projects: One located in the hot environment of the Middle East (reverse stack effect). The other case is located in an arid climate (both hot and cold) in the Americas. The presentation also discussed