Reverse Stack Effect: In hot weather conditions, a reverse process can be observed; here, the relatively cooler indoor air of a high-rise building precipitates, creating a pressure build-up around the lower levels of the high-rise building that pushes the air out and draws the air in from upper levels of the high-rise building. The hot air that has been drawn in is then cooled down by the building services and closes the cycle of the buoyancy-driven reverse stack effect process.

In both types of the stack effect processes, there is usually a change in direction of the pressure gradient and flow at the building envelope which indicates that, at some point along the height of the building, there is a zone of neutral pressure plane where the internal & external pressures are equalized. It has also been observed that the effect of wind pressure that is acting on the exterior part of the building is also an important contributor to the overall performance of a high-rise building.

Mechartes uses its expertise to carry out “Stack Effect Analysis” for high rise buildings using multi- network model of CONTAMW which calculates the air flow & pressure differences inside the building based on the inputs of various flow paths, air-tightness/ leakage data of building components and other boundary conditions.

The common problems that Mechartes solve in high rise buildings due to stack effect can be as follows:
Increase of heat & cooling energy consumption due to excessive infiltration or/and ex-filtration.

Excessive Air Flow Movement which might cause:

The spread of smoke in the building in case of fire.

Propagation of odors & unwanted contaminants throughout the building.

Unwanted flow rates in key occupied areas.

Noise and draft through narrow gaps of the doors.

Difficulty in opening and closing of staircase doors & swing doors.

Difficulty in operation or malfunction of elevated doors.