Stack effect


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stack effect

[′stak i‚fekt]
(mechanical engineering)
The pressure difference between the confined hot gas in a chimney or stack and the cool outside air surrounding the outlet.

Stack effect

Also referred to as the chimney effect, this is one of three primary forces that drive air leakage in buildings. When warm air is in a column, such as a building, its buoyancy pulls in the colder air that is low in buildings, as the buoyant, warmer air exerts pressure to escape out the top. The pressure of stack effect is proportional to the height of the column of air and the temperature difference between the air in the column and ambient air. Stack effect is much stronger in cold climates during the heating season than in hot climates during the cooling season.

chimney effect, flue effect, stack effect

The tendency of air or gas in a shaft or other vertical passage to rise when heated, owing to its lower density compared with that of the surrounding air or gas.
References in periodicals archive ?
The principle differences affecting smoke control for a super tall building are the increased contribution of height to stack effect and wind effect.
The form of the architecture exploits passive methods of cooling through shading, thermal mass, stack effect ventilation and prevailing winds.
Higher air temperature in the indoor space means higher infiltration rate due to the stack effect, which promotes more outdoor air with low moisture content to penetrate indoors and increases the real air dryness.
The stack effect and the reverse stack effect occur due to temperature differences between the building and outside air.
The only caveat is that the double facade runs around the building, so it is slightly difficult to imagine the stack effect of rising warm air being fully effective on the north facade.
Stair pressurization can be very difficult in tall buildings due to stack effect and floor-to-floor variations in flow resistance.
The natural ventilation mode was a significant driver in refining the building's form and skin, and following extensive CFD and wind-tunnel modelling it has been proved that, as the atria cut across the high and low pressure zones created by the curved form, a pressure gradient is created that will improve cross ventilation between two-pack atria, and boost the natural buoyancy of the stack effect through the six packs.
The upward force experienced by the lighter, hot gases is often referred to as stack effect or chimney effect, and it can be a major factor in determining the route that smoke will take during a high-rise fire.
The outer rainscreen of 10mm toughened glass has a 103mm cavity behind, vented to create a stack effect, and an inner layer of double-glazed units and insulated aluminium-faced panels.
This difficulty is compounded by the number of occupants in these structures, the stack effect and fire fighting operations, as well as changing demographics, and risk perception and human behavior in a post September 11th environment.
The courtyard produces a stack effect through its glass roof that is opened to allow the escape of hot air, and hence initiate air movement inside the house.
Environmental considerations encompass natural ventilation through the stack effect, a concrete structure to increase thermal mass and the use of river water as a cooling agent.