In buildings there can be two stack effect regimes: normal and reverse. The normal stack effect occurs in buildings that are kept at a temperature higher than the outside environment. The warm air inside the building has a low density (or a high specific volume) and has a greater buoyant force. Consequently, it rises from the lower levels to the higher ones through the penetrations between plants. This causes the floors located below the neutral axis of the building to have a negative net pressure, while the floors located above the neutral axis have a positive net pressure. Net negative pressure on lower floors can induce outside air to infiltrate the building through doors, windows, or ducts without return air dampers. The hot air will try to leave the building envelope through the floors above the neutral axis.

Mechanical cooling equipment provides sensible and latent cooling during the summer months. This reduces the dry bulb temperature of the air inside the building relative to the outside ambient air. It also decreases the specific volume of air contained in the building, thus reducing the buoyant force. Consequently, cold air will move vertically through the building through elevator shafts, stairwells, and unsealed utility penetrations (i.e., hydronic, electrical, and water). Once conditioned air reaches the lower floors below the neutral axis, it infiltrates the building envelope through unsealed openings such as dampers, curtain walls, etc. Exfiltration air on floors below the neutral axis will induce outside air to infiltrate the building envelope through unsealed openings.

The chimney effect in chimneys: pressure gauges represent the absolute pressure of the air and the air flow is indicated by light gray arrows. The gauges move clockwise as the pressure increases.

The chimney effect in industrial chimneys is similar to that of buildings, with the difference that the hot combustion gases have large temperature differences with the outside air. Additionally, an industrial flue gas chimney typically offers little obstruction to flue gases along its length and, in fact, is typically optimized to improve the stack effect to reduce fan energy requirements.

Large temperature differences between the outside air and the flue gases can create a strong chimney effect in buildings that use a chimney for heating.

Before the development of large volume fans, mines were ventilated using the stack effect. A descending shaft allowed air to enter the mine. At the foot of the ascending shaft a furnace was kept burning. The shaft (which was usually several hundred meters deep) behaved like a chimney and air rose through it, dragging fresh air down the descending chimney and around the mine.

There is a pressure difference between the outside air and the inside air of the building caused by the temperature difference between the outside air and the inside air. This pressure difference ( ΔP ) is the driving force of the stack effect and can be calculated with the equations presented below.[7]​[8]​ The equations only apply to buildings in which air is both inside and outside of them. For one- or two-story buildings, h is the height of the building. In multi-story, high-rise buildings, h is the distance between the neutral pressure level (NPL) openings of the building and the openings above or below. Reference [7] explains how NPL affects the stack effect in tall buildings.

In the case of chimneys and flues, where the air is outside and the combustion gases are inside, the equations only provide an approximation and h is the height of the flue or chimney.

The draft flow induced by the stack effect can be calculated with the equation presented below[9]​[10]​ The equation applies only to buildings in which the air is both inside and outside. For one- or two-story buildings, h is the height of the building and A is the flow area of ​​the openings. In multi-story, high-rise buildings, A is the flow area of ​​the openings and h is the distance from the openings at the neutral pressure level (NPL) of the building to the openings above or below. Reference [7] explains how NPL affects the stack effect in tall buildings.

For flue gas chimneys, where the air is outside and the flue gases are inside, the equation only provides an approximation. Additionally, A is the cross-flow area and h is the stack height.

This equation assumes that draft flow resistance is similar to flow resistance through an orifice characterized by a discharge coefficient C.

In buildings there can be two stack effect regimes: normal and reverse. The normal stack effect occurs in buildings that are kept at a temperature higher than the outside environment. The warm air inside the building has a low density (or a high specific volume) and has a greater buoyant force. Consequently, it rises from the lower levels to the higher ones through the penetrations between plants. This causes the floors located below the neutral axis of the building to have a negative net pressure, while the floors located above the neutral axis have a positive net pressure. Net negative pressure on lower floors can induce outside air to infiltrate the building through doors, windows, or ducts without return air dampers. The hot air will try to leave the building envelope through the floors above the neutral axis.

Mechanical cooling equipment provides sensible and latent cooling during the summer months. This reduces the dry bulb temperature of the air inside the building relative to the outside ambient air. It also decreases the specific volume of air contained in the building, thus reducing the buoyant force. Consequently, cold air will move vertically through the building through elevator shafts, stairwells, and unsealed utility penetrations (i.e., hydronic, electrical, and water). Once conditioned air reaches the lower floors below the neutral axis, it infiltrates the building envelope through unsealed openings such as dampers, curtain walls, etc. Exfiltration air on floors below the neutral axis will induce outside air to infiltrate the building envelope through unsealed openings.

The chimney effect in chimneys: pressure gauges represent the absolute pressure of the air and the air flow is indicated by light gray arrows. The gauges move clockwise as the pressure increases.

The chimney effect in industrial chimneys is similar to that of buildings, with the difference that the hot combustion gases have large temperature differences with the outside air. Additionally, an industrial flue gas chimney typically offers little obstruction to flue gases along its length and, in fact, is typically optimized to improve the stack effect to reduce fan energy requirements.

Large temperature differences between the outside air and the flue gases can create a strong chimney effect in buildings that use a chimney for heating.

Before the development of large volume fans, mines were ventilated using the stack effect. A descending shaft allowed air to enter the mine. At the foot of the ascending shaft a furnace was kept burning. The shaft (which was usually several hundred meters deep) behaved like a chimney and air rose through it, dragging fresh air down the descending chimney and around the mine.

There is a pressure difference between the outside air and the inside air of the building caused by the temperature difference between the outside air and the inside air. This pressure difference ( ΔP ) is the driving force of the stack effect and can be calculated with the equations presented below.[7]​[8]​ The equations only apply to buildings in which air is both inside and outside of them. For one- or two-story buildings, h is the height of the building. In multi-story, high-rise buildings, h is the distance between the neutral pressure level (NPL) openings of the building and the openings above or below. Reference [7] explains how NPL affects the stack effect in tall buildings.

In the case of chimneys and flues, where the air is outside and the combustion gases are inside, the equations only provide an approximation and h is the height of the flue or chimney.

The draft flow induced by the stack effect can be calculated with the equation presented below[9]​[10]​ The equation applies only to buildings in which the air is both inside and outside. For one- or two-story buildings, h is the height of the building and A is the flow area of ​​the openings. In multi-story, high-rise buildings, A is the flow area of ​​the openings and h is the distance from the openings at the neutral pressure level (NPL) of the building to the openings above or below. Reference [7] explains how NPL affects the stack effect in tall buildings.

For flue gas chimneys, where the air is outside and the flue gases are inside, the equation only provides an approximation. Additionally, A is the cross-flow area and h is the stack height.

This equation assumes that draft flow resistance is similar to flow resistance through an orifice characterized by a discharge coefficient C.