What is the stack effect in a building?

The stack effect refers to the phenomenon where heated air rises within a building due to differences in temperature and density, leading to pressure changes that can affect airflow. In a typical scenario, warm air inside the building becomes less dense than the cooler air outside, causing it to rise and escape through openings at the top of the structure, such as vents or gaps in the roof. This upward movement creates a negative pressure area at lower levels, which draws in cooler air from the outside through lower openings.

This natural circulation can influence indoor air quality and the distribution of indoor pollutants, including radon gas, which can infiltrate from the ground. Understanding the stack effect is crucial for designing effective ventilation systems in buildings and mitigating potential radon accumulation inside.