What causes the stack effect in buildings?

The stack effect in buildings is primarily driven by temperature differentials. This phenomenon occurs when there is a significant difference between indoor and outdoor air temperatures, leading to variations in air density. Warmer air inside the building tends to rise due to its lower density compared to cooler air outside. As the warm air ascends, it creates a pressure differential, causing cooler air to be drawn in from lower openings in the building to replace the rising warm air.

This effect is especially pronounced in taller buildings, where the vertical movement of air can be substantial. When indoor temperatures are higher than external ones, the result is a natural stack effect that contributes to ventilation and air circulation within the building. Understanding this principle is crucial for radon measurement technicians because the stack effect can influence how radon gas enters and disperses within structures, impacting the accuracy of radon measurements and mitigation strategies.