How do exhaust ventilation systems create negative pressures?

Exhaust ventilation systems create negative pressures in a building by actively removing air from inside, which allows outside air to enter through any available leaks or openings in the building shell. When fans in an exhaust system pull air out of the building, they lower the internal air pressure. As a result, the pressure inside the building becomes lower than the pressure outside, prompting outside air to be drawn in through cracks, gaps, or any other unsealed areas. This process effectively changes the pressure differential, causing air to flow into the building from these leakage points.

This principle is critical to understanding how exhaust ventilation works, particularly in terms of air quality and energy efficiency in building design. Properly managing the balance of air intake and exhaust is essential for achieving a healthy indoor environment.