How to Calculate the Free Area of a Window

How to Calculate the Free Area of a Window

When creating a smoke ventilation system, natural ventilation provides a simple, reliable solution, with low noise and energy usage. The use of windows as natural smoke vents is a popular choice, as they are often already included in a building’s design, and can increase the amount of natural light in an area, which wouldn’t be possible when using dedicated vents. But what is the 'free area' and how is it calculated?