When cross ventilation is possible, which side should windows be opened first?

In the context of firefighting and building ventilation strategies, opening the windows on the leeward side first is crucial for effective cross ventilation. The leeward side is the side that is opposite to the direction from which the wind is coming. By opening windows on this side, firefighters can create a pathway for smoke and heat to escape from the structure, enhancing the ventilation process.

When windows are opened on the windward side first – the side facing the wind – it can potentially push smoke and heat deeper into the building as the wind forces these elements to mix and spread. This can lead to a dangerous situation where visibility decreases, and fire conditions may become more severe.

By prioritizing the leeward side, you facilitate a more controlled and effective evacuation of heat and smoke, which is essential for improving conditions for both occupants inside and for firefighting operations. It also helps to establish a more manageable airflow throughout the structure, improving overall safety and effectiveness during response efforts.