Which action should be avoided when performing horizontal natural ventilation?

When performing horizontal natural ventilation, it is essential to create a controlled and effective airflow to help clear smoke and heat from the structure. Opening upwind windows first can disrupt the intended flow of air and may complicate the ventilation process. The goal of natural ventilation is to create a draft that allows for the smoke and heat to exit efficiently; starting with upwind openings might allow smoke to linger or potentially worsen conditions inside the building.

By opening the downwind or other strategic openings first, firefighters can create a pathway for the fresh air to enter and push the smoke and heat out more effectively. This technique can help improve visibility and conditions for both the firefighters and any occupants needing rescue. Ensuring the proper sequence of openings is critical for an optimal and safe ventilation process, which is why opening upwind windows first should be avoided in a horizontal natural ventilation strategy.