A smoke test makes an invisible air path easy to see. This one uses a 40-foot high-cube container with two BigAir 45 vents near opposite upper corners. There is no fan running; the smoke that leaves is moving through passive openings.
Watch where the smoke goes
The south wall is in the sun and the wind is moving west to east. In those conditions, smoke exits one vent while the other acts as an intake. The direction is a result of that day’s conditions, not a permanent label for either opening. On another day, wind or temperature could change the pattern.
The limit of the demonstration
When the team checks the container roughly an hour later, smoke remains inside. Channing says it has not achieved a complete air exchange. That is an important distinction: seeing smoke leave confirms movement through the vents, but the video does not measure a ventilation rate or prove that every part of the container has cleared.
The setup also has only two high vents. The presenter would prefer additional low openings in a 40-foot container to make a longer high-to-low route for air. Treat the demonstration as a visual planning aid, then choose placement and vent count for your own container and use.
Watch the original full-length video or read the source post. This article is a practical summary of the spoken walkthrough; always use the instructions supplied with your exact product.