Brad Diepholz found the following information.
Ever wonder how ventilation works? The word ventilate comes from the Latin word for “to fan”, the action of causing air to move. This is how ventilation works. It provides the conditions that allow air to move.
Effective ventilation requires a very specific type of air movement. We are not interested in moving air just to create a breeze that cools us by speeding evaporation.
Instead we want ventilation that provides year around benefits. If you have ever walked into the stuffy confines of a room that has been completely closed for a lengthy period of time, you know air tends to stay in place.
Just opening a door or window does not solve the problem immediately. A flow of air must be established to produce the air changes needed to remove all the stale air.
This is what a efficient ventilation system must do also. It should provide a steady high volume of air movement. That means the system components must be sized and positioned to provide a constant flow of air moving in a constant direction.
Air movement can be created in one of two ways. One way is using natural ventilation or mechanical ventilation. When using natural ventilation, two key forces create natural air movement: thermal and wind.
Thermal effect is the inherent property of warm air to rise. A well designed system takes advantage of that movement in two ways. First of all warm air rises. An effective system will include exhaust vents at or near the ridge of the roof.
That placement allows the hottest air to be removed from the attic most efficiently. Second the thermal effect creates a natural circulation of air because warm air rises and cooler air falls. A well designed system assists this momentum by placing intake vents at the lowest point in the attic.
Typically in the soffit or near the roof’s edge. The cooler air entering these vents speeds this circulation of air.
In the next blog I will start with “wind” as a natural air movement.
Typed by Brad Diepholz