Suspended facade system with ventilated air gap it is a special case of walling ventilated air gap. Flow of air is free-convection in vertical ventilated channel. Convection - one of the most economical and practical method of removing moisture from the air gap.The question is, what should be the size (width) of the gap,which providing maximum air flow pass? We reviewed version of the definition an optimal hydraulic hinged ventilated channel for buildings in this article.