Before the industrial revolution and the invention of mixed air systems, the only way to cool buildings was by building them in a location where cool air was or in a location where a breeze could be channeled throughout the building. These buildings relied upon the fact that gravity will keep denser, fresher air near the ground so that natural convection (the rising of heated air) will cause hot air to drift away to the ceiling. Displacement ventilation, using Hero FabriDuct™ does not fight gravity, but rather utilizes it, resulting in a cleaner environment and substantial energy savings. Since the air is introduced slowly, there is no mixing of dirty and fresh air.