Proctor Ventient devices can be used as part of natural, mechanical or mixed mode ventilation approaches to make use of outdoor/indoor pressure differentials to bring in natural, clean, outside air.  Unlike conventional systems such as operable windows or louvres, Proctor Ventient can be left to get on with the job of proving fresh air circulation with less worry about negative impacts on indoor environment quality resulting from airborne contaminants, noise, high winds and rain ingress.