Ventilation has historically been applied and viewed as both a desirable and effective technique in improving thermal comfort and general air quality and comfort in buildings. It has been used to dilute and exhaust unwanted contaminants such as combustion by-products, lavatory and cooking odors, heat and moisture, etc. from residential and nonresidential buildings. Exhaust ventilation is widely used in industry to remove contaminants at their source to reduce worker exposure and health risks. General dilution ventilation induced and delivered by mechanical fans is used in office, commercial and retail, and institutional buildings to maintain acceptable air quality.