Mechanical Ventilation: Window and Exhaust Fans

Window fans are best used in windows facing the prevailing wind or away from it to provide cross-ventilation. Window fans augment any breeze or create a breeze when the is still. If the wind direction changes frequently in your area, use reversible-type window fans so you can either pull air into the home or push air out, depending on which way the wind blows. Experiment with positioning the fans in different windows to see which arrangement gives the best cooling effect.

In a larger house, consider installing a win- dow fan that blows air in through a lower-level window in a cool area and another window fan that blows air out through a higher-level window in a hotter area.

Use exhaust fans in the kitchen and bath to remove and humidity when cooking and bathing. Larger, securely installed exhaust fans can ventilate homes where an open window would be a security issue. Large exhaust fans can be mounted outdoors on a wall or to reduce indoor noise.

Be cautious with these large exhaust fans. If enough ventilation isn't provided, the fans can pull combustion products (e.g., from furnaces or heaters) into your living space.