How to Calculate Gravity Ventilation
- 1). Analyze summer and winter month ventilation. Attic ventilation is required to provide proper temperature and moisture control depends on the solar radiation, construction details and rate of ventilation throughout the home.
- 2). Calculate the ventilation needed for the summer months. Measure the volume of attic space and divide the attic space by 2. For example, in a rectangular home the volume is determined by multiplying the height from the ceiling to the peak/ridge (H) times the width of the house (W), times the length of the house (L) and dividing by 2. The resultant will be in cubic feet per minute of ventilation air needed.
- 3). Compute the ventilation needed for the winter months. Divide one tenth of the summer's ventilation requirement to determine the winter month requirement. Winter attic ventilation need only be sufficient to remove moisture vapor moving from the living space to the attic.
- 4). Use a gravity, wind assisted or powered device to ventilate the attic space. Visit the local hardware store and purchase the device that best meets the needs of the home.
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