b'THE OFFICIAL NFBA MAGAZINEcontinued from page: 19Once a building is constructed, not much can be done aboutMoisturegenerationdurationcontinuousor increasing the R-value of a component.If condensation isintermittentforming on the inside surface for an unacceptable amountAir temperature rise from outside to insideof time, then one must use ventilation to remove moisture from inside the building.A properly operating ventilationA properly sized ventilation system has just enough capacity system will decrease the inside dew point temperature asto remove the excess moisture generated inside the building moisture is removed.The amount of ventilation needs towhile maintaining adequate indoor air quality.Keeping be high enough so that condensation no longer forms onthe ventilation capacity correct will minimize the amount the inside surfaces. of supplemental heating required to maintain the inside The reason a ventilation system can remove moisturetemperature during winter.RESEARCH & TECHNOLOGYfrom inside a building can be graphically seen in FigureAll ventilation systems have the following five functional 4.When air is heated (increasing the air temperature), itcomponents:can hold more moisture.The heated dry air from outside can absorb indoor moisture and will remove moisture from1.Inletlocation(s) for air to enter the building spacethe building when the air is exhausted out of the building.2.Outletlocation(s) for air to leave the building spaceThis type of ventilation exchanges air by removing inside air and replacing it with outside air. 3.Driving Forcereason air moves through the building Figure 4 space (the force that moves the air)4.Distributionhow and where air moves through the building space5.Pathhow and where air moves through the building systemA properly operating ventilation system will include all five functional components.Experience has shown that most operational ventilation system problems can be traced to the inadequacy of one or more of the functional components.SummaryBuilding ventilation is done to:Remove excess moistureoAnd must be continuous when a continuous moisture generation source is presentoOr can be intermittent to control periodicindoor moisture problemsImprove and maintain indoor air qualityThe amount of ventilation needed depends upon several of the following factors:Moisture generation rate20 / FRAME BUILDER - VOL5 4'