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Venting protects against moisture buildup in the attic and framing materials and helps keep the home cooler. In the summer, a tremendous amount of heat can build up in the attic, which can make the air conditioning system work much harder than it needs to. Venting keeps the attic cooler because it allows that hot air a place to escape. In the winter, vapor occurs when the warm air inside the house meets the cool air outside and condenses into water droplets. Ventilation keeps this moisture from rotting insulation and framing materials.