Open crawl space vents allow hot humid air into the crawl space in warmer months and cold air winter months. In the summer, this damp air contributes to the high relative humidity in the space and results in microbial growth, damaged insulation, and moist or rotted wood. In the winter, it leaves the homeowners with freezing floors. Year-round, the homeowners are combating high energy bills, drafts, and compromised indoor air quality.