I recently had an indoor air quality expert advise that I install a Crawlspace vent vs Encapsulating the space. They advised this would be cost-effective approach. Vent would be humidity controlled and would turn on if crawlspace humidity was higher than outdoor humidity. Crawlspace would be sealed as best possible using weather stripping on the access door (inside) and any gaps and cracks around pipes sealed with foam. Duct worked to be sealed if any leaks. I live in the South and furnace/ac is in the crawlspace. My concern is that fan would not run as it would be rare that outside humidity would be lower than in crawlspace so it would remain a "wet" space. Also, that limited sealing approach recommended would be ineffective in my 1950s home (hardwood floors in kitchen above crawl are cupped due to excess moisture). Are my concerns valid? FYI - Expert was not pushing approach to gain any additional business.