[usurper]

Is there some code requirements that require venting? Or some advantage, maybe in cooling?

If its not vented, humidity builds up and you get mold and other nasty stuff.

[SaxxonWoods]

A builder was telling me recently that codes require new houses to be so airtight some people get sick and he tells them when they move in to call him if that happens. Once the Certificate of Occupancy is in place the builder can bring more air into to house.