What are your thoughts regarding sealing an attic without vents?

Air Vent believes it is possible to safely seal (not vent) an attic in new construction but not in remodeling or reroofing applications.

Air Vent does believe it is possible to safely seal (not vent) an attic in new construction. In remodeling or reroofing applications sealing is not as practical or possible. In general, attic ventilation, however, is more forgiving in that it allows an exit for heat and moisture from an attic. Furthermore, it remains to be seen if the substantial upfront cost to properly seal an attic brings a return on investment.