Airflow iCONstant Timer dMEV Fan The use of continuous ventilation has increased rapidly as homes become better insualted but can sometimes suffer with additional condensation issues.The iCONstant provides a ventilation solution that satisfies the need for an energy efficient, economical to run and low noise fan with minimum human intervention as it helps eliminate the problems of condensation and mould growth by continuously extracting the damp, moist air that is source of the problem.