A method and apparatus for a retrofit energy device and system to modify, manipulate and optimize airflow in vertical open-case refrigeration units. An open refrigerated display case includes a refrigerated display area comprising one or more shelves, an air outlet and an air inlet opening into the display area and spaced from one another, and a duct configured to direct air flow out of the air outlet across the display area and toward the air inlet to form an air curtain across the display area, each one or more shelves provided

A ventilation device includes: a lid configured to open and close a ventilation port, a drive mechanism configured to displace the lid between an opening position and a closing position; a sealing member located between the base portion and the lid and surrounding the ventilation port; and a pressing portion configured to press the lid toward the base portion.