Abstract: A damper for determining and regulating amount of airflow admitted into a heating, ventilation, and air conditioning (HVAC) duct of a building from the ambient includes a variable position gate. The gate is configured to generate a continuous access opening into the duct from the ambient. The damper also includes a mechanism configured to select a position for the gate between and inclusive of fully opened and fully closed and a first sensor configured to sense a velocity of the airflow admitted into the duct. The selected position of the gate determines an area of the continuous access opening and regulates the amount of airflow admitted into the duct. Additionally, when the continuous access opening is not fully closed, the airflow admitted into the duct by the gate is substantially uniform. An HVAC system employing the damper and a method for controlling a temperature inside the building are also disclosed.