A ram circuit for an environmental control system of an aircraft, the ram air circuit comprising: a ram inlet able to be in fluid communication with an external area of the aircraft, and a ram outlet able to be in fluid communication with an internal area of the environmental control system disposed within the aircraft; a heat exchanger assembly interposed in fluid communication between the ram inlet and the ram outlet; and a ram air flow modulation valve characterised in that the ram air flow modulation valve is disposed directly against an outlet of the heat exchanger assembly such that the ram air flow modulation valve is disposed upstream from the ram outlet, the ram air flow modulation valve configured to operate in a plurality of positions to regulate airflow delivered to the ram outlet, wherein the ram air flow modulation valve comprises: a plurality of louvers movable between a first position that allows airflow to pass and a second position that inhibits airflow; an actuator connected to a respective louver among the plurality of louvers, each actuator configured to move the respective louver between the first position and the second position in response to at least one electrical signal; and a louver position sensor in signal communication with a respective louver (120 among the plurality of louvers, each louver position sensor configured to determine a position of the respective louver and output a position signal indicating the position, wherein at least one first louver among the plurality of louvers is independently adjustable with respect to at least one remaining louver among the plurality of louvers. a ram inlet able to be in fluid communication with an external area of the aircraft, and a ram outlet able to be in fluid communication with an internal area of the environmental control system disposed within the aircraft; a heat exchanger assembly interposed in fluid communication between the ram inlet and the ram outlet; and a ram air flow modulation valve characterised in that the ram air flow modulation valve is disposed directly against an outlet of the heat exchanger assembly such that the ram air flow modulation valve is disposed upstream from the ram outlet, the ram air flow modulation valve configured to operate in a plurality of positions to regulate airflow delivered to the ram outlet, wherein the ram air flow modulation valve comprises: a plurality of louvers movable between a first position that allows airflow to pass and a second position that inhibits airflow; an actuator connected to a respective louver among the plurality of louvers, each actuator configured to move the respective louver between the first position and the second position in response to at least one electrical signal; and a louver position sensor in signal communication with a respective louver (120 among the plurality of louvers, each louver position sensor configured to determine a position of the respective louver and output a position signal indicating the position, wherein at least one first louver among the plurality of louvers is independently adjustable with respect to at least one remaining louver among the plurality of louvers. a plurality of louvers movable between a first position that allows airflow to pass and a second position that inhibits airflow; an actuator connected to a respective louver among the plurality of louvers, each actuator configured to move the respective louver between the first position and the second position in response to at least one electrical signal; and a louver position sensor in signal communication with a respective louver (120 among the plurality of louvers, each louver position sensor configured to determine a position of the respective louver and output a position signal indicating the position, wherein at least one first louver among the plurality of louvers is independently adjustable with respect to at least one remaining louver among the plurality of louvers.