An environmental control system includes a plurality of inlets for receiving a plurality of mediums including a first medium and a second medium and an outlet for delivering a conditioned flow of the second medium to one or more loads of the aircraft. A ram air circuit includes a ram air shell having at least one heat exchanger positioned therein and a compressing device is arranged in fluid communication with the ram air circuit and the outlet. The compressing device includes a compressor and at least one turbine operably coupled via a shaft. The environmental control system is operable in a first mode and a second mode. In the second mode, a pressure of the second medium output from the compressor is equal to the pressure of the second medium provided to the outlet.