An environmental control system of an aircraft includes a compressing device including a compressor and a turbine configured to receive a flow of first medium sequentially and a second turbine arranged in fluid communication with an outlet of the compressor. The second turbine is configured to receive a flow of second medium distinct from the first medium. A dehumidification system is arranged in fluid communication with the turbine, a first bypass valve is configured to divert at least a portion of the flow of the first medium output from the compressor around the turbine, and a second bypass valve configured to divert at least a portion of the flow of first medium output from the compressor to the second turbine.