Due to this SBB Cargo decided to order new dual power electro-diesel locomotives which could be used on the entire SBB network as the dual power design allowed them to operate efficiently on both the electrified rails and the short unelectrified sidings.

Because of the adoption of the Eem 923 SBB expects it can achieve a reduction in CO2 emissions of more than 4000 tonnes per annum compared with the current locomotives.

While operating on electrified lines the locomotives are capable of producing a power output of 1,500 kW (2,012 hp).

[4] When operating on non-electrified sidings, the locomotives are powered by a diesel engine-generator set which produced 290 kW (389 hp) at the wheel.

[4][5] The design of the Eem 923 is derived from the Ee 922, an electrically powered two-axle locomotive also used by the SBB and produced by Stadler.