Ratio between the galaxy-scale and sub-pc scale outflow momentum rates for different QSOs hosting UFOs. Measurements for individual objects are shown in blue with the respective errorbars, using different markers according to the gas phase of the observed large scale outflow. The galaxy points are ordered by increasing L_Bol. The horizontal dashed line shows the prediction for a momentum-driven wind (ṗ_out/ṗ_UFO = 1), while the orange rectangles indicate the individual predictions for energy-driven winds. Filled and empty squares represent ionised outflow measurements based on Hα and [O III] emission, respectively. For HS 0810+2554, our [O III]-based measurement is shown both alone and combined with the CO-measurement of the molecular outflow (Chartas et al. 2020), with the respective symbol and combination of symbols (see the plot legend).