Feedback energy from a stellar population as a function of metallicity for different density and radii is shown with blue cross symbols. The red dots indicate the energy feedback from CCSNe and stellar winds in FIRE-3 (Hopkins et al. 2023), while the orange dots include additionally photoionisation feedback that is assumed to have a coupling efficiency of 3 per cent. All values are IMF-weighted (normalised to the total mass in stars above 8 M_⊙).