IMF-weighted (normalised to the total mass in stars above 8 M_⊙) cumulative energy flow for the single star models with metallicity Z = 0.0001 and no initial rotation. From top to bottom, the rows in each panel show kinetic, thermal, and total energy flow, while the columns show different initial ambient densities. Additionally, the sum of the energy inputs from SN, stellar winds and an estimate of the photoionisation energy is shown (labelled ‘Star’), and the energy input excluding the photionisation energy (labelled ‘no ph’).