A new scaling of the mean rate of turbulent kinetic energy dissipation is proposed for application to free shear flows. The advantage of the proposed scaling is that it permits a direct comparison of the dissipation rate in flows driven by completely different mechanisms (e.g. inertia or buoyancy forces) and of different flow configurations. The same scaling, when applied to pipe flow suggests that the non-dimensional parameter so formed is analogous to a ‘friction factor’ for this motion. Application of this development to the motion of buoyant jets and plumes suggests that the mean rate of dissipation in buoyancy driven plume flows may be twice that for jets and is associated with the larger rate of entrainment in such flows.