3GPP 23.501 v20.2.0 — the document's own text
5.51.8 Energy-Aware User Plane path selection
Taught in 27. Overload, energy, deployment and the rest (The 5G system architecture, in depth).
The User Plane path selection and reselection can consider the Energy-Aware NF discovery and selection as specified in clause 5.51.7 for the discovery and selection of the SMF(s) and UPF(s) in order to determine the optimal User Plane path for a PDU session based on energy criteria.