Once the implementation stage of the project is completed, the energy saving monitoring and payback stage begins. The monitoring and evaluation of the energy saving  is carried out in a mutually accepted manner. The monitoring method and the payback terms are specified in the contract. The monitoring method may be based: a) exclusively on calculations; b) on a mutually accepted evaluation method; or c) on continuous measurements.

A new vocabulary
Energy perfromance contract

A contractual agreement between the beneficiary and the provider (usually an ESCO) for the implementation of an energy efficiency measure, according to which payments for the investments are made in relation to the contractually agreed level of energy efficiency attained.