An energy efficiency obligation (EEO) requires obligated parties to meet energy savings targets by delivering or procuring eligible energy savings as a result of approved end-use energy efficiency (EE) measures. An effective EEO scheme establishes a framework for defining eligible energy savings activities, methods for measuring and verifying the resulting energy savings, and confirming that the activities actually took place. At an energy efficiency obligation workshop hosted by the Latvian Ministry of Economics, Eoin Lees explored the complexities of calculating energy savings within EEO schemes, including rebound effects, materiality, additionality, and free riders. He explains the nuances of these calculations and provides guidance on how to preclude double-counting of efficiency measures.