Energy conservation measures (ECMs), also referred to as interventions, are a set of actions intended to enhance energy efficiency or conserve energy consumption. When implementing an intervention in a building or a set of buildings, the actual energy savings cannot be directly quantified. Alternately, savings are calculated by comparing the energy consumption before and after interventions while adjusting to condition changes. Based on the literature, systematic approaches for determining the true impact of an investment in energy efficiency are collectively referred to as measurement and verification (M&V) methods, supported by a well-established set of guidelines, directives, and protocols, e.g. International Performance Measurement and Verification Protocol (IPMVP). Therefore, the paper proposes a methodology based on the available M&V methods to validate, quantify, monitor, and report the achieved energy savings with large-scale aggregated during an operational year. It is designed to integrate and consolidate the available information and provide insights to validate the impact of the energy consumption optimisation strategy. The method describes all the steps, from gathering the data to feature selection to model selection and saving quantification and performance evaluation. The proposed methodology’s practical application is demonstrated through its testing on Danish residential buildings in the Municipality of Aalborg. A shared adjusted baseline model is constructed per cluster of buildings to predict post-intervention energy consumption. The results show that the method reduces the computational effort of calculating the energy consumption of a series of buildings separately and delivers reliable predictions, underscoring its practical value.