Modern industrial electricity production is embedded in a global paradigm shift associated with the end of fossil fuels due to climate change, which has led to increased interest in leaving testament of power plants. Multi-Criteria Decision Analysis (MCDA) can help analyse complex interactions between industrial elements, society, culture and nature, providing key benefits when approaching heritage investigations. In this context, this research concerned the design of a Multi-Expert (ME) MCDA methodology to support the selection of paramount heritage elements in power plants based on the collection, processing and harmonisation of the views of a group of international experts in the field. This approach was tested using a case study in the As Pontes power plant (NW Spain), which will be dismantled in a near future. The results achieved pointed out to cooling towers, boilers, chimney and turbine hall as the fundamental elements to preserve due to their relevance across a set of technical, historical and sociocultural criteria. These outcomes proved the usefulness of the proposed approach in favouring the valorisation of industrial facilities as heritage areas protecting the social and cultural history of a territory.