A specialty of the OptEEmAL project is the direct involvement of the end-users in the development process of the platform: Three of the consortium members are directly in charge of designing retrofitting projects at district level. They play a central role in the design of the platform and an even more crucial one for its validation procedure. The partners Habitech, Fomento San Sebastián and the city of Lund explain their roles, their contributions and their benefits from participating in the OptEEmAL project. Three different stakeholders in charge of designing retrofitting projects at district level are essential to become test-beds for validation within OptEEmAL: A municipality (the city of Lund in Sweden), a private consortium of technical offices (Habitech in Italy) and a municipal company (Fomento San Sebastián in Spain). Each will head the demonstration of the performance, usefulness and user-friendliness of the tool for developing Integrated District Energy Efficient Retrofitting Plans in real environments. TO READ THE FULL INTERVIEW, PLEASE VISIT THE OptEEmAL WEBSITE NEWS SECTION