The building sector is responsible for a large part of the final energy consumption in Europe. One of the most relevant steps in the process of reducing energy consumption in buildings is the energy performance diagnostic. In this paper, a data-driven methodology to obtain early energy performance assessment of commercial buildings using the energy signature approach is used. As a result, a web-dashboard and API that can analyse user data input and produce streamlined outputs like suggestions for energy-saving measures is developed. In order to prove the correct functioning of the tool, a demo site of a commercial building in Dublin has been used.