Nowadays the electric energy has become a fundamental need in our society. According to the World Energy Outlook the world electricity demand is expected to increase every year. Considering that the resources on earth are limited, it is obvious that this situation can not last over time. The only two ways out are as follows: Either humankind manages to produce more using the same amount of resources or society diminishes their consumption. The first approach refers to a technological improvement in the production of electric energy whereas the second one refers to consume more efficiently. Energy audits point out to the second part of the solution and they are the main focus of this work. The main drawback of performing a traditional energy audit is its cost and time consumption. With the recent advances in data science, an innovative way of performing an energy audit is emerging, which are the so-called online energy audits. In this work, both traditional and online energy audits are carried out in a real case and the procedure to execute them is explained. The results obtained will be analysed and the feasibility for online energy audit will be studied.