The article presents the results of the analysis, which was carried out in 2015-2017 on the example of autothermal installation of thermophilic sludge stabilization (ATAD) in a sewage treatment plant in Giżycko. The installation was created in 2003 as the first of its kind and works until now. The purpose of the conducted research was to assess the suitability of the analyzed technological parameters as tools that can be used by operators to determine the real possibilities of changing the operating conditions of the installation or to develop an optimization strategy to reduce the energy demand. The dry mass content and organic dry mass content was used as the assessment indicators. In the analysed period, sludge from the process contained from 47.47% to 60.80% of organic matter in the dry mass of the sludge. The organic dry matter decrease as due to the process was also calculated, and it ranged from 26.4% to 48.7%. The amount of sludge undergoing the process and the amount of electricity consumption were also analysed. On this basis, the energy consumption indicators in the ATAD process were calculated.