This work deals with the energy balance of the hot end of the production area of the glassworks Stölzle Oberglas GmbH in Köflach by the approach of the energy audit standard EN 16247-1. Initially the border of the energy balance, the period and reference ratings had been set. After validation of the data situation a measurement campaign to determine missing data was developed and carried out. The balance of the hot end of the production process and the exhaust gas was shown graphically. Further a Sankey diagram was used to show the overall situation. Finally, the quantity of the waste heat as well as the industrial waste heat potential of the plant were determined and optimization potentials were shown.