Inconsistent results about heat transfer effects on performance and poor understanding of the aerothermodynamics loss mechanisms related to heat transfer in turbocharger turbine motivated this study. This study aimed to investigate the sensitivity of performance to heat loss and to quantify loss mechanisms associated with heat transfer in a turbine by using exergy analysis. A hybrid simulation methodology, i.e. Detached Eddy Simulation (DES) was used to compute the three-dimensional flow field of a turbine operating under hot gas stand continuous flow condition. Principal findings of this study were 1) Pressure ratio is less sensitive to heat loss as compared to turbine power, 2) Turbine power drop due to heat loss is relatively insignificant as compared to the exergy lost by heat transport and exergy destroyed by thermal irreversibilities, and 3) Assuming the most ideal isentropic gas expansion, more than 80% of the inflow exergy is unutilized in the investigated turbine system.