  We investigate the power dissipated by an electronic current flowing through
a quantum point contact in a two-dimensional electron gas. Based on the
Landauer-B\"uttiker approach to quantum transport, we evaluate the power that
is dissipated on the two sides of the constriction as a function of the Fermi
energy, temperature, and applied voltage. We demonstrate that an asymmetry
appears in the dissipation, which is most pronounced when the quantum point
contact is tuned to a conductance step where the transmission strongly depends
on energy. At low temperatures, the asymmetry is enhanced when the temperature
increases. An estimation for the position of the maximum dissipation is
provided.
