The influence of a ground shield on the heat flux to a substrate ina parallel-plate plasma system was investigated experimentally using anoriginal temperature measurement technique. The evaluation of the temperaturerise curve shows that the heat flux from the plasma towards the substrateincreases from 8% of the rf power to 26% by surrounding the poweredelectrode with the ground shield. The flux density on the powered electrode is350 W m-2 at an rf power of 50 W and pressure of 50 mTorr, and the valueincreases to 1150 W m-2 by shielding. However, the total power into theelectrode is 23-26% of the rf power in both cases, after accounting for thelarger plasma facing surface area of the unshielded system. By shielding, aself-bias voltage decreases from 80% of the applied rf voltage to 73% due toa contracted spatial distribution of the electron density between theelectrodes by shielding. The ion flux is smaller than the heat flux obtainedfrom the substrate temperature rise and it increases by shielding.