Just curious about windshield heating

[steelgray]

On the ACC panel there is one button at the top right position that is called "To defrost windows and remove condensation" that clears the windshield very fast when car is cold. Does anyone know how it works? Does it use an electrical heater to get warm air to the windshield or do the system direct coolant fluid directly from the engine to get warmer air quicker to this function? It seems to work so fast that it must be more than just the full blast of the fan that does the work.