This is true, but I almost think ksantoso was asking if the system directs external air through the device or if it draws the heated air out of the device, allowing physics to take care of the rest.
Much like how electronic cooling fans can be reversed dependent on your preference.
The few times the fans have run on mine, it was blowing air out the top. I'm not sure where it is pulling it in. Not sure if the cooling is done before or after the fans, or both.
IIRC it pulls it in one set of vents and out another - I think the sides on the upper edges in and out the top vents IIRC. I sent mine back. My Surface had vents that started just above the Kick-stand hinge and went around the top edge.