URGENT Does FPGA EP4CE15F17C8N requires heat sink?

I entered some random numbers to reach total power of ~1.5W (at ambient of 25C, without heat sink and no airflow) --> the maximum allowed T_ambient is about 38C.

Of course this is not the correct way to do it (random guessing is never dependable) :) The EPE can import .csv file generated by Quartus (if you have the design) that fills up the resource usage for you. After entering the ambient temp, you should see the maximum allowed T_ambient on the top right of the table.