They might save a small portion of their cooling costs. They won't go even by a long stretch. Keep in mind that in Luleå the summers reach 22-23 degrees Celsius easily. People are tanned and wear t-shirts, shorts and skirts up there during the summer just like anywhere else down south.
It'll be a similar design to the datacenters in Prineville, Oregon and Forest City, NC. They pull in outside air, cool it a little bit with evaporative mist, mix it with air already in the datacenter, and then send it to the servers.
The air doesn't need to be 50F, just cool enough and at a sufficient pressure to circulate heat off the servers. Sweden will work great.
But it is "Open the doors and cool the servers" cold in winter at least, so savings from cooling are sure to be substantial. Coupled with the cheap electricity in summer, and well developed infrastructure, and you can see why it was chosen.
It can be warm in Lulea, in fact it reached 30C when I was last there in June, but that was exceptional. Typically, it's sub-zero for half the year and the summer is very mild.