Well, i hope that splitting a 550 cord in half was a joke because you can't do that to 550 cord.

If i had to get out of a building with 550 cord i would tie one end to my belt and loop the rope around something VERY solid and immobile and lower myself down. I would be happy with any bones i broke if/when the rope fails since it would have been much worse to jump out the window. I guess if you had enough 550 cord you could knot the middle to your belt and increase the odds that your cord not failing.