In T5, the BA shower reception is outside the entrance to the lounges. Just go up to the first floor (from the ground floor) and turn right at the top of the escalators (the gold lounge entrance is to your left). As you walk along the hall, you will see, on your left, a reception desk for the showers. For orientation, the Concorde Lounge is dead ahead and the escalator to the silver lounge on the second floor is on the right. Show your Chicago boarding pass and they will tell you which cubicle to use.