A long overdue addition! I'm glad that the zoo has taken this simple but effective and important step to improve the indoor accommodations for the elephants until the barn can be fully renovated in the next couple of years.
@pachyderm pro - Sorry for the late reply, but yes, as @Moebelle has said, the building is historically listed; however, that really only applies to the general structure (I'm not sure what the restrictions are for adding on to such a structure, though), as the inside of the building has been changed and rearranged on a number of occasions. That said I do not know exactly what the renovations will entail beyond Thane Maynard's statement that "the zoo is committed to exhibiting and caring elephants long-term," and their next major project after the completion of Gorilla World will be "to see a complete renovation and expansion of the elephant outdoor and indoor exhibit space and holding areas, providing the elephants with a much larger and more stimulating environment year-round." I imagine we will not hear much more about the details of the project until the Gorilla World expansion and renovations are closer to being completed.