Location of sustainability function in a corporation?

The trend is to locate the sustainability vertical in the corporate affairs and / or communications function. While this is a good move when a company is in the process of setting up its sustainability practice and needs to communicate internally, externally and to the Board it’s ongoing efforts in seeding a social and environmental quotient, it’s detrimental in the long run to continue to preserve this location. As sustainability moves from philanthropy to a core business competency, it needs to be a seperate function with its own evangelist team and sustainable business verticals.