It's the sort of project we'll be seeing a lot more of in the coming years, the greening of a mid-century building. In this case it's the greening of a very large icon, Willis (nee Sears) Tower in Chicago.
The scale of this sort of project is unreal. Just walking through the numbers gets your blood pumping (if you are geek like me, I mean.) Annual projections include; saving 24 million gallons of water, a 50% reduction in the heating load, and reducing carbon dioxide emissions by millions of pounds.
The other part of the story that will become familiar is the disconnect between the measures that are most effective and the measures that attract most of our attention. It is lovely and wonderful that the green roofs of such a tower attract ladybugs to the 90th floor (one wonders, though, if they came with the plantings.) But the yeomans work in terms of energy and water savings will be in less photogenic projects like replacing the 16,000 single pane windows, swapping the lighting for modern, vastly more efficient units and controls, and installing high-efficiency plumbing fixtures.
It's great to see such a signature building get the green treatment. The American downtown is a veritable sea of office towers from the same generation, wrapped in the same poorly performing skin. Here's hoping their owners are watching.