Well, in the U.S. we have a listing of buildings. It's usually around architectural significance, historical significance, cultural significance, and integrity that makes for a building to be listed on our National Register of Historic Places, and in many instances on state registers as well.
We have looked at all the existing buildings in the 50 largest cities in the U.S. and only 4% of them are actually protected by a landmarks designation. You have a whole range of buildings that are old, that have not been designated. This gets to the heart of your question.
I think we've been too quick in the past to say this building has outlived its usefulness. One thing we're saying is that when we think about taking that material and putting it in the landfill, as we're thinking about the environmental impacts of carbon and the like, there's a lot of embedded energy in these older buildings. They may not be historic, but being able to reuse them is important. We look at those cases and say that we want you to think about all the impacts of reusing these buildings and not just whether it is a heritage building.