Extra work that roofing companies need to do.. where does that money come from, what other investments in their business that the company that occupies the building needs to do won't happen because the company had to invest in a green roof by law. What employment and job growth will that kill. What about the additional water that will be required to keep these roofs green. Studies show these roofs are a lot more costly and less effective in arid environments. If all of the offsets to installation cost were real and quantifiable companies would already be investing in these roofs if they provided the returns they claim. Drink Brawndo. It has the electrolytes plants crave.