It's a concrete jungle out there -- literally. Humans today consume more concrete than any substance aside from water. That presents a huge problem for the environment. Concrete comes from cement, and each ton of cement generates a matching ton of carbon emissions. Many builders and designers are recycling water or installing energy efficient light bulbs in hopes of reducing their buildings' carbon footprint. But those approaches can only go so far. Instead, employers and builders must think about going green the moment they decide to construct a new office -- or renovate an old one. New technologies and building techniques can empower them to do so.