We like challenges -- and opportunities. And we see both when we look at green building. Let’s start with the challenges. Buildings account for a $222 billion annual energy bill in the United States today, and they’re responsible for 38 percent of greenhouse gas emissions and 50 percent of national energy demand. That’s a lot of environmental downside. But there’s a significant upside as well: The United States Green Building Council estimates that green building currently reduces energy use by 30 percent, carbon emissions by 35 percent and water use by 30 to 50 percent while generating waste cost savings of 50 to 90 percent. A study by the Commission for Environmental Cooperation says that green building could result in annual reductions of 1,711 megatons of CO2 emissions in