According to the USGBC, buildings worldwide account for 14% of potable water use, 39% of greenhouse gas (carbon dioxide) emissions, and 40% of material and energy use. By building green and obtaining LEED certification you can realize up to 50% energy savings, 35% reduction of CO2 emissions, 30 to 50% water use reductions and 50 to 70% reduction in solid waste. In addition, benefits of decreased operating costs, increased property values, increased productivity, reduced absenteeism, improved risk management, and verified building performance are seen with LEED certified buildings. And the additional construction costs for LEED certification are only 1 to 7%.

From: Building Green is in the LEED by Vince McLeod, CIH in The Safety Guys