Inter Press Service: Making buildings more environmentally friendly is the easiest and most effective way to cut climate-changing carbon emissions, often slashing energy costs by up to 70 percent. So why isn’t there a massive effort to "green up" existing buildings and set green standards for all new construction? North America’s buildings are responsible for a staggering 2,200 megatonnes of carbon dioxide (CO2) emissions — 35 percent of the continent’s annual total. A new report released …