This is the title of a new study by McKinsey & Company that investigates the GHG abatement cost curve across regions and sectors. The study can be accessed at www.mckinsey.com. The buildings sector is identified as the sector with the lowest abatement cost; the buildings sector actually has a negative life-cycle cost. The study does not go into detailed best practices, but does offer a way to analyze abatement potential between sectors and helps its readers to understand how their sector fits into the global GHG economy.