The word "green" gets tossed around a lot, but what exactly does it mean? The truth is, it's more of a talking point than a meaningful term. There are dozens of green building councils worldwide. Each has its own rating methodologies, and each is competing for dominance in the international market.
Even amongst these erstwhile competitors, however, there's agreement on the need for a common vernacular for carbon emissions. In 2009, the leading energy ratings systems -- BREEAM (U.K.), LEED (U.S.) and Green Star (Australia) -- signed a memorandum of understanding stating that they would work together to develop common metrics to measure CO2 emissions for new homes and buildings.
For now, energy rating systems are diverse and, some say, confusing. In 2010, the European Union issued a directive requiring all EU nations to adopt A-G grading-style energy efficiency ratings for all home sale advertisements by 2012. Meanwhile, the U.S. Department of Energy recently completed testing on a mile-per-gallon type rating system that may soon be adopted by participating Home Energy Score Partners.
In the coming years, homebuyers worldwide can likely look forward to a simplified, streamlined green energy scoring system. For the time being, however, they'll need to do their research to sort the "green" from the merely "greenwashed."