How familiar are you with LEED? At the very least, you probably understand that it’s a rating system that is supposed to tell you how environmentally responsible your building really is. And you’d be right. LEED has been around since 2001 and has often been credited as the catalyst for the ever-expanding green building movement.

Now, how much do you know about Green Globes? Have you even heard of it? Don’t feel bad if you answered “No.” Most probably will. So, what is it?

Green Globes, which was brought to the U.S. in 2004 by an organization called the Green Building Initiative (GBI), is essentially a self-assessing green building rating system that may eventually, though certainly not yet, compete with LEED as the standard for defining a green building. It’s basically a tool to continuously evaluate your building’s greenness throughout the design and construction process based on a rather extensive questionnaire about your building’s characteristics. But if you want independent, third-party certification that you met certain sustainable benchmarks, Green Globes can do that, too.

Hence, the main difference between Green Globes and LEED: The U.S. Green Building Council (USGBC) built LEED intending its users to certify, whereas GBI is mostly happy if you use Green Globes as an assessment tool.

But as Green Globes’ Web site states, there are more similarities than differences, and there isn’t enough room here to get into the subtle differences of the rating systems themselves. But suffice it to say that both are applicable to either new construction or existing buildings. And both organizations claim their rating systems are more stringent. USGBC would probably say LEED is more universally applicable and GBI says that’s fine – for now their focus is smaller buildings that would have trouble justifying the extra cost of LEED certification.

As the wave of green-focused legislation continues to roll, several city and state governments are beginning to include language that mandates or strongly recommends a green building rating system like LEED or similar for all new public buildings. In other words, no longer is LEED the only game in town.

Of course, both organizations will use the “a rising tide lifts all boats,” line to downplay the competition and emphasize that the more green buildings that are built, the better. But the “or similar” language certainly opens the door for other rating systems like Green Globes. And Green Globes is working hard to step in.