Though it may be hard to believe for those who haven’t spent any time in “Second Life,” brisk business is currently being done in the 3-D model world.

Digital whizzes use Google’s free SketchUp software to whip together models of everything from skyscrapers to washing machines to solar panels, then share them with each other via Google’s 3-D Warehouse. The models are rated as simple, moderate or complex, and can be downloaded by other users. Designers grab the models they like for use in conceptual drawings, renderings and other graphic representations.

Now, companies such as Hawthorne-based Blue Marble Project are professionalizing the 3-D world, offering their services to designers and companies interested in making, using, or sharing models but lacking the SketchUp skills to do so. Blue Marble creates models for customers such as Whirlpool (NYSE: WHR) that want to encourage designers to use their products in conceptual drawings—a way of subtly marketing products to prospective buyers.

Now, both Blue Marble and Google are applying SketchUp’s capabilities to green building. A U.S. Department of Energy (DOE) plug-in allows SketchUp models to be used with DOE’s powerful EnergyPlus modeling software.

While Blue Marble has the jump on its competitors for now, a growing number of designers are opting to use SketchUp, particularly in the very early design stages, because the models are simple to create, use, change and understand.