RGB Custom Builders recently completed a three-bedroom home that became the first in the nation to earn the National Green Building Standard’s top certification

Since January, when the American National Standards Institute approved the National Green Building Standard, more than 1,000 homes have been scored to the standard using the online scoring tool at NAHBGreen, according to the National Association of Realtors.

The first home to actually be certified by the NAHB Research Center to the standard (known formally as the ICC-700 2008 National Green Building Standard) was a home in Upper Marlboro, Maryland, that was featured ABC’s Extreme Makeover: Home Edition in March.

However, the first home to be certified to the standard’s highest rating, known as Emerald, is a 1,645 sq. ft. colonial in Eastern Pennsylvania’s Smithfield Township (which, coincidentally, won a Monroe County Chamber of Commerce “Save the Planet” Green Award for the green construction of its new municipal building).

In a recent press release, NAHB says the house, constructed by RGB Custom Builders, of East Stroudsburg, Pennsylvania, scored of 724 points in the six categories of the standard, which include energy, water and resource efficiency, indoor environmental quality, lot and site development, and homeowner education and maintenance.

RGB co-owner Bob Brown told NAHB that the home’s green amenities, including a $20,000 ground-source heat pump, added about $45,000 to the total construction cost of the project. But he added that, because he now has a better working knowledge of the scoring system and certification process, he could have trimmed about $15,000 off the final cost and still earned an Emerald rating.

The new house is 38% more efficient than the standard home RGB builds, which scores at the Silver level, the NAHB release notes.

Brown said he’ll likely offer as an NGBS Gold rating for an extra $3,000, which would pay for certification, low-flow toilets and the other products he will need to reach that level.