The National Green Building Standard, also known as ICC-700, grew out of NAHB’s earlier Model Green Building Guidelines. NGBS includes a number of mandatory practices, none of which are worth any points toward certification. Many are in the energy efficiency area and include requirements for caulking or otherwise sealing windows and doors, insulating skylight shafts and kneewalls, using airtight, IC-rated recessed lighting fixtures and running Manual J calculations for sizing heating and cooling equipment.
The NGBS has four compliance levels. While LEED for Homes calls its levels certified, silver, gold, and platinum, NGBS uses the terms bronze, silver, gold, and emerald.
Builders must accrue points by incorporating features in six areas: site development, water conservation, energy conservation, resource conservation, indoor air quality, and homeowner education. Houses over 4,000 square feet will need more points for a given certification level than smaller houses.
NGBS requires progressively more points in the energy-efficiency category to climb the ladder from a bronze to an emerald rating, starting at 30 points at the bronze level and going to 120 at emerald. A number of mandatory measures also must be met, for which no points are awarded. On the alternative performance path, at the bronze level the house must be 15% more efficient than a house built to the 2006 International Energy Conservation Code (the same as an Energy Star qualified home). For silver, it increases to 30%; gold, 50%; and emerald, 60% better than IECC.
All houses must include a mechanical ventilation system complying with ASHRAE Standard 62.2.
Although energy compliance depends strongly on climate zone, most ICC-700 checklist points (including water-saving measures) apply nationwide. There are a few exceptions, however; as Don Carr, NAHB’s national green building certification program manager, pointed out, “The standard includes a termite zone map, a radon map, and rainfall map.”
The NAHB Research Center has established…