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News Room: Industry News

NAHB Green Home Standard Ups Ante on Energy, Water

Wednesday, February 27, 2013   (0 Comments)
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What's Happening fromEnvironmental Building News


By Paula Melton

NAHB Standards, Old and New

The number of total points for some categories has decreased because more green building practices are now mandatory. The relative importance of water efficiency has increased. Click to enlarge table.


TheNational Green Building Standard (NGBS) for homeshas increased energy- and water-efficiency requirements with the release of its first update. Other major changes include a broader palette of green building practices to choose from as well as a more streamlined certification process for renovations and additions.

"The energy-efficiency baseline was bumped up,” said Michelle Desiderio of theNational Association of Home Builders (NAHB) Research Center, which develops the standard. She explained that the original version of the NGBS required 15% better performance than the 2006 International Energy Conservation Code (IECC) for Bronze certification, while the new one requires 15% improvement over the 2009 IECC—thus aiming for energy performance "about the equivalent of the 2012 IECC.”

The new energy standard may be stringent enough to fundamentally change how green homes are built, says Laura Capps, director of residential green building services at Southface. "It’s no longer the case that you can change a few practices and get where you’re trying to go within a reasonable price range,” she said. "You will need to look at the design of the home, the layout, and the features within the home and how everything works together.” She speculates that this will make an integrative design process more likely for homes targeting the new standard.

"We did a lot more analysis this time for the water chapter,” adds Robert Hill, also of the NAHB Research Center. "We better aligned the points you were getting so it was relative to the amount of water saved.”

Although there are no minimum requirements for water efficiency (as there are for energy efficiency), the new version offers much more generous incentives for hot-water use reductions and is stingy with points for fixtures and appliances that only slightly reduce water use. The relative importance of water efficiency for achieving certification has also increased significantly.

NGBS has been criticized in the past for encouraging energy efficiency without requiring whole-home ventilation. There’s been movement on that, notes Capps, but developers "could have been a little more aggressive.” Although the standard now requires that relatively airtight homes (those with less than 5.0 air changes per hour at 50 pascals) should have mechanical ventilation if a blower-door test is done, the blower-door test is not actually required. "They heavily incentivize testing, so the probability of testing is greater,” she says, "but with referencing the 2009 IECC, with its air-sealing measures, how could they not be getting a tight home at the end of the day?”

Another point of contention has been the difficulty of certifying home renovations. Getting a retrofit certified through NGBS used to be "very confusing,” admits Desiderio. "We wanted to make that much easier, so we added two new chapters.” One chapter deals with overall home remodeling; instead of flipping through all the other chapters choosing points, "you only have to go to one place to see everything you need to do.” The other chapter deals with small projects, like a bathroom remodel or home addition. "There are no points to get with small projects,” she explained. "It’s just a checklist of practices that you have to do.”

Capps applauds this move: "This is exciting. It’s one of those areas that our market has not figured out how to approach effectively. We are eager to learn from the pilot program.”

Other changes to the standard, say Hill and Desiderio, include the addition of universal design elements that will help older residents "age in place” as well as more stringent indoor air quality requirements.

Desiderio notes that builders have until May 1, 2013, to register projects under the 2008 version of the standard; after that, the 2012 version will be the only one available. "We’re looking forward to working with builders to make the transition,” she adds.


February 22, 2013
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