Building envelope blends old and new techniques for long-term performance (video)
Story by Steve Arel.
The Proud Green Home at Serenbe is a marvel of high-performance residential construction. Its striking curb appeal and interior charm have wowed visitors from across the country since its mid-August unveiling.
But the real innovation behind much of the Proud Green Home’s ability to achieve superior sustainability and efficiency – helping it earn the highest sustainable construction rating possible – can be found in the building’s shell, masked by the siding, walls and ceilings.
A host of novel approaches were used to build the Proud Green Home. Some techniques have existed for years, just not used often in residential projects.
The designers of the home, Atlanta-based LG Squared Inc., credited the early and likely long-term success of the home to the mix of traditional and high-tech materials within the structure, as well as to an understanding of how best to use them.
"We're not NASA engineers,” said Jodi Laumer-Giddens, one of the architects. “It’s wood and concrete that everyone is using. If you put them together in a certain way, they perform better."
Framing. Traditional framing uses 2x4 studs spaced 16 inches apart. The Proud Green Home features 2x6 studs spaced at 24 inches apart. The additional width of the wood makes the walls slightly thicker for durability. But the extra space along the width and thickness of the walls enables builders to squeeze in more insulation. It also reduces the amount of wood required to assemble the walls.
Co-architect Chris Laumer-Giddens said builders must exercise caution when using such an approach, ensuring the wider stud pattern doesn’t go across too long a stretch and potentially compromise the integrity of the wall.
A similar method was incorporated into the frames of the windows. Instead of multiple studs being positioned vertically across the tops and bottoms of the frames, one stud was nailed in horizontally between the outer studs of the frames to eliminate interior studs. Again, the approach meant using fewer studs and provided more room for additional insulation.
See builder Luis Imery talk about advanced framing techniques.
California corners. The walls inside most homes meet at a solid corner put together with multiple studs. OSB boards are then nailed around the exterior to close in the structure.
In the Proud Green Home, studded walls lack the studded corners. Instead, the walls come together at adjoining points that leave those corners hollow once the OSB boards are added. In doing so, builders are able to fills those openings with additional spray foam. California corners provide dual benefits. Not only is there protection from heat and cold, but the technique also demands less wood.
Insulation. The Proud Green Home follows a whole-home concept when it comes to insulation. Foam, sprayed on in a loose, semi-solid state that expands and hardens when it dries, seals the entire home.
See builder Luis Imery talk about spray-foam insulation.
Insulation fills the space between wall studs. It fills crevasses around the foundation. It also fills the gaps atop the ceilings and is spread several inches thick between the rafters in the attic that comprise the roof. There is even an inch-thick layer along the entire exterior walls, helping create what’s known as a perfect wall of insulated durability.
|Architect Chris Laumer-Giddens displays a sample of the spray-foam insulation inside the walls and roof of the Proud Green Home at Serenbe. Photo by Steve Arel.|
Unlike in traditional homes where barriers are designed to stop dangers, such as air and moisture from penetrating the interior walls, the perfect design aims to stop threats first from the outside.
"It's like putting an insulated raincoat around you," Chris Laumer-Giddens said.
Read more about theProud Green Home at Serenbe.
Companies: ProudGreenHome.com, Southface Energy Institute, Kohler, BASF Corporation, PPG Pittsburgh Paints, Kleendeck, LLC, Serenbe Sustainable Community, LG Squared, Inc., The Imery Group, Zehnder America, SmartBIM, Huber Engineered Woods, Wood-Mode, Inc.