Las Vegas — The 2016 version of the New American Home (TNAH) packs a lot of plastics throughout the 5,280-square-foot structure, contributing to its distinction as the greenest showcase of best practices ever offered by the National Association of Home Builders (NAHB).
NAHB and its supply partners use the latest construction techniques and products for TNAH, which is unveiled annually in conjunction with association's International Builders Show to inspire and educate the construction industry about the latest building methods and design trends.
IBS and TNAH officially open to the public Jan. 19 through Jan. 21 but Plastics News got a sneak peak of the contemporary dwelling in the foothills of the desert on Jan. 18. With features like solar panels on the roof and Owens Corning insulation products in seven places — even under the slab foundation — TNAH for 2016 has the best energy performance in the program's 33-year history.
The two-story residence achieved a Home Energy Rating System (HERS) Index rating of minus 17 — the lower the number the better — and is expected to not only consume 122 percent less energy than if it were built to code but generate energy.
“That's the lowest [HERS] we've ever been. This is the most energy efficient new American home that's ever been built,” said Drew Smith, chief operating officer of Two Trails Inc. in Sarasota, Fla., which is a sustainable building consulting firm. “We've really pushed the bar pretty high on this one.”
Smith announced Jan. 18 that TNAH also achieved the highest rating of platinum from the Leadership in Energy and Environmental Design (LEED) program. The house was designed and constructed by Element Design Build of Las Vegas.
Like the 2015 version of TNAH, this year's house also meets requirements for designation as a zero-net energy (ZNE) home, which means the energy produced onsite equals the energy consumed. In the case of this year's house, ZNE is exceeded and it is considered a “positive energy house.”
“In an ideal situation, once you get below zero on the HERS index you start producing more energy than the house needs,” Smith said, noting this year's house is set up for net metering, which means the buyers will be able to feed electricity they don't use back to the grid.
However, that doesn't mean the owners won't get any monthly electrical bills.
“There's one little caveat,” Smith added. “You're selling the energy produced back to the grid typically during the day and at night — unless you have battery back up — you're still buying power back from the power company. But at the end of the year, you should end up with no electric bill based on the credit you're getting from selling energy back.”
North America is the leading ZNE home market. In the next 10 years it is expected to grow from 750 newly constructed houses in 2015 to 27,000 in 2025, according to a report released late last year by Navigant Research, a market research firm based in Boulder, Colo. The report says stricter energy efficiency standards, particularly in California, where all new homes have to be zero net starting in 2020, will spur the growth along with consumer desire to lower or eliminate monthly energy bills and reduce their environmental impact.
While the 19.215 kilowatt solar panel system is key to the ZNE status, Smith said the Owens Corning Corp. blown-in roof insulation and the company's extruded polystyrene (XPS) used under the slab and on the perimeter walls contributed to the tight building envelope.
Achilles Karagiozis, the global director of building science for Owens Corning, explained why two inches of XPS in the form of Foamular 250 insulation product was used below the slab.
“It's absolutely not common,” he said. “It was the odd thing to do because code does not require it but based on the amount of windows and glass this house has we had to extract every possible amount of energy savings to create an extremely energy-efficient structure. This will help minimize the energy lost from the building. In the summer, you don't want the hot ground to conduct heat through the ground to the inside. We're short circuiting or stopping the flow of heat in the summer months and in winter time it does the opposite.”
Without the solar panels, TNAH comes in at 47 on the HERS Index because of the tight building envelope while the standard new home is about 100.
The builders of the TNAH also used Logix insulated concrete forms, which are made of expanded polystyrene foam, for the basement walls.
“It gave great insulation value below ground where you don't want moisture to get in and you want to maintain the cool temperature,” Smith said. “Using that block as opposed to a cement block was a real benefit both in ease of construction and the insulation properties.”
Other plastic products used in TNAH include butyl-based FlexWrap to seal window sills as well as Zodiaq counters by DuPont Co.; XPS foam board by Kingspan Insulation; and cross-linked polyethylene pipes by Uponor.
TNAH incorporates best practices in building that can be replicated anywhere and in any price range as well the latest design trends, such as mixed stone and veneer materials on the exterior, linear electric fireplaces, freestanding baths, and massive sliding glass doors that essentially are moving walls to connect living spaces to the outdoors.