advertisement
advertisement
advertisement

This Home Makes All Its Own Energy. Will We All Soon Be Living In One?

It’s a grand experiment in “net zero” living–and it’s working. But we can’t move in just yet.

This Home Makes All Its Own Energy. Will We All Soon Be Living In One?
[Photos: by Ofer Wolberger]

The 560-acre campus of the National Institute of Standards and Technology (NIST) is a state-of-the-art federal research facility in Gai­thersburg, Maryland, staffed by an elite group of scientists. They work out of several dozen industrial-scale buildings. But the campus also has one suburban home–a year old, 2,700 square feet, and sited smack-dab in the center of the grounds, as if a tornado sucked it up from a nearby subdivision and dropped it down intact, just inside NIST’s main security gate.

advertisement
  1. Under the roof, thick layers of insulation boast an extreme R-value of 75.
  2. Solar panels are situated in an optimal direction, and with an ideal pitch, to collect sunlight.
  3. Beneath the siding, a black rubber membrane seals the house from outside cold and heat.
  4. Insanely efficient windows, with an ultralow U-value rating of .2, keep air leakage to a minimum.
  5. The yard covers a subterranean network of geothermal coils to collect energy.
  6. All inside lights utilize LEDs or CFLs to keep energy usage low.

It’s not a pleasant place to live. Showers abruptly turn themselves on and off, and constant clicking noises come from everywhere. It also has a terribly unwelcoming name: the Net Zero Energy Residential Test Facility. But that’s fine. Nobody is expected to move in–until one day, perhaps, when friendlier versions are built in our own neighborhoods and we all live in them. For now, it’s an experiment: How close can we come to building affordable houses, on a mass scale, that produce as much energy as residents tend to consume during a given year?

This goal reaches beyond the increasingly common motif of “greener” living. It’s aimed at the far harder ideal of true sustainability, which would deliver an enormous environmental payoff. Residences use about 21% of all the energy consumed in the U.S. They also produce 16% of U.S. greenhouse-gas emissions. Change the house, the thinking goes, and you can help change the future.

Early results are promising. Researchers marked the first complete year of the experiment in June, announcing that the home produced slightly more energy than real-life residents would have consumed–and that was after a particularly brutal winter.

But creating a “net zero” home was the easy part. Now comes the big challenge: building the house at a price people can actually afford. This house cost $652,000, or roughly $162,000 more than a conventional, energy-efficient home. That’s a high price tag for clean living.


How do scientists know that the house creates enough energy for real people, when no real people live inside? They fill the house with ghosts. “We call them the Nisters. They’re a family of four that’s been living here for a year,” says Hunter Fanney, an engineer who has managed the house since it was conceived in 2011. The Nisters’ name comes from the National Institute of Standar…well, you get the idea.

advertisement

Save for the fact that they’re the product of a software program, the Nisters act like typical Americans. They comprise a mom, a dad, and two children, ages 8 and 14. “These virtual people have a minute-by-minute script of how they live their lives,” Fanney explains. They get up at 6 a.m., roll out of bed to make coffee, then check the fridge. The kids sleep late and play Xbox. For the most part, the adults take eight-minute showers–which is to say, showers switch on automatically and are measured by a large bucket in the stall.

A variety of combined sensors and emitters stationed around the house, meanwhile, simulate the energy consumption of the coffeemaker and flat-screen TV and give off micro-bursts of heat just as these machines do in the real world. Other sensor emitters mimic the energy given off by four humans, who in combination put out the equivalent of about four 60-watt incandescent bulbs. This produces 700 measurements every minute. It’s all reported back to the garage, where computer servers direct the activity.

But the main focus is on the performance of the house rather than the people inside. Hot water for showers comes mainly from solar water heaters on the roof. Electricity for the lights, fridge, stove, and boiler largely come from solar photovoltaic panels, also on the roof. This is all available to consumers today, though installation takes some effort.

The house’s biggest achievement is how it limits what’s known as infiltration. NIST engineers and the house’s architects, the Boston firm Building Science Corporation, went to extreme lengths to keep frigid air from seeping in during the winter and air-conditioned air from seeping out during the summer. “Basically, you would like the house to be like a thermos jug,” says Fanning. The house was built with thicker-than-usual walls, lined with copious amounts of high-performance insulation and state-of-the-art windows. Above all, it was wrapped, pretty much from top to bottom, in a black rubber membrane before putting on the siding and roofing.

The Nisters’ house, therefore, doesn’t “breathe” like most homes do–and without proper ventilation, a home’s occupant is in trouble. The builders, Therrien Waddell, had to create special circulation systems for fresh air and utilize materials with minimal levels of what are known as volatile organic compounds, or VOCs, which get emitted from everything from floor varnish to cabinets. After all, who wants to live in a superefficient house if it makes you feel ill?


When NIST announced its results in June, proving that a smartly built house can be self-sustaining, environmentalists were thrilled. But that $162,000 premium remains a difficult issue. Some of the cost is offset by energy-bill savings (annual bill: $0), says Joshua Kneifel, an economist at NIST. “But if you’re just looking at a purely economic standpoint–you own this home until you pass away–I wouldn’t say that it’s cost effective.”

advertisement

There are ways to put a more positive spin on this. The price of energy-efficient materials and skilled labor could likely drop if a market in net-zero houses scales up. Government incentives could also help offset costs and lure buyers. California has already set a goal to have all new houses be net zero by 2020. And Kneifel believes that the higher resale value of a house that effectively costs nothing to run could also make the investment attractive.

Still, scientists working here acknowledge the cost problem and have adjusted their expectations. “We’ve learned that you don’t have to get to net zero,” Fanney says, “but if you show you can significantly reduce energy use, you’ve gone a long way.”

As an experiment, the Nisters’ prototype home is certainly a success. It’s a way to answer, definitively, a lot of energy-efficiency questions. What if you bulked up the insulation on new residential buildings? What if you built homes with a slightly different kind of interior framing that allowed for a tighter envelope? Are solar water heaters better than gas heaters? This coming year, researchers will measure the performance of various geothermal energy systems–essentially coils of fluid-filled pipes, buried in the backyard, that harness the heat energy of the earth. Perhaps that’s more efficient (and cheaper) than solar.

But these aren’t just lessons for the future. NIST research already suggests that the most logical next step for the average person building a new home is clear: bulk up on insulation, which gives the most return for every dollar spent, and forgo the hefty expense of solar panels. It won’t be net zero, but it’ll get you into net zero’s neighborhood. When you get there, be sure to wave to the Nisters.

A house in order: Sensor emitters such as these are everywhere in the net-zero home–even in its fridge.

The Price of Going “Net Zero”

The government’s test house cost $162,000 more to build than a home of the same size that conforms to the International Energy Conservation Code (IECC), the current gold standard of energy efficiency. These are some of the reasons why.

Building systems

Net Zero: $112,000
IECC: $51,500
Difference: $60,500
Reason: Intricate plumbing, electric wiring, duplicate HVAC system, in-floor radiant heating, and pipe loops that create geothermal energy.

advertisement

Concrete Pouring

Net Zero: $10,800
IECC: $10,400
Difference: $400
Reason: Additional insulation under foundation and cost of building in the
radiant heating system.

Exterior Finishes

Net Zero: $83,900
IECC: $74,100
Difference: $9,800
Reason: Cost of attaching complex siding and energy-efficient windows.

Insulation

Net Zero: $37,800
IECC: $6,500
Difference: $31,300
Reason: High-quality insulation, sometimes double the thickness of normal houses, requires meticulous application of tape to seal.

Interior Finishes

Net Zero: $173,450
IECC: $166,950
Difference: $6,500
Reason: Basement drywall and installation.

Net-Zero Premiums

Net Zero: $30,750
IECC: $10,550
Difference: $20,200
Reason: Contractor will be slowed down because the home requires many unfamiliar, nonstandard processes and applications.

Rough Framing

Net Zero: $84,300
IECC: $64,700
Difference: $19,600
Reason: IMore steps in construction and installing insulation.