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Buildings Despite a harsh winter that left the Net-Zero Energy Residential Test Facility's photovoltaic and solar thermal panels covered with snow on 38 days, the energy-efficient house produced more energy than it used over the course of a year.
Image Credit: NIST

Published on July 7th, 2014 | by James Ayre

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NIST Net-Zero Energy Test House Blows Past Goals In One-Year Trial

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July 7th, 2014 by
 
The National Institute of Standards and Technology’s (NIST) net-zero energy test house blew past the goals set by researchers for its first year of operation. It even managed to produce enough surplus energy to power an electric car for over 1400 miles.

To put it another way — and perhaps even more impressively — the net-zero system allowed for almost $4400 (average annual bill for a comparable modern home in the region) in saved/avoided energy costs, while also actually earning the virtual family of four residing there a cash credit via the exportation of surplus energy to the local utility.

Despite a harsh winter that left the Net-Zero Energy Residential Test Facility's photovoltaic and solar thermal panels covered with snow on 38 days, the energy-efficient house produced more energy than it used over the course of a year. Image Credit: NIST

Despite a harsh winter that left the Net-Zero Energy Residential Test Facility’s photovoltaic and solar thermal panels covered with snow on 38 days, the energy-efficient house produced more energy than it used over the course of a year. Image Credit: NIST

This impressive performance by Net-Zero Energy Residential Test Facility (NZERTF) was despite five months of below-average temperatures and twice the normal amount of snowfall, so “average” years would have allowed for even more impressive performances.

“We made it — and by a convincing margin,” stated Hunter Fanney, the mechanical engineer who leads NZERTF-based research. “From here on in, our job will be to develop tests and measurements that will help to improve the energy efficiency of the nation’s housing stock and support the development and adoption of cost-effective, net-zero energy designs and technologies, construction methods and building codes.”

The press release from NIST provides more:

Both a laboratory and a house, the two-story, four-bedroom, three-bath NZERTF would blend in nicely in a new suburban subdivision. But it was designed and built to be about 60% more energy efficient than houses built to meet the requirements of the 2012 version of the International Energy Conservation Code, which Maryland has adopted.

The 2,700 square-foot (252-square-meter) test house’s features include energy-efficient construction and appliances, as well as energy-generating technologies, such as solar water heating and a solar photovoltaic system.

Despite 38 days when the test house’s solar panels were covered with snow or ice, the NZERTF’s sun-powered generation system produced 13,577 kilowatt hours of energy. That’s 491 kilowatt hours more than used by the house and its occupants, a computer-simulated family of two working parents and two children, ages 8 and 14.


As far as energy consumed per unit of living space, the NIST house is calculated to be about 70% more efficient than the average house in the region.

“The most important difference between this home and a Maryland code-compliant home is the improvement in the thermal envelope — the insulation and air barrier,” states NIST mechanical engineer Mark Davis. “By nearly eliminating the unintended air infiltration and doubling the insulation level in the walls and roof, the heating and cooling load was decreased dramatically.”

This high level of energy efficiency doesn’t come cheap though — by incorporating all of the NZERTF’s energy-related technologies and efficiency-enhancing construction improvements you would add around $162,700 to the price of a similar house built to Maryland’s state building code. So, with about $4,500 in annual energy savings, it would take about three decades to recoup the financial costs.

In related news, for all of the latest announcements about energy efficiency and solar energy, I recommend that you check out our latest “news carnival” on these subjects.

Everything from the increasing efficiency of Yingli solar cells, to solar skyscrapers in Germany, to DIY solar panels on Amazon, to “tiny” homes, to the increasing energy efficiency of malls, is discussed therein. Enjoy.

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About the Author

's background is predominantly in geopolitics and history, but he has an obsessive interest in pretty much everything. After an early life spent in the Imperial Free City of Dortmund, James followed the river Ruhr to Cofbuokheim, where he attended the University of Astnide. And where he also briefly considered entering the coal mining business. He currently writes for a living, on a broad variety of subjects, ranging from science, to politics, to military history, to renewable energy. You can follow his work on Google+.



  • Bob_Wallace

    I really don’t understand the high cost. You could use double stud walls with massive insulation between, PV solar, and geothermal heating/cooling along with high efficiency windows and thermal blinds and not be all that much more expensive than a normal house.

    It looks like they’ve killed any winter solar gain with the large porch. And for best protection it seems that it would have made more sense to put the garage on the north side where it could block winter storms (assuming that’s the storm direction).

  • Doug

    I really must question the sanity of this study. Spending $160,000 is an order of magnitude too expensive.

  • Matt

    Sounds like the spent $160k extra to “prove” it could not be done for everyday people. There have been several NetZero office buildings that were built at no extra cost. So WTF?

    • Doug

      Yep. How about ten $16,000 investments in ten homes and take the average.

  • Rick Kargaard

    160 grand extra would make it difficult for a lot of people to qualify for a mortgage.

  • http://MrEnergyCzar.com/ MrEnergyCzar

    I added solar to my typical home to make it a net-zero. It cost just over $30k but it covers 100% of the homes total utility needs and powers my plug-in car 6,000 miles per year. No oil or gas entering the home. Not sure why you need a test house. Powerdown and change the way you live and its a lot easier to do.

  • spec9

    I’ve got the electricity aspect down but it is hard to manage the heating. I’m guessing this house has a geothermal heat-pump which helps a lot. But I guess if I work on insulation, I can greatly reduce my heating costs.

    • Bob_Wallace

      Tighten it up. Add insulation where it makes sense (lots in the attic). Insulating curtains can make a big difference for relatively small money.

      And keep your eye on local geothermal system prices. It looks like a geothermal system in some locations is running about the price of a new central HVAC system. For some people replacing a worn out traditional system with a geothermal heat pump makes sense right now.

  • SunSource Homes

    We design/build Net-Zero homes in the midwest. The $160,000.00 number is way out of line. The extra cost of a super-insulated building envelope, geothermal heating/cooling, and a large 15kW solar PV system would only add about $40K to the cost of the house after the US Federal Tax Credit for the geothermal and solar. In most cases the payback for the increased cost of these features is around 5-7 years. If you factor in the increase in property value payback is usually 1-2 years. I think articles/stories like this discourage people from looking into a “Green” home and especially Net-Zero homes. It would be great in the future to add some additional commentary about how it can be done for much less money. Every house we design/build now is Net-Zero, and we’ve never had a customer complain about the additional end-cost or choose to remove any of the energy-saving features. The time for Net-Zero building is now!

    • LookingForward

      In Holland, by law, from 2020 onward, every new house needs to be net-zero, the US should do that too.

      • No way

        Net-zero energy? Or net-zero electricity? How will that law affect heating?

        • LookingForward

          net-zero energy.
          Holland is building alot of city-heating (using acces heat from power, metal and glas industry) to heat homes and commercial buildings and the rest will get electric geo and solar heating.

      • Doug

        Impressive.

    • Rick Kargaard

      Hear, hear

  • Jan Veselý

    What cost so much extra money ($160 000)? I live in a house with similar energy efficiency and consumption. Insulation + “superwindows” cost about $7 000 extra, heat pump cost about $3 000 extra (2 year payback :-) and sufficient PV+solar heating will definitely get under $20 000. That’s 7 years payback. Pure no-brainer.
    Where are avoided costs?

    • Doug

      Agree. It doesn’t take $160k to get adequate energy savings. The first $16k should have approached 90% of the goal.

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