Environment

Net-zero energy test home ends year-long study with surplus energy

Net-zero energy test home ends...
The net-zero test home at the National Institute of Standards and Technology (NIST)
The net-zero test home at the National Institute of Standards and Technology (NIST)
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The 2,700 ft sq (252 sq m) two-story construction was developed to look like a regular home, but function as a laboratory for clean energy research
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The 2,700 ft sq (252 sq m) two-story construction was developed to look like a regular home, but function as a laboratory for clean energy research
Over the 12 month period, the home generated 13,577 kWh of energy
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Over the 12 month period, the home generated 13,577 kWh of energy
The 2,700 ft sq (252 sq m) two-story construction was developed to look like a regular home, but function as a laboratory for clean energy research
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The 2,700 ft sq (252 sq m) two-story construction was developed to look like a regular home, but function as a laboratory for clean energy research
The NIST test home has 32 photovoltaic panels fixed to the roof
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The NIST test home has 32 photovoltaic panels fixed to the roof
NIST estimates that fitting out a similar-sized house with all the bells and whistles of its test home would cost around US$162,700
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NIST estimates that fitting out a similar-sized house with all the bells and whistles of its test home would cost around US$162,700
The home combines largely stable ground temperatures with geothermal systems to minimize heating and cooling loads throughout the building
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The home combines largely stable ground temperatures with geothermal systems to minimize heating and cooling loads throughout the building
The net-zero test home at the National Institute of Standards and Technology (NIST)
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The net-zero test home at the National Institute of Standards and Technology (NIST)
The 2,700 ft sq (252 sq m) two-story construction was developed to look like a regular home, but function as a laboratory for clean energy research
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The 2,700 ft sq (252 sq m) two-story construction was developed to look like a regular home, but function as a laboratory for clean energy research

Braving a harsh winter with snow-covered solar panels, the Net-Zero Energy Residential Test Facility (NZERTF) in Washington DC has come up trumps in a year-long study of its energy harvesting capabilities. Located on campus at the National Institute of Standards and Technology (NIST), researchers used computer simulation to replicate the energy consumption of a family of four. At the end of its first 12 months, there was a large enough surplus to power an electric car for 1,440 miles (2,317 km).

The 2,700 ft sq (252 sq m) two-story construction was developed to look like a regular home, but function as a laboratory for clean energy research. Much like the Honda Smart Home, NIST's effort combines stable ground temperatures with geothermal systems to minimize heating and cooling loads throughout the building. Another factor in overall energy efficiency is a doubling of insulation levels, sealed by special sheeting that reportedly heals itself when pierced.

"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," says NIST mechanical engineer Mark Davis.

On July 1 2013, the research team began the experiment by moving a virtual family into the home. A computer simulator syndicated the energy consumption with that of a typical American family of four, the inhabitants going about everyday activities such as taking showers, watching TV and charging laptops. There was more at play than a life-sized game of The Sims, however, with the researchers able to gain realistic insights into the energy efficiency and how viable planting such a home into a real-life American neighborhood could be.

The 2,700 ft sq (252 sq m) two-story construction was developed to look like a regular home, but function as a laboratory for clean energy research
The 2,700 ft sq (252 sq m) two-story construction was developed to look like a regular home, but function as a laboratory for clean energy research

The energy surplus and the home's claim to net-zero living was compounded by a stretch of severe weather. For 38 days through winter, the 32 photovoltaic panels were largely covered in snow and ice, hampering their ability to harvest energy from the sun. But over the 12 month period, the home generated 13,577 kWh of energy. This surpassed the virtual family's energy usage by 491 kWh, an excess that could in theory be directed toward an electric vehicle or back into the grid.

"We made it, and by a convincing margin," said 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."

Despite boasting the aesthetics of a typical suburban house, adoption of the technologies used will largely come down to cost. NIST estimates that fitting out a similar-sized house with all the bells and whistles of its test home would cost around US$162,700. On the upside, it puts savings in electricity costs at $4,373 for the year.

Further research will center on how the measurements of the home can improve its energy efficiency and addressing the difference in up-front costs and long term savings. NIST is hopeful its findings will lead to improved energy efficiency standards as a resource for builders, regulators and home buyers.

The video below gives an overview of the project.

Source: NIST

Energy to Spare: NIST Completes Successful Net-Zero Energy House Experiment

20 comments
Rt1583
So it only takes 37 years to pay all the systems off? Sign me up! That sounds like the deal of a lifetime! In all seriousness, it is great that they proved what they did but until prices become more realistic there won't be enough people who can afford to do this.
Slowburn
Of course it would not do near as well with a real family living in it with the children leaving doors open, people staring in the fridge, and of course light left on all the time.
Milton
@ Slowburn: They said their energy-usage was exactly the average. So, being an average... everything you mention has already been factored in... along with the intelligent kids/adults who know how to shut-doors and turn-off lights.
Slowburn
@ Milton I know what they said it is just I don't believe they got it right.
The Skud
I agree with Slowburn - A useful exercise, but it could prove difficult to duplicate in a real life situation,no matter how "average" the computer simulations are. You could probably up the power usage by 10% with a real family. That negates the power surplus so you are left with a fairly expensive (although maybe usefully off-grid somewhere) home to pay off.
Mark A
Send the virtual kid up to clean the snow off the panels and performance would have been even better. And for his allowance - bitcoins.
Slowburn
Also average means that half is higher.
TeeWee
Please take note, a real family did not live In this house. A computer lived in the house and was programed to 'average' but not real. With all the homeless families out there don't you think this outfit could have moved a real family into the house rent free and obtained a more accurate assessment of real life. I know people who live off grid in Colorado and they need back up generators when the sun dosen't shine and the wind doesn't blow. This was likely a grant funded project designed to show a predictable result.
Greg Proefrock
All y'all, Some important factors are missing from your criticisms of the value of the project. Before laying out a judgment, how about getting all the relevant information? For example, while the article states savings on electricity, it doesn't state savings on fuel for heating, perhaps substantial due to the better air barrier and insulation, or for a car (replaced by elec, as noted). So, we don't have enough info to calculate payback time. Payback time doesn't matter much if I finance it with PACE loans, so the cost stays with the house, not with the borrower; so I can move to another house before it pays back fully and not lose money. I hear of more and more places where that is becoming an option. Houses that are sealed and insulated well tend to be more evenly comfortable throughout the spaces, throughout time. What value of happiness? They tend to be more healthful places. What value of not getting sick as much? As energy rates rise, per the long term trend, the rate of savings increases. So, payback time occurs faster than the calculations in these comments. Currently, the initial cost can be reduced in a few ways. First, some energy systems (like solar power, solar thermal, etc.) can be leased; little or no upfront cost; system designed to optimize your expenses & savings. Also, there are federal tax credits for power systems (30% cost reduction) and tax credits or cash rebates in various states and utility districts. These often lead to a total cost reduction of 50% to 60%, thereby reducing payback time. There are state and district incentives for energy efficient construction (air barrier, insulation, better furnace, better duct design, etc.). Those reduce the cost noted here. How about home value? If you sell a home with solar power and a record of lower heating bills, plus good testimonials about comfort, how much more would you get in the sale? If you show a banker that your operating cost is lower than usual, what better terms on a loan for a car or a business startup could you get? Very few homes are off the grid. That comment about people in Colorado is not relevant enough to reject the project in general. In most places, a home with a solar power systems is required to be connected to the grid, if it is already on the grid. So, the grid provides power when the home system doesn't generate. If the grid goes down, you can still get power during generating times (if you have the right kind of inverter, like Sunny Island as well as the common Sunny Boy). Then, sure, you can have batteries for the rare times when the grid is down and there is no home power generation. Generally, the article is incomplete, lacks many of the benefits in a cost-benefit analysis. No assessment can be made, with integrity. Would you want someone to evaluate you, without considering all of your virtues?
slider99
How can they only use 491kWH a month? I average 1,550 a month and have a new home very well insulated.