Using BIM to design a ‘Net Zero’ home

Courtesy of John Zona III

In nature, nothing is perfectly square, and organisms orient themselves by the sun. Both truths explain the fresh design of the “net zero” Zona home.

The Jacksonville, Florida, residence, designed using ArchiCAD software from , the personal home of by architect John Zona III and his wife. It features a main residence and guest cottage/studio, both with American football-shaped footprints to minimize the considerable cooling demands of homes in Southern climes.

Courtesy of John Zona III

The long edges of the home and studio face the south and north. A northern exposure is naturally cool, and deep porches on the south side shade windows from any direct sunlight. The points of the football face the higher-intensity east and west, offering very little surface area to absorb heat.

It’s nothing like the original plan. “I started out with a nice design for a typical architects’ home,” says Zona. “As I was about to file for permits, I found myself at an American Institute of Architects seminar on sustainable design. Although I’ve always loved sustainable design, I kind of woke up and said, ‘What the heck am I doing? I have a golden opportunity to build one last home, and I’m building the proverbial architect’s house like everybody else? Why am I doing this?’ So I stepped out of the box, as we have always done for our clients. I tore up the plans and started sketching anew, literally on the back of a napkin.”

first floor plan
second floor plan

He drew a football shape. Then another. And went on from there.

Energy-efficient ingredients

He added a third building, a greenhouse in the clearing, which plays a key role in the home’s net zero status. As a net zero home, the Zona property consumes no more power than it produces. The greenhouse carries solar photovoltaic panels that can produce 6.5 kwH. A special electric meter enables the compound to sell electricity back to the grid during sunny spells and borrow from the grid when sunlight is scarce. “We could go completely off the grid,” Zona explains, “but batteries are not yet efficient enough to economically store solar-based electricity.”

Zona added a geothermal cooling system that consumes less than half the energy of even the most efficient conventional air conditioning. It draws 70 degree F water from an aquifer 300 feet below ground, runs the cool water through a heat exchanger to blow 55 degree F air, then returns the water to the aquifer. Conventional systems waste enormous amounts of energy cooling air that starts out as hot as 100 degrees F.

Courtesy of John Zona III

Next he designed in an 8,000-gallon tower to collect rainwater for bathing, dishwashing, laundry and other non- drinking use. Gray water is filtered separately and reused for irrigation. Organic waste – including food scraps that traditionally would go down a garbage disposal – is composted for the landscape and garden.

Zona chose to illuminate the home with LED accent lighting and low-voltage fluorescent lights – both of which produce light as warm as traditional incandescent lights. The home is wired to accept LED lighting throughout just as soon as the technology is affordable.

The cladding – surprisingly attractive vertical corrugated metal – reflects, rather than absorbs, sunlight.

“To have net zero home, you have to spend a lot of time thinking about every one of these decisions,” says Zona. “If you don’t site the home correctly in the first place, it’s an uphill battle all the way. ArchiCAD helped us orient the buildings and panels for both protection from the sun’s heat and maximum capture of the sun’s electrical potential. Every electrical device that goes into the home – pumps, fans, lights, and appliances – needs to be analyzed to ensure you don’t exceed 6.5 kwH. You need to consider: How much energy does this device consume? How long does it run? And how do you capture the benefits with techniques like efficient insulation? You need to end up with a surplus instead of a deficit.”

sections

There are green concerns beyond sheer energy efficiency. In addition to the judicious reuse of water, all materials are locally sourced, and all wood scrap from building the home is being recycled into new boards.

The crucial role of BIM

ArchiCAD’s building information modeling (BIM) software – and its companion products from GRAPHISOFT, EcoDesigner for sustainable design and MEP Modeler for mechanical, electrical and plumbing design – enabled Zona to quickly model the house in three dimensions.

Courtesy of John Zona III

“I mean, how are you going draw the inside of a football with a 2D software and have any kind of accuracy?” Zona asks. “We probably never would have finished the design. The only way you can do it is with 3D BIM software like ArchiCAD. You can walk though the building and see how dramatic these spaces really are. You can understand the uniquely shaped spaces, including the thermal qualities of volumes two stories deep. You can experiment with different materials, colors, textures, and furniture placements inside and out. I’m treading new ground with these curved walls, and I wanted to see how they’d look and feel before I opened the bank account on construction.”

Once a building is modeled in ArchiCAD, the user can automatically pump out 2-D CAD-compatible 2D floor plans, elevations, sections and orthographic projections for the builders. “The drawings are automatic and five times faster than 2-D CAD, which is becoming a white elephant. ArchiCAD is hands down faster than 2-D CAD and easier. For this particular home, ArchiCAD was mandatory to make any sense out of what we were envisioning. As a result, our dream home has come true”.

Cite: Graphisoft, Graphisoft. "Using BIM to design a ‘Net Zero’ home" 08 Feb 2011. ArchDaily. Accessed 23 Aug 2014. <http://www.archdaily.com/?p=108482>

19 comments

  1. Thumb up Thumb down 0

    “We could go completely off the grid,” Zona explains, “but batteries are not yet efficient enough to economically store solar-based electricity.”

    So its not NET ZERO then? just wondering…

    • Thumb up Thumb down 0

      It’s a net zero. Net Zero homes produce more power than they consume.

      Read the paragraph above the quote…

      “As a net zero home, the Zona property consumes no more power than it produces. The greenhouse carries solar photovoltaic panels that can produce 6.5 kwH. “

      • Thumb up Thumb down 0

        That’s an off the grid house, a bit more daring than net zero. Either way, I hope this trend catches on. We use way too much power.

  2. Thumb up Thumb down +1

    So love the three SUV’s in the second shot…
    [wishful thinking]Maybe they’re just the contractor’s[/wishful thinking]

    • Thumb up Thumb down 0

      considering the house under construction in the background, the suv being the contractor’s isn’t really wishful thinking.. prius-es cant fit construction drawings, much less excess lumber

  3. Thumb up Thumb down 0

    Rich,

    The two comments below seem to contradict for sure…

    It’s a net zero. Net Zero homes produce more power than they consume.

    “We could go completely off the grid,” Zona explains, “but batteries are not yet efficient enough to economically store solar-based electricity.”

    Are they not consuming grid energy ???? I guess over the long run they will give some back and thus consider it net zero?

    To me NET Zero should mean if it does not… YOu cannot take energy from the grid… Or rather the big hoopla should be about the house that doesnt take from the grid!

    • Thumb up Thumb down 0

      That’s an off the grid house, a bit more daring than net zero. Either way, I hope this trend catches on. We use way too much power.

  4. Thumb up Thumb down 0

    The batteries would be used to sustain the house through the night. The house still has to be on the grid during this time because the batteries are not good enough and then the solar panels would put the energy back into the grid during the day when the occupants are at work.

    • Thumb up Thumb down 0

      Thanks for the description. That helps. Too bad bout the batteries though….. hopefully soon.

  5. Thumb up Thumb down 0

    I hope to never hear the phrase “Using BIM to design” again as long as I live. You used BIM as a tool to draw, not to design, unless you want to promote soul-less architecture.

    Is the art of ‘proper’ design where architects convey spacial awareness with a pen and in their mind gone? Are we now at the stage where if a computer program doesn’t show someone a “great” space then they aren’t convinced they can deliver one?

    I don’t mean to go on a rant, the house is ok and I appreciate that it takes some guts to have your work critiqued on the internet. My point is about the role of BIM and the decline of old-fashioned design skills in general.

    • Thumb up Thumb down 0

      this argument works for speaking about students of architecture design studios, but in the real world, i cant help but see the positives that BIM presents to us architects

  6. Thumb up Thumb down 0

    200 years from now some new technology will come along and people will feel the same nostalgia for BIM as you feel with pen and pencil. BIM will be the future’s “good old fashioned design skills” of which you speak. If we never evolved, we would still be finger painting on cave walls.

  7. Thumb up Thumb down 0

    Yeah, “Net zeros” are no different then “off the grids”, I say net zeros are better because it provides a means of economic payback when considering the life-cycle costing of maintenance etc. i.e. Monetary gains from supplying energy to public power grids.

  8. Thumb up Thumb down 0

    EL PROYECTO DE TALLER 3 DEL CHITO!!!!!!………NO SE PUEDE TRABAJAR CON LA VENTANA ABIERTA CHITO.

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