Something for Nothing


[ David Vandervort Architects ]

The Issaquah net-zero energy homes project broke ground on Monday, just three months after Howland Homes took over the project from Noland Homes. Check out the project web site for a graphical explanation for how net-zero is hoped to be achieved.

The rendering above shows what appears to be an innovative integration of vertical concrete walls to provide thermal mass. It also shows a whole lot of photovoltaic (PV) panel on the roofs, which is necessary for achieving net-zero energy use, but adds about $35k to the cost of each unit. At a typical Seattle-area electricity cost of 6 cents/kWh, the 5255 kWh per unit generated by the PV is worth about $315 per year. With no incentives and assuming electricity rates don’t go up, that translates to a 111 year payback. Ouch. Of course, that payback would be a lot shorter if we were paying the true cost of that electricity, include all the externalities, but our economic system isn’t that smart.

It will interesting to see if the project can actually achieve net-zero. For one thing, resident behavior will be a big factor — one big-screen plasma TV and it’s game over. As of 2007, only one house in the United States has demonstrated a full 12 months of net-zero energy performance. So far, it seems the zero-energy label has been applied to projects a little too liberally, as with the Zero Energy Idea House, which “opted to forego ‘true’ zero energy.” Even the noted BedZED project in Britain has had operational issues that have precluded the achievement of net-zero.

I don’t mean to come across as a big bad naysayer on this. These projects are models for what we should be shooting for with every new building. But let’s not be deceived about the challenge.

15 Responses to “Something for Nothing”

  1. Matt the Engineer

    I’ll be a big bad naysayer: I challenge the one net zero house in the entire US statistic. I’ve known several people that live completely off grid, and they are only a few of thousands (even millions?). I suppose it depends on how you draw the line – is burning wood (a completely renewable resource) not allowed? Even then, there have to be many homes in the more comfortable regions that don’t need any heat.

    Ok, enough of that. Net zero is a wonderful thing to aim for, and I love that our region has more than a handful of architects committed to making net zero designs work.

  2. Sabina Pade

    I’m very interested to see how liveable these homes prove to be.

    Net-Zero is a concept one can only applaud. Glad it has at last arrived in Seattle. But how will the occupants of a low-rise dwelling fare, psychologically, living behind 10″ of insulation and obliged to keep the windows closed throughout most of the year?

    Commonly, the joy of low-rise living derives in significant measure from the sonic backdrop one perceives while indoors, the sense of being protected from one’s physical environment while remaining connected to it. We love to hear the sound of birds, of rain, of wind in the trees, of the postman slipping letters into the mailbox or the of the spouse coming up the driveway.

    Much of this sonic panorama lies in a frequency range silenced by thick insulation and airtight windows. The background sounds that remain will be primarily those generated indoors, by electrical equipment. The acoustical experience of living inside a Net-Zero house may prove akin to that of living inside an airport during nighttime shutdown.

  3. dan cortland

    Maybe in the winter, but since net zero homes are likely to save energy by having operable windows and natural ventilation, that silence won’t be year-round. And winters in snowy places are pretty silent.

  4. Sabina Pade

    DC, you may well be right; yet during the heating season, which in Seattle lasts from September through June, effecting natural ventilation via open windows would seem to defeat the purpose of the Net-Zero house’s heat-recovery forced-air ventilation.

    As for those few authentically warm summer days in Seattle, would it truly be in lieu of operating an air-conditioner that the windows would be open? How many low-rise dwellings in Seattle actually have air-con?

  5. dan cortland

    Sabina, in response to your first point, presumably the occupants will open the windows to maintain the inside temp in the range they find comfortable, which is the temperature that the heat recovery system would on average be operating with no matter how that temperature is established or maintained. If they leave the windows open long or wide enough to chill the house to the outside temperature, it’s true there won’t be any heat to recover, but they probably won’t do this. But maybe I’m missing your point. Not operating a forced air system is preferable to operating one if adequate natural ventilation is provided and seasonally appropriate. Fan-driven systems can have passive fresh air intakes (e.g., below-window vents that bring air in over a hydronic warmer element) that allow outside sounds inside.

    Regarding you second point: I wasn’t suggesting that introducing natural ventilation to residential buildings would save a lot of energy in Seattle: as you write, already very few people use AC here. I’m suggesting that natural ventilation (and thus exposure to outside sounds) will be a feature of net zero houses generally, including in climates where AC is now the routine solution.

  6. Joe Feese

    The Zero Energy Idea House was called an “Idea” house because it is an experiment to see what one couple can do to build a house that is as close to zero energy as possible. Right now the house is in the virtual world of engineers, evolving constantly. In fact, the statement that Dan quoted from the house’s website is no longer true; the builders are looking at solar for the radiant floor heat, which would help them move closer to zero energy. Their decision on this depends on how much energy the on-site wind turbine will create.

    The biggest difference between the Issaquah net-zero energy homes and the Zero Energy Idea House? Instead of using standard double-stud walls, the Zero Energy Idea House is using Structural Insulated Panels (SIPs), one of the most environmentally responsible building systems available. A SIP building envelope provides high levels of insulation and is extremely airtight, meaning the amount of energy used to heat and cool a home can be cut by up to 50 percent.

    (Disclosure: The builders of the Zero Energy Idea House, Donna and Riley Shirey, are my clients through their business, Shirey Contracting.)

  7. Brad Liljequist

    Sorry it’s taken so long to comment on this, I appreciate you talking about the project.

    Lots of great thoughts here, I appreciate them all. So maybe I’ll just roll through them.

    Dan – yes, PV is expensive. I guess I would argue that the tax incentives ARE real and in some way a reflection of externalities, albeit not going far enough and in a haphazard way. I also believe there is an argument to be made that even though PVs are expensive now, as the market for them ramps up, they will get cheaper. That’s the logic I took when I paid custom prices several years ago for a tankless hot water heater – to some degree I was subsidizing the future market acceptance – and I note now they are indeed a lot cheaper to install.

    Regarding achieving net zero – ultimately, achieving this goal will indeed be in the residents’ hands. Once you cut all the fat out of homes’ energy use, the plug loads dominate, and there is a very wide range of what individuals do on this front. The design team had many, many hours of conversations about what were reasonable assumptions for our typical residents. We folded those into the energy model. We will be sharing those with the residents as they move in so they understand what assumptions we made for them (in the case of TV – a 28″ LCD operating two hours a day).

    Regarding the zero energy label, I agree, wholeheartedly, it is far too broadly used. At a minimum, you are running a detailed energy model that converts all energy expected to be used into a common standard measure and demonstrates you will be completely offsetting that energy by on site production. In many parts of the country (not here) it is de rigeur to say your project is “zero energy” simply because you are participating in the DOE zero energy by 2030 program – to me, false advertising in the worst sense.

    In regards to BedZED, it is indeed having a hard time getting to zero (they are very close), but I don’t believe that project ever had a ZE goal. ? Certainly, other projects in Germany are achieving the ZE goal, which gives me some confidence with zHome.

    Sabina – I really appreciated your comments. We haven’t looked in detail at acoustic transmittance – obviously, these will be quiet homes. But I suspect most of the sounds you’re talking about are coming through windows rather than walls in a typical new home. And we’re using double, rather than triple paned windows, so the noise transmittance will be the same as a new home, at least through the windows.

    Joe – the Shireys deserve a lot of credit for pursuing their very green project – they truly are green building pioneers who have been an inspiration for me and many others. It sounds like they are introducing more rigor into their pursuit of zero energy. I should add that zHome will be using SIPs for roofs (this is not stated on our website at this time). I should add that other differences are that zHome is an attached, market rate, production project (ie, uber green for the masses), and also as I stated above has performed a detailed, thorough energy model to demonstrate achievement of true zero net energy usage (again, assuming green oriented occupants). But at the end of the day, I’m just glad to see more advanced, ultra sustainable building going on – it’s time to quit messing around and change how we’re doing things.

    We will be adding a ton of technical details to our website (www.z-home.org) in the coming months so stay tuned there for more info (especially our Dig Deeper section and blog).

  8. Brad Liljequist

    Oh…and you might be wondering who the heck I am – I am the project manager for zHome for the City of Issaquah – which is spearheading the project.

  9. unbelieveable

    The zHome website doesn’t even mention the architect or engineers responsible in the “who’s behind it” section.

    Kudos to the city of issaquah for having the infinite wisdom to approve and administer approval paperwork for the project. Kudos to PSE, WAZU energy, King Co. and built green for endorsing themselves.

    Kudos to Vandervort, Howland and their team of uncredited professional engineers and consultants for actually doing the work.

    “Something for nothing” is right.

  10. unbelieveable

    oh and one more thing….
    Having some historical knowledge of both washington projects it is interesting that issaquah based Shirey was mid way through their 1 1/2 long plans review debacle when C of I decided to announce its own zero net energy project.

    Lets hope that future projects aren’t hampered by political Eco-one-upmanship.

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  14. Dan Bertolet looks at success, cost efficiency of Issaquah’s Z-Home « DJC Green Building Blog

    [...] forced the original builder to back out. Howland Homes took over in Summer 2008, and the project broke ground that September. Faced with financing challenges and delays, Howland then partnered with Ichijo, a [...]

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