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Passivhaus, Part 1: Concepts and Basics

The Green Architects' Lounge finally takes on the Passivhaus standard, the housing industry's simplest yet most rigorous and challenging energy consumption standard

Posted on Mar 29 2011 by Christopher Briley

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There's a perceptible buzz in the air about the Passivhaus standard within the green building community. In fact, it's becoming downright inescapable in these hallowed halls, forums, blogs, and seminars. So naturally it's time for the less-than-hallowed reaches of the blogosphere, such as the Green Architects' Lounge, to jump in and join the conversation.

Before you press download or play Part 1, I'd like to point out a couple of things. First, you may have noticed that we now reside in our own blog section (no longer under Design Matters), and for those of you who subscribe to us on iTunes, you may have noticed we now have our own dedicated feed — or rather, you may have noticed that this didn't show up on your normal feed. (It is great to be on our own, but we will miss the honor of sharing with Dr. Joe and Dr. John.) In my next post, I'll leave links and instructions on subscribing to the new feed. I'll also post instructions from the old feed itself.

Also, we have a new e-mail address. If you have a great idea for an upcoming topic, want to leave general feedback, or want to share your favorite cocktail recipe, you can e-mail us at GALounge@greenbuildingadvisor.com. If you'd like to complain about these changes, or the apparent irreverence of the hosts, or the many sentence fragments in my recorded speech patterns, you can email us at Complaints@StraightToTheTrashBin.com.

Now back to the topic at hand.

In Part 1 of the podcast, we discuss the basics:

  • "Passive houseA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates." is not the same as a "passive solar house"
  • The recipe for a passive house: thick insulation, elimination of thermal bridgingHeat flow that occurs across more conductive components in an otherwise well-insulated material, resulting in disproportionately significant heat loss. For example, steel studs in an insulated wall dramatically reduce the overall energy performance of the wall, because of thermal bridging through the steel. , air sealing, high-quality windows and doors, HRV(HRV). Balanced ventilation system in which most of the heat from outgoing exhaust air is transferred to incoming fresh air via an air-to-air heat exchanger; a similar device, an energy-recovery ventilator, also transfers water vapor. HRVs recover 50% to 80% of the heat in exhausted air. In hot climates, the function is reversed so that the cooler inside air reduces the temperature of the incoming hot air. (or ERV(ERV). The part of a balanced ventilation system that captures water vapor and heat from one airstream to condition another. In cold climates, water vapor captured from the outgoing airstream by ERVs can humidify incoming air. In hot-humid climates, ERVs can help maintain (but not reduce) the interior relative humidity as outside air is conditioned by the ERV.)
  • Why do a passive house?
  • Reduce energy consumption
  • Reduce carbon emissions
  • "Payback" will likely not be your reason
  • History of the Passivhaus movement
  • I realize that in Part 1 we haven't yet made it to the standards that clearly define what constitutes a passive house. That is the very topic of Part 2 of this episode. But if you can't wait, I urge you to click on this link to Dan Morrison's GBAGreenBuildingAdvisor.com pagee, "Passivhaus Homes are Extremely Tight and Energy-Efficient." That Web page is an aggregate source for links to GBA's extensive information on the subject of the Passivhaus standard.

    I mention in this part of the episode that I'm working on a passive house in Maine. If you are interested in following along, my client has started a blog for it. We're calling it EdgewaterHaus. I should also include this link to Passipedia and also to PHIUS.

    Stay tuned for Part 2, The Standards. Cheers.

    TRANSCRIPT

    Phil Kaplan: Today, we’re going to be talking about Passivhaus, a very exciting topic. People are starting to get to know what this is. It took them a little while to catch up with LEEDLeadership in Energy and Environmental Design. LEED for Homes is the residential green building program from the United States Green Building Council (USGBC). While this program is primarily designed for and applicable to new home projects, major gut rehabs can qualify. — they still call it “LEEDS.” But the tipping point for Passivhaus came about a year ago. It was an article in the New York Times about a couple who heat their house with nothing. It was the most e-mailed article from the New York Times website for weeks! All right, the energy geeks were out there! That was a good sign, and here we are.

    Chris Briley: Right now, I’ve just started working on my first passive house. You know, we haven’t done one of these on LEED, but that’s old hat now — and two years from now, maybe this will be.

    Phil: If you’re on Green Building Advisor, LEED is 'old hat' already.

    Chris: Before we dive into Passivhaus, it’s cocktail time. Cheers!

    [The guys talk about Man of the Moment and the practicality of keeping Grande Marnier in the glove compartment.]

    Phil: This is like a Shirley Temple with Scotch… OK, to dig into Passivhaus, let’s start with what Chris is working on right now. He’s more of an expert than I am.

    Chris: I’ll preface this by saying it’s all new to me. I’m not a consultant; I haven’t had the training. So, a passive house is…

    Phil: It’s not a passive solar house!

    Chris: Right. We get that a lot. A passive solar house recipe is a lot of thermal massHeavy, high-heat-capacity material that can absorb and store a significant amount of heat; used in passive solar heating to keep the house warm at night. , a lot of solar glazingWhen referring to windows or doors, the transparent or translucent layer that transmits light. High-performance glazing may include multiple layers of glass or plastic, low-e coatings, and low-conductivity gas fill., you’re heating with the sun — that’s passive solar design. The basic philosophy of Passivhaus is you improve the thermal envelope — you reduce the heat demand — so you can eliminate the mechanical system. That’s your cost-effective measure: You put your money toward the thermal envelope. The recipe is thick insulation — walls of at least R-40; elimination of thermal bridging — minimizing conductionMovement of heat through a material as kinetic energy is transferred from molecule to molecule; the handle of an iron skillet on the stove gets hot due to heat conduction. R-value is a measure of resistance to conductive heat flow. through studs; and airtightness. To severely restrict air leakage, you need a balanced energy recovery system. You actually have to submit recordings of how you balanced the system and what the settings are when you apply for the Passivhaus certificate. Windows are also a big part of the recipe — insulated glazing.

    Phil: Passivhaus takes thermal bridging to the next level, really examining every corner and every detail and every window.

    Chris: So, why do a Passivhaus?

    Phil: Buildings consume about 50 percent of our energy right now. If we want to change our world, we have to start with buildings. And who’s in charge of buildings?

    Chris: Um, me?

    Phil: Yeah, you are!

    Chris: All of us are…

    Phil: Yeah, architects and builders…

    Chris: The people who started the Passivhaus movement — their number-one reason? Climate change. That doesn’t resonate with the same power here in the States. There’s probably 30 percent of the community who won’t listen to that reason…

    Phil: It is sort of ephemeral, when people want to talk about payback immediately. And payback may be a tough part of the equation.

    Chris: Some people would be on board with the idea that the house is not just for them, but it’s also for the next generation. We’re trying to reduce carbon emissions, and some 40 to 50 percent of U.S. carbon emissions come from building centers — what houses consume and how we build them.

    Phil: It’s really about energy. It’s different from LEED; we’re not talking about recycled materials, just energy. The Germans have based this standard on a 90 percent reduction in energy consumption.

    Chris: Here’s a little history. In the 1970s, folks at the University of Illinois coined the term “superinsulation.” There was also a book by a Harvard physicist, William Shurcliff, called Super Insulated Houses and Double Envelope Houses, which always gets mentioned as an influential stepping stone. The folks in Europe looked very hard at what was going on at the University of Illinois and in this book. Sweden came up with rigorous energy standards, and a professor named Bo Adamson and a German physicist named Dr. Wolgang Feist designed the first Passivhaus, as proof that these standards were not only achievable, but could be surpassed and work. The heat load was 10 watts per square meter. Amory Lovins convinced Dr. Feist that he didn’t just have a science experiment, but something for the public; he could take this to the next step. So, in 1996, Dr. Feist founded the Passivhaus Institut, and using that first house as a model, came up with the Passivhaus standards. In 2003, I think, Katrin Klingenberg built the first passive house in the States—the Smith House.

    Phil: She got 14 inches of rigid insulation under the slab.

    Chris: People thought she went overboard…

    Phil: And then they saw the numbers and the feedback, and their eyes opened.

    Chris: Then she started the E-Co Lab to promote the Passivhaus idea. As these houses are built in the States, there’s a way to monitor and promote them. And then in 1998 along with builder Mike Kernagis, they founded Passive House Institute U.S., and now here we are with Passive House Alliances forming. There’s also a great resource now called Passipedia.com.

    [Part 2 of this episode is now available.]


    Tags: , , , , , , ,

    1.
    Mar 29, 2011 6:36 PM ET

    Thanks for the latest installment
    by Brian O' Hanlon

    I'll look forward to listening to this as soon as I can.


    2.
    Mar 29, 2011 8:50 PM ET

    Drawing the Line
    by deniz bilge

    While I understand the concepts idea behind Passivhaus, I still think it's WAY overboard. I have several points to consider. First, on any function curve, there is a point of perfect balance (or tangent)--in this case, a balance between energy efficiency and cost. Anything below this point means greater energy efficiency achieved with fewer dollars. Anything above the point means exponentially increasing dollars for linear increases in efficiency. It just doesn't make sense. For example --the woman who put 14 inches of foam under her slab must have paid between $11-15/sq. ft. for the foam. Data from the Census Bureau and the National Association of Realtors indicates that the average length of home ownership is 6-8 years. How long will it take to not only recoup her initial investment, but see return on it? How much money is really being saved here? (If foam isn't expensive enough, how about the difference between buying energy efficient windows on the mid-scale (R-6-8) vs high scale (R-11-14+)...It's definitely big bucks for not that much of a big deal in my mind. Besides, they're windows...are we not allowed to open them? God forbid we let any air in or out!! A bit overboard....

    Secondly, I think there's more to green building than creating an airtight refrigerator to move into. What's next -- air pressure regulatory systems like in airplanes? We'll have such airtight buildings that we'll have to mechanically control the air pressure and oxygen mixture too!! As well as moisture levels, etc...THIS IS WAY TOO COMPLICATED for a simple home which we go to in order to eat, sleep, shower, and if there's time, to relax. Once again--balance! In my opinion, there's nothing wrong with R-20 below grade floor, R-30 walls, R-50 ceilings, give or take. We're quickly transforming into a society that are first of all germophobic (hand sanitizers at banks!), and unwilling to deal with the elements. If it's 100 degrees outside, the inside of my house doesn't have to be 66. It's OK to be 82 degrees. Likewise, if it's -4 degrees outside, it's OK if it's 56 inside. Put a sweater on! I believe that human nature is to out do and over do and get carried away with that which starts out in good favor, to the point where we forget how we lived for the past 10,000 years.

    The state's (NJ) first PassivHaus certified home is currently under construction virtually around the corner from me. Here's the catch: It's to be 6,900 sq. ft.. Is it just me or is a 6900 sq ft house for a family of 4 a bit over doing it to begin with? And not to mention the clear cutting of 5 acres prior to building... I feel that there's no difference between this PassivHause project and another less stringently complying energy efficient house which is more reasonably sized.

    Next, what about all the trash? The more foam, the more trash. Recyclable or not, the shavings and scraps get blown around, and what is left to clean finds its way to the dumpster. Also, I sure hope none of these houses catches fire. I just don't see the big hype about extreme amounts of foam.

    I'm currently building a home for my family. I admit that my basement/foundation walls are foam icf, but the remaining of my half million pounds of concrete / steel house are breathable--mainly mineral wool, roxul insulation board. I think that homes need to be able to "breathe", in order to maintain relative humidity and to keep moisture constantly on the move. I simply don't buy into the idea that a house with no possible way to breathe other than a mechanical system is good for anyone or the house itself in the long term. Human kind was designed to breathe fresh air and be part of the environment around them. Like the difference between wearing a cotton shirt and polyester, a house needs to sweat properly, regardless of an ERV or equivalent system. The human error factor, specifically regarding potential sizing and performance problems of mechanical systems, in combination with another human element --laziness or unawareness of the homeowner (filter changes, system maintenance), poses a viable threat to this perfectly designed system. Let's not forget to consider power outages or other extraordinary circumstances which may lead to failure of a mechanical system.


    3.
    Mar 30, 2011 1:14 AM ET

    Edited Mar 30, 2011 1:16 AM ET.

    14" of sub slab foam
    by mike eliason

    ugh. can we please stop using the propotype/experimental house as the norm... bitte?!?

    take almost any project designed for a central european climate, migrate the project (via PHPP) to similar HDD in the united states, and it performs significantly better. the 'sweet spot' for central european single family homes tends to be between R-30-R-45, far below the R-65 slab mentioned above.

    the best windows coming out of europe are in the R-6 to R-8 range. and in a passivhaus - not only can you open them - but you can use them for ventilation when heat recovery isn't needed! just like a normal inefficient house!

    there is nothing wrong with R-20 below grade floor, R-30 walls, R-50 ceilings - if these will hit passivhaus - and they can in many parts of the country.

    superinsulation is not a requirement of passivhaus!

    did the NJ passivhaus grow 50%? last published numbers i saw had at 4400sf. still obese, but far from 6900sf.

    'house sweat' leads to mold - i can attest to that for the suburbs of DC and the pacific northwest. nice, black, respiratory problem-inducing mold

    finally, those that live in 500,000lb concrete/steel homes shouldn't cast green stones...
    300,000 lbs of concrete emits ca. 225,000 lbs of CO2 (on the lowside)..

    you could erect a solid 25' x 40' x 20' high box of type IX EPS and still have emitted less carbon than the amount emitted creating your concrete walls.

    and that's before you get to the steel (hopefully recycled), which emits even more CO2/pound than concrete.


    4.
    Mar 30, 2011 6:56 AM ET

    Edited Mar 30, 2011 6:59 AM ET.

    Breathing and Sweating?!?
    by albert rooks

    Hi deniz,

    Your confusing vapor management and air-sealing. They are two separate issues handled by two separate tasks.

    People need to breath. Houses (wall and roof systems) do not. By using Roxul and other vapor permeable layers in the right sequence, your wall system will allow water to exit and not remain trapped, leading to mold growth.

    When walls dry out by air movement, heat energy will leave with the water vapor. One of the reasons that Roxul is such a great insulation material is that it is typically dense enough to not allow air movement, but... It is vapor permeable. When it's vapor permeable, water will "dry out" of the system by evaporation.

    Regardless of the material, foam, cellulose, roxul etc... You can have a house very air tight or very leaky and still grow mold. That's a function of trapping water and is the outcome of poor design. It's not a function of being air tight.

    If you want to have healthy indoor air for the people inside the house, then exchange the indoor air with fresh clean air regularly by ventilation. A house without a ventilation system will pull the new air in through leaks in the construction at an unintended exchange rate. Air coming in through these leaks is picking up dust & debris. It's the least "clean" delivery system for fresh indoor air possible.

    Now compare that to a house with a ventilation system and no building leaks. It provides a steady exchange of fresh clean air by direct venting at an intended exchange rate. Route that air through a heat exchanger and you now have a steady stream of fresh air for people, while leaving most of the "heat energy" inside.

    It's a much better design! Clean air for people, and moisture management for the structure holding the heat inside.


    5.
    Mar 30, 2011 7:31 AM ET

    Response to Albert Rooks
    by Martin Holladay

    Albert,
    Do you have a source to back up your statement, "One of the reasons that Roxul is such a great insulation material is that it is typically dense enough to not allow air movement"?

    I don't think that's true. Mineral fiber batts are air-permeable, like fiberglass batts, and they cannot be used as an air barrier.


    6.
    Mar 30, 2011 7:07 PM ET

    Edited Mar 30, 2011 7:13 PM ET.

    To Deniz
    by Christopher Briley

    Making an "argument" for why we should all build to a passive house standard is akin to making the argument that we should all put PV panels on our house. Everyone places a different value on different things. For some it’s money, for others it’s consuming less fossil fuel.

    So to your first point, using present-day economics as your primary metric, it is very hard to have the passive house standard "make sense" as you put it. The person designing to this standard is more than likely thinking about future economics as well as their own impact on the earth's climate, and the building's future burden (or lack thereof) on its future occupants. (Spoiler Alert: in Part Three Phil and I chat about his own feelings about this issue. He feels much more comfortable talking about Net-Zero mostly for these economic reasons.)

    10 years ago many people would have thought the very house you described, and are about to build, would be going WAY overboard. I wonder, 10 years from now, what will we think of these passive houses? Seriously, I wonder.

    Albert spoke very well to your second point about breathing buildings. A healthy house leaks, and energy efficient house controls how it leaks. (I'm not sure I can take full credit for that expression, I've been saying it for so long.) I'd just also like to point out that for those who engage in high altitude or cold condition expeditions, cotton is also known as the fabric of death for its inability to deal with moisture and air movement properly. (But I get your point ;) I'll only add that sealing a structure and adding an HRV or ERV is not at all complicated. (though sealing to 0.6 ACH50 is indeed challenging, I'll grant you that)

    Chris Briley, Architect


    7.
    Mar 30, 2011 7:09 PM ET

    concepts and basics
    by deniz bilge

    Mike, --. Trees emit CO2, not steel. no further comment.

    Albert,
    I just don't agree. There's a difference between water and water vapor. To illustrate what I mean, here is a brief excerpt of a paper:

    "Vapor permeability is a property reflecting the rate of movement of water
    molecules, H2O, directly through a material. It should not be confused with
    infiltration, which is leakage through gaps between separate pieces of material.
    Rather, permeability is determined by the openness of the physical structure
    within the same material, such as wall board, insulation or a vapor barrier.
    Moisture transport due to permeability is usually small compared to that from
    infiltration and ventilation, wherein the major water vapor transport mechanism
    is its movement in flowing air. However, permeability in
    the right kind of materials does play a profound role in allowing moisture to
    escape from building materials before mold formation becomes a problem.
    The physical process responsible for vapor permeability of a building envelope is
    called diffusion. Matter is transported spontaneously as a result of the intrinsic
    kinetic energy and random thermal motion of molecules. Within a gaseous
    medium such as air the individual molecules mix and redistribute. There is no
    bulk flow; that is, no net transfer of mass to or from any region of interest.
    Diffusion of moisture in air involves movement of water molecules as well as the
    molecules of oxygen, nitrogen, and minor components such as carbon dioxide.
    Net diffusion is driven by a gradient of airborne water vapor concentration or
    H2O partial pressure. Water molecules dissolved in the vapor phase are
    spontaneously transported from volumes of higher concentration to those of
    lower concentration, until the concentration is uniform. This slow process is
    affected by both temperature and pressure.
    In the initial phase of diffusion, the
    molecules of different gaseous components are far from equilibrium. In the
    extreme, simplistic case that is illustrated, let us suppose that all of the molecules
    inside the “home” are water vapor and that all of the molecules outside are
    oxygen, just one component of air. (Of course, there is no such thing as an
    “air” molecule!) As diffusion proceeds (intermediate drawing), water molecules
    begin to move outside and are replaced by oxygen molecules moving inside.
    Finally, if and whenever the system reaches equilibrium, all of the molecules are
    uniformly distributed although still moving randomly".

    *This information is credit to Neil May of Natural Building Technologies in the UK;
    His paper, entitled Breathability: The Key to Building Performance.


    8.
    Apr 1, 2011 5:35 PM ET

    Edited Apr 2, 2011 1:40 PM ET.

    @ Chris Briley
    by Brian O' Hanlon

    The person designing to this standard is more than likely thinking about future economics as well as their own impact on the earth's climate, and the building's future burden (or lack thereof) on its future occupants.

    Coming at it from the point of view of an architectural training, I think Chris is pulling punches. Holding back. People, (that is clients and their design consultants), may be building Passive homes in the 2010's, to prove to themselves that it is possible, and that they can. What I mean is, Mies van der Rohe and Ms. Farnsworth collaborated on a house together, to show how a definition of living could be expanded in new directions, in 1950s America. At the same time I guess, as society around it was expanding and evolving in many ways.

    The same with Neutra on the west coast. They were looking to define a relationship between themselves and that new landscape, that new urbanism of the west coast. Not always succeeding, but trying all the same. Were the efforts of the earlier practitioners any less Green, or natural than the passive house is today? At least in aspiration terms.

    Not saying that the 1920s or 1940s design, would stand up to todays energy conservation regulations. One looks at photos from that earlier era. People were willing to endure more and wrap up in clothing. They had less comfort and expected less. Would the Farnsworth house be any less spectacular with PV panelling? Would that be vandalism? How about a satellite dish for 99 channels of TV? Would that less the tone? How about the Villa Savoie, heated using a ground source heat pump? I am sure it would improve the comfort levels, and Le Corbusiers architecture is robust enough to take that kind of mechanical addition. It was designed in the spirit of machines after all.

    Lets be honest. A photograph of a 1920s villa, may show an attractive lady lying back relaxing in a Le Corbusier designed lounge chair. But, in real life, was she really that warm and comfortable to stay in that position for longer than the photo shoot?

    So the question is, are we seeing an image of how people really lived in Le Corbusier's villas in the 1920s? Or are we looking at a vision of a way of life, that Le Corbusier epoused to, but could not quite achieve or deliver? That is, a bit like a photo of a person using a personal computer in the 1980s, and pretending, this is so totally awesome. When we know now, that poor guy probably had to work with a blinking, monotone screen, and not HAL 9000.

    Okay, so in 2011, Le Corbusier's villa Savoie would have its own wireless network, and the lady on the lounge chair would have a netbook. Would it decrease from the architecture? Hardly. I could not think of a more high tech environment in which to browse the GreenBuildingAdvisor website, than in Villa Savoie.

    I own a nice photo book of different generations of computer technology from the World Wars onwards. I always found it interesting, because the relationship between people and their technology changed so rapidly over the 20th century, as did their relationship with their living space.

    Or did their relationship to their living space really change that much? Isn't it interesting, that after personal computer technologies and multimedia, we are adopting the cellular plan more and more, to enable more privacy and working alone. Which is different to the open plan idea of the 1920s, and 'modernism', before they had computer technology. So much for the lady in the lounge chair using her netbook.

    One thing I do know, is that the 1920s and 30s in Europe was an era of great passionate debate about architecture and design. When I read the following from Mike Eliason's blog entry here at GBA, Amazingly, instead of deflating all 170 attendees, reactions were varied — agreement, disagreement and probably even a little rage!

    I could not help but remember the pages I read in architecture school, from Le Corbusier's early, angry manifesto, Towards Architecture.


    9.
    Apr 1, 2011 5:45 PM ET

    Say what??
    by Garth Sproule 7B

    Deniz says;
    "Mike, --. Trees emit CO2, not steel. no further comment." HUH???


    10.
    Apr 1, 2011 6:10 PM ET

    Edited Apr 2, 2011 1:48 PM ET.

    Second Part of the Above Contribution
    by Brian O' Hanlon

    I was joking sort of, about der Rohe and Farnsworth in collaboration. It was more of a one way street than a collaboration. Are designers today imposing a philosophy upon their clients as der Rohe did back then? I leave that question for people to consider.

    Rietveld and Schroder did have a real working relationship on a dwelling project in Holland, by accounts I have heard close to the source. Ms. Schroder would not give up on Mr. Rietveld until he had scrapped several some earlier designs, (wait for it), which did not go far enough. Is the conversation that different in 2011, as when the Shroder house was first conceived?

    There you have it. We build sometimes to prove to ourselves that it can be done. The definition can be expanded, it can evolve. Maybe we can build a dwelling, in order to imagine what a future may look like. Maybe we are guilty of trying to imagine something that is too different from a reality. Maybe sometimes, we are guilty of not trying to imagine at all. The relationship between the client and architect, is often such that one party is left out of the loop. That is, not made aware of the full ambitious-ness of the goal, by the other party. The client may think they are getting a house, not trying to expand the definition of living itself. Sometimes, the client may be chasing after a definition of living, but all they receive is a house. My Luis Barragan example below will try to demonstrate that concept.

    I remember a funny story told about Frank Llyod Wright. He was invited to a party at Philip Johnson's glass house one evening. Wright spent the evening walking around the house and knocking at the panes of glass. He was pretending to be confused, and could not find the entrance. It was a subtle way of telling the audience present, that his conception of a dwelling was not compatible with Mr. Johnson's statement. I wonder, if there was a party in a Net Zero house, attended by a Passive house group, would they would find ways to poke fun at the other's design philosophy? Or visa versa. There is something to think about.

    I used to have a video link once, to a documentary about El Pedregal. El Pedregal was one of my favourite architectural works in housing and residential planning that I knew, during my time as an architectural student, only from books. I would sit and stare at the images of Barragan's project at El Pedregal in astonishment. Then I discovered the YouTube video. It turns out that El Pedregal was purely an advertising campaign and a land speculation, which Barragan himself benefitted from. He sold the idea of this new way of living, to a new middle class in Mexico city. The reality as it was built, Barragan making a lot of money on the land sales, was nothing like in the photographic images I knew from my days as an Architectural student.

    Is the Passive house to modern day America, what El Pedregal was to the young Mexico city middle classes? There is a something for Phil and Chris to chew on. With that I say all the best, until I think of something other to contribute.


    11.
    Apr 4, 2011 7:40 AM ET

    economic payback
    by darald bantel

    I noted a comment which accurately indicated that the economic payoff to a Passivhaus was definitely longer than the average ownership period in North America. Perhaps that is the problem. Houses are designed to last possibly 1 generation and built, most often, to minimum codes. Hmmmmmmmm and we wonder why housing is considered disposable. If we looked at residences as 200 (perhaps even longer) residences we would be less concerned with a 3 year payback as a 10 year pay off would still be great.

    I helped a friend build a house in the mid 80s who went to R 40 walls and R 60 attic. I asked him a few years ago what he would do if he were to build again (he isn´t!). His comment - - I would use even more insulation. His house was perhaps the most comfortable home I have ever been in the North America (besides having an incredibly low heating bill for his area!!).


    12.
    Apr 4, 2011 9:44 AM ET

    Edited Apr 4, 2011 9:49 AM ET.

    Passiv Haus Standard
    by James Hoffman

    With respect to the NJ PassivHaus of somewhere between 4000 and 6900 sf., I thought the standard was something akin to 500sf/occupant. So, how can a 4000sf house for a family of 4 even qualify? Of did I miss a change to accommodative US tastes for big houses?

    As to 11" of foam under a slab,I wish I had done that instead of 12" of engineered, compacted fill +2" of foam on my certified Net Zero Energy home!


    13.
    Apr 4, 2011 10:34 AM ET

    James, The model would have
    by mike eliason

    James,

    The model would have to pass at 537sf pp max (roughly), so with 7.5 people (I don’t recall off-hand how rounding is done and don’t have the manual in front of me).

    I think this means the measured energy usage would be slightly higher than actual, due to increased modeled electrical loads, increased water heating, etc.


    14.
    Apr 4, 2011 10:55 AM ET

    Edited Apr 4, 2011 11:03 AM ET.

    per SF not per person
    by Christopher Briley

    James,
    At the moment, the Passivhaus requirement is based on square footage not occupant load. There is activity at the Passivhaus institute to consider 'per occupant' standards, possibly giving you the choice of 'per occupant' or 'per SF'. But at the moment (as far as I know) it is still per SF. The primary reason for this is that occupancy, over time, can change. An exrtra large house that used to only house a couple and their butler, could now be divided into 12 condos, or even be turned into a hotel. Likewise, somene might buy up 8 condos, and turn them into his own off-season bachelor pad.

    'Per Person' relates to the community and geo-political consequences.
    'Per Square Foot' relates to the building itself without regard to community or geo-political consequences.

    Brian,
    I for one enjoyed the Van der Rohe and Farnswort analogy and find it to be quite apt. I also enjoyed the Frank Lloyd Write story, I hadn't heard that one before. And thanks for making me look up El Pedregal!

    Chris Briley, Architect


    15.
    Apr 4, 2011 1:51 PM ET

    Architectural References
    by Brian O' Hanlon

    It would be no good at all, if someone didn't challenge you to position yourself in relation to the classical icons of 20th century architecture. There has to be some attempt at theoretical polo-neck-ery in the middle of all this common sense and heat loss calculation. B.


    16.
    Jan 17, 2012 6:45 PM ET

    Passivhaus Consultant - Listener from Ireland
    by Darren O Gorman

    Enjoyable Podcast - interesting comments also.


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