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Musings of an Energy Nerd

Report from the Passive House Conference in Maine

Dr. Wolfgang Feist came to Portland to deliver the keynote address

Dr. Wolfgang Feist, the founder of the Passivhaus Institut in Darmstadt, Germany, delivered the keynote address at the recent Passive House conference in Portland, Maine.
Image Credit: Image #1: Scott Gibson

The North American Passive House Network held a two-day conference in Portland, Maine, this month. The well-attended conference drew attendees from all over the U.S., as well as from China, the U.K., and Germany.

Because it was a four-track conference, it was impossible to attend every session — a frustrating fact for attendees. Many of the experts who gave presentations at the Portland conference have written for, or been featured in, Green Building Advisor; among the familiar names were Matthew O’Malia, Chris Corson, Dylan Lamar, Malcolm Isaacs, Nabih Tahan, Peter Schneider, Graham Irwin, Marc Rosenbaum, Tim Eian, Jesper Kruse, and Phil Kaplan.

With so many smart people gathered together under one roof, the conversations in the hallways and at the lunch tables were almost as valuable as the presentations. Like most people who attended the conference, I learned a lot while I was there.

It was exciting to see so many consultants, designers, and builders present their latest projects. These construction professionals are doing excellent work. At the Portland conference, they talked about their mistakes, presented information on new methods, and shared data. In many cases, Passivhaus builders are discovering new, less expensive ways to build excellent buildings — including some of the best homes being built in North America today.

Dr. Feist flew in from Europe

Dr. Wolfgang Feist, the founder of the Passivhaus Institut in Darmstadt, Germany, gave the conference’s keynote address on Monday morning, September 22.

According to my notes, Feist made five important points:

  • The Passivhaus standard is based on science.
  • Building to the Passivhaus standard is cost-effective.
  • There is no need for climate-specific standards.
  • The Passivhaus Institut has developed a primary energy factor for renewable energy.
  • The Passivhaus Institut has announced three new construction standards.

The Passivhaus standard is based on science

At the…

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  1. Expert Member
    Dana Dorsett | | #1

    But Martin, you just don't get it...
    ... Feist's amplifier goes to FIFTEEN , not just 11 ( which is already better than 10!) :-)

    The whole notion that the magic 15 kwh/m2*year number (or any other number) works everywhere and for all time as the energy use for emitting the occupant's "fair share" of atmospheric carbon is shrouded in mystery, and highly suspect given that not all energy sources emit the same amount of carbon.


    "Feist calculates that a house can’t truly be considered net-zero unless it has a PV array that generates about twice as much electricity on an annual basis as its occupants use."

    That is a crude but not entirely incorrect estimate, but that will become more affordable than building to PassiveHouse energy use levels in cold/very cold climates within 20 years, given price trajectory of the long term 15-22% "learning rate" of PV. At the more recent ~40% learning rate it could be true in under 10 years:

    A PV array that size might not fit on the house with only ~R35-R40 wall type construction at 15% panel efficiency, but in many instances that is not a huge constraint. The upcharge for ~20% efficiency panels right now is not huge, and 20% efficiency will likely become the standard commodity panel efficiency by 2030.

    Given that these price points for PV will be met WELL within the lifecycle of a house, the rationale for building to a 15 kwh/m2*year spec a cold climate today needs a firmer footing, and needs to be better explained.

    It's not clear exactly if/when ~30% efficiency perovskite/silicon hybrid panels will become commercialized commodities, but if/when that day comes, a PV array that delivers 2x the homes energy use will fit on the roof at well below PassiveHouse insulation levels, even in Minneapolis or Fargo.

    The rigidity behind Feist's thinking is hard to figure, and that rigidity is not particularly useful in the face of a transforming energy reality.

  2. kevin_in_denver | | #2

    Another Arbitrary Number: 2X
    "Feist calculates that a house can’t truly be considered net-zero unless it has a PV array that generates about twice as much electricity on an annual basis as its occupants use."


    I don't see how an off-grid house without fossil fuel usage WOULDN'T be "net zero" by definition.

  3. STEPHEN SHEEHY | | #3

    Extra PV production
    Here in Maine, if we produce more PV power than the amount we use, on an annual basis, the power company keeps the excess. As a result, on my new house, I have a financial incentive to size the system to produce just what I expect to use over the year because I'd be paying for panels that produce power for Central Maine Power, not for me.
    I'd rather give the excess to my neighbours than have CMP sell it to them.

  4. Expert Member
    Dana Dorsett | | #4

    Still, Kevin...
    ...the presumptive model is still grid-tied, not off-grid.

    It's an arbitrary number that lacks precision, but would be pretty-much true in many cases. The current costs of going off-grid with most/all of the energy use from PV + batteries is pretty daunting, even at PassiveHouse energy use levels.

    Battery storage costs should be coming down as electric vehicle market penetration rises, but there isn't a good enough relevant history on battery technology to derive a learning rate from which to project storage costs. Battery technology has seen something more akin to quantum shifts rather than the decades long logarithmic decay curve seen in PV or wind power.

    For all of the "...Feist calculates..." clauses floating around the PassiveHouse world, the actual math would be far more interesting to see than the mere answer. Peer review can get to the underlying assumptions, and the validity of the model as applied in other circumstances. Asking the world to take the magic number results as fact merely on his say-so feels a bit off. There are many unstated underlying assumptions, particularly about the carbon content & financial cost of future energy that would skew the answer, yet the number is always " 15 kwh/m2*year ". ( It feels a bit like "faith-based science" to this humble observer. The number is right, so we must make it so. )

  5. GBA Editor
    Martin Holladay | | #5

    Response to Dana Dorsett (Comment #1)
    You call Feist's proposed primary energy factor for renewable energy "a crude but not entirely incorrect estimate."

    I think that his reasoning is defensible. He explained where the math came from; at least he's made an attempt to come up with a way to account for this problem -- how to deal with the fact that PV-equipped homes in cold climates require more electricity in the winter than the summer, but produce more electricity in the summer than the winter.

    My gut feeling is that the factor developed by the Passivhaus Institut is more of an academic exercise (a useful one, to be sure) than an actual prediction about the widespread deployment of hydrogen electrolysis equipment.

    Here's the thing, though: this issue is a three-dimensional chess game, and the rules are changing every month. While Feist is looking at this issue from an energy perspective, most homeowners will look at this from a cost perspective. If my local utility wants to buy my PV-produced electricity for 6 cents/kWh, and wants to sell me electricity for 12 cents/kWh, I will have a strong incentive to find ways to use my PV electricity directly (on site) rather than sell it. That will quickly change consumption patterns (and will be a driver for the development of new types of appliances).

    The bottom line: the most important moving piece in this chess game is the net metering contract offered by utilities. The details of those contracts are political issues -- they have nothing to do with energy calculations, physics, or mathematics.

  6. GBA Editor
    Martin Holladay | | #6

    Response to Kevin Dickson (Comment #2)
    You called Feist's proposed primary energy factor for renewable energy "another arbitrary number."

    But it's not arbitrary. It was calculated, and he explained his reasoning and the math. If you want to develop a different factor, you are free to do so -- and to provide your own reasoning.

    You also wrote, "I don't see how an off-grid house without fossil fuel usage WOULDN'T be net zero by definition." Well, I live in an off-grid house, and so do many of my friends. None of us are capable of living without fossil fuels. Even in the old days, before I began using electricity, I had kerosene lights. All of us use gasoline or propane to fuel our generators in November, December, and January.

    I know of one off-grid house that is fossil-fuel free; it is powered by hydro power. I am sure there are a few others like it, but they are rare.

  7. GBA Editor
    Martin Holladay | | #7

    Response to Stephen Sheehy (Comment #3)
    Thanks for your comments. You wrote, "Here in Maine, if we produce more PV power than the amount we use, on an annual basis, the power company keeps the excess."

    Your point is relevant. The most important factor determining whether homeowners want to install a PV array, and how big the array should be, is the net metering contract offered by the local utility. Those contracts are all over the map, and are changing all the time.

  8. GBA Editor
    Martin Holladay | | #8

    Response to Dana Dorsett (Comment #4)
    Although the cost of battery storage may be coming down, I agree with Feist that the use of batteries for seasonal storage of electricity is a pipe dream. Off-grid homeowners can't use batteries to save electricity produced in July for use in January.

  9. user-1072251 | | #9

    PHIUS vs PHI
    First, I haven't built a Passive House so this issue has not affected me directly. I consider Dr Feist's work in compiling and analyzing the results of the work of so many building pioneers, then working out a mathematical model to aid in the design to be both groundbreaking and invaluable to today's builders, as clearly demonstrated in North America by the many builders who have utilized his techniques, whether in building certified buildings or not. The Maine conference was interesting in that there were as many or possibly more non-certified building discussed as those certified by some entity. So in that, this community seems to agree with the approach taken by Mark Rosenbaum, Martin and others. What confuses me is why the organizations involved have chosen to align themselves with PHI who seems to be saying "my way or the highway". What is the rational for aligning with one or the other organization? By the way, I originally thought this was the PHIUS conference;it wasn't but was a great conference and I thank all of the people that worked so hard to put it on.

  10. Expert Member
    Dana Dorsett | | #10

    Sure! (Response to Martin)
    Yes seasonal battery storage sufficient to heat/cool the house won't be viable any time soon- which is pretty much what I said (or thought I said, anyway, though in the re-read that isn't so obvious).

    And I was agreeing with Feist that it would take roughly 2x the amount of PV-sourced energy that the house would use annual to make it net-zero, give or take. (In some instances it might only be 1.5x, others it might be as high as 2.5x, but it's the right ball park.)

    My primary point was that the cost of PV sufficient to supply 2x the annual energy use (at well under PassiveHouse envelope performance) is soon going become more affordable than building the envelope to PassiveHouse levels. It may be within a decade, but it will be at most two decades. The multiple references I linked to in support that point are more than idle armchair theory.

    By 2030 PV is going to be dirt-cheap. It's already cheaper than $100/bbl oil on an end-use basis- either leveraged with heat pumps at 3:1 or even automotive use (due to the abyssmal thermal efficiency of internal combustion compared to EVs, even with grid-losses factored in. See: ) We have to stop thinking of PV as expensive energy. What was once true is far less so today, and it will become the cheapest energy source around before a decently built house is even 1/4 way through it's lifecycle.

    And that's independent of any issues about net-metering, etc, the long term price of electricity, etc.

    On that point, if the utility will only pay 6 cents and charges you 12, local storage sufficient for supporting several hours of house load or net PV output is already close to affordable, and will clearly be affordable before 2025 (maybe before 2020) if electric cars take off. Grid defection is already financially rational on a lifecycle basis in Australia, where the residential retail rates are about 30-35 US-cents, and they get paide only 12-15 cents(?) for any instantaneous excess being supplied to the grid. Even with that onerous not-so-net metering scheme the cost of electricity is high enough there that (with incentives and regulatory permission) PV penetration is quite high, but the current administration seems hell bent on dialing all that back in an (ill-considered, IMHO) attempt to save the flailing Australian coal mining industry, now that both China & India are cutting back on imports. The imbalance between what the utilities pay and what they charge means that the financially-optimal array size is much smaller than in the US where net-metering is in effect (1-3kw vs. 5-10kw). But driven by high electricity prices, the total amount of distributed PV is 3-4x that in California, which has a similar sized population.

    As both PV and storage gets cheaper, inequitable compensation schemes will inevitably drive people off the grid, provided they have the real estate and finances to do so. The West Australia grid is particularly at risk, since the high PV penetration has resulted in them having to increase rates to cover their sunk costs on now-stranded generating assets. But as the rates rise, the more rational it is to simply un-plug, and buy more PV + battery.

  11. GBA Editor
    Martin Holladay | | #11

    Response to Dana Dorsett
    Thanks very much for your comments. We're in agreement. (My responses to your comments were intended as clarifications, not disagreement.)

  12. Expert Member
    Dana Dorsett | | #12

    More on the grid-defection tipping points...
    ...can be found in Morgan Stanley's analysis 2 months ago:

    (The section most relevant to the US utility markets begins on page 36.)

    Bottom line, those utilities who can't figure out a better business model reaction to the looming PV tsunami are doomed. It's already cresting in Hawaii (where some analysts give them 5 years at most before the utilities are bankrupt, despite belated attempts to readjust.)

    The retail cost of energy is likely to begin falling by 2030, according to multiple banking sector analyses, whereas most of the cost-effectiveness calculations on building envelopes I see presume the energy price inflation rate seen since 1970 (or even higher) will continue in-perpetuity, or at best level-off. That presumption would appear to be no longer true.

    And just as it should give the oil-industry & utility businesses pause, builders of high-performance buildings need to re-calculate their assumptions too. It's unlikely that retail priced electricity can rise to much more than the lifecycle cost of PV installed in 2014, which is already at grid-parity in many parts of the US. By 2025 new PV will be at grid-parity everywhere in the US, which will put serious downward pressure on energy prices in multiple sectors. That will reduce the financial value of that "extra" R30 or whatever that it takes to hit PassiveHouse levels on a house built in 2014.

    In effect, the sunk cost of that much-higher R house becomes a stranded asset, just as much as developed oil fields & reserves that can only be extracted profitably at a world price of $100/bbl or $125/bbl will have zero value as the transportation paradigm shifts. Sure, it will be slightly cheaper to operate than a mere net-zero type house, but not enough to ever recover the sunk costs.

    It takes a much clearer crystal ball than I own to know exactly when general energy costs will begin to erode, and how fast it will sink. Future energy costs have always been tough to call, but the 3-4 decade habit of prognosticators has been to overestimate future costs. But the PV curve is finally hitting the crossover points with rising fossil-energy price inflation (which was a very volatile & noisy signal in the first place), which will disrupt the trend since 1970. Future of energy pricing can't be derived from past performance, and unlike fossil fuel prices, the energy cost of PV for the next 20 years is known the day you sign off on the financing & install it, and it is continuing to get cheaper to install every year. That is a setup for energy price deflation, which is unfamiliar territory for the energy markets.

  13. GBA Editor
    Martin Holladay | | #13

    Response to Dana Dorsett
    I agree with your comment: "It's unlikely that retail priced electricity can rise to much more than the lifecycle cost of PV installed in 2014."

    I wrote something similar in an article published in 2011: "It’s hard to imagine a future in which energy costs rise to a level that is higher than the current cost of PV ... If you add more insulation than this benchmark justifies, you are planning for a future that will never come."

  14. Robert Swinburne | | #14

    Forest for the trees
    I seem to remember in my own Passive House Consultant training that the metrics were based on being able to heat a house in Germany with supplementary heat in the air exchange system rather then a separate heating system. If so then the regional approach is faulty as PHIUS claims. I have managed to pay little attention to this whole debate. What drew me to the Passive House crowd was that these folks are at the bleeding edge of building science - figuring out what works, what's going to last, what represents the simplest solution to the problems etc. Regardless of whether a building achieves certification or not. I had a great time at the conference and thoroughly enjoyed Mark Rosenbaum playing devil's advocate with the whole excessive foam under the slab topic. I think he did too.

  15. Expert Member
    MALCOLM TAYLOR | | #15

    Reply to Robert
    Regardless as to which side (if any) you take on the Passive House squabble I agree we all owe a debt to the "crowd" for their work advancing energy efficiency. I'm not as convinced about their approach to what's going to last. A lot of the materials and envelope build-ups used in these houses may prove to be a lot less resilient than the leaky under-insulated buildings they replace. I notice a distinct tendency to relegate issues of structure and longevity to a back seat while the adherents concentrate single-mindedly on increasing efficiency.

  16. GBA Editor
    Martin Holladay | | #16

    Response to Robert Swinburne
    Thanks for your comments.

    You wrote, "What drew me to the Passive House crowd was that these folks are at the bleeding edge of building science - figuring out ... what represents the simplest solution to the problems."

    Not every Passivhaus designer follows the path you recommend, however. John Straube and Marc Rosenbaum have done a good job showing that $3,000 of extra sub-slab foam (required to meet PHPP targets) often saves much less energy than the installation of $3,000 of PV modules (not a solution usually endorsed by Passivhaus designers) -- raising an important question: Which solution is simpler? Certain, the PV route is cheaper -- and puts more money every month in the homeowner's pocket.

  17. Robert Swinburne | | #17

    It's all good.
    Then there is the embodied energy of panels and how long do they last etc. I studiously avoid such questions for I am only an architect and more concerned with the big picture, plus designing pretty things. I have to laugh at the current Net Zero vs Passive house discourse because "it's all good!" The bar is being raised and that's a good thing right? Plus there are sites unsuitable for PV (my own house) We are looking into community solar however...

  18. Expert Member
    Dana Dorsett | | #18

    And that was at 2011 PV prices! (response to Martin, #13)
    In 2011 the installed cost of sub-10kw grid-tied rooftop PV was over six bucks a watt. In 2009 it was over $8/w. See the graph clipped from a Lawrence Berkeley analysis:

    The cost has been fallen about 40% since 2011, more than 50% since 2009!

    I've personally reviewed quote for $3.75/watt rooftop installations, but that was SOooooo Q1 2014. I'm sure somebody in my neighborhood has installed PV for less than $3.50/watt by now (pre-subsidy.)

    Like the electric utility companies, I expect Darmstadt didn't see this coming, and when the did see it they continued to be in denial for some time. It seems as if PHI is still in denial mode (as are many US utilities), but reality is, they're installing PV on roofs in Germany for under $2/watt right now, at a levelized cost of about 8 euro-cents ($0.10 USD), per the Fraunhofer paper I linked to in my first post on this thread.

    That's 75-80% cheaper than in 2007 when Feist was protesting:

    “At the moment, the cost of electricity produced by photovoltaics is in the range of 40 to 50 cents per kWh, which is still ten times the cost of electricity produced by oil or gas,”

    All kidding aside, if PassiveHouse building envelopes were possible to challenge on lifecycle cost grounds relative to PV prices 5-7 years ago, given the price trajectory PV has taken since then, it's a truly daunting rationale to be making today, now that it's 2014 cost is a few nickels (if not quite pennies) on the dollar.

    The world has changed, yet 15 kwh/m2*year has not. Why?

    PV is now cheaper than just the marginal FUEL cost of electricity produced by oil (forget amortizing the capital cost of the generator), if still more expensive than the lifecycle cost of natural gas in a new combined-cycle power plant at recent US gas prices (assuming gas prices never rise.) It's only a matter of time before that threshold has been crossed too. (Wind power at a paltry 25% capacity factor is already cheaper than new cc gas in the US.)

  19. ErgoDesk | | #19

    The Passivhaus standard is based on science
    The Passivhaus standard is based on science, yes, but is being executed by full and part time idiots. In an effort to find a new income stream for their business. Many are using old and outdated methods to accomplish this ever changing science. It's time to stop this herd mentality and put the science into the construction methods and materials as well as the strong science behind the "Passive House" package.

  20. Marc Rosenbaum | | #20

    Consequence of low cost PV and net metering going away
    As people have commented above, notably Dana, PV costs have dropped and the utilities are fighting a last ditch effort to roll back net metering - they came very close to succeeding in MA in July. My crystal ball is not great, but I think that if our approach is not absolutist (i.e., we must replace ALL imported energy used in the building) then near-term technologies in most US climates are going to substantially reduce our need to do the import/export net metering game seasonally and daily (daily is important - in my last house, I used 17% of the PV generated on site, and exported 83% of it, so net metering was critical). CO2 based heat pumps making high temperature water will allow us to store hot water during the day in the heating season and heat the house and provide DHW at night. Li-ion batteries will allow electricity storage to run the lights and appliances for a couple of cloudy days. The winter won't be without some energy importing but it will be small. The summer will have an excess and perhaps that will be traded for the right to export onto the grid, or will fuel electric vehicles.

    Finally, I don't understand why a kWh exported in the summer, assuming the load is there on the grid, doesn't offset as much fossil fuel as one generated on site in the winter that avoids the import of a unit of fossil fuel or electricity. Burning less coal or nat gas at any time of year is good.

  21. jinmtvt | | #21

    PH is a religion :p
    Again thanks Sifu Martin for the nice sum up of the conference... i really missed the boat, really wanted to be there with you and learn more from all that was time maybe.

    Dana : ahhahahah i love that "Nigel" youtube...i'll bookmark it for future use on n00bs i meet . !!! haha

    Back to topic...

    Even for a beginner as myself, the rigid PHI standard seems completely absurd,
    and defending it makes dr Feist look very bad in my book.
    I can only imagine how that works in some of your "advanced" brains :p

    But then, i always have the tendency to think of European buildings are very long lasting ones.
    How many times we see very very old buildings still fully functional in most of european large cities.

    If you think of PV versus insulation, insulation wins the efficiency race because of TIME.
    That cannot be argued over, insulation should still be saving energy without any maintenance or replacement on a well designed building much longer after PV will have had to be replaced,
    and even if newer PV modules in 30-40years achieve higher efficiency, they will still need to be purchased and some energy/materials is used in the manufacturing.

    This is where as Malcolm i believe pointed out, longevity of builiding designs needs to be brought back from the corner it has been pushed in the last decades.
    ( just look at Martin's article on old building archtiectural flashing as an example )

    I have seen many 200+W full panels listed for less than 0.75$/w bought in pallet quantities recently.
    Anyone with a little man talent should be able to install any size of array on its property for less than 2$/W already.
    Even with my local Hydro situation of 0.6-7$ a kwh, this would push payback to lower than then warranty of 25 years most panel comes with now ( i calculated around 18-20 years current payback time ...waiting for 15 or less to jump on it now )

    As Dana pointed it, and as Martin predicted it in 2011 ( WOW! u guys never cease to amaze me! )
    Energy prices AREN'T going to go up as much as predicted in the recent past at all.

    Then, the more i read about Co2 and other pollutants on earth, the more i steer away from the "green road" of building efficiency and drive toward economics reasons. The only reason why buildings thermal regulation have been large polluants in the past was because most of US use of fuels for heating. ( we almost fell in this trap here in the 50's to the 70's ).
    This is rapidly changing with PV, cleaner sources and recent efficiency of HP .

    These times are very encouraging for energy efficiency and a less FF dependent future
    ( which is what we all want , but does not seem to be regulated for the REAL offenders )

    BUT it is also a very CONFUSING time for newcomers as myself who are trying to understand
    where we are all going and what is the best path to choose for a "healthy" future.

    I am only 35 old, and i would very much like to build super high performance buildings in the near future ( thanks to GBA and people like Martin, Dana and multiple others show sparked my interest and pushed my daily to question myself and learn ) but the path ahead of me is still somewhat blurred , and probably many feel like me.

    And to confirm how PHI cannot be right with their universal figures, i view all of our discussion from my local situation POV and most of you probably view it differently from theirs too.
    There is only a single answer to each question, but questions can vary much.

  22. STEPHEN SHEEHY | | #22

    response to Marc
    Further supporting your point about exporting power from a PV array, that extra kwh in the summer replaces a kwh produced by an inefficient peak load fossil fuel generator, while the kwh you import in the winter is more likely to be produced by an efficient base load hydro, nuclear or newer, combined cycle gas generator. If the net is a wash over the year in kwh, the net should be a reduction in fossil fuel use.

  23. user-1110235 | | #23

    Other Parts of the Conference?
    Hi Martin, I agree with the 4 tracks of the conference I missed much of the content that I wish I could have caught. (although i was very pleased with all the presentations i did attend) Will you be posting on some of the other presentations and content? (aside from your interview with Feist? ) I was hoping that i might glean some of the missed content from GBA.

  24. kevin_in_denver | | #24

    Going Off-Grid in the City
    Just thinking ahead:

    1. Net zero homes are usually all-electric, and already are off the natural gas grid.
    2. Misguided utilities and PUCs may ruin net metering. This makes it desirable to go off grid if your climate is sunny enough.
    3. Batteries can provide daily backup.
    4. A propane generator is currently the most logical off-grid backup electric source for long sunless periods.
    5. If your climate isn't sunny enough, then you may want to get back ON the natural gas grid.

    A comment about home design:

    An off-grid house needs a much steeper tilt angle for the PV panels, to produce more in the winter and not over-produce in summer. This has another benefit of shedding snow better.

  25. GBA Editor
    Martin Holladay | | #25

    Response to Tim Naugler
    GBA sent two reporters to the conference: Scott Gibson and me. Both of us will be (eventually) reporting on some of the presentations we attended. Stay tuned.

  26. AntonioO | | #26

    Offset use or make unnecesssary
    I am a first time commenter here on GBA. But I have consumed many comments since I first found this site many months ago after deciding that the house I am planning to build should incorporate a strong energy efficiency component in the design goals. I have been compelled to make this first blog response because I believe this article gets at the heart of the decision one must make when considering an energy efficiency strategy in a home build--how far to go in reducing energy use and by what means. In this current conversation the question comes down to the pros and cons of offsetting the use of a unit of energy (by PV generation) or making the use of that unit of energy unnecessary (by super insulating). Dr. Feist and the PH group has decided that it's better to just not use that unit of energy at all (setting aside embedded energy in insulation and in panels too for that matter). I agree with Dr. Feist up to a point. It seems to me that it's nearly always better if you can make the use of a unit of energy unnecessary. Well, like with most things, economic realities come into play here. There is a point of diminishing economic returns. For the record, I have decided to go beyond the point of diminishing economic returns in some respects for my own project, with full knowledge that some of the products, materials, methodologies will not pay for themselves. And for the record, I doubt I will end up with anything close to a PH or NZE home. At the same time, a lot of choices I will make in this house will have no effect on energy use and absolutely no economic return. If I put in enough insulation that it makes more sense to put some of that insulation in a neighbor's house it's because I can effect change at my house but have little say so--actually none--over my neighbor's house. But just to be clear, there will not be seven layers of 2" foam under my house. Of course all of this is from a personal preference perspective. I think everything changes when we get to the point of making policy decisions. However, right now minimum building standards and practices are so far below the energy efficiency practices and suggestions often debated in this forum that it seems mostly academic. So far I'm a fan of the "pretty good" house or maybe I should say "pretty good +," meaning my house will be far above the average in most respects when it comes to energy use and might really shine in a few respects when it comes to energy use.

  27. watercop | | #27

    Let's bring back PGH
    The Pretty Good House

  28. jinmtvt | | #28

    Feist et al decided on a
    Feist et al decided on a fixed energy standard some years ago,
    when PV where not quite there yet. PV changes everything, just as modern mini splits/HP does.

    The goals is to reduce energy consumption from ALL of the buildings, not just a few;
    and that is where PH will stop unfortunately.

    What PH is doing though, is showing that it is possible to design for high efficiency,
    and it is possible now.

    Every situation deserves some analysis and will end up with different requirements.

    Building a ultra-PH house on a coastal land with an energy and ROI of 100years + might not be soo great if the house gets underwater level within 50 years from now.

  29. jackofalltrades777 | | #29

    PHIUS is the answer
    Don't want to fuel the fire of the PHI vs PHIUS and we are not privy to the inner dynamics that caused the PHIUS split from the PHI. What is clear is that PHIUS is ADAPTING to the various US energy climates and it's ADAPTING to the changing PV Solar pricing and it's ADAPTING to code changes and strategies. The problem with PHI is that it is RIGID and the parameters are set in stone and Dr. Feist refuses to change. I believe this factor played a huge part in why there was a split between the two organizations. This is also why the PHI will not succeed in the US market and the PHIUS will. It makes no sense to push European/German standards on US climates that are so diverse. The old saying "adapt or die" might be fitting here...

  30. GBA Editor
    Martin Holladay | | #30

    Response to Marc Rosenbaum (Comment #21)
    Your PV production graphs from sunny Martha's Vineyard -- [Note to readers: I'll be reporting later on Marc's presentation in Portland] -- are evidence that the November through early February dark days experienced in northern Vermont aren't universal. I knew that, of course, but your PV data reminded me of that fact. Boulder, Colorado and Martha's Vineyard, Mass. get a lot more winter sun than northern Vermont.

    As PV prices continue to drop, long-term storage becomes less of an issue, especially in sunnier areas of the U.S.

    I just read that wind projects in the Midwest that are just coming on line this year are offering contracts to sell electricity to local utilities at 2.5 cents per kWh -- the lowest prices in history for wind energy in the U.S. Everything is changing very quickly now; we're at a tipping point.

    Your prediction about using Eco Cute water heaters (the CO2-based air-to-water heat pumps sold in Japan) to make hot water when energy is abundant or cheap is an interesting prediction. We'll see if it pans out.

  31. GBA Editor
    Martin Holladay | | #31

    Reponse to Antonio Oliver (Comment #26)
    You wrote, "I have decided to go beyond the point of diminishing economic returns in some respects for my own project, with full knowledge that some of the products, materials, methodologies will not pay for themselves."

    That's fine. In fact, it's admirable. I've done the same thing at my house. Your attitude is shared by almost all Passivhaus homeowners. There's nothing wrong with this approach.

    We can learn a lot from experimental homes that push the envelope.

    However, the idea behind the "pretty good house" movement -- if we can call it a movement -- is to get smart about how we build. We want to build smart houses: elegant homes with elegant technical solutions. These homes should be simple, durable, and not too expensive. We want to put our limited amount of money where it will do the most good.

    We're learning a lot about how we can reach these goals. In most climates, reaching these goals does not require Passivhaus levels of insulation.

  32. AntonioO | | #32

    Response to response (post 31)

    I don't think we are in much disagreement. I tried to be careful to point out the difference between a homeowner's personal preferences and building policy.

    On a separate but somewhat related note, I am a bit disappointed that super insulation like low density silica aerogel (of which I studied mechanical properties as a postdoc some ten years or so ago) has not really made the jump from the laboratory to market in any appreciable way. I was in a materials surface and interface science group in graduate school, and I'm amazed at the relative progress that PVs have made in comparison.

  33. user-874928 | | #33

    I hear the ROI comment continuously. And that seems to be a driver in an evolving standard. If ROI is the driver for energy efficiency, then those driving a Prius are guilty of failing miserably. There is absolutely no ROI in a Prius. Perhaps we should start to measure mpg with cars rolling down hill, in order to be more inclusive.

  34. GBA Editor
    Martin Holladay | | #34

    Response to Barry Stephens
    There are lots of ways to determine the value of our investments in energy-saving equipment: return on investment, net present value, or simple payback. I think you are probably right that the upcharge for a Prius (compared to an inexpensive 4-cylinder car with a conventional internal combustion engine and no electric motors) isn't cost-effective at current energy prices in the U.S.

    When it comes to appliances like the ones you sell (Zehnder HRVs), there's a good argument to be made concerning non-energy benefits like improved comfort or (perhaps) health. That complicates the economic analysis.

    Further complicating the analysis is the fact that the prices for fossil fuels in the U.S. are artificially low, because they don't include the cost of remedying the damages caused by carbon emissions. If fossil fuel prices included a carbon tax that fairly represented these external costs, it would be easier to make these calculations.

    Homeowners lucky enough to live in an all-electric net-zero-energy home -- with a PV array sized to meet 100% of the annual electricity budget (if you are an American) or 200% (if you are German) -- have an easier time making these calculations, because their electricity is (arguably) carbon-free.

    OK -- as long as the house is grid-connected, there is usually a carbon emissions calculation that needs to be made. But gradually, our grid is getting cleaner.

  35. Expert Member
    Dana Dorsett | | #35

    Do the math.
    At $4/gallon there is definitely a net-present-value upside to a Prius on a 10 year analysis driving 15-20,000 miles/year compared to a comparably gutless non-hybrid that size. Not so much at $1.50/gallon. Whether it wins or loses depends a lot on what you think future fuel pricing will be. (I'm not betting on $1.50 gas over the lifecycle of a Prius.)

    If you're type who trades cares in every 3-5 years, or drives maybe 5000 miles/year, fuggedaboudit.

    Full disclosure: About a year ago I was given a 10 year old Prius, making it a no-brainer type of investment for me. ($1 + registration costs- I made out pretty good on the first 10 gallons! :-) ) In the summer it gets about 60mpg on my daily commute (without resorting to fanatic hypermiling antics). Winters it gets maybe 50mpg.

    The cash analysis for straight EVs is more nuanced. It's hard to make a strictly cash argument for a Tesla vs. a comparable performance luxury sedan, but fairly easy to make the case for a Chevy Spark EV over the gas version at California type gas prices and electricity rates. It get's stickier if you have to spring for a charging station to make it work for you though. But the sheer FUN factor of the Spark EV is phenomenal- the acceleration & handling comparisons to the BMW i3 EV or Mini-Cooper are apt. It's a whole-other car than the Spark gas model, despite sharing a common uni-body. Too bad it's not more available in the US.

  36. jinmtvt | | #36

    prius are for ...

    Check out
    and you'll see that there are now many other alternatives
    to sh#*b0x that are the prius et all ( i am not sorry if i offended a prius owner, this thing drives like a girl and feels like a 1988 chevy spring/geo metro as far as quality goes )

    No cars is every worth it as new, and the hybrids aren't exception.

    Look at the new honda accord hybrid with the new atkinson engine.
    i've seen many report of sub 4.0l/100km ( for you amaricanz, recent Prius = 4~5l /100km )
    and is a superb "regular" car with real driving value.
    But you'd need to use it alot of get back the ~ 2-3000$ added tot he price of a similarly equipped gaz accord which already hits 6 l/100km on the highway.
    Then, if you make more KM on the car, the reselling price is going to be lower.
    At least you are burning a little less fuel and we arne't talking about 10 000$ investment.

    But neway we are still ( again ) late to the game as the new diesel engines from european manufacturers trumps everything else ( or almost ) .
    Newer diesel bimmers go down to ~ 4.0l/100km with 250lbs of torque in a ~ 3500lbs fully equiped and fun to drive sedan.

    Hybrids are good for city driving though where the brake/accel regen is use is high.

    If you've driven an i3 , you also know how even a small electrical car ca be fun.

    If you live in a city, or drive between 50 and 100km daily to work,
    electric cars ( assuming you have a second family car for long week end trips ) is the way to go.
    Always some good deals on used LEAFS .

    Damn here in Quebec, the i3 drives a 100km trip to lower than 1$CAD :p

    Dana: don't bring up gm cars please, they'll probably fall in parts well before their ecological fairshare is paid.

    If the euro manufacturers push it fast enough,
    the most economical/ecological cars for the next ~10years might be driven by
    electric motors powered by small size battery pack in conjunction with a diesel generator.
    Still waiting ..

    BTW : just to prove how much newer diesel engines have grown up,
    look at 2009+ bmw X5 diesel engine
    This suv weights near 5klbs i think; and alot manage to get in the 7l/100km range on highways.

    I believe the newer dodge diesel ( jeep? ) engines are very near behind @ 8 .

    Antonio : have you recently looked at the price per R value or aerogel blankets ??
    their only value resides in the thickness ,
    but they cost something like 10 times more than all other insulation products for the same insulative values, that does not help their market position much for now.
    As far as i know, it is still costly to make,
    and uses chemicals that are discarded to empty the filled matrix .

  37. GBA Editor
    Martin Holladay | | #37

    Is the Prius upcharge worth it?
    Clearly (after reading Dana and Jin's opposing positions on whether there is any economic justification for the upcharge for a Prius) there is no consensus on this issue. So it's best to follow Dana's advice and do the math.

    If you don't drive many miles per year, or you live somewhere with cheap gasoline, it's hard to justify the upcharge.

    If you drive lots of miles, and you live somewhere with expensive gasoline, the Prius upcharge begins to make a little more sense.

    The other factor, of course, is the cost of the non-hybrid car you would buy if you didn't buy a Prius. The cheaper the gas-powered car, and the more expensive the Prius, the harder the Prius is to justify.

    Finally, I'm well aware that gasoline-only cars emit more carbon than a Prius or a Leaf. As the old saying goes, "Your mileage may vary," -- so do the math, and include your own carbon multiplication factor to account for environmental issues.

  38. Expert Member
    Dana Dorsett | | #38

    Jin- if it makes any difference...
    The tiny GM EVs are made in Korea, and have few things in common with GM-USA. (For better or ill.)

    Part of the reason the Spark rollout isn't happening massively in the US is because production is largely sold-out, to an avid Asian customer base. SFAIK in N. America it's only sold in CA & OR, largely due to state incentive programs and strong state policy promotion of EV charging infrastructure in those states (though I know of people in WA who dared to drive it across the bridge... :-) ) The thing has VERY comparable acceleration & handling performance to the much more expensive i3. The Spark EV is more fun to drive than the Leaf. (The temptation to embarrass a 5 liter Mustang or even a Ferrari off the line is omnipresent, which could lead to more wear & tear, I suppose. :-) )

    The comparative simplicity of EV drive trains compared to internal combustion engines and multi-speed transmissions make the ''...probably fall in parts well before their ecological fairshare is paid..." problem much lower. The VERY low maintenance costs of EV needs to be factored in, not just fuel costs. (An EV never needs a tune-up or oil change, doesn't have a starter-motor or clutch replacement or transmission fluid issue, brakes last 3-5x as long due to regenerative braking systems, etc.)

    BTW: The ideal driving situation for a Prius isn't stop & go urban driving, but rather 55-65kph (35-40mph) rural roads with few stop signs/lights and only modest hills. In that kind of driving I can easily beat 75 miles per gallon on dry roads. (Fuel economy seems to suffer a 3-5% hit when the pavement is wet.) Urban driving is fairly ideal for all-electric EVs though.

  39. jinmtvt | | #39

    Dana Spark EV ...
    They wouldn't happen to be built by the same Daewoo/suzuki consortium that built all of the CRAPS
    imports GM ever sold?
    Believe me, i've ( unfortunately ) wasted half of my current life working in the recycling/used parts automotive industry ( family business from which i am trying to part now )

    I know you "amaricans" don't like to hear that ,
    but i've long learned to stay away from anything that comes from the big 3 .

    Not to say that Hyundais are better, because they aren't...
    but almost every ( there was some ok to good cars ) cars sold by GM/DODGE/FORD has some major issues which prevent it to be economically viable as a "pre-owned" car .

    But hey, i can't complain ...we've made money because of that fact,
    and now that cars are without value after only 10 years, its going to even speed up.

    If i told you that we daily buy 2003-2006 cars ( Hyundai accents up to Caravans ) for 1-300$
    and are totally through in every way it can be.

    At least, nowadays, 90%of cars materials is recycled so the environmental impact of current cars is more the energy used to produce/recycle it rather than loss in materials/contaminents.

    Anyhow, don't try and seduce me with the Spark.
    It's probably even worse than the Prius/Yaris interior finish.

    But anything goes if it can help boosts the sales of EVs and competent hybrids.

    I forgot the Prius was "simulating" an atkinson engine too ..
    the older prius and most honda hybrids were the ones good for regen the stop and go activity.

    Some companies are working on using a "double" sized standard battery but with high capacity
    ( probably li-on for now ) in conjunction with an electric drive in between tranny and engine
    to lower the stop/go hybrids setup in smaller cars.

    So many possibilities now.

    Martin : fully agree to maths on everything

    and i could add to try and guess what would be the resale value
    of the car you are purchasing after the intended use
    ( more mileage = less value )

    Also most people tend to see a car cost as its price per month when they buy it,
    but it should be seen as a fixed expense per month or per KM of use
    when figuring out the following simple equation :

    (Cost or purchase - resale value + km fuel cost ) / either total KM or months or years
    and compare a few different cars you are alooking at.

    Then factor in the environmental impact in a personal attributed value .

    Now can we go back to PH topic!! :p
    Can't wait to read the reports on the conference !! :)

  40. thoughtful | | #40

    Wow, Passive House, Wow!
    It is great to read all the comments & controversy developed when Dr. Feist comes to town!

    In a way the Passive House standard is arbitrary but the target was well chosen through a logical process and backed up by a great deal of data. We can argue for a different set of criteria but this would be even more difficult for us efficiency geeks to understand, let alone the average homeowner who just wants to do the right thing. And nobody is saying that every client needs to hit the Passive House mark. I always model projects to the Passive House standard but I always have alternative options for clients to choose based on personal priorities. In the end about 2/3 choose Passive House while the rest don't. And yes, the target is high, but achievable. The PHPP is a very flexible open source tool that allows energy modelling to any level of performance.

    I seriously take issue with those who say that the Passive House focus on efficiency is at the expense of overall building quality. At Passive House events I have never been more engaged in the issue of building quality. Most builders/consultants are obsessing about dew-points, vapour open membranes, super-duper tapes and sealants, low-U windows and doors and the list goes on... I have worked in the building world for many years and it is so refreshing that every one on a project is passionate about constructing a comfortable, healthy, long lasting and, oh I almost forgot, energy efficient building.

    The building science isn't always perfect but we are engaged and learning from our mistakes!

    Whether you like it or not the Passive House target gives folks something to talk about. This, I think, is one of the greatest benefit as it engages folks in the process of transitioning to a renewable energy economy. It makes the process real and proves that it is achievable with the additional goals of quality, comfort, low maintenance & a longer lasting building.

    Thanks to everyone for all the great comments, discussion & controversy.

    Go Passive House Go!

  41. Expert Member
    MALCOLM TAYLOR | | #41

    Reply to Garth
    You are probably referring to my comments about "Passive House focus on efficiency being at the expense of overall building quality" so perhaps i should clarify them.
    I don't think that at all. But what I do see as a tendency common to a lot of those with a strong interest in energy efficiency is that if the demands two aspects of the building, say a robust structure or the use of a material that might prove problematic in the future, come into conflict with increasing efficiency, they often come down on the side of improved energy option and are then quick to dismiss the trade off they have just made. You see this in discussions about framing, foundations, natural ventilation, architectural concerns - well just about anything that isn't the building envelope. Even the list of obsessions you detailed includes nothing outside that focus.
    I'm also wary of the claims some builders are making about greater longevity. While the careful attention to building science may yield more comfortable houses which perform better than their surrounding peers, there isn't a lot to suggest they will survive any longer. Many appear quite delicate and unlikely to do well unless they remain under the continuing watchful eye of energy enthusiasts.

  42. girwin | | #42

    Magic Beans
    In our practice, we “focus forward” on building performance to seek what is feasibly possible vs. that which is merely “adequate,” and we’re quite analytical. In this context, we use the Passive House standard as a reference baseline - some projects meet it, some don’t, but most exceed it. Any “magic” in the Passive House standard for us is that it provides a comfortable, healthy and robust response to the climate crisis. Our clients know that their buildings will be sustainable in the long term, regardless of the vagaries of energy and PV prices, and we see that as the clear intention of Passive House. In the spirit of a great old physicist (Albert Einstein), I would propose some “Gedanken” (thought) experiments for you net-zero fanatics to ponder.

    1) Considering this chart (, if we’re facing a crisis with renewable energy in the solution, does it make big-picture sense to put PV panels in New England (or Germany, for that matter) when the same panels would generate up to twice as much energy in sunnier locations? Might it be wiser to “max out” high insolation locations before installing in less productive areas?

    2) If one postulates that PV panel prices will continue to drop, will we reach a point where you advocate for single-story buildings in northern areas to increase the roof space? Will we reach a point where you’ll argue that sprawling layouts are preferable for the same reason?

    3) If one accepts surplus summer energy production as a valid “offset” for winter fossil fuel use, should not folks with buildings located near mass transit also be allowed to trade that off against their slab insulation thickness? How about people who bike, walk, telecommute, or work from home? People who eat little or no red meat? All of these approaches are far more cost-effective means of carbon reduction than PV panels.

    4) What happens to the cost-effectiveness calculus of PV panels when summer electricity assumes a negative wholesale price (i.e. they can’t give it away fast enough)? This has already occurred in Germany during summer where renewable energy has reached a modest, yet enviable, market penetration of about 20% of total and 50% of peak demand. ( In northern areas, particularly, there is an inherent mismatch between the energy demand of houses and the energy output of solar. This is no coincidence, it is causal – the reason these buildings need more energy in winter is that the sun is not shining as much!

  43. GBA Editor
    Martin Holladay | | #43

    Response to Graham Irwin
    Q. "Does it make big-picture sense to put PV panels in New England (or Germany, for that matter) when the same panels would generate up to twice as much energy in sunnier locations?"

    A. I'm happy to stipulate that it would be great if the federal government had a policy to prioritize PV installation in sunny climates. Right now, our patchwork of local laws and incentives does the opposite -- for example, policies in Florida tend to discourage the installation of PV, while policies in NJ and NY tend to encourage the installation of PV. Illogical? You bet.

    That said, there are advantages to distributed generation -- that is, scattering lots of small arrays all over the place. That requires fewer new high-power transmission lines than the "put everything in Arizona" approach; it's more resilient; and it helps local utilities with peak load problems.

    Q. "Will we reach a point where you advocate for single-story buildings in northern areas to increase the roof space?" The factors dictating whether to choose a one-story design, two-story design, or three-story design are multiple; I doubt that the need for PV area will ever be the most important factor. (It's not as if there aren't already plenty of suburban subdivisions filled with one-story homes, for better or worse.) I vote that we put the PV arrays on shade structures to cover asphalt parking lots.

    Q. "Should not folks with buildings located near mass transit also be allowed to trade that off against their slab insulation thickness? How about people who bike, walk, telecommute, or work from home? People who eat little or no red meat? All of these approaches are far more cost-effective means of carbon reduction than PV panels."

    A. All of the practices you list are good practices that are worth encouraging. Whether or not to include these in some kind of green-building / point-counting program is another matter. If someone wants to try to develop a new LEED system that gives points for vegetarianism, I have no objection -- other than the obvious fact that the last thing we need is a new green building certification system.

    Q. "What happens to the cost-effectiveness calculus of PV panels when summer electricity assumes a negative wholesale price (i.e. they can’t give it away fast enough)?"

    A. Clearly, at that point the market will have to adjust. (For example, I'm sure that plants that manufacture and sell ice would be glad to accept electricity with a negative price during the summer.) We're not there yet -- but with the galloping changes (dropping prices for wind power and solar electric power) now happening, it's going to be a very interesting decade.

  44. Nick_Grant | | #44

    Might have missed some of Graham's points

    Sorry we didn't get to chat in Maine.

    It is the big picture discussion that is interesting. Anyone just interested in ROI can try and get into a National PV Ponzi Scheme quick before there are too many subscribers - thats the deal in the UK as I see it, I can't speak for the US.

    Anyone who wants to go off grid and stock up with tinned food and ammo, then there are other forums for that (I lived off grid for 8 years so I'm like a reformed smoker).

    And there are even cheaper and easier ways to a net zero, clear conscience. Easiest is to run the Hummer and house on palm oil biodiesel and adopt an orphan orangutang. In the UK you can be paid to burn forests, other countries may be less ahead of the curve.

    All seductive and internally consistent but not big picture for anyone concerned about climate change.

    Having had some great discussions about all this with Graham Irwin at the Maine conference I would guess that his point about vegetarianism and local transport has been missed! The questions why stop at the building envelope is a serious one but I doubt Graham is suggesting that diet forms part of the energy assessment. I read that as a way to parody the absurdity the net zero obsession.

    I tried to make similar points in old, but I think still relevant, blog posts titled Supply and Demand, Allowable Solutions and Zero Intelligence:

    Whilst I'd rather the Passivhaus standard didn't get sucked into addressing net zero, I do think there is a lot of thought behind the new PHI primary energy factors. These are relevant to building designers when choosing between energy sources. Electricity used when renewable supplies are available has a different cost and impact than electricity used when renewables are not available and the factors try and address that. As you have argued, PV is a good match for peak cooling loads. However in a heating and cooling climate insulation would have reduced heating AND cooling loads. If we want to come off fossil fuels then peak power loads and load matching are more important than anual energy. If looking at personal ROI, none of this matters for now.

    Graham made another crucial point about market prices and I don't see how ice makers offering to take surplus electric for free improves the economics of a truly renewable grid. We could close a small vegetable shop (not many left) by setting up a street stall with no overheads and selling really cheap fruit and veg for the one month of the year when we have more than we and all our friends can eat.

    As you say, there are great ideas beyond the building such as PV shaded parking lots (in sunnier countries than mine). But do we design them to cover the cars and maximise the efficient use of space in the sunniest parts of the lot or do we do a daft calculation to offset the theoretical fuel used for out of town shopping over a year so that the mall can offer a guilt free zero carbon shopping experience? Or let people buy carbon pardons, similar schemes were really popular in medieval England.

    The real satisfaction for me comes from helping design buildings that really work and ideally for less money than the client was about to spend. I have no experience of Minnesota, but in the UK, Passivhaus seems a really sensible target for new build. By doing it over and over it is getting easier and cheaper and with so many more benefits than lower energy bills.

    And if your climate is too cold and lacking in sun for the standard Passivhaus targets to be sensible, then stop short, consistent with comfort and economy. But don't argue for an arbitrary generation technology to meet a shortfall in an arbitrary energy target based on an arbitrary system boundary.

  45. GBA Editor
    Martin Holladay | | #45

    Response to Nick Grant
    Your comment about wealthy "environmentalists" running their Hummers on palm oil and assuaging their consciences by adopting an orangutan, although satirical in intent, comes closer to fact than most of us acknowledge. A wry observation, perhaps, but irrelevant to anything I have advocated.

    You posit that Graham Irwin's list of good practices (locating buildings near mass transit, biking to work, or limiting one's consumption of red meat) were intended as a parody of the absurdity the net zero obsession. I may be in a minority here, but I actually think they are good practices.

    You wrote, "I don't see how ice makers offering to take surplus electric for free improves the economics of a truly renewable grid." I used the example to explain how the market will need to react to the existence of electricity with a negative price. There are already buildings in the U.S. that make ice during off-peak hours, and use the ice to provide space cooling the following day, during peak electrical hours. These types of schemes become more cost-effective when summer electricity is offered at a negative price. If the source of the electricity is a PV array, then this approach certainly brings us closer to a renewable grid (your intended goal).

    You wrote, "The real satisfaction for me comes from helping design buildings that really work and ideally for less money than the client was about to spend." I agree with your goal. In many regions of the U.S. today, achieving that goal is more likely to require the inclusion of a PV array than Passivhaus levels of insulation.

    You wrote, "Don't argue for an arbitrary generation technology." I don't know why PV is an "arbitrary generation technology." It works; it's real; it is powering my computer right now. And in many areas of the U.S., PV-generated electricity costs less than electricity generated by fossil fuels.

  46. thoughtful | | #46

    Response to Malcolm Taylor

    Could you provide an example of the compromise you speak of?

    When building science is considered, there are (to simplify) two extremes that work. The old fashioned house leaks, is well ventilated uncomfortable and consumes large amounts of energy. It does last because moisture never collects in the structure (assuming good roofing, flashing etc). Very good building science that has proved the test of time.

    The other extreme is a super air sealed structure that breathes to one, or better both, sides of the envelope. And of course continuous mechanical ventilation is necessary. Very good building science that hasn't been proven through with the test of time.

    The stuff in the middle is where the problems lie and this is how most new homes are built. We already know that many of these homes will develop major issues and it often doesn't take very long.

    I don't think it is fair to criticize the efforts of Passive House builders in trying to build energy efficient houses before it is proven that it doesn't work. Someone needs to take the good building science theories and apply them. Our current crop of Passive House builders are the innovators and experimenters trying to find better ways to build in an energy conscious world. The Passive House community has already learned a few things from early experiments. Without doing we will never know what works and what doesn't.

    The other option is to go back to the old leaky house - which in most jurisdictions we aren't even allowed to build.

    So in my experience the exact opposite is true of what you say about quality. In my work I have opportunities to see almost every example of home building. In almost every project there are compromises made for budgetary reasons. In the Passive House projects the building science is always part of the discussion and rarely sacrificed.

    As well the Passive House builders tend to be actively researching and networking for best possible solutions. When issues arise the information gets through this community very quickly. Although there is likely one out there, I have yet to meet a Passive House builder where quality doesn't always come first.

    Only time will tell if the Passive House claims of resiliency are true but I am sure that it will be better than the average code built house I see. Let's hope it is as good as the old ones while using a lot less energy!

  47. 0321_Tad | | #47

    A Pretty Good Standard
    All things considered, the Passive House Standard promulgated by the Passivhaus Institut is a pretty good standard.

    Equity and Unity
    For me, the first step in evaluating a standard is to know the goal.

    What motivates me to improve building performance is my fear that my daughters and their friends all people their age, and people yet to come will struggle to survive in a burning world.

    Almost all climate scientists tell us that the weather we’ve created is starting to kick our **ses. And it will get worse over time.

    What is perhaps less well known is that climate scientists predict that the people (and their ancestors) who did the least to cause this problem will get punished first and worse. Global inequality will be compounded by global warming inequity.

    The only rational response is “All Hands on Deck.” Yet, our governments mainly pontificate about future goals, boast measly incremental improvement, and argue about relative fault and pain in solving this crisis. It’s “first world” v. emerging nations; US historical fossil fuel consumption v. current Chinese coal consumption; etc.

    The main reason I like the Standard is that it cuts through the noise and selfish positioning for short-term advantage. It may be rough justice, but it works. Everywhere people attempt it, they build buildings that use far less energy.

    It may not be perfect for any climate or nation, but it applies equally to every unit of area of conditioned building in the world.

    With Chris Benedict’s new 24-unit apartment building in NYC meeting the Standard, and the 20-unit Kiln apartments here in Portland, Oregon meeting the same Standard, we join hands with both Europe and China (which just completed its first apartment building (46 units) meeting the Standard.

    The nations largely responsible for creating our climate catastrophe (alongside the nations that aspire to the standard of living which would doom the Earth) all set the same high goal, reach for it, and meet it. Even acknowledging the short-term sacrifice of higher first costs.

    We may complain about these higher first costs for additional insulation or expensive equipment, but people who didn’t cause the climate catastrophe are already dying from it. In finally responding to the catastrophe by building buildings that aren’t energy hogs, we’re paying a higher costs. However, our pain is nothing in comparison with their pain.

    In addition to rough justice and uniform improvement, the Standard is accessible and educates.

    Even laypeople with little understanding of climate change, fossil fuel consumption, and energy consumption in buildings, understand the Standard.

    This is particularly important if we hope politicians and governments will become part of the solution. Even politicians can understand this Standard. Some cities and regional governments have already implemented it.

    In short, this Standard has the virtue of simplicity, and I agree with Katrin Klingenberg who taught me that “Keep It Simple Stupid” is one of the most useful principles to keep in mind when designing and building high-performance buildings.

    The Standard is not only relatively equitable, simple, and understandable, but it also inspires. In spite of the name, hardly any building is strictly passive. However, the name keeps the concept of the ideal (passive) building in our minds during all of the many decisions we make when we design and construct buildings to any standard.

    Perfection is the Enemy of the Good, and although discussion may be fun and even illuminating, it seems to me unwise to spend much time arguing about imperfections in a building standard when we all face a climate catastrophe that requires unprecedented, universal sacrifice and cooperation.

    Thanks for the Great Coverage and Comments
    I offer this comment with deep humility since I work in one of the easiest climates in the world to design and construct a building to meet the Standard (Portland, Oregon). I salute those achieving the Standard in near-arctic and near-tropical climates.

  48. Expert Member
    MALCOLM TAYLOR | | #48

    Response to Garth
    Off the top of my head a few examples of allowing envelope concerns to over-ride other ones come to mind.

    One of the chief virtues of western platform framing is the redundancy in the structure makes it very robust. Anyone involved in renovating an old, decaying or compromised building has had their "what's holding this up?" moment when they marvelled at it's resiliency.

    Recently questions have come up about potential moisture problems in the exterior sheathing in deep framed walls. One of the solutions which is frequently suggested is to eliminate the sheathing altogether and substitute let-in bracing or non-structural materials. This can work, but it is at the expense of some resiliency in the structure. Sheathing plays a number of roles besides just providing lateral support. It makes the whole wall a box beam helping to spread load in the event that the structure underneath becomes compromised.

    Similarly, Advanced Framing, while a technically elegant way to eliminate thermal bridging, does so at the expense not only of structural robustness but also compromised architectural values such as the placement of openings. Over the years I have had three of the house I've built in the PNW hit by trees. None of them suffered much damage, probably in part because they didn't incorporate either of those methods.

    A third example would be the almost ubiquitous use of foam. Under structural elements, on exteriors requiring that the siding be supported by long fasteners, and in situations where it is potentially subject to damage.

    And finally, the reliance on mechanical ventilation presupposes a certain future for the house. One in which the occupants continuously maintain the system over the lifespan of the structure. How do these buildings fair if this isn't the case? Do these houses still work if the neighbourhood changes, their upper-middle class owners leave and more transient tenants move in?

    I think it's fair to say that all of the examples I've given represent a compromise to achieve other ends over the techniques they replaced. They are less robust and their longevity is probably less.

    I guess where our experiences differ is that all my I have lived in and among houses that used large amounts of energy but otherwise performed just fine. The 1910 brick townhouse I grew up in is still going strong. The houses built here under the BC building code are tight and well protected from bulk water intrusion. I'd bet a "code minimum" house constructed here by a diligent builder would compare well against a Passive House in pretty well every category but energy use. As you say, time will tell.

  49. GBA Editor
    Martin Holladay | | #49

    Response to Tad Everhart
    You wrote, "All things considered, the Passive House Standard promulgated by the Passivhaus Institut is a pretty good standard."

    Am I ever confused now! If what you say is true, what will we call the standard being developed in Maine by our friends who coined the term "pretty good house"?

  50. thoughtful | | #50

    Response to Malcolm Taylor
    I guess my simple question back to you is:

    How do we achieve both the longevity and durability of older energy hogs and reduce the energy consumption significantly? I think we all know this is a necessity in a world where we must transition away from fossil fuels.

    Regarding mechanical ventilation this is something we must find a way to make work (at least until something better comes along) if we are going to insulate houses. Both the health of the home and occupants rely on it. We wouldn't ask the human body to function without mechanical ventilation so I don't know why we would think a passive ventilation system will work for buildings?

    Our first Passive House was so over built that our inspector didn't bat an eye when we did non-conventional things. We had two sheathing layers and three framing layers (two structural). As well we used lots of glue and screws so every layer increases structural integrity. We used almost no spray foam in the project and look forward to the day when we can use none.

    I guess my point is that anything can be done poorly but we need to be careful about branding a whole movement because of a few shoddy projects. Passive House is not the issue here as any builder can cut corners at the expense of project integrity.

  51. Expert Member
    MALCOLM TAYLOR | | #51

    Reply to Garth
    Practice good architecture. Cover all the bases. Integrate energy efficiency into a bigger process, rather than using it as the prime concern and generator of form and structure. Look at the problem from a wider cultural standpoint, not just the building envelope. Start from where architecture always has without imposing a set of standards the project must meet which prioritize energy savings and penalize good design.
    Critically assessing any movement - especially one you think holds promise - has always been as essential in developing it as cheerleading. I'm not against mechanical ventilation, advanced framing or any of the other techniques I listed. What I was saying is you need to look at the whole picture and not ignore potential downsides.
    I see a lot of very hopeful things in how building is transforming itself. I also see some things that trouble me. One is the way that Passive House seems to claim a monopoly on having the right solution and seems frustrated when others want to keep exploring outside the parameters it has chosen.
    So far, while it has spawned a number of interesting buildings and techniques, neither Passive House nor the wider energy efficient movement has made any meaningful contribution to alleviating any of the pressing problems we currently face. How it is going to do so remains, at least for me, to be seen.

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