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Community and Q&A

What is the point of Passivhaus certification?

davorradman | Posted in PassivHaus on

I see this come up often in cost analysis discussions, but I fail to see how certification can be anything other than a sunk cost. Unless I have a completely wrong perception of the process.

Are there direct subsidies in some places?

If certification is done after the house has been built, how can it help you build a better house?

If certification starts with designing, why would passivhaus certifiers be any better then other people who measure air leakage and calculate necessary insulation etc?

In other words, what is the difference between 2 houses with the exact same performance that adheres to passivhaus standard, except one is certified, the other is not?

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Davor,
    The short answer is: certification gives you quality assurance (to verify that the construction quality meets certain standards) and bragging rights (and the right to install a plaque, if you want to).

    For more information on the type of dispute that has arisen, historically, on this issue, see this article: "Is This Building Passivhaus-Certified?"

    The article described a famous dispute that involved two issues: Did the builder use the correct efficiency assumptions for the HRV? And did the builder use the correct assumptions on how much shading was provided by a large tree near the site?

    If these kinds of disputes matter to you, you'll want to be sure that you are on the correct side of the line when the fighting starts. If you're that type of person, you may be willing to pay $8,000 to one of the two certification organizations (PHI and PHIUS) to get your plaque.

  2. Andrew_C | | #2

    What is the point of [blank] certification?

    Some people like to brag. Some builders like to prove they can build to high standards. There are a lot of motivations that we can assign to other people’s doings.

    In my mind, the real value of aiming for certification is that you will be forced, in the design stage, to think about things that matter. And the certification is both motivation and evidence, of sorts, that you followed through on your plans. In general terms, if you don’t measure anything, you won’t get better. Appropriate metrics drive desired behaviors.

    The pros and cons of any particular program/certification for any particular climate can be debated endlessly, as has been proven on many websites. But having a goal with results that can be measured that results in better-than-standard buildings is generally a good thing.

  3. Expert Member
    MALCOLM TAYLOR | | #3

    Some people can maintain an exercise programme on their own, some need the help of a Fitbit watch or personal trainer.

    My concerns with the certification programmes aren't in their content, it's that they seem to inevitably campaign to make them mandatory - as witnessed by the inroads both LEED and Passive House have made lobbying municipal governments to adopt their standards.

    Building codes and zoning are the appropriate mechanisms for deciding how structures must be constructed. Another layer of essentially privately developed regulations are unnecessary.

  4. seabornman | | #4

    My experience has been that it's much easier to say "We followed the guidelines but we just didn't pay for the certification" than to actually follow through and do it right. Then you can skip the commissioning, blower door tests, verification of VOCs, etc. and tell the client they're the proud owner of a "green" building.

  5. Expert Member
    MALCOLM TAYLOR | | #5

    Joel,

    Do you know if the Passive house certification fee includes the cost of those necessary steps, or would those be an additional expense?

  6. seabornman | | #6

    Malcolm, sorry I don't know. My direct experience is with LEED certification.

  7. mark_be | | #7

    My wife and I will be doing a gut Enerphit retrofit and although we had considered getting our house certified, finally decided against it. I will be functioning as g/c.

    Our architects are passive house certified and used the phpp to ensure that the design met passive house standards.

    Passive house certification happens in two stages. The first stage occurs after the building is designed - building plans, and output from, as well as some inputs to, the phpp, are submitted and reviewed. The certifiers say that yes, if the building is built as specified the house will meet the standard, or no, even if it is built as specified, it will not meet the standard.

    To us, this phase really just represents a second pair of knowledgable eyes reviewing our architects' work. Since we trust our architects, and both are involved in the project, we didn't really see this as a necessity.

    The second phase occurs after construction has been completed, or at least, after all passive related construction has been completed. Extensive photographic documentation of construction details is provided and reviewed. Blower door results are provided. Certifiers determine if construction was done in accordance with passive house requirements.

    At this point, however, it seems to us, that either construction will have to be halted until review is complete, which is impractical, or you don't find out if you meet the standards until after construction is complete, which seems pointless, since we would have no inclination to start opening up walls, etc. to redo work that doesn't meet standards.

    The key during construction, to us, is to understand exactly what needs to be done, review work ourselves, have architects review work as needed, and have knowledgable, preferably passive house certified, contractors who you trust and are comfortable with to do the passive house relevant work. Several blower door tests will be done at the appropriate times.

    Another consideration for us is that the passive house standard will probably not be fixed in stone forever. Although a house built in 2018 may meet the current standard, there is no guarantee that that house will meet 2020 standards.

    Also, you may not meet the passive house standard for what we would consider to be a trivial reason. In our case, our southern facing windows were too big for our climate, shading, etc. The phpp showed that we would require cooling 11 days out of the year, one more than our maximum allowance of 10 days. While we were able to make other adjustments to keep the windows the desired size and stay within the 10 day allowance, we would not have been willing to reduce the size of the windows because a software program projected one extra day of mechanical cooling per year.

    Hope this helps.

    Mark

  8. davorradman | | #8

    Thanks everyone for the input.

    Basically my question should have been:
    can you make an actual passivhaus (or a house adhering to set standards) without certification, and would it be harder this way?

    So, Markberg says it comes up during design, so that's something I guess, if your architect is not as reliable.

    If it's only for bragging rights, and on the other hand solars are (rightfully) being called not cost-effective, and people are discussing about cost-effectiveness of PV and additional insulation, 8000$ for a piece of paper sounds ludicrous to me.

    So if I build a house using correct design principles, and after 2-3 seasons of actual real world usage I calculate that my actual power usage exceeds passivhaus standard, for bragging right, I'd like to call someone official to verify my monitoring data and give me cert. But I guess it would have to be much cheaper this way, and no foolproof data logger exists, so that's not gonna happen.

  9. GBA Editor
    Martin Holladay | | #9

    Davor,
    You can't certify a construction project as Passivhaus-certified after the project is over. You have to involve a Passivhaus consultant before construction begins.

    Actual energy use has little to do with complying with the Passivhaus standard. Many certified Passivhaus buildings are owned by homeowners who use much more energy than the PHPP software predicted. They still get to brag, however.

  10. Jon_Lawrence | | #10

    Davor,

    As Martin points out, usage does not factor into certification. Certification is based on 1) an approved design, modeled in either PHPP or WUFI, 2) confirmation by a PH Rater the the final product complies with the model and 3) testament by the Builder that the completed project was built as modeled. This certification does not come cheap, because in addition to the fees, there are things done in the design that most would consider unnecessary but are done to squeeze a few less btu's out of the modeled energy usage. An example of this is sub-slab foam. I have heard lots of stories of people bumping up the foam to over 12" just to reach the modeled performance requirements when 4" would have been enough to meet comfort targets and reach net-zero with solar. Also, to echo one of Markberg's points, there are constraints on what you can do, which is problematic when trying to build a custom home.

    I considered getting my house that I am currently building certified. In preparation I also got myself certified as a PH Builder, Consultant and Tradesperson. So I have drunk the cool-aid, but after doing so, it became clear that it did not make sense in my case to go that route because my goals were to build a comfortable, custom house that was net-zero and I did not need to incur the added expense of getting certified to reach those goals.

    That is not to say there is no place for certification. I think there is value for someone who wants to have a high-performance house, but does not know anything about construction and/or does not have the time to become involved in the construction. The certification in this case is insurance that things were designed and built to a certain set of specifications that should produce a finished product that meets certain design criteria for energy usage and comfort. In that case, it may actually be money well spent.

  11. JC72 | | #11

    Davor,

    It's not ludicrous when the certification is considered in light of resale. $8,000 for PH cert on a $750,000 house is nothing.

    In reality it's no worse of a sunk cost than when someone demos an old home to build new.

  12. Expert Member
    Michael Maines | | #12

    Certification is not just for bragging rights, though that is certainly one benefit. I have no experience with the PHIUS/WUFI approach, but as a certified passive house consultant, I have gone through the PHPP for several projects. Although it is very accurate (for the things it can be accurate about--i.e., not occupant behavior), there are a LOT of inputs and it's good to have someone very experienced review the numbers and suggest changes. It's easy to fudge numbers or to just plain make mistakes without a certifier reviewing everything in detail. I see it as akin to commissioning an HVAC system--adjustment and confirmation that the system will run as intended.

    I tell clients that certification probably benefits me more than it does them, as it shows that I know what I'm doing. For them, they get to be leaders in the field of super high performance construction, which has a value--without leaders the industry would stagnate. Most PH consultants that I know of pay for their own certification, unless they get a homeowner who wants to be a benefactor as well, which was the case for several projects I'm aware of by other CPHCs.

    I know there are stories about projects where actual energy use is higher than modeled, but I know of at least a couple of projects where energy use came in well below the model. One interesting anecdote--in the last year I have consulted on two projects for single retirees. The PHPP does not allow single-person occupancy, so all of the loads and heat gains are off. It probably helped us, actually, as the heat from occupants contributes a significant portion of the space heat in a cold climate. In general, though, the PHPP and the certification process are very conservative--they have built a brand for super high performance, and they are careful to protect that brand, which as annoying as it is when you can't meet the standard, I see as an overall good thing.

    Regarding whether certification is necessary, I've heard Dr. Wolfgang Feist say himself that the most important thing is to build houses that meet that level of energy use, implying that certification is not strictly necessary. I do a lot of projects using Passive House principles, as do most "green" designers and builders these days, without going through certification.

    As for the cost, it depends on the situation (as does everything in construction, of course). It varies a lot with the complexity of the project and the experience of the consultant. It takes anywhere from 10 to 50 hours to assemble and tune a PHPP energy model, and there are also discussions about material types and sourcing, installation methods, and a thousand other variables. Once you submit info to a certifier, they review and comment, so garbage in = garbage out. Then it goes to the central agency for their overview and approval. It's a rigorous process, and to be clear, one I have not completed myself yet. (Though I did lead certification efforts for a building system, which was at least as difficult as certifying a house, and have been close to meeting the numbers on several projects.)

  13. Trevor_Lambert | | #13

    I will weigh in as a homeowner acting as GC who drank the PassivHaus Kool-Aid, and also decided against seeking certification. The way I looked at it was the actual certification was only valuable as a tool to hold contractors accountable, and not a very effective tool at that. If you've ever worked with people in the construction industry, you understand what I mean. You'd have a hard time getting anyone to agree to meet terms like that, and even if you did they have a well earned reputation of skirting their obligations (and also just going out of business). You also put limits on yourself, as mentioned above. We based our design on the PHPP modelling, and we plan to do a blower door test, but that's about it. Passing the blower door test was a contract requirement for our "shell package" builder, but they gradually became less and less reliable until we had to terminate the contract. So far, I still think we made the right decision. I'm one of those people who has 12" of foam under the slab. The incremental cost of putting 8" more was perhaps $4500. A solar installation was in the ballpark of $55000 (no grid tie option). The added insulation under the slab helped to allow for a heating system without a furnace or boiler, which was a big savings (not only cost but floor space). The way I see it, the insulation is always going to be there, and it will never cost another dime after install.

  14. davorradman | | #14

    I can see why "Pretty good house" is a more sensible way to approach the project of building a house for yourself where you plan on living for foreseeable future.

    I guess some of the benefits to trickle out to general population, if some solutions which turn out good reach mainstream. So it's not sunk cost for general population :)

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