Why PHIUS? To Be Part of the Solution

Some inspirations from the Seattle conference to kick off 2018

At PHIUS, we’ve been at this passive building business for a good long while. And we’ve been inspired to see so, so many professionals join and build our community. Every year we’re all so busy that it’s pretty hard to find the time to just talk about why we’re all doing what we do. That’s why each conference is such a blast.

To capture a little of that fun–and inspiration–we asked a question of some attendees at the 2017 North American Passive House Conference in Seattle, Washington. The question:

Why do you build to PHIUS standards?

Here are some answers and comments we received–we hope you can relate to one or more of them, and please feel free to chip in your own answers in the comments section.

Elizabeth Correa, LMN Architects, Seattle: I design to PHIUS standards because it was a standard that allowed me to align my principles, my design principles, and ethical principles.


Sam Rodell, Rodell.Design, Spokane, Washinton: Building to the PHIUS standard is, I would say, our practice considers that to be our baseline and I think that anyone who builds today and does not consider the possibilities of what is happening here with building science wanders around in a dangerous territory of what I would consider to be professional negligence.


Lindsay Schack, Love | Schack Architecture, Bozeman, Montana/ Driggs, Idaho: I found PHIUS when I was researching affordable and high-performance wall assemblies for a client of mine. And once I found out about PHIUS, I went down this rabbit hole of learning building science, and now I can’t go back. I can’t, with good conscience, build to code anymore. I have to push farther.


Doug Farr, Farr Associates, Chicago, Illinois: Our practice is devoted to sustainability. We’re architects and we are striving to achieve PHIUS+ on a couple of projects, one is a new build and one is a rehabilitation. It’s challenging and frankly, that’s why I like it.

Schack: PHIUS, the institute, not only provides you with support and knowledge, it provides you with camaraderie, and I’ve learned from great professionals, and it has pushed my projects to a level that is gaining notice in my industry and where I live.

Correa: And that marriage between building science and architecture through PHIUS has made me passionate about architecture again and passionate about our mission to address the problems of climate change.

Farr: Some of the other systems which are also worthy and ambitious also are hard to do, but they all have what Kat always calls a ‘get out of jail free card,’ which is that you can always compensate for building a less efficient building by adding more PV or renewable energy.

Correa: And I realize that buildings being a large percentage of the carbon emissions problem and I don’t wanna be part of the problem. That is why PHIUS is especially important to me.

Farr: Passive House is the gold standard.

Correa: I’m part of the solution and I’m not any longer part of the problem.

PHIUS+: The path to positive energy

Become a PHIUS+ Professional and be a leader in the industry


Feedback on the standard adaption: A summary

GWLast year the PHIUS Technical Committee published its draft report on a climate specific passive building standard. It also called for formal public comment. Here, with an update on that process, is PHIUS Senior Scientist Graham Wright.

We got some good feedback on our standard-adaptation work – fourteen folks submitted some fifty pages of formal commentary altogether. Thanks to all who took the time to write out their thoughts. The PHIUS Technical Committee (TC) reviewed all the feedback.

I’ll summarize the process, but first you might remember that our report is also a report to U.S. Department of Energy Building America (BA) program, a proposal for the next-generation Zero Energy Ready program (ZERH). The reviewers for BA sent 134 line-item comments on the draft report. (We’ve been busy responding to those, and we think the final report is much better now!)

Click on the cover graphic to download the final U.S. DOE Building America report at the Building Science Corporation site.

The DOE/BA and the passive house community have the same goals and are, at a broad conceptual level, working on the same thing (otherwise this work would not have been funded.)  At the workaday level though, there are a lot of differences, and also a lot of investment by the two communities in their own approaches – it’s part-and-parcel with the commitment and passion for better building that both communities share.  But when you ask the questions “is there anything passive house can bring to BA/ZERH” and “is there anything BA can bring to passive building,” it turns out the answer is yes.

The TC believes we’ve achieved a fruitful synthesis, a best-of-both-worlds combination. For example, when it comes to designing for high performance, we agree it’s better to set performance targets and do an energy design than to use prescriptive tables (and by the way that design can be somewhat site-specific). But when it comes to field quality assurance, then  a checklist table – like the BA approach — is the right tool for the job.

To put a finer point on it, we at PHIUS hope the final report persuades BA that the ZERH program should be a performance standard, with criteria on both heating/cooling loads and on total source energy, and that those performance targets are predicated on ducts inside, strict air-tightness, and using really good windows for comfort reasons.

Likewise we hope it makes the case to the passive building community that the heating/cooling criteria can be adjusted for economic feasibility / competitiveness in a climate-sensitive way, that the risks to comfort and building durability are low, and that the heating/cooling energy savings are still impressively deep.  Over all the climate locations studied, the proposed criteria represent median reductions in peak heat load of ~77%, annual heating of ~86%, peak cooling of ~69%, and annual cooling of ~46%.  (The baseline is 2009 IECC code.)

So, about those formal comments: Most commenters checked either 12-20 or 20+ years experience. In terms of survey questions we asked, no one liked star-ratings, so pass-fail it is. In going through the feedback the TC found no surprises–most all of the concerns had indeed been fully vetted en route a consensus over the past two+ years.  Here are some of the specific questions we received, along with answers:

Q: Could WP software be modified to make heating/cooling load calculations consistent with ACCA Manual J and ANSI/ASHRAE/ACCA Standard 183?
A: That is possible!  Added to the feature request list.

Q: Could PHIUS consider consolidating QA/QC checklist to be free standing from DOE ZERH and EPA Energy Star (for both residential and commercial projects)?
A: Some progress has been made on this. Stay tuned.

Q: Will the standard help me design smaller passive houses?
A: The short answer is probably yes.  There is no explicit “small house break” but there are three changes that indirectly tend to benefit small detached buildings at least in some climates:  air-tightness criterion by shell area instead of volume, source energy allowance per person instead of per square foot, and higher plug load defaults and detailed internal-gain accounting.

Q: Has there been any progress with PHIUS and NFRC in aligning data to meet PHIUS needs and possibly using NFRC data?
A: Not a lot. But we want to get it done this year. Third quarter.

Q: Please explain why you chose the specific denominators in the formulas. For example, why $ 0.155 electricity? 482 kWh? 1341 HDD65?
A: Those are the best-fit numbers determined by the regression analysis, that is, it’s like when you fit a line to a trend in x,y data, the trendline formula has the form y = m*x + b.  The numbers in the denominator are like the m, the slope or sensitivity to each of the factors.

In terms of final refinements to the new standard, PHIUS has been operating an alternate certification path along the lines of the BA draft report for some months as a pilot program. In the February and March meetings, the TC did pass some changes in advance of broader implementation. The changes came from both the feedback and the pilot program experience.

One kind of comment that spoke to us was, “this isn’t disruptive but you might want to change this to align with, or not conflict with, the building code.” The most to-the-point answer to feedback about rules is what gets changed or upheld, so here is the list of changes the TC agreed on:

  • Source energy: The U.S. source energy factor for electricity is adjusted to 3.16 (aligns with IECC 2015). The residential source energy limit is adjusted to 6200 kWh/person.yr.
  • Air-tightness criterion: 0.05 cfm50/sf of envelope area or 0.08 cfm75/sf (testing at 75 Pa aligns with commercial code and U.S. Army Corps). If testing at 75 Pa, report the flow coefficient and exponent from the blower door tests (that way the software can extrapolate to 50 Pa for compatibility of figuring the natural air change rate for infiltration losses).
  • Non-threatening air leakage: If the air-tightness criterion is missed, and the extra leakage can be proven to be due to a non-assembly-threatening leakage element such as a vent damper, certification staff may allow that element to be taped off for the purpose of passing the air-tightness criterion. The un-taped test result must be used for the energy model.
  • Phase-in period:  Dual certification path continues until September 15, after that the old protocol is phased out for PHIUS+ 2015.
  • Break-in period: If a project is seriously constrained on one of the criteria, a case-by-case overage may be allowed on any one of the four space conditioning criteria, or source energy, for the next year.
  • Retrofit:  The retrofit criteria are the same as new construction, except for a case-by-case energy allowance for foundation perimeter thermal bridges or other such hard-to-fix structural thermal bridges. Provided the design is “damage-free” that is, low risk from a moisture point of view.
  • Add-on badge: for supply air heating and cooling sufficient, per static calculation, with the average ventilation rate no more than 0.3-0.4 air changes per hour. (That is, low peak heating load and low peak cooling load. Special recognition for those who favor and design to this particular “functional definition” of a passive building.)

And finally, Katrin’s long-awaited favorite:

  • Add-on badge: for source net zero.  Onsite renewable electricity generation above any that was already credited as coincident-production-and-use, counts towards net zero with the same source energy factor multiplier for electricity, i.e., 3.16.

To me the most substantial comment was along the lines that cost has been added on to the building delivery process, when you consider the labor of the CPHC, the pre-certification review, and the rater visits for quality assurance. The TC believes much of this concern is simply a matter of getting used to the requirements until it becomes the new normal, but we know that there is room for improvement on making the planning tools easier to use, and we will keep working hard on that.  Most commenters felt it was also very important to get the standard written out in human-readable form, not just encoded in WUFI Passive, and we will work on this as well.

Overall, we believe that PHIUS+ 2015 will make passive building more cost-effective across climate zones. The community’s collective experience informed all the work–so thank you all for all your input and hard work and again, thanks to everyone who took the time to submit formal comment. We’re excited to implement the new standard and believe it will dramatically increase adoption of passive building.


Looking back and ahead at passive building

Today PHIUS delivers its CPHC training virtually and and across the country, and in partnership with organizations like Yestermorrow and the U.S. Army Corps of Engineers. It all started with the first class in Urbana, Ill., in 2008, pictured above. Bottom row, from l-r:  John Essig, Dave Brach, Mary Graham, Katrin Klingenberg, Laura Briggs, Jonah Stanford. Second row: Christina Snyder, Luis Martinez, Jim Olson, Lance Wright, Paul Eldrenkamp, Hayden Robinson, Henry Gifford, David White, Graham Irwin. Back row: Katia Sussman, Tim Moran, Ian Schnack, Al Hothan, John Highland, Gino Mazzaferro, Mark Hoberecht, Ed Shank, Bogdan Zagorowski, Jesper Kruse, Steve Robinson, Matt Howard, Tim Eian, Harold Finigan, Vahid Mojarrab, Tad Everhart, Marc Rosenbaum

I wrote in my last post about how my diagnosis with MS motivated me to rebalance my lifestyle and nutrition. One other positive by-product has been an opportunity to reflect. Once again, reflection and mindfulness – like good nutrition – have always been a goal. But the MS forced the issue by slowing me down (at least for awhile).

And I was reminded of what a rich and wonderful journey it’s been, and how far we’ve come together.

When I set out a dozen years ago, it was not simply to advance passive house principles. It was to help shrink our carbon footprint—and the effects of climate change. Passive building seemed then as it does now to be a critical part of the solution.

I started by building my own residence in Urbana, Ill. Then Mike Kernagis joined me as construction manager on two affordable passive houses built in partnership with the City of Urbana. One other affordable home was built in 2011, and we designed three private homes. And, the Solar Decathlon Home 2009 came home from D.C. after placing second, bringing the number of passive homes in the Champaign-Urbana area to eight.

The reaction — from points far and wide across the country was — so strong and positive that we assembled the first English language CPHC (Certified Passive House Consultant) training program in 2008.

It’s been a whirlwind since then. In 2009 we founded the Passive House Alliance US (PHAUS) and communities of our trainees coalesced in their respective regions, forming groups such as PHCA, PHNW, NYPH and PHNE. PHAUS, a PHIUS program, has added more than a dozen chapters under the PHAUS umbrella nationwide.

Most important, we deliver the training nationally and virtually now, and the community of PHIUS-trained CPHCs (now 550+ strong) started building real, successful projects across North America’s climate zones. Some of the bleeding edge heroes of the effort include Dan Whitmore, Jan Fillinger, Win Swafford, Tad Everhart, Blake Bilyeu, Randy Foster and Tessa Smith, Alex Boetzel and Stephan Aiguier, Rob Hawthorne, Margo Rettig, Jesse Thomas, Joe Giampietro, Graham Wright and Sam Hagerman in the Northwest. In the Bay Area, the torch was carried by Allen Gilliland (the first NZE home in Calif.), Graham Irwin, Rick Milburn, Nabih Tahan, Lowell Moulton, Katy Hollbacher and Prudence Ferreira.

The Northeast honor roll: Laura Briggs, Paul Eldrenkamp, Marc Rosenbaum, Peter Schneider and J.B. Clancy, Mike Duclos and Paul Panish, Alan Gibson and Matt O’Malia, Svea Tullberg, Jesper Kruse, Stephanie Bassler, Jesse Thompson, Laura Blau, Tim McDonald, Chris Benedict and Henry Gifford, Dennis Wedlick, David White, Ken Levenson, Jordan Goldman and Stephanie Horowitz, Andreas Benzing, Julie Torres-Moskovitz.

David Peabody, Adam Cohen, John Semmelhack, Michael Hindle, Barbara Gehrung, Alan Abrams and Dan Levy have led the way in the Mid-Atlantic region; Chris Senior, Clarke Snell and Jeff Buscher in the Carolinas; Ed Shank and Mark Hoberecht, Eric Lang, Pat Murphy, Mary Rogero and Faith Morgan in Ohio.

In Kentucky, Ginger Watkins and Michael Hughes have been leaders; way up North Stephan Tanner, Tim Eian, Carly Colson, Rachel Wagner and Mike LeBeau carried the banner. Lance Wright and Brian Fuentes sparked the community in Colorado; Joaquin Karcher and Jonah Stanford in New Mexico; Dave Brach in Salt Lake; Vic Weber in Idaho; Ross Elliott and Natalie Leonard in Canada; Thorsten Chlupp in Alaska: Linda Metropulos, Laura Nettleton and Michael Whartnaby in Pennsylvania; Tom Bassett-Dilley, Mark Miller and Patrick Danaher in Chicago. Finally, Dave Stecher, Dylan Lamar (who also did the first IP version of PHPP while at PHIUS, a critical step), Ian Schnack, Ryan Abendroth and Darcy Bean helped blaze trails back at home in Urbana, and later on their own in Phoenix, St.Louis, Portland Ore. and Pittsburgh. Pa.

There are more—like Corey Saft who had the gumption to build a passive house in Louisiana. We learned so much from that project. Surely I am omitting people – I apologize for any memory lapse. The point is, there’s no substitute for all of your commitment. I feel privileged to be part of your community.

We are headed toward our 9th Annual Conference, and today, in addition to CPHC training, we offer PHIUS Certified Builders Training, and a PHIUS+ Rater training that enables HERS raters to accurately rate passive houses. These programs are relatively new, but the Certified Builder program is always sold out and already the community of PHIUS Certified Builders is approaching 100; and the Rater community is right behind it.

We’ve forged strategic partnerships with the likes of the U.S. DOE, Building Science Corporation, RESNET, Rocky Mountain Institute. We’ve also established  relationships with the prestigious Fraunhofer IBP, Owens Corning and Oak Ridge National Lab—a partnership that produced WUFI Passive. WUFI Passive is a fantastic software modeling tool that is making passive energy modeling easier, more accurate, and integrated with WUFI hygrothermal analysis. It’s a commercial grade software tool with a streamlined GUI and the most powerful passive and hygrothermal modeling capabilities on the market. It is, simply, a leap forward.

Looking back, I see there was another critical group—and I mean critical. Let’s call them the passive house skeptics. They’ve ranged from Marc Rosenbaum to Joe Lstiburek to Martin Holladay.

When I set out to prove passive house principles in the United States, I was energetic, armed with information from the German PHI, and … a little naïve. Passivhaus was new to me and the majority of people I talked to about it. And I thought—like a lot of like-minded people—that I’d discovered something brand new.

After I built my own passive house in 2002, and we started getting some attention in the mainstream and trade press, I began hearing from energy conservation pioneers. On one hand, they were excited to see conservation back on the front burner, after interest in it trailed off back in the 80s.

But some were also a bit miffed. I didn’t understand it at the time – and misunderstood it as resistance to change. It was quite the opposite. It was the notion that this passivhaus or passive house was new that was irksome to them.

Indeed, I learned that the foundation principles that distinguished what I called passive house in English or passivhaus in German were not at all new. Superinsulation, high-performance doors and windows, removing thermal bridges, energy recovery ventilation/minimizing mechanicals, managing solar gain. A group of pioneers — including some in my own backyard in Urbana at the University of Illinois—had formulated these concepts decades earlier.

What we have learned – and I say we because we’ve learned it side-by-side with CPHCs and builders who’ve faced real-world challenges across climates—is that this group of early pioneers had valid misgivings about passive house as formulated in Europe. The concerns included the small-house penalty, North American issues with latent humidity, and the cost-effectiveness of investing in the envelope as opposed to renewables. The biggest concern: deep disagreement that a single numerical standard for all climate zones could make sense.

Reasonable people can and will disagree. But on the single standard, we at PHIUS have come to agree that a one-size-fits-all-climates standard is flawed, and is a major factor holding back adoption. I, like a lot of people, found the notion that a single number could work for all climates magnetically attractive. But in our experience designing, building, certifying and monitoring, we’ve concluded it doesn’t work. That’s an important departure, but not a disagreement about passive house principles being the best place to start for high performance building.

That’s why we’re engaged with Building Science Corporation in testing climate-specific standards that use the peak load calculation (which underlies also the European standard) as a baseline. (BTW, again—climate-specific doesn’t necessarily mean “easier.” In some climate zones, we expect the standard to tighten.)

Now, make no mistake: When interest in conservation waned in the United States and Canada in the 80s, the efforts of Drs. Bo Adamson and Wolfgang Feist to formulate passive principles for Europe were heroic, and Dr. Feist’s continuing efforts with PHI have been invaluable. In particular the PHPP was an important step toward putting modeling within reach of passive house professionals. We owe them gratitude. But the work of our entire community, the advancement of building science and innovation must quite naturally go on. There is no holy grail here.

Some lament the differences that exist within the passive building community. To be sure, some of the harsh rhetoric and hurt feelings have been regrettable (and, I think, entirely avoidable moving forward). But we see different and competing ideas as healthy and necessary. It’s only natural that as a community grows, it grows more vital and diverse, and that competing views—and to be sure, competing interests—arise.

The entire passive house community, regardless of scientific position or organizational loyalties, is pulling toward conserving energy and reducing carbon emissions, while constructing extremely comfortable, healthy and resilient buildings. And we agree that passive is a great way to do that. But honest competition has always driven growth and innovation. Trying to put a lid on ideas suppresses growth, and leaves us fighting over a very small pie.

Here’s to a vibrant and diverse passive house community, and to a much, much larger pie!




What does MS have to do with climate change?

Last September I was diagnosed with remitting-relapsing multiple sclerosis after a first—and frightening—attack. Despite the grim news I was intrigued by the elusiveness of the disease, and I started my journey of searching for answers and solutions to the question of how to best prevent or delay further attacks. I’ve learned a lot—and been reminded of a lot along the way.

Multiple Sclerosis (MS) is a strange disease, characterized by so many different symptoms that some call it the disease with a 1000 faces. Little is known about the causes and consequently all approved therapies and medications aim at reducing symptoms, not at addressing a cause.

Yet, one thing most experts agree on is that there is likely a very strong environmental component to the disease. It is generally considered an autoimmune disorder —that is, the system that ordinarily protects one’s body from infections and other threats goes haywire. The autoimmune system attacks the body.

MS was first noted at the onset of the industrialized age at the end of the 19th century. There is no previous record of its incidence. Its occurrence has increased dramatically since and mostly in the developed richer nations. Significantly, the increase is most prevalent in nations that eat mostly a “meat and potato” diet, rather than a more Mediterranean or asian cuisine.

Changes in lifestyle over the past century (active/outdoor to sedentary/indoor), environmental factors such as increased toxins in air and water, and a shift in nutrition characterized by high animal fat intakes and highly processed food supplies are broadly suspected to be a significant part of the problem.

It’s been months since my diagnosis—during that time, after a lot of research, I made a decision to pursue a nutritional path to managing the disease over medication. Since that decision, the world has changed quite a bit for me for the better.

I found that the suggested causes and remedies were somewhat related to what started to look like an energy balance for a building. My systems had seriously gotten out of balance on every nutritional and lifestyle level! It’s become clear that my lifestyle for the last 10 or so years has systematically depleted my resources! I was running on fumes.

I felt somewhat consoled and excited by the fact that I knew something about rebalancing a system. I was accustomed to working on getting first to a balanced state through conservation and then eventually to a positive energy balance through consequent repletion. My thoughts were, if you can build a passive house you can rebalance your body, right? And here I went.

I began seeing real parallels between our efforts in the passive building community to rebalance resources with my individual efforts to rebalance my intakes. In each case, the goal is to assure that the taking and the giving is brought back into balance. A global society that constantly over-consumes and dumps tons and tons of carbon into the atmosphere as a result will eventually overwhelm the system and cause its collapse—just like my constantly depleting lifestyle depleted my body—and led to its attack on itself.

We live our lives by constantly going into debt with the planet’s resources (our body is a planetary resource) and think if we can just pay the minimum payment each month it does not matter how big our total balance is. Over-consuming and getting further away from being in balance and zeroing out our account, our modern lifestyles suffer from a similar effect.

I’ve read extensively about the interplay of ultra-busy but sedentary lifestyles and the perils of fast/processed food, factory farms and antibiotics, toxins, and increases in food allergies.

I’ve concluded that both MS and climate change are symptoms of excessive in-debtness with ourselves in the name of a convenient modern life style based on consumption, a life out of balance.

Ten years ago I made a resolution as an architect to work exclusively on passive buildings to take responsibility for my share of the rebalancing act. After my MS diagnosis, I made a similar resolution to rebalance my body and lifestyle instead of treating the symptoms with expensive medication and its own side effects. I soon found myself calculating an energy balance for my body, counting all different kinds of fats and oils and balancing them appropriately.  Every day I eat 7-10 servings of fruits and vegetables, multiple grain servings and watch out for a whole set of other interesting nutritional factors to strengthen the brain, rebuild the nervous system, the autoimmune system and the cardiovascular system. I have not been so clear headed, focused and energetic in years. I have lost 30 pounds without trying…but I still have work to do on my exercise regimen.

All this has dovetailed with my professional mission: my carbon footprint has significantly improved! I’ve almost entirely eliminated meat, and I forgo gluten, dairy, processed grains, and other packaged food products (all energy-intensive foods). I buy organic and pastured chicken, local if possible.

In a way it was easy for me to make that decision—MS is a powerful motivator. I always wanted to eat this way but never was able to maintain it because I managed to justify the modern shortcuts of fast food, pizza and beer in the name of convenience, helping me to de-stress and save time and work more.

But I’ve learned that equation doesn’t add up in the end, and that this type of diet is broadly recommended to avoid the most common diseases like cancer, heart disease, diabetes and other autoimmune diseases. All of these diseases are on a disturbing upswing. Just as the consequences of climate change is.

MS and climate change: they are similar looming invisible threats to our quality of life. Once an attack subsides things appear to be normal again and one is tempted to go back to business as usual and ignore the problem. But leaving the causes unattended will debilitate again, destroying quality of life, or life itself.

Here is my resolution: I don’t want to take any chances, neither with my body, the only one I have–nor with the planet, the only one I have. My body is an extension of my family, my house, my community, my city, my country, my planet.

MS and climate change are opportunities: they are second chances for us to end our follies and fix what we broke so that we may once again live in balance and peace. And that’s what I intend to do. And I think being in the passive house community puts me in terrific company. I’ve had terrific support, and I thank you all.

Meantime, there’s more to say about all this, but I’ll save it for a second installment….