Building a ZERO Carbon Future, Together!

Katrin HeadshotPhius Co-Founder and Executive Director Katrin Klingenberg wrote this week’s blog post in advance of her “Zero Energy and the Future of Phius” webinar on Sept. 14. It covers a variety of topics related to Phius’ work and the expanded vision of the organization.

“The west is on fire, and the east is drowning.”

Those attention-grabbing words were the first thing I heard when I turned on my TV the other day.

“The levees held, but the power grid folded”

That was a headline from the day after hurricane Ida swept across Louisiana. Most of the state was left without power; temperatures in the aftermath were predicted to rise into the 100s, all after a ton of rain and flooding. The combination of high temperatures and humidity is life-threatening — on top of all the other hardships brought on by the storm.

And then there was the Texas winter with the grid folding and people and pipes freezing in homes…

The urgency is clear. At our most recent Phius board retreat there was consensus: we are in dire straits climate-wise — it is now or never.

Since its inception, Phius’ vision has had a North Star: to create a carbon-neutral, healthy, safe, and just future for everyone by mitigating the climate crisis. And our mission is to do just that by making passive house and building standards mainstream.

The vision was extended to using passive house and building principles as the basis for all zero-energy and carbon designs. We added the Phius Source Zero certification program in 2012. Net zero is a good first step, but we need to revise the framework. In practice, net zero isn’t enough. 

The conclusion we at Phius have reached — following the thought leadership of our Senior Scientist Graham Wright — is that we need to aim to reach absolute zero in short order to avert the ultimate climate crisis. And that is absolute zero as per the original definition of zero – the absence of a measurable quantity.

A New Brand

We are upping our game on multiple levels in order to emphasize our renewed commitment to solving the ZERO-carbon puzzle for buildings. 

New Brand Same Phius GraphicWe started by reimagining the Phius brand. We are updating its look and making products and messages more relatable without sacrificing what we are known for: scientific rigor, precision, quality assurance, proven guidance, and performance. We are also unifying and expanding our suite of certifications for buildings, products and professionals. We are upping the ante on benefits to our professional members under the Phius Alliance leadership and yes, we are creating exceptionally cool swag to encourage everyone to join our tribe and make it our lifestyle together! Together, our community is creating momentum in the market — and having fun with it!

We also re-organized ourselves internally in more efficient ways over the last year, invested in a new website and a CRM, architecture. And we doubled our staff — to aim for greater, faster and increasingly exponential impact and service for our stakeholders. 

In addition, we are making dedicated efforts to reach out to communities beyond the building industry, to explain why what we do matters to everyone. Renters and owners all have a stake in what we do, and we are all one or the other. We want to give everyone an opportunity to get involved. It is up to all of us now! Join us!

Expanded Vision

Over the last decade, Phius has become the global leader in defining cost-effective and climate-optimized, passive house and building standards. Phius certified projects are now coming in at little or no cost premium compared to conventional buildings. Phius also leads in professional training, certification, and workforce development. We also provide an element critical to mainstream adoption: Quality assurance and risk management.

The building sector accounts for 40 percent of carbon emissions, and is key to achieving emissions reduction goals. Passive house and building principles have been, and will continue to be, CORE to our efforts. In that spirit, the formerly known PHIUS+ building certifications have been renamed and expanded. 

PHIUS+ will now be referred to as Phius CORE (before renewables) and PHIUS+ Source Zero will now be Phius ZERO (based on CORE), and will extend to netting out emissions on an annual basis. New passive house and building retrofit certifications are in the offing as well. Phius CORE REVIVE and Phius ZERO REVIVE, as well as a new commercial building certification called Phius CORE COMM and Phius ZERO COMM will be introduced in 2022. 

Phius certifications have grown exponentially around the continent in recent years. Policy progress nationwide has been impressive to say the least. We are in Tarrytown, New York, for PhiusCon 2021 (formerly North American Passive House Conference) to celebrate the leadership of New York State/NYSERDA in formulating an aggressive climate action plan — a process which Phius helped inform. Other states, such as Massachusetts, have modeled their plans after New York’s. Phius’ pre- and fully certified unit count in Massachusetts over the last few years alone is impressive.

Phius Housing Units (In Process or Complete)

 

The Phius Alliance has expanded nationally, and the global network continues to grow. Phius projects have now been completed or are under way in many countries with varying climate zones. The Phius professional training has been translated into Japanese and has been taught this year successfully in Japan by Phius partner PHIJP.

The last decade was focused on figuring out the building part of the decarbonization equation (mission accomplished — solving for climate, cost, comfort). Now it’s time to expand beyond the building itself. We see Phius buildings as valuable capacitors of the new, renewable grid. They are low-load buildings that have the ability to load-shift and shed, which is immensely beneficial to the optimization of the overall grid design and resilience. 

Phius has begun to assess and measure the benefits of low-load buildings for the overall grid design, including micro and nano grid models. We call this initiative Phius GEB (Phius Grid-interactive Efficient Buildings) led by our Associate Director Lisa White. A pilot for a microgrid Phius community certification is underway. Buildings plug into the grid, and new opportunities for synergies and resilience arise. Design for the best result does not stop at the building envelope or lot line. 

Our new teal-colored logo symbolizes this expanded vision. It is a closed loop symbolizing whole systems design on all levels, aiming at harvesting adjacent system synergies: “The whole is greater than the sum of its parts.” The color teal represents clarity of thought, rejuvenation, open communication and integrity. 

Same Phius

While Phius will be steadily expanding its zero-carbon framework beyond its hallmark passive house and building standards, we will maintain our core competencies of aiding in design, building, policy writing and quality assurance. We are working to solidify and upgrade our foundational programs. Certification staff has doubled and processes are being refined. We are working on getting even better at what we already do well!

The Phius focus has evolved to the broader task of decarbonization. We’ll do so with the same scientific rigor and attention to detail as before. Our goal is the next level of systems optimization so we as a society can make real-time ZERO carbon (not just net) a reality soon!

We hope you’ll join us and continue to trust us to pave the way for the future of decarbonization strategies. There is still lots to do, so let’s get to it!

The Phius Difference: Custom Energy Design Targets for Heating and Cooling — The Key to Zero

Katrin Klingenberg -- Co-Founder & Executive Director, Phius (Passive House Institute US)

Katrin Klingenberg — Co-Founder & Executive Director, Phius (Passive House Institute US)

The Klingenblog’s namesake, Katrin Klingenberg, wrote this week’s blog, examining custom energy design targets and how Phius’ approach to them sets the organization apart in the quest for Zero.

Designing zero energy and zero carbon buildings today can be cost effective if guided by the appropriate targets for investment in efficiency first. These targets are cost-optimized limits on heating and cooling loads.

The limits on heating and cooling loads are set to guide the design to a cost-optimal investment in passive conservation strategies: insulation (the appropriate amount, properly installed), dedicated continuous air, water, and vapor control layers, mitigation and avoidance of thermal bridging, high-performance windows (with appropriately tuned solar gain) and dedicated balanced ventilation with filtration and energy recovery. These principles ensure building resilience, health, comfort, safety and durability.

The cost optimization to set the targets focused on achieving the highest source energy savings (relative to a code baseline) for the least total cost (including the up-front cost of energy-saving measures, and ongoing operational costs). It factors in the cost of materials and the cost of energy supply in each particular region to calculate the sweet-spot. At some point, up-front conservation measures don’t pencil, and that’s when any additional investment should shift to active conservation strategies or active renewable energy generation systems.  These climate-optimized, project-specific targets for thermal performance define the cost-effective sweet spot on the path to zero.

The thermal performance targets are known in the industry as “Annual Heating Demand” and “Annual Cooling Demand.” They are expressed in kBTU per square foot per year or — in the metric world — in kWh per square meter per year. They are, in concept, similar to the Energy Use Intensity (EUI), but refer to the delivered heating and cooling energy required by the building. These annual space conditioning demands can only be met with passive measures and dial in the thermal performance of the building. Once those are met, a conservation-first focused total energy budget is set to guide investment in active measures. This limit is also project-specific, and can be expressed in the EUI we are all familiar with — the amount of energy used by a building per unit of floor area per year, including space conditioning and all other energy uses. That EUI can be converted into an emissions equivalent as needed to determine offsets needed to achieve zero carbon. Voila! It’s that easy!

Phius is the only building certification program that has developed such design and certification targets. They are available on the Phius website in an easy-to-use calculator. Choose climate, enter building square footage and occupancy, and you get your optimized design parameters! They are also built into the easy-to-use design and certification tool, WUFI(R)  Passive.

Before supercomputing, managing such a complex, dynamic system of variables to generate custom targets as a designer was impossible. The task of energy optimization was handled by specialized engineering firms doing the modeling — a costly and external process. Small budget projects such as single-family and small multifamily projects could not take advantage of it. Even larger projects often took the prescriptive path to eliminate the cost of custom optimization. 

Today, the reliable and detailed accounting of emissions in the building sector is necessary on a per-building basis. Many cities have passed climate action plans with extremely specific emissions reduction targets to meet over the next few decades. The Phius standard now provides an easy-to-apply, cost-effective design, and certification methodology alongside accurate accounting of carbon emissions for any building in the building sector.

With some training, architects can now easily perform these calculations themselves and build it into their design workflows right from the beginning, making sure their design is on track from start to finish.

The framework for the Phius standard today was conceived in 2015, updated in 2018, and refined again in 2021. Many municipalities have leaned on and incentivized the Phius framework to meet their climate action plans. At the forefront was New York State Energy Research and Development Authority (NYSERDA) in the State of NY. They designed a proof-of-concept program early on called Buildings of Excellence. The agency now offers cost and performance data for representative groups of completed projects using varying techniques for low energy design and accounting.

C3RRO, a third-party consulting firm under the leadership of Florian Antretter, has graphed the NYSERDA cost and measured performance data for various approaches and graciously made it available to Phius for publication. The results are proving the concept. 

Graph

As envisioned, the Phius Standard, design, and certification methodology has led to projects that not only perform the best, but are also constructed at minimal additional upfront cost. (PHI projects that use a single target for heating and cooling limits in all climates also perform reasonably well but are more expensive to build).

The new comprehensive guidebook explaining the Phius Standard design and certification methodology is now available here.

We are well on our way to (Phius) ZERO emissions!

Help Wanted: Identifying conditions that can complicate retrofits

32tev__gPhius Senior Scientist Graham Wright weighs in here with a guest post about some on-the-ground research he did regarding retrofits. Graham conducted a brief street-view survey of residential housing in Portland, Oregon (Glenfair, Glendoveer, Rockwood neighborhoods), and documented conditions that would complicate panelized retrofit solutions. He invites you to do the same in your neighborhood, and to submit what you find to advance research on panelized retrofit solutions.

It looks like I will be pivoting to concentrate my work on retrofit for a while. This is in connection with the Advanced Building Construction Initiative (ABC) of the U.S. Department of Energy. Under the program, RMI was funded to set up a collaborative and phius is a member. The vision shared at the recent summit is to figure out how to decarbonize ALL BUILDINGS by 2050. A study of the building typologies is underway, led by NREL.

It is already clear that single-family detached houses are the vast majority of buildings by number, they probably also dominate the aggregated “thermal loads” of heating, cooling, and hot water that comprise most of the energy/emissions savings opportunity.

The NREL data set does not have all the building properties that one would need to identify the technical barriers to deep energy retrofits. There is general awareness on the ABC team that the U.S. housing stock is very diverse and that this is a challenge to the concept of industrialized retrofit. So to get a better sense of this I spent a couple of hours looking at houses within walking distance of where I live in east Portland, Oregon. I looked for conditions that would complicate an exterior panelized envelope insulation retrofit, or that would complicate air-sealing. I looked at 33 houses and noted 30 separate conditions. These are assigned four-letter codes as shown in the table below. Some were much more common than others, such as attached garages, and some were so universal I did not even list them, such as gutters/downspouts.

My takeaway from this excursion was that the number of conditions that one would need to have a plan for is large but not endless. There are obviously some missing, such as balconies and widow’s walks. It’s not a large sample and I could only see one or two sides of the houses from the sidewalk. Many of the houses pictured are on crawl space foundations as indicated by vents, and that could also be considered an air-sealing complication, though I did not call it out here.

Here’s a slide show with problem conditions annotated:

 

Please send photos of houses near you! If possible, annotate conditions as I have in the gallery, using  the codes in the table below, or adding other conditions not listed, that also seem troublesome from the point of view of exterior retrofit and air-sealing.

Here are the problem conditions I classified, along with the number of cases I identified on my walking tour:

ACOD – air conditioner outdoor unit (3)
AGAR – attached garage (10)
CATV – cable tv line (1)
DISH – satellite dish (5)
DRYV – dryer vent (2)
E@RF – electrical mast through the roof (8)
EMTR – electrical meter (3)
EOUT – electrical outlet (1)
FENC – adjacent fence (13)
FCHM – fireplace chimney (17)
GCHM – gas appliance chimney (5)
GMTR – gas meter (3)
HOSE – hose bib / reel (3)
MLCA – mature landscaping close aboard (9)
MSXT – masonry extension from wall (5)
OV@R – overhang attached at roof (5)
OV@W – overhang attached at wall (5)
PBVT – roof plumbing vent (3)
PBCO – plumbing clean out (1)
RFVT – roof vent (4)
SKLT – skylight / sun tunnel (3)
SOFF – overhang with soffit (3)
STOV – wood/pellet stove chimney (1)
TCOM – telecom or mystery wall box (7)
THIC – change in cladding thickness (5)
TITE – can’t add wall thickness (20)
WART – wall art (1)
WBOX – window box (2)
WING – wing or fin wall (1)
XTLT – exterior light fixture (12)

Policy Update: The Massachusetts Stretch

isaac pic

Isaac Elnecave, a member of the PHIUS certification team, has written this update on the Massachusetts stretch cove, the latest installment of his policy updates.

Over the last 8 years, Massachusetts has made significant progress towards making the passive house (PHIUS+) standard an integral part of its building energy code. This effort points the way to the end goal of creating a cost-effective net-zero energy code.

Besides its statewide base energy code, which is an amended version of the latest International Energy Conservation Code (IECC) model code, the Board of Building Regulations and Standards (BBRS) in Massachusetts has, since 2009, promulgated a “stretch” energy code. The base energy code governs the minimum energy saving requirements in buildings throughout the state. The requirements include: the amount of insulation required in ceilings, walls and foundations; window performance; the level of air tightness; ventilation requirements; the efficacy of lighting and the efficiency of HVAC equipment. It is often described as the worst possible building (from an energy perspective) that can legally be built.

A stretch energy code incorporates similar measures and design approaches but mandates energy efficiency requirements that result in higher performance buildings than those meeting the base energy code. While the base energy code is the default requirement across all towns and cities in the Commonwealth, the stretch energy code must be affirmatively adopted by local municipalities that want to enforce it (at which point, it supplements and overrides the base energy code in that jurisdiction). Importantly, unlike New York State, because the BBRS approves the stretch code, municipalities that adopt it cannot amend it.

In both the Base and Stretch codes in Massachusetts, there is a section for alternative compliance strategies, which specifically includes passive house in both the low-rise residential energy code chapter and the commercial energy code chapter. Under the requirements of its current edition, and in fact since 2012, in any jurisdiction that adopts the stretch code in Massachusetts, a PHIUS+ certified passive house automatically meets code. The current code amendments specify that the annual heating demand for PHIUS certified home or commercial building must be less than 10 kbtu/ft2/year; a value easily met by all certified PHIUS buildings.

The latest edition of the Massachusetts stretch code has just been adopted but has not yet been promulgated* — the expected promulgation date is February 8, 2020 with an effective date of Aug 8, 2020. There will be two significant changes. First, PHIUS itself has updated its standard to PHIUS + 2018 from PHIUS + 2015. Second, with this new edition, a residential or commercial building will be code compliant when it passes the pre-certification stage (much like saying a typical house is given code approval once the plans have been approved.) The updated energy code, based on the IECC 2018, shifts the passive house compliance option from the 10 kBtu/ft2/year metric to an option to seek PHIUS precertification prior to pulling a permit. A project must demonstrate that it has been submitted for final certification by PHIUS to receive the certificate of occupancy. Because PHIUS maintains a rigorous review process through the end of construction, this approach ensures a high quality of construction.

Passive house certification requirements are significantly more stringent than even the other alternative paths in the stretch code (the most commonly used path in the Massachusetts residential stretch code allows for an Energy Rating Index score of 55, which is well above the score typically achieved by a certified passive house).

Massachusetts provides an excellent example of how to use incentives to spur the development of high-performance buildings. Mass Save®, the statewide energy efficiency program in Massachusetts, launched a mid- to high-rise passive house incentive program in the summer of 2019. In the first 6 months over 40 projects with over 3,000 passive house units in development have signed up for the program.  As more projects are built meeting PHIUS standards either through the stretch code or through Mass Save, the universe of designers and builders who become proficient in the construction of high-performance builders grows. This proficiency will result in greater confidence among construction professionals and lower costs with respect to high performance buildings.

As the PHIUS standard includes a pathway to net-zero construction, including it in the stretch and base energy code provides a path for future improvements. In Massachusetts, stretch code development will now focus on a ‘net-zero’ code to run alongside an amended IECC 2021 base code. Having the passive house pathway in the energy codes has introduced designers and builders to the tools and techniques necessary for building cost-effective net-zero single-family and multi-family dwelling. PHIUS looks forward to working with Massachusetts Department of Energy Resources, BBRS and other key stakeholders in making a net-zero code a reality.

Massachusetts in one of three states and one municipality that have incorporated the PHIUS standard in the energy code. New York was discussed in a previous blog (Policy Update: New York State, Two Steps Forward, One Step Back, January 16, 2020). I’ll discuss efforts in Washington State and the city of Denver in a future post.

* Adoption means voting and signing by government official. Promulgation (it specifically means the decree that puts a law into effect), in practice, refers to when the agency in charge of enforcing the law signs off on the rules and regulations relating to the law.

 

Many Cereals, One Cereal Aisle

GW

Graham Wright

The PHIUS+ standard has evolved on a very different path than the PHI standard, and they are in no way equivalent. That’s by design, based on deliberate decisions and building science, with a focus on cost-optimization and climate specificity. Still, confusion remains in some corners of the marketplace, confusion that is worsened by articles like the one that appeared in BuildingGreen a few weeks ago. (You can also read Chris McTaggart’s rebuttal at Building Green.)

Here, to provide a full accounting of how and why the standards are different, is PHIUS Senior Scientist Graham Wright. 

At the Seattle PHIUS annual conference in 2017, one of the keynote speakers, Doug Farr, came to a line in his speech saying “many boxes, one cereal.” The point he was making (as I heard it) was that there are a whole lot of “green” and “sustainable” and “high-performance” building programs, badges, and ratings all competing for attention or mind-share, and that this was not good because it made for a diffuse effort toward solving our sustainability problem. What you have, he said, is like a whole bunch of different cereal boxes on the shelf, but inside it’s “all kind of the same stuff.” It would be better if all these different outfits would get together to advocate with one voice.

While I agree that joining forces sounds like a good idea in general, personally I think he got the rest of it almost exactly backwards. For one of the other keynote speakers, Eric Werling, one of his major points was that the details matter. In terms of cereals, it is not all the same stuff — muesli is different from oatmeal or cornflakes or Cap’n Crunch®. We do not have many boxes — one cereal, rather we have many cereals, one cereal aisle. The bacon and hash browns are in another aisle. For the building industry the name of that aisle is probably “Green Building,” I think that’s the broadest and most recognizable term for what we’re talking about, and could encompass high-performance, sustainable, resilient, natural, living, green, healthy, net-zero, and of course, passive. Things it does not encompass but at most only overlaps with would be for example: secure, co-housing, modernist, Usonian, affordable, vernacular, brutalist, social, connected, low-tech and so on — these are quite different “programmatic” considerations and have their own aisles in the pan-galactic building store.

One of these things...

One of these things…

In the case of cereals the reason there are different kinds is because tastes differ, but also because values differ — if I value yumminess above all I will get Cap’n Crunch, but if I value avoiding the family curse of heart attack above all, I will get the oatmeal. In Green Building even more so, we have different programs because of differences in truly heartfelt values. Both builders and their clients bring different values to their meetings — if I am concerned about not polluting the environment, respecting brother salmon, I will go into natural building; if my children are prone to allergies I will look for healthy-home builders; if I

...is not like the other.

…is not like the other.

hate paying utility bills I will go for net-zero, and so on. So it is useful to have badges and rating systems corresponding to these different values or priorities, for matchmaking between builders and buyers of buildings.

Back to the common ground for a moment. It has dawned on many people I think that these different aspects of green building are connected, by a general crisis of climate and sustainability with industrial civilization, that we do have common ground in making the point that we must stop using fossil fuels and putting CO2 and other pollutants into the environment and doing so much mining, if we expect to also keep getting things like fish and wood and well water out of it at the same time, and that we might be able to form a chorus of voices calling for this.

I know of three such separate “common voice” efforts (heh) arising in the last couple of years:

PHIUS has joined Shift Zero, which has come together around the Architecture 2030 definition of zero net carbon buildings. Washington State already has one of the strictest state building energy codes, more stringent than IECC 2015, according to ACEEE, but at the initial Shift Zero summit meeting, the item “Roadmap to a Net Zero Building Code” was chosen as a major focus. This is relevant to us for two reasons: 1) We believe passive building should be on that road! The PHIUS vision statement is to “make high-performance passive building commonplace,” which it would be if it was Screen Shot 2019-08-27 at 1.46.00 PMcode. Also, 2) although it’s not spelled out in the short mission statement on the web site, the long version in the business plan speaks of the climate crisis and how passive building can both mitigate and adapt to climate change. We concur that as a society overall we must get to Zero, not just net-zero but Absolute Zero in terms of emissions, or 100% renewable energy to put it the other way. (The PHIUS Technical Committee has already taken this definition of Zero Net Carbon into consideration for our PHIUS+ 2018 standard update.)

Moreover, we are pursuing an ANSI-approved passive building standard, via the ASHRAE Standard Project Committee 227P. Participation in Shift Zero should allow us to both contribute to and be informed by a Shift Zero effort on Washington State code.

Our aim here is not to “get PHIUS written into WA code”, nor to “get an ANSI stamp” on PHIUS+ 2015 or even 2018, but to develop something that is both rigorous and more flexible, and of more enduring value. Our current standard is mostly performance-based, that is, based on modeled energy use. This requires modeling protocol, modeling software, and training in using it, for both project planners and verification/enforcement caseworkers. The vision for the ANSI/ASHRAE passive standard is that it would use a combination of prescriptive, performance, and outcome-based compliance paths to support the whole range of project scales – from small projects in backwater jurisdictions with few planning or enforcement resources to large projects in capitols that could take on custom cost-optimization studies. The value of PHIUS+ lies not only or even mainly in the current criteria but rather in the principles and methods underlying them, such as the priority on passive measures and conservation, the constrained cost-optimization for the heating and cooling criteria or the fair-share and national-solidarity principles for total energy use.

The “A” in both ASHRAE and ANSI stands for American. The ANSI mission statement is U.S. focused and the web page has a U.S. flag image. But the ASHRAE mission states pointedly that while they started out in U.S. they now have worldwide membership and global services, advancing sustainable technology for the built environment.

An ASHRAE passive building standard then, ought to be serviceable globally (at least in those parts of the globe that have building professionals.)

In my opinion PHIUS brings a track record of experience and care to this effort, as well as integrity, and humility.

As most of you will know, we started out practicing an “International standard” from PHI in Germany, applying it in the U.S. Our first major adaptation was in 2012 with the addition of greatly expanded quality assurance requirements from U.S. DOE programs. We found that the U.S. building industry simply needed a lot more guardrails on quality. This was in essence a cultural adaptation, as was our early support for the inch-pound unit system. Our second major change was a climateadaptation, in 2015 with the elaboration of the climate-specific criteria for heating and cooling.

To make a long story short, we found that the PHI heating and cooling criteria became disconnected from the principle of economic feasibility that supposedly underlay them, when applied to most climates in the U.S. and Canada, and we set out to redeem that promise. That disconnect affected both the heating and the cooling criteria in different ways, and was apparent in the data of PHI’s own climate parametric study of 20111. As a result of that study, PHI indeed adjusted their cooling criteria, adding to the (not climate specific) fixed base cooling demand a substantial and variable allowance for dehumidification (fair enough, there are not many passive measures that do this.) But the heating criteria still only made sense in one climate, and this was never fixed. Most of the U.S. being heating-dominated we thought that important and so went to work on it in 2013-14.

To make the story just a bit longer, what I would call the first-generation passive builders were splinter group off of the “passive solar” or “solar home” movement in the 1970s. Their differentiation was less mass-and-glass, less gain, more insulation, build light and tight. They tended to speak of “superinsulation” to differentiate themselves from the passive solar people, but passive building really is a better word for it; it’s not just about insulation. The canonical work summing up the first-generation ideas is The Superinsulated Home Book. Their concept of what counted as such a home was a little vague – they speak of reducing the heat losses until the building really starts to “act different” – but the definitional ideas included both low annual heating bills and low peak heating loads, that is, very small heating system capacity required, even to the point where a dedicated furnace was no longer needed; “just steal a little heat from the water heater.” This aspect I think forms the appeal to the heart of the “passive-house flavor” of green building cereal — the “self-heating building,” the “furnace-free house.”

The Superinsulated Home Book

The Superinsulated Home Book was published in the early 1980s, just as the bottom fell out of the solar movement stateside. The torch passed to Europe, and when PHI wrote their definition of a passive house, they focused on that low peak heat load concept and drew a line in the sand on how low it should be — basically, the point where the ventilation and heat distribution systems could be combined. This was reasonable and it does give a target number for design heat load, about 10 W per m2 of floor area, that would apply everywhere, at least in any heating-dominated climate. But when it came to writing certification criteria, an alternate compliance path was added by which one could meet a corresponding annual heating demand. Corresponding that is, in the climate of central Europe. This is the notorious 15 kWh/m2 or 4.75 kBtu/ft2, per year. If a building was designed to meet a peak of 10 W/m2 in central Europe, this is the resulting heating demand.

The problem, I say the glaring problem, is that that alternate criterion doesn’t correspond to the peak load definition in other climates. Again, this is according to PHI’s own study from 20111-2012. They took a study building, moved it around to a lot of different climates, adjusted the upgrades to meet the 10 W/m2 peak heat load definition, and plotted the resulting annual heat demand. It varied a lot, generally increasing as the annual average temperature got lower, but there was a lot of scatter, because annual temperature and peak load design temperature aren’t necessarily that closely related, it depends a lot on how close you are to the ocean.

Nevertheless, the PHI heating criteria remained the same two numbers for everywhere, either 10 W/m2 peak, corresponding to their definition, or 15 kW/m2.yr, which mostly doesn’t. Why? I have always darkly suspected that it is because in continental interior climates, the design temperatures for peak heating load are quite low, making the 10 W/m2 much the more difficult of the two numbers to meet. I think they could tell that it would be impractical for single-family dwellings, even attached like a townhouse end unit, to meet the ostensible definition, and so left the 15 kWh/m2 alternate in there as a close-enough cheat. I say it drives bad design, over-glazing, because solar gains do more to lower the annual heat demand than the peak load. (We showed evidence of this in our PHIUS+ 2015 development report published by NREL.)

Therefore, as I mentioned above, after a few years of applying PHI’s standard in the U.S., and noticing this lack of integrity with the heating criteria, we embarked on a reconsideration of the whole thing, in 2013-14. To my recollection, it just so happened that PHIUS and PHI both officially made standards announcements on the same day, March 15, 2015. PHIUS did make changes to all 3 “pillars” or marquee-level criteria — space conditioning, primary energy, and air-tightness. But, as evidenced by what got elaborated, it was clear that PHI had spent most of 2014 working on primary energy, the big change was the new and more nuanced Primary Energy Renewable (PER) metric, while PHIUS had spent most of that time working on new and more nuanced heating and cooling criteria. To go ahead and put a fine point on it, PHIUS took more care in 2014 with the core concept — the passive measures and how far to push them to drive down the heating and cooling loads.

(I must say it was irksome to get comments like, “sounds like PHIUS+ 2015 is just about bolting on some PV.’ when all we had done was put PV on the same footing as solar hot water, while PHI had spent the whole year working on renewable energy.)

Therefore, I think it is fair to say as a general matter, PHIUS has learned the importance of both “cultural” factors and climate factors to the development of passive building standards, and will bring this to an ANSI/ASHRAE standard development project. The approach to climate I think we have a fairly good handle on, and the multiple compliance options mentioned above should be able to accommodate various “building delivery processes”.

Lately it seems, we hear a lot of glossing over the differences between PHI and PHIUS. “It’s all good” kind of talk, “the differences are for nerds” and the like. At some level, this is fair enough. Yes we heart the furnace-free house, yes we like the EN/ISO 13790 monthly method for annual heating and cooling calculation and the EN 12831 for peak heating load, no we are not trying to be “lite” in general; honestly we get as much “we’re going with PHI because it’s easier” as the other way around.

But at some level the details do matter. In particular when it comes to talking about building energy code, mandatory, enforcement, permits approved or denied, people are going to want to know quite specifically what are the rules, yes?

Let’s think about the most simple and straightforward proposal I’ve heard for a building energy code: enacted in a skit by Henry Gifford and Chris Benedict of New York City, they propose the code consists of just a criterion on the design heating system capacity, that is, a peak heat load. Even with just that, you can see it would take some pages to spell out: by what method or methods of calculation? Do the methods vary for residential versus nonresidential buildings? Are solar gains or thermal mass to be credited with reducing peak loads? By what method are the design temperatures to be determined? Shall these be historical or forward-looking at climate change? Who is qualified to perform the load calculations and to review them? Does the criterion apply zone-by-zone or to the building as a whole? What if I have multiple buildings served by a central system?

So yes, at some level it is fair to say, PHI and PHIUS that is blueberry muesli, all good. But when it comes to the Food and Drug Administration, and to many customers, it is going to matter what is in those blueberries exactly. Are those real blueberries or fake f@#$% blueberries? Are the real blueberries GMO Roundup-ready blueberries or organic blueberries?

At PHIUS I think we have demonstrated some care and forethought in adapting our program and standards in the direction of suitability for incentives and codification in North America, while remaining faithful to the heart of the passive building concept. We will bring this experience and intention to the development of a more widely/globally applicable ANSI/ASHRAE Passive Building Design Standard With Path to Zero Emission or 100% Renewable Energy Society or the like.

ASHRAE requires a fairly public and transparent process and we seek the participation of the best building energy experts anywhere who find this vision agreeable — including PHI, with just one proviso: that 15 kWh/m2 everywhere is not going to make it, that is fake blueberry and we cannot have it in this muesli. If you can let that one thing go at last, the possibilities for fruitful collaboration open up. As those conveners I mentioned in Bonn, Seattle, and Portland have been suggesting, let us get the oars in the water and try to row in a more coordinated way at the goal of a Zero emission / 100% renewable built environment.

1 Schneiders, J.; Feist, F.; Schulz, T.; Krick, B.; Rongen, L.; Wirtz, R. (2012). Passive Houses for Different Climate Zones. Passive House Institute and University of Innsbruck.