PHIUS+ 2018 Webinar Q&A

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PHIUS Senior Scientist Graham Wright and Certification Manager Lisa White answer questions that were submitted during and after the live PHIUS+ 2018 Webinar on November 8, 2018.

You can view a recording of the webinar at the PHIUS.org site.

*Note: Some questions have been edited for publication

Q: Has PHIUS started to look at overall GWP in the materials used to make these high performance buildings? To save the balance of the climate, reducing our emissions in the next 20 years is critical. Lots of XPS and spray foam make a low energy building but don’t do anything to help our climate goals.

A: The short answer is yes. We do have a GWP impact calculator for insulation. Its use is not required for project certification but we encourage it when we see large areas of XPS or SPF proposed. Our product certification program for construction systems has a requirement for a sustainability or health certification; there are several options recognized.

Q: Can you explain the exuberance concept?

A: We remain enthusiastic about the “tiny heating system” / “tiny heating bill” idea.

Q: Thanks for including Quebec Province! I believe in 2015+, all of North America was calculated according to a blanket value for cleanliness of the grid. Is 2018 adapted to different grids, and how do you deal with Quebec’s very cheap and clean hydroelectricity? Renewables are a tough sell here. Zero government incentives and at 7 cents/kWh, our energy costs would have to more than treble in order to make PV make financial sense.

A: In the standard-setting study itself we used the same factor all the time, but because the buildings were (almost) all electric, it canceled out. The PV generation is multiplied by the same factor as the usage, so source net zero is achieved with the same size PV array as for site net zero.

The philosophy is that CO2 emissions anywhere affect everyone everywhere. We all share one atmosphere, so by a principle of solidarity we should really use the world average source energy factor for electricity. That is, people with clean grids do not get to play “we’ve got ours” and use more energy. Even if your local grid is clean we want to drive additional action such as REC purchases that fund new clean energy projects. In certification we do allow the use of national averages, so we actually just request solidarity at the national level. Canada has a cleaner grid than the US overall, and thus Canadian projects will not have to take as many measures for net source energy reduction. The source energy factor for electricity in Canada is 1.96, whereas it is 2.8 for the US.

The electricity cost does affect some of the space conditioning criteria because higher energy prices justify more conservation measures and thus tighter targets. We calculate this with state-by-state averages, so Quebec projects will have less stringent targets than neighbors in Maine and Vermont.

 

Q: The word “townhouse” usually means a single-family building, but you seem to be using it differently.

A: The individual dwelling units are “single-family, attached”. That is, they share walls but not floor/ceiling. Speaking loosely, the whole row of attached units is the Townhouse, and the study building is 8 or 16 attached units.

Q: Is the mandatory minimum for window upgrades done because it wouldn’t be cost effective otherwise?

A: Yes. Window costs have come down but this still had to be forced in most cases. The starting points were still “in the money” though. There were a few times when the optimizer bought them on its own, but it took a long heating season and high energy price to motivate it. 

 

Q: Is this modeled EUI directly from WUFI Passive in the “Modeled vs. Measured” slide?

A: Yes, the WUFI Passive energy model used for certification.

Q: Do the new non-residential commissioning requirements apply to the common areas of residential buildings or only to all non-residential buildings?

A: TBD. Our current definition (for source energy target purposes) hinges on whether the spaces serve outside clients / customers or just the residents.

 

Q: Are you considering using the last 5 years of climate data vs ASHRAE to deal with global weirdness?

A: No, but we are working on future climate data for 2090 as an informational resource.

 

Q: Any comments on using low-iron glass (easily found in EU / just starting to appear in US)? Does the visible transmittance increase relative to ordinary US glass (which has a green tint to natural light)?

A: Alpen for a while had a low-iron glass option in their certified products, but they discontinued it.

 

Q: Instead of ignoring PV in competing with efficiency measures, why not look at PV with storage for the costs? This may not take care of seasonal differences, but it would take care of daily or weekly changes.

A: We may have have explored it if that was an option in BEopt, but it isn’t yet. Our current thinking is that what batteries do for you depends, in normal operation, on what the time-of-use rate structure looks like, and they are also good for you in outage situations. We are working on a calculation protocol for outages and waiting for utilities or other researchers to converge on time-of-use rate structure(s).

 

Q: Is there an ASHRAE 55 comfort analysis or PMV for PHIUS+?

A: The new window comfort calculator is based on relatively recent research on Predicted Percentage Dissatisfied specifically for draft at the ankle – it doesn’t just hark back to the PMV/PPD that was determined in 1970.

I (Graham) also wrote a paper for the 2016 conference looking at the radiant temperature effect of windows on comfort.

In certification we mostly take the same kind of simple view as in building code, e.g., “thou shalt maintain a dry bulb temperature set point of X and Y”. Sophisticated comfort analyses are more appropriate for workplace and nonresidential cases where clothing and metabolic profiles of occupants can be pinned down (as required by ASHRAE 55), and one might not have to worry so much about frail or sensitive occupants.

 

Comment: Adaptation is why I pursued CPHC in the first place!

Graham Wright: Thanks! Lisa presented on passive survivability at the Boston conference, and we will have more to say about this in the future.

Q: How does the new standard accommodate variable occupancy patterns/equipment usage in non-residential buildings?

A: With respect to the performance targets, as a first step, we will allow two different occupancies to be used to determine the annual demand targets vs. peak loads. Also, we can develop custom criteria for unusual situations (additional fee applies).

With respect to energy modeling protocol, it is already required to enter patterns for occupancy, ventilation and lighting, but this is mostly about getting the annual total energy right for source energy limit purposes.

 

Q: Please define HDD65, IGA, CDD50, TCD, IGCL and DDHR.

A: HDD65 = Heating degree-days, base 65 F;

IGA = Solar Irradiance, global, annual;

CDD50 = Cooling degree-days, base 50 F;

TCD = Temperature, cooling design day;

IGCL = Irradiance, global, cooling load design condition;

DDHR = Dehumidification design humidity ratio.

 

Q: If a project is considering registering under either 2015 or 2018, can we register under 2015 then change to 2018 (as circumstances change) without an additional registration fee?

A: Yes, you can always pursue a newer version of the standard. You are not able to pursue older versions if the contract date is later than the last day to submit under that older standard. In order to register for PHIUS+ 2015, the contract must be submitted before April 1, 2019.

 

Q: Are there updates to WUFI to accommodate the 2018+ standard? And when will it be available?

A: Yes, the next version of WUFI Passive will be released by the end of 2018. We will notify all of PHIUS’ mailing list.

 

 

 

 

 

 

 

 

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.

 

Comments on climate-specific standards study now open

ClimateSpecificColor
In cooperation with Building Science Corporation, under a U.S. DOE Building America Grant, the PHIUS Technical Committee has completed exhaustive research and testing toward new passive house standards that take into account a broad range of climate conditions and other variables in North American climate zones and markets.

This report contains findings that will be adapted for use as the basis for implementing climate-specific standards in the PHIUS+ project certification program in early 2015. Furthermore, as materials, markets and – climates – change, the PHIUS Technical Committee will periodically review and adapt the standard to reflect those changes.

  • We invite formal comment on the science. Please use this online form to submit. Deadline for formal comment: January 16, 2015.
  • Formal comments will not be public, and are for Tech Committee review only. (The Tech Committee or PHIUS staff will contact you for permission, should we be interested in publishing your comments.) All formal comments will be reviewed, but we cannot guarantee an individual response.
  • Passive House Alliance US Members: An online informal discussion forum is available to all members. The forum discussion will be visible to the general public, but only PHAUS members can make comments. Comments on the discussion forum are not guaranteed to be reviewed by the Technical Committee.
  • If you are not a PHAUS member, use the blog comments section below. Comments on the blog cannot be guaranteed to be reviewed by the Technical Committee. To ensure Committee review, use the online formal comment form.

The standard: Less energy, less pollution, more comfort.

I’ve been on the road a lot lately but let me thank you again for your thoughtful contributions and the

Solar radiation exposure is one factor that differs dramatically between Germany and the US. (National Renewable Energy Laboratory, European Commission)

healthy debate sparked by my first blog post, “15kwh is Dead, Long Live 15kwh.” In the post I put forth PHIUS’ plans to modify the passive house standard to address the specific climate and market needs of the North American market. A quick summary of the changes and their value:

  • Modifications will be based on the first and only large-scale analysis of passive house buildings in the United States and Canada – the 100+ buildings certified/under review by PHIUS.
  • They will address the substantive and reasonable critiques (such as the small-home penalty) of leading building scientists in North America like John Straube, Marc Rosenbaum, and Martin Holladay.
  • They will safeguard the high quality for which passive house is known by acknowledging

    View Marc Rosenbaum's presentation on passive house in the United States from the 2011 North American Passive House Conference

    fundamental differences (e.g., building in high-humidity zones presents unique quality challenges).

  • Modifications will calibrate envelope improvements more precisely for each climate and will be more cost effective than the one-size-fits-all approach. They will improve cost effectiveness in colder climates while maintaining comfort and quality of the envelope. And they will actually tighten the standard in climates where there is opportunity for more stringent targets.

The post touched off a great deal of constructive discussion and supportive comments – many folks expressing support for an idea they believe was long overdue.

Understandably, the prospect of change also caused some angst. Recently, a petition was circulated asking folks to sign-on in support of maintaining a single numerical standard associated with the term passive house. I fully understand the response – years ago, I might have signed on myself. But since then, based on the collective experience of passive house consultants who have designed and constructed projects across the continent, it’s become clear that adaptation is critical.

It’s also become clear that we at PHIUS need to get better at explaining the rationale for the modifications that we’re proposing and how they will help propel the market forward while maintaining the core principles of passive house.

To that end, I’d like to respond to some of the concerns and ensuing discussion around the petition mentioned earlier.

Let’s start with a sentiment expressed in a Green Building Advisor article related to the petition topic:  It was expressed that the “beauty of the standard is its purity.”  Purity implies uniformity, and my intended point is that 15kwh is not a universal truth, and therefore not practical for all climate regions.  The rigor of passive house is universal.  In the US, 15kwh is rigorous and practical in the Pacific Northwest  but hat’s not the case in most of the other North American climate zones.

By the same token, in some areas of the United States – Southern California, for example – it’s technically and economically practical to do better than 15kwh.  And it’s worth reiterating: adjusting the standard will allow us to do away with the small-house penalty (that being that it’s actually easier to achieve 15kwh in a larger structure than a small one, thereby presenting an incentive to build larger).

As mentioned in the first blog post, other parts of the world have already concluded that 15kwh is not universal. This is really not a new development.

More important, is the suggestion that modifying the standard creates market confusion. Three points argue against this being a concern:

1. Passive house is not a brand. Passive house is a generic term for structures that require little or no actively generated energy for heating and cooling. Put another way: “Passive house” is the equivalent to “hybrid automobile.” Car manufacturers now make their versions with their brands.

2. Passive house applies to the principles and practices – which are universal – required to build passive structures. Many of them — superinsulation, airtightness, energy recovery ventilation, managing solar gain — originated in the United States and Canada. They don’t belong to anyone. They are not brands. And they are available to all designers and builders who want to learn to apply them. They remain intact and powerful regardless of any number.

3. As more competitors arrive in a growing market wishing to offer passive house products clear branding of different passive house products (different trainings, quality assurance protocols or standard variations) is important to avoid confusion in the market place. PHIUS has differentiated its product by creating the PHIUS+ program.

Market size is a bigger concern. Passive house has come a long, long way in the past several years. But the market is still tiny. The imperative is to grow the market. And it will not grow if we adhere to a standard that isn’t practical in large swaths of the continent.

By making the standard applicable across the continent, and teaching professionals how to make passive house work where they work, we can help passive house principles go mainstream here in North America. We can make passive house principle best practice. And that will achieve all of our ultimate goals: Less energy, less pollution, more comfort. All thanks to passive house.