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!

It’s Here! The Phius Certification Guidebook v3.0

SONY DSCIn this week’s blog, Phius Associate Director Lisa White introduces the Phius Certification Guidebook v3.0 and explains how to get the most out of the newest guidebook iteration.

The Phius Certification Guidebook is the one-stop-shop for all things related to the Phius project certification program.

The guidebook contains information ranging from Tips for Designing a Low Cost Passive Building to Energy Modeling Protocols and What to Avoid. It continues to evolve alongside Phius’ growing certification program and standard updates. 

Guidebook CoverOne great reason to certify a project is to share knowledge with the passive building community, which accelerates growth. This guidebook is the keeper of that knowledge as well as lessons learned from the expanding base of certified projects. The Phius Certification team receives a myriad of questions from project teams related to unique circumstances and first-time design decisions that often require developing new guidelines and protocols to be applied on future projects — and those end up in the Guidebook. On top of that, the detailed review of projects throughout design and construction illuminates opportunities for the certification team to improve the guidance we provide to our constituents.

Version 1.0, released five years ago to support PHIUS+ 2015, clocked in at 87 pages. Version 2 followed to support PHIUS+ 2018 at 157 pages, and the most recent update, Version 3, supports Phius 2021, with 190 pages. The guidebook is a key resource for Phius professionals — but we’re often told it’s too long! I’m certain it can feel much shorter, and be incredibly useful, if you know how to navigate it. Anyone can get around a big city with the right map!

View this Table of Contents: Updates Summary which outlines what is new and updated in v3.0.

The document is split into 8 main sections followed by appendices.

The Sections

  • Sections 1 & 2 contain high-level information that is invaluable to first-time project teams and building owners/clients.
  • Section 3 is arguably the most important section, outlining all the certification requirements. Under Phius 2021, there are substantial updates to this section, most notably outlining the requirements of the performance and prescriptive paths side by side, as well as comparing and contrasting how each path handles items such as passive and active conservation strategies.
  • Sections 4 & 5 are key for setting expectations and understanding the workflows and fees associated with the certification process. There is a great high-level graphic showing three phases of certification steps at the beginning of section 4.
  • Section 6 is chock full of detailed energy modeling protocol. This section is laid out in order of the WUFI® Passive tree structure, guiding modelers top down with information ranging from early design defaults to detailed inputs for unique situations.
  • Sections 7 & 8 outline monitoring building performance as well as additional certification badges available. 

The Appendices

    • Appendix A is a consolidated resource about renewable energy. It explains how it can be used in the calculation of source energy use, and guidelines for procuring off site renewable energy.
    • Appendix B is likely the most often overlooked section, while also the appendix most referenced in project certification reviews. This appendix outlines the prescriptive approach to achieving moisture control in opaque assemblies. This most recent update splits this appendix into four types of guidelines: general, for walls, for roofs, and for floors. Do yourself a favor and vet the assemblies used on your next project (certifying or not!) against the guidelines listed here.
    • Appendices C & D are carried over from the previous version, outlining how to assess when a cooling system is recommended (App C) and internal load equipment tables for non-residential buildings (App D).
    • Appendices E, F, & G are great resources for the Phius Certified Rater or Verifier.  Appendix E is the Phius Certified Rater/Verifier manual. It outlines detailed technical inspection and field requirements, post-construction requirements, as well as how to maintain or renew the professional credential. Appendix F describes the procedure to prepare the building for airtightness testing, while Appendix G provides the onsite testing requirements for multifamily buildings.
    • Appendix H describes the Phius 2021 target setting updates, similar to what was found in the previously released “Standard Setting Documentation”
    • Appendix I is new to this version, and holds important information — most notably tips for passive building design about keeping costs low, assembly & window selection, and ventilation systems.
    • Appendix J talks about Co-Generation on-site, and how it affects the source energy factor for natural gas or grid electricity used on-site (depending on how the co-gen is prioritized). This is carried over from a previous version.
    • Appendix K is brand new, outlining definitions and requirements for electric vehicle charging infrastructure to supplement the requirement outlined in Section 3. EV capability is required in some fashion for all residential Phius 2021 projects.
    • Appendix L is also brand new and only applies to Phius CORE projects, as it describes electrification readiness requirements for combustion equipment. As a reminder, fossil-fuel combustion on-site is only permitted for Phius CORE projects, and not allowed for projects pursuing Phius ZERO or Phius CORE Prescriptive.
    • Appendix N closes out the document with normative information. Most notably, N-7 describes many of the underlying formulae for the Phius CORE Prescriptive path which is brand new to Phius 2021. It also contains the formulas and calculation methods used for lighting and miscellaneous electric load calculations, for example.

General Tips

  1. Utilize the Table of Contents and click to the section you need.
  2. Use the ‘find’ function (Ctrl+F) when in doubt of where to look to search for keywords. If taking this route, take note of what section your results are in – for example, is it a requirement or just informative?
  3. Bookmark the Guidebook link! (And follow Phius’ newsletters to be sure you’re aware when new versions are released).
  4. If you are the…
    1. Building Owner/Client — read Sections 1.1-1.4 and Appendix I-1 and review the graphic on the first page of Section 4.
    2. Project Team Member — read through Section 3 one time in its entirety if Phius Certification is a goal of the project. It’s only 18 pages, there are tables and pictures, and you can make it an excuse to have a beer.
    3. Project Submitter — read through Section 4 one time to set expectations, you will be happy you did. Also note Section 2.2, “Yellow Flag” items.
    4. CPHC / Energy Modeler — bookmark Section 6 for reference as you work through the WUFI Passive model.
    5. Phius Certified Rater/Verifier — bookmark Appendix E & F.
    6. One who loves the nitty gritty of passive building — print it, read it cover to cover.

Each iteration of the Guidebook reflects the aggregate knowledge gained by your efforts. Thank you! Feel free to use the comments section below for suggestions and questions.

WUFI® Passive V.3.2.0.1 validation using ANSI/ASHRAE Standard 140-2017

Good news: PHIUS has completed modeling to validate WUFI Passive according to ASHRAE 140. Read the full report here

ASHRAE 140 is a comprehensive Standard Method of Test (SMOT) for the evaluation of building energy analysis computer programs. The ASHRAE 140 report provides the information accrediting agencies or jurisdictions need for validation or acceptance of WUFI ® Passive for code and policy purposes. In short, the standard describes test buildings (cases) in significant detail in order to model the building and compare results versus other software. It contains a comprehensive description of test procedures, as well as predictions generated by WUFI Passive software evaluated against predictive benchmarks.

The table below provides a description of the test cases used for ASHRAE 140 Validation. 

Table 1

Annual Heating and Annual Cooling Load results were reported for most cases, except for L302-L324A which only analyzed heating. WUFI Passive results fell well into the suggested acceptance ranges in all test cases when following Class II Procedures of ASHRAE Standard 140.  Most results fell toward the center of the confidence range as shown in the graphs below.
AHL Results

ACL Results

Authors: Lisa White, Jasmine Garland

 

PHIUS+ 2018 Webinar Q&A

Screen Shot 2018-12-11 at 10.44.53 AM

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.

 

 

 

 

 

 

 

 

Transitioning from PHIUS+ to the PHIUS+ 2015 Passive Building Standard

Lisa White, PHIUS Certification Manager

 

Lisa White, PHIUS Certification Manager

Lisa White, PHIUS Certification Manager

Certification Update: PHIUS will not accept PHPP v9 for PHIUS+ 2015 Project Certification

Up until now, Passive House Institute US (PHIUS) has allowed project teams pursuing PHIUS+ Certification to use one of two passive house modeling tools to model their projects: 1) WUFI® Passive, the passive building modeling software developed by Fraunhofer IBP in collaboration with PHIUS and Owens Corning, and 2) Passive House Planning Package (PHPP), the passive house modeling tool developed by the Passivhaus Institut (PHI). However going forward PHIUS will not be accepting the latest version of PHPP v9 for PHIUS+ 2015 project certification.

Since the release of the PHIUS+ 2015 Passive Building Standard in March of 2015, PHIUS’ standard now differs significantly from the PHI standard. Specifically, the PHIUS+ 2015 Standard uses climate-specific targets for space conditioning energy use (the first such passive building standard to do so), limits overall energy use for residential buildings on a per person basis (rather than a square footage basis), and now uses a different metric for air infiltration.

For the first six months after the PHIUS+ 2015 Standard went live, project teams could elect to pursue either the earlier PHIUS+ Standard or the new PHIUS+ 2015 Standard. All new projects registered after September of 2015 are required to pursue certification under the PHIUS+ 2015 Standard.

 

Modeling Tools for Certification

Since the release of WUFI Passive in 2012, PHIUS has stopped teaching PHPP software during Certified Passive House Consultant (CPHC®) training and began exclusively teaching passive building energy modeling with WUFI Passive. PHIUS has since trained over 1,100 building professionals in the WUFI Passive software to date. In conjunction with the release of the PHIUS+ 2015 Standard, Fraunhofer released WUFI Passive v3.0, which includes a “PHIUS+ 2015 mode”. This software is uniquely suited to PHIUS+ 2015 projects, the North American passive building market, and is available for free on the Fraunhofer website.

Previously, project teams could use either WUFI Passive or PHPP for PHIUS+ project certification, and PHIUS continued to accept both modeling tools even after the release of the PHIUS+ 2015 standard. However, this was not without extra effort from the PHIUS project reviewers, as each PHPP submitted for PHIUS+ 2015 certification required a bit of “jury-rigging” in order to verify compliance with the PHIUS+ 2015 Standard. This adds time, and likely an extra layer of confusion, to the certification process.

In October 2015, the PHI released PHPP v9[1]. While this new software offers a variety of updates and new calculation protocols, PHIUS feels this software is no longer appropriate to verify compliance with the PHIUS+ 2015 Standard. As these two passive building standards diverge, the verification software also suitably continues to diverge. This ultimately does not come down to which software is “better”, but rather is simply about which software tool is most appropriate for each standard.

PHIUS will continue to accept earlier versions of PHPP for PHIUS+ 2015 certification, from the “06-02-10” IP overlay of the 2007 PHPP up through PHPPv8.5, but will not accept PHPP v9 for PHIUS+2015 certification. Eventually PHIUS will only be accepting WUFI Passive for modeling of PHIUS+ 2015 projects, but the date for this has not yet been determined.

For project teams with completed PHPPs that would like to transition over to WUFI WUFI logoPassive, PHIUS is offering a new service for a “one-time conversion” of your project from PHPP to WUFI Passive. The flat fee of $1000 for this service also includes the creation of a SketchUp file for the building and a walk-through of the completed model with PHIUS Certification staff. Contact certification@passivehouse.us for more information.

If you are a CPHC who has been meaning to venture into the world of WUFI Passive, PHIUS offers WUFI Passive training programs at various locations throughout the year to help get you up to speed on creating your own models in the software. Visit the WUFI Passive Training page for more information and to register for upcoming trainings.

Lastly, keep in mind that modeling tools are a small (albeit integral) part of the big picture. Try not to lose sight of the overall goal, which is to build energy efficient and resilient buildings that help to reduce the carbon footprint of the built environment. Regardless of your program preference, every step toward these goals is a step in the right direction.

 

[1] PHI allows project teams to pursue certification under previous iterations of their passive house standard as well as earlier versions of PHPP. However PHI’s new PER metric (the PE metric was used previously) requires using PHPP v9, the only version of the software able to calculate this. Thus PHPP v9 is not yet required for all projects; a sunset date for older versions of the standard and software has not yet been determined. For more information, see the “Criteria for the Passive House, EnerPHit and PHI Low Energy Building Standard” document on PHI’s website.

 

 

About WUFI Passive 

WUFI Passive is a powerful modeling program that dramatically improves the quality and efficiency of the passive building design process for Certified Passive House Consultants (CPHC®). The software allows for calculation of both static passive building energy modeling, as well as dynamic energy modeling for comfort and hygrothermal analysis. The user-friendly interface allows for SketchUp & Revit import, incorporates a seamless toggle between SI-IP, and generates high quality results reports for communication with clients and the PHIUS Certification team. Learn more at the WUFI website.

 

About the PHIUS+ 2015 Passive Building Standard 

Developed in cooperation with Building Science Corporation under a US Department of Energy grant, the PHIUS+ 2015 Passive Building Standard is the first and only passive building standard based upon climate-specific comfort and performance criteria aimed at presenting an affordable solution to achieving the most durable, resilient, energy-efficient building possible for a specific location. PHIUS+ 2015 is also the only passive building standard on the market that requires onsite QA/QC for certification.

Buildings designed and built to the PHIUS standard consume 86% less energy for heating and 46% less energy for cooling (depending on climate zone and building type) when compared to a code-compliant building (International Energy Conservation Code IECC 2009), resulting in an overall site Energy Use Intensity (EUI) of approximately 10-20 kBTU/ft2 year.