PHIUS Certified Data for Windows program online

Graham Wright, who heads up the PHIUS Certified Data for Windows program, joins us today to provide clarifications on some key features of the program. And to clear up some misinformation.

I get and see online a lot of questions about the PHIUS Certified Data for Windows program, and how it differs from PHI’s Euro-centric program. Apologies—it’s clear that we haven’t communicated the program as well as we should have—but we are catching up to ourselves.

I’m happy to report that we’ve got data and climate recommendations for a nice range of windows online here.

The table lists products, climate zone recommendations, full data certificates and supporting THERM files.

There are a lot more coming—and we’ll be converting this static table to an online database soon.

For manufacturers and suppliers, we invite you to download a detailed description of the certification process (with an application form), and the document is also available at the program overview page.

In the meantime, I hope to clear up misconceptions and concerns about the program:

I heard that the PHIUS Certified Data for Windows program doesn’t account for whole-window R-value. Is that correct?

In fact, the program does provide recommendations based on whole-window R-value, and all have the force of criteria as far as manufacturers are concerned. Also the program provides recommendations / criteria on solar heat gain coefficient.  (They vary by climate from about R-5 to R-9.)

Why doesn’t the program address surface temperature factor (“fRsi”)?

Eventually, it probably will – but on the list of important future program improvements for North America, it’s pretty far down the list, after data publication, NFRC harmonization, air-tightness-durability, and Canadian Energy Rating. That’s partly because fRsi isn’t pertinent to hot climates (and there’s a lot of hot climate zone in North America), and we decided to pay more attention to solar heat gain coefficient.

We cover the condensation / fRsi issue by providing the THERM files, which allow consultants to calculate it if they wish, and more precisely, with respect to the expected interior humidity conditions for their particular project and climate. (I made an ASHRAE 160 + ISO 13788 calculator for computing fRsi requirements climate- and project- specifically. We make it available during CPHC training, and if you email me at, I’ll be happy to send it to you.)

Moreover, both the fRsi criterion and the single-height bar on U-value (at about R-7) look to be legacies of the single-zone origin of PHI’s window program.

Setting that high bar at R-7 has certainly spurred innovation. But our multi-zone system does the same thing – people want to “level up” from zone 3 to 4 or from 4 to 5.  A single standard, when it comes to windows, fails to inform a shopper whether a window is appropriate for a passive house project because it’s overkill in some places and under kill in others.

It also hurts manufacturers—many of them mainstream producers of very affordable windows—who, right now, offer windows that will work well in mild climates. Designers, builders and clients should have those options.

Moreover, we find much to admire in the NFRC system and would like to get the best of both worlds. Funding for such harmonization work is being applied for.

Do we really need the PHIUS window program?


PHIUS’ window program is moving toward a critical goal: producing data in the format that passive house consultants need, and that enables direct comparison to windows rated by other EN-based outfits like PHI or say, IFT Rosenheim. Both window industry representatives and passive designers have told us this is critical if we want to energize the market. To be sure, the programs’ fundamentals are aligned, but the presentation and recommendation level is different in a number of ways. For example, PHIUS’ program is more fussy about solar heat gain and zone granularity. PHI’s is more fussy about horizontal / vertical.

At PHIUS we believe that passive house principles apply universally, but a single criterion does not. From their Greenbuild presentation, it was clear to me that PHI recognizes the need for climate-specific recommendations for components, including windows.  But as I understand it their window certification is still pass/fail at one level. PHIUS has moved more quickly on this front. Going forward, if you hear “this is a passive house window” people should know to ask:  for what climate?  Be wary of claims about passive house windows that don’t show any numbers or label or certificate, it might just be loose talk.

Why such a long name? Why not just PHIUS Certified Window, for example

We settled on the name with care. The AAMA or NFRC would say, you don’t have a “window certification program” unless you address air / water / structural issues. So PHIUS is not certifying windows (and neither does PHI by such lights).

We’re certifying certain data about windows, namely thermal performance, modeled. Hence, “PHIUS Certified Data for Window Performance Program.”

We did not include the term “passive house” because while designed with passive house in mind, the data—even for windows that don’t receive recommendations for passive application—will be extremely useful for designers.

Part 3: NESEA BE13–the passive building journey continues…


OK, the finale! In part one we looked at the growth of passive building and how it’s reflected in Passive Place at BE13.

In part two we embarked on the passive building tour of the BE13 trade show floor–mapped to the fundamental principles of passive building.

Today, we introduce some unofficial passive building principles and visit some terrific partners.


Unofficial passive building principle No. 6:


Only PHIUS+ projects earn the plaque!

PHIUS ( offers certification programs for projects and products. PHIUS+ Certification for new and retrofit applications is the only voluntary certification program in North America that requires a thorough design as well as an onsite third party review process. PHIUS+ certification is the most rigorous on the market–and the best value. That’s because PHIUS has partnered with the Department of Energy and RESNET. That means industry-standard certification protocols for design and onsite verification. And it means one-stop certification shopping. Earning PHIUS+ Certification also nets a HERS rating, DOE Challenge Home Status, and EnergyStar status.

PHIUS+ has jumpstarted certifications. We expect to have fully certified approximately 100 passive building projects by the end of 2013 in North America (if apartments are counted, then the number is closer to 200) and yes, the growth is exponential!

At the 7th Annual North American Passive House Conference in Denver last September, PHIUS launched its Window Data Verification Program. In cooperation with NFRC PHIUS is identifying a North American window data verification protocol and climate appropriate guidelines and recommendations. Several leading window manufacturers have signed on and submitted various window frame and glazing combinations for calculation and verification, and listing in the coming PHIUS window data base.

PHIUS recently partnered with PowerWise Systems–Booth 961 ( to promote their newest product – the inView Passive™ monitoring package. PowerWise offers all kinds of monitoring solutions for all building types—but we’re really excited about the value that the inView Passive monitoring package brings to our community. For passive builders, the proof is in the pudding–monitored performance is where it’s at. inView Passive includes monitoring dashboards optimized for typical passive house components and systems. We think it’s a great tool for anyone certifying a project through the PHIUS+ Certification and Quality Assurance Program.

Besides verifying predicted performance, monitoring systems like inView Passive can serve as early alerts for routine maintenance. For example, energy consumption might rise because a filter in the ventilator has not been cleaned on schedule. Monitoring also provides safety. Say one of the two ventilator fans fail; this could depressurize the house. Without monitoring, it might take some time to notice that indoor air quality declined, back drafting on vented appliances or fireplaces might have occurred or radon levels might have climbed.

inView Passive includes dashboards for typical passive house systems and components and indoor air aspects. Even a closed ground loop defrost system dashboard is included. Information on ordering the system and prices can be found on PHIUS’s website or on the PowerWise website. PHIUS has negotiated a 5% discount for all PHIUS+ certification enrolled projects and the Promo Code is available through PHIUS when registering.

The Energy Conservatory–Booth 828 ( is the PHIUS+ Certified Rater’s best friend. Commissioning equipment for low load and airtight superinsulated homes has become more sophisticated and is now affordable.  What exactly has to be commissioned and tested? The most obvious—the air-tightness of the envelope needs to get tested during construction and then again upon project completion. For very tight homes the rater can now use the Mini-Fan Blower Door System, a duct blaster in a newly developed red door insert to test the entire building, A small fan is all it takes if the home is that tight! The mechanical ventilation system also has to be commissioned and flows have to be verified. Very small ventilation air flows need to be measured. The Energy Conservatory Flow Blaster Accessory measures air flows at diffusers down to very low levels such as 10 CFMs. And lastly FLIR infrared cameras are used to check insulation quality, thermal bridging and also interior surface temperatures. Indispensable tools throughout QAQC process to verify a building has been built as designed and performs.


Unofficial passive building principle No. 7:


The leading national passive building research, education and alliance organizations are the Passive House Institute US (PHIUS) ( and the Passive House Alliance US (PHAUS) (

PHIUS was founded by myself and Mike Kernagis in 2003, initially as Ecological Construction Laboratory, a non-profit, promoting and building passive houses for low income home buyers. It changed its name later to Passive House Institute US when it went national. Since 2008 PHIUS has been offering the hugely successful CPHC®Passive House Consultant training nationwide (NEW in 2013: Virtual segment online saving cost and travel time), we have added Certified PHIUS+ Rater trainings and PHIUS Certified Builder trainings over the last few years. We have trained more than 800 architects, engineers, energy consultants and builders and have certified more 500 of them as CPHCs, PHIUS Certified Builders and PHIUS+ Raters in the US and Canada. These are the folks you want on your passive building team!

In 2013 the renowned Fraunhofer Institute for Building Physics, PHIUS and Owens Corning collaborated on a new next-generation passive building modeling tool – WUFI© Passive. WUFI Passive now replaces PHPP as the backbone tool of the CPHC training. Like PHPP, the tool includes a static passive house energy balancing capability. But it also offers dynamic whole building energy modeling and individual component hygrothermal analysis. And it covers another critical modeling variable: thermal mass, which is necessary for the cooling energy balance. In WUFI Passive all of these assessments use the same project data; no double entry of project data in multiple modeling tools is necessary. Risk and performance management all in one. This tool is seriously cool!

In 2009 PHIUS launched a membership/chapter program, the Passive House Alliance US (PHAUS). The mission: to support the community of professionals who had been trained, to educate the public, and drive the market by involving manufacturers and advocating for making passive building standards the norm in North America. Since Mark Miller took on the Executive Director role of this ambitious program in 2011, PHAUS has a thriving and growing membership program, now up to 350 members. PHAUS’ manufacturer sponsors program (amongst them founding sponsor CertainTeed and Rocky Mountain Institute) is growing, as is the chapter organization—now up to 13 nationwide Chapters with two pending.

PHIUS and PHAUS have significantly shaped the landscape of passive buildings in America over the past 10 years and will continue on our mission: the transformation of the marketplace to make passive buildings commonplace. We are a non-profit and if you like what we have done so far and would like to help, you can donate to PHIUS, become a PHAUS member, or certify and train with us.

Building Science Corporation (  has been a leader in high performance building consulting and education for decades. BSC Principal Joe Lstiburek was a pioneer way back in the 1970s; that’s why at his keynote address at last year’s 7th Annual North American Passive House Conference, he closed his presentation with: “You guys are family.” I was totally moved—and I wasn’t alone. It was inspiring. Joe started building superinsulated buildings in the late 70s when he was just 23 years old!!! The details matched what we consider to be good passive building practice today. He has been on the forefront all along – vapor retarders, thermally broken fasteners, insulated foundation systems, energy heel trusses and even earth tubes (which he is not a great fan of )(link to his article). He knows what the trenches look like.

Building on that energy from the conference, BSC and PHIUS resolved to work together in promoting passive buildings. A first step: We decided to cooperate on the Passive Building University which lives on the PHAUS website (link): BSC bookends PHIUS executive certification classes with a Building Science Fundamentals program, the ultimate preparation for the CPHC Passive House Consultant class. BSC also offers Advanced Hygrothermal Analysis, truly building a science master class. I encourage you to visit BSCs table as they have the best selection of  cutting edge literature that applies to passive buildings. Be prepared to spend some money and schlep books home!

The most recent Yestermorrow CPHC class.

Yestermorrow Design/Build School ( This past December I arrived in Warren, Vt.,for the second CPHC class offered through the Yestermorrow Design/Build school. Yet another full class, intense and dynamic.

How is Yestermorrow different? It teaches all modules in person on 8 consecutive days with the exam on the 9th. People are on site 24/7, they form study and discussion groups beyond the class time and prep for exam together. You talk bonding…the food is exceptional and the people who show up for this are some of the smartest and unique. Yestermorrow truly attracts exceptional individuals. The classes took the passive discussion to new heights and aside from that, Vermont is just stunningly beautiful – an unforgettable learning experience with a retreat flavor.

Passive House New England ( is one of the first independent passive house groups in the country. Many of its members are some of the most experienced CPHCs in the country with one or more certified passive houses under their belts. This group is a great resource for anyone who is interested in building a passive house or building in the North East region. The group has a very active meet up group schedule and hosts a passive house symposium annually in the fall highlighting most recent projects of special interest. Great group: Get involved!

Passivhaus Maine ( is carrying flag in Maine in regards to passive house (don’t you love the lobster in the logo?). This is also an area that has very many experienced passive house consultants and builders solidly on their way. This group also is making strides by providing great information and by putting on symposia. Join the meet up group and help getting the word out!

Well, that’s about it–and that’s plenty!

Thanks to NESEA and all the friends out East that have given me the opportunity to do this review and I hope to see a few of you on the BE13 NESEA trade show floor!!!!!!


CPHC® goes virtual – Training to become a Certified Passive House Consultant now more convenient and affordable

The PHIUS Certified Passive House Consultant (CPHC) training—launched in 2008—is the first and still only training program geared to North America’s unique climates, construction details and market conditions. Over the years we’ve made strides toward streamlining the process—for example, we’ve implemented computerized testing at the end of each session, offered the training at multiple locations across the United States, and offered more standalone test opportunities nationwide. As a result, PHIUS is far and away leading training provider in the United States and Canada. More than 850 professionals have takend the 9-day training; 450 have gone on to pass the exam and earn the CPHC credential.

Now it’s time to take another leap forward. During our recent constituent survey, you were good enough to spend your valuable time and give us your feedback and loads of great suggestions. Many of you said that you want to take the CPHC training but you simply couldn’t  be away from work for 9 days; that traveling once for a five-day session was a limit. That the time and travel for two in-class sessions was just too much.

We heard you: To make the training more accessible, we are making a portion of the class available in live, virtual format:

  • Phase I will now be available via eight three-hour virtual sessions presented in collaboration with GreenExpo365, a national leader in virtual sustainable building training. Lecture and homework sessions—which are well-suited for this format—will be delivered twice a week for four weeks. The sessions will be taught live by PHIUS trainers and will feature live interaction. They will be also be recorded and made available to registered students for review and exam prep. Instructors will also hold “office hours” outside of class time to field questions from participants.
  • Phase II will still be delivered in-class over 5 days—students can choose the most convenient of several in-class locations  in the US and Canada. (See schedule here.)

The new format cuts travel and accommodation requirements in half. It allows students to take Phase I from their home or office. And—it allows PHIUS to reduce course fees, which are being reduced by $300! (See the full description here).

We’re very excited to launch this new format in April (see the schedule here) and we think it will open opportunities for more and more professionals to become CPHCs.

Still, you might be wondering why we have not taken the entire training online.

A proficient CPHC must fully understand the core underlying passive house principles, and have ability to optimize a project’s

For modeling and other training components, there is no substitute in-class in-person instruction.

energy balance and performance,  all within the context of a realistic budget.  Years of in-class instruction have taught us that mastering tools like WUFI Passive or PHPP demands personal interaction. Classroom give-and-take between a student and experienced instructor is critical to understanding work flows, appropriate component choices according to climate, and making cost-effective design choices based on modeling results.

In person, group interaction also greatly enhances the mechanical systems design exercises. Perhaps most important: We’ve seen firsthand the kind of personal connections that develop among classmates and between students and instructors.  It has fostered a spirit of sharing and exchange, and forged connections that are the foundation of the passive house community. It has made us strong.

The PHIUS CPHC curriculum is constantly evolving—and it’s better than ever. It reflects the ever-growing collective knowledge and practical experience of our trainers–the most active CPHC consultants, who have build the most certified projects nationwide. Students received a binder of passive house information as well as CDs of class content.

And the CPHC training now incorporates  the new  WUFI Passive modeling tool. It is truly the dawn of a new age for passive designers! In addition to integrating WUFI Passive into CPHC training, PHIUS is offering three-day, standalone WUFI Passive training. It’s a great opportunity for CPHCs to refresh and upgrade their modeling skills.

I just finished participating in the first ever WUFI Passive 3-day training at Parsons College in NYC. CPHCs from the Northeast, Southeast, the Midwest and California and even CPHCs from areas with extreme climates like Texas and Toronto made the trek—and the energy was fantastic! (We just added WUFI Passive trainings in Chicago and Portland, Ore.)

This is a modern production tool with a terrific user interface. On day one we created a 3-D visualization in Sketch-up, imported it into WUFI Passive,  and assigned window properties to the model. On day two we built assemblies in WUFI P in the 3D detail visualizer and on day three we’re trying out the dynamic options of the model for hygrothermal and comfort assessments.

We’re very excited about this new tool and the new CPHC training format. We expect that our partnership with the DOE—PHIUS+ Certification now also earns DOE Challenge Home and Energy Star designation—will put passive house on the national stage. And the demand for CPHCs will grow faster than ever.

We hope to see you all in 2013 and hope you will find the new format as exciting as we do!



Climate Data—When to Request a Custom Dataset

Ryan Abendroth–CPHC and former Certification Manager at PHIUS–with guidance on Abendroth, headshotselecting datasets for passive modeling.

CPHCs should use the guidelines below to determine which dataset will most accurately represent their current project’s location. Generally, for most projects, one of the existing downloadable datasets will be accurate and appropriate for use with WUFI Passive or the PHPP. In some cases, though, a project will require a more refined dataset customized to a very granular level in terms of location and conditions.

–To start, avoid using data for a location more than fifty linear miles from your project location.

It’s worth noting that even projects within this range may–in some cases–benefit from custom generated data. This is especially true if there are microclimate issues or impacts from geographical features including altitude changes between the project site and the weather station. (Site elevation is a modifier on the climate page in the PHPP that is often overlooked.)

–We recommend using a different/custom dataset if the difference in elevation between the project site and station location is greater than 300-400 feet.

The climate modifier in the PHPP adjusts the data by taking every 1000 feet of elevation change and adjusting it by 3.6 degrees Fahrenheit. We have seen very large discrepancies due to this adjustment because often times, the real world conditions for high elevation changes consist of microclimate situations that are difficult for the linear scaling of the modifier to accurately reflect. If there is not a station location within 300-400 feet of the project site, check for local data. The elevation modifier can also be used to adjust a data set to be in line with local data sources. This is helpful in cases where there may not be a Typical Meteorological Year (TMY3) station for more than 50 miles, or there may be microclimate effects that occur at a given project location that are not able to be accounted for in the base data set. By using the modifier, a dataset can be adjusted up or down to account for the difference in temperatures between the generated data set and local, measured values.

Why accurate data is critical

Having exact sets generated for data points nearest to the project is important because in passive buildings, we are reducing the energy loads so dramatically. Small changes (say 1 degree) in the average temperature throughout the year can have dramatic effects. For a 2000 sq. ft. treated floor area (TFA) building in San Francisco that was meeting passive house criteria, the difference was ~15% for the Annual Heat Demand. This is especially important when considering all of the factors mentioned above. For one project location, I gathered data directly from the station point and then generated a second set based on interpolation through Meteonorm to the exact same coordinates of the station. The result was a variance of +/- 4 degrees Fahrenheit as compared to the base non-interpolated values which equated to ~25%+ difference in Annual Heat Demand in that particular project.

Nothing changed about the location, just the method of generation that was utilized (straight derivation or interpolation). This is the basis behind my insistence on using TMY3 station points whenever possible.

News in the world of Climate File Generation:

The iPHA recently published a tool to generate climate data files for locations where none yet exist. It is an excellent attempt but the fine print recommends use for design only—not certification. This is because the granularity of the tool is only 75 miles by 75 miles, a resolution not small enough for most locations in the United States. It may be relatively accurate in the central plains, but once major geographical features come into play, the microclimate effects will make the iPHA tool only a rough estimate (which reflects the stipulation to use it as a design tool only) due to the spatial resolution being roughly 1 degree about the equator with some data being even less precise (referenced in page 321 of the 16th International Passive House Conference 2012 – Conference Proceedings).


Frequently asked questions:

Is the Climate Data robust enough?

Yes. The passive house verification in WUFI Passive and in PHPP allow architects/designers to design buildings based on two methods, either annual or monthly. The monthly method is the one you want to use for a variety of reasons (more on this later). Because of this, the climate data has been set up to not require very small increments or time steps in the calculation. The actual data sets are a representation of the hourly data from TMY3 sets. It has just been broken down into month-by-month averages instead of a large drawn out set with values every 15 minute or every hour.

What about more exact time steps or hourly values?

If greater specificity is needed in terms of time steps a different program should be used that has dynamic calculation capabilities instead of a standard static model. In many cases, this is not necessary as the passive house verification in WUFI Passive (and PHPP) has been set up to simulate dynamic modeling for passive house buildings. This is made possible because the short term fluctuations should matter less as the lag effect due to super insulation, air-tightness, and thermal mass, provides a buffer against isolated peak conditions.

This past May, the average monthly temperature was 73.2 degrees F, but the PHPP has the temperature as 64.2 degrees F?

Prolonged peak conditions have a large effect in terms of real world performance. However, there is a real difference between weather and climate. The climate is a an average of many years, while the weather is what occurs at any given time.  Climate data is unable to predict any given trend in the future weather. Next year, the monthly average for may could be 55F and even out this year’s unseasonable warm spell.

What about climate change? Should we make data for the future?

This is inherently difficult to predict. While many places represent a trend that is most likely warming, there are others where opposite phenomena could occur. Also changing could be the amount of rain, and the corresponding changes in radiation associated with an increase or decrease in cloud cover. Therefore, we should use the data that is available for our area and worry about updating it when new data comes out, but not worry about trying to predict the future.

What about humidity?

Humidity can be determined through the dew point temperature and average temperature within the climate data set.  As mentioned earlier, this is a monthly value and not as specific as may be needed for some modeling methods, but should be fine in most climates (more on this from future PHIUS Technical Committee articles).

Where can I see the most up to date list of available data sets?

All 1000+ climate data sets which have already been generated by PHIUS are available to download for PHAUS Professional level members at no charge. All existing climate data sets are shown on this map.

If I need a set generated, how does that work?

First, check the map linked to above to make sure that a suitable climate data set does not already exist for your location. A “custom” data set means that we will generate a new climate data set for you if one does not already exist. If this is the case, inquire with to determine the suitability of a site or to have a custom data set generated.

What does a custom generated dataset cost?

Custom data sets cost $75 for everyone, including PHAUS Members and non-members.

Email for more information about custom data sets.

Last call for 2012 / pre-Challenge Home PHIUS+ projects!

Hello, it’s Ryan Abendroth here. I’m the Certification Manager at PHIUS. With the new year coming, it’s a good time to discuss the upcoming changes to the certification process and what it means for project teams pursuing PHIUS+ Certification.

Starting January 1, 2013, projects submitted for PHIUS+ Certification must meet the U.S. Department of Energy’s Challenge Home and the DOE/EPA Energy Star 3.0 requirements. This is a good thing—and will result in a streamlined, one-stop certification process, as I’ll explain later in the blog.

But, if you’re a CPHC with an ongoing project designed with the current certification requirements in mind, I encourage you to submit it for PHIUS+ Certification before the end of the year. Any project submitted before January 1 will be PHIUS+ Certified to current (2012) QA/QC requirements and will not need to also meet Challenge Home and Energy Star status. This will avoid any additional work on projects that were designed before the Challenge Home harmonization (this is especially important for projects that PHIUS first reviewed years ago, before PHIUS+ was established, but have been delayed).

For your project to be recognized as submitted you must supply a signed contract and PHIUS+ Certification payment. You’ll find the fee schedule here.

  • You can request the contract directly from me or simply email
  • You can sign, scan and  return the contract electronically or by snail mail to the PHIUS address: 110 S. Race, Suites 202, Urbana, IL 61801
  • Payment can be made by check via mail or via PayPal on the PHIUS Web site

For projects with expected completion dates in the next several months, I strongly encourage you to submit your documentation for certification before the end of the year—they likely were designed well before the US DOE and PHIUS established the new partnership.

Come 2013, earning PHIUS+ certification also earns the DOE Challenge Home designation.

Moving forward, I firmly believe that the upcoming changes streamline and simplify the PHIUS+ Certification process. In most cases, design changes will not be necessary for passive houses to achieve all three certifications. Currently, the QA/QC process for PHIUS+ includes a spreadsheet to be filled out by the PHIUS+ Rater in addition to the required tests of ventilation commissioning and blower door. With the new Challenge Home requirements, the PHIUS+ Spreadsheet will shrink in scope and complexity. The Energy Star 3.0 and Challenge Home checklists will take the place of some of the provisions currently in the PHIUS+ spreadsheet. You can download the new PHIUS+ spreadsheet here.

As mentioned above, starting January 1, 2013, all projects pursuing PHIUS+ Certification will be required to meet the specification for Energy Star and the US Department of Energy’s Challenge Home Certifications. Through the partnership between Challenge Home and PHIUS, there have been some exemptions granted within the Challenge Home and Energy Star requirements for projects pursuing PHIUS+ Certification. More news on these exemptions will be provided as soon as the updated Challenge Home documents are released.

Feel free to ask any questions here via comments here on the blog or by email at

Happy Holidays,