### Image Credits:

1. NK Architects

1.
Sep 28, 2017 9:01 AM ET

Edited Sep 28, 2017 9:01 PM ET.

Math education for architects
by Charlie Sullivan

"Save up to 75%" would mean going from a baseline code-built building down by 75% of that baseline, to 25% of it, a factor of 4 difference in energy use. That's not consistent with the other statement here about 75%, described as as an increase from the passive house by 75%, or a factor of 1.75. Those two statements sound the same to the mathematically illiterate, but their meaning differs by more than a factor of two. The former is not plausible given the description of the boxes or the experimental results, in which the code-build house melted 57% more ice, and the passive-house box melted 36% less ice.

It is easy to let sloppy statements slip in a spoken interview. But a similar statement appears on the NK Architects blog.

On the ice box challenge web site, it's framed as the idea that passive house buildings "use up to 90% less energy for heating and cooling than other buildings do." That reminds me of the recent discussion here about that 90% less energy claim. Maybe it's not that the people who say that really think that they can reduce energy use by a factor of 10. Maybe it's just that they don't understand how percentages work.

[Edit: it's also easy to let sloppy typos slip in an online comment. I hope I've gotten them fixed now.]

2.
Sep 28, 2017 10:06 AM ET

Edited Sep 28, 2017 10:10 AM ET.

Response to Charlie Sullivan

Charlie,
You get my "favorite comment of the week" award. Thanks.

Architects aren't mathematicians. The majority of Americans don't understand percentages, and in this country, architects are mostly American.

In the article you refer to ("Does a Passive House Use 90 Percent Less Energy?"), I estimated that the typical Passive House uses less energy than a code-minimum home -- somewhere between 24% less and 54% less. Data from two people -- David Murakami Wood and Katrin Klingenberg -- became available after my article was written. David's data fell smack in the middle of my range.

Katrin's data indicate that savings may be less than I estimated -- on the order of 17% to 28%.

In other words, nowhere near 90% savings.

3.
Sep 28, 2017 10:52 AM ET

Edited Sep 28, 2017 10:53 AM ET.

Math
by ven sonata

The Vancouver experiment is more understandable as: the code house lost 793 lbs. and the passivhaus lost 561 lbs. Or the code house paid \$793 in heat bills and the passivhaus \$561. The passivhaus saved \$232. The passivhaus saves 30% on heating bills. Now that is actually a tribute to Vancouver code building rather that a diminishment of passivhaus standards.

4.
Sep 28, 2017 11:01 AM ET

Cost?
by stephen sheehy

Without a cost comparison, I'm not sure this proves much, other than that better insulation and air sealing, with better windows, is more energy efficient. Duh!
Why R 38? R 10,000 would be even better, especially with sextuple pane windows.
They could have used the same building envelope and called it a pretty good house.

5.
Sep 28, 2017 11:21 AM ET

Response to Stephen Sheehy

Stephen,
You're right. If a version of the Passivhaus Standard (one requiring R-38 walls) ever becomes code, it would be possible to build two new huts: A Passivhaus hut with R-38 walls and an even better hut with R-76 walls. Clearly, the Passivhaus hut would lose this contest -- and the contest would prove nothing.

6.
Sep 29, 2017 7:41 AM ET

by Reid Baldwin

Since we are comparing cooling loads instead of heating loads, why do they focus on the wall insulation. Both buildings appear to have white roofs and to be located in the shade. A more meaningful demonstration would have the same color roof that is common in the region and be out in the sun. How does the roof insulation compare? The window fraction looks pretty low compared to typical buildings. The number of panes in the windows is not as important as the SHGC. With air leakage being such an important aspect of passive haus, why no blower door testing?

7.
Oct 13, 2017 7:38 PM ET

Oakland Ice Box Challenge - More Results
by Bronwyn Barry

Scott - thanks for writing about these fun demonstrations! Another version was recently held in Oakland and ran concurrently to the NAPHN17 conference, just two blocks away. Attendees were encouraged to visit the two boxes and take part in the online competition to guess the weight of the remaining ice at the end of the week.

The California team designed and built their boxes to be more representative of typical California homes. They installed two windows in each box - one facing south and the other facing west. Triple-pane and double-pane units were installed in the PH and code boxes respectively. This provided a great opportunity to not only test the influence of solar heat gain in a sunny climate, but also see just how well the 2016 Cal Residential Code stacked up to Passive House standard for this region, which meant only a little more insulation and better windows. (Our team was worried the results would not be too different.)

Outside temperatures for the week of the experiment ranged in the low 70's, with full sun all day. The boxes were opened and the runoff from the ice was removed via the single-hung windows each evening. By the end of the week, the Passive House box retained DOUBLE the amount of ice compared to the code-compliant box. Exact results may be viewed here: https://oakland.iceboxchallenge.com/

We could draw a number of conclusions from all three of these Ice Box Challenge experiences. I've followed them all closely and think that they'd make an excellent basis for an undergraduate thesis study. What I've found most notable are the non-performance-based results evident in the remaining ice from all three locations: in Vancouver, the code-box ice was noticeably dirty - a result of the fires in the surrounding region - but the Passive House box ice remained clean and clear. This demonstrates an added benefit of more rigorous air sealing. In Seattle, the ice both shifted inside the box and melted much more unevenly than that of the PH box. In Oakland, there was barely enough ice left in the code box to draw additional conclusions, other than the code compliant structure clearly overheated more than its Passive House equivalent.

You'll likely be able to see similar boxes in your own town soon. As you reported, the Vancouver boxes will be traveling on to Portland, OR. The Oakland boxes will head down the coast here early next year. Based on recent email exchanges, I understand that New York and Pittsburg may also be hosting their own Ice Box Challenges, all using local code vs localized Passive House assemblies. New Zealand also hosted their own Ice Box Challenge recently in Christchurch, so it looks like we’ll learn a lot more about how ice melts in various climates across the country and around the world. Who knew that would be so much fun?!

8.
Oct 13, 2017 8:22 PM ET

Edited Oct 13, 2017 8:23 PM ET.

Vancouver Standards
by Malcolm Taylor

There is a misapprehension in the article that Vancouver will eventually require all buildings to be built to Passive House standards. What the municipal council has adopted is the Step Code, an incremental increase in energy efficiency eventually leading to standards close to those advocated by Passive House. There is no relationship between the new code provisions and Passive House standards or certification beyond that they both lead to energy efficient design.

How this will play out in practice will be very interesting. The most common form of housing now being built in Vancouver are curtain-wall high-rise condominiums, which don't usually meet current code energy requirements. Making that housing form meet very stringent new levels of efficiency will be extremely challenging.

9.
Oct 13, 2017 9:19 PM ET

Training available
by Bronwyn Barry

Malcolm - I'd encourage you to take one of the many Passive House training courses now widely available all across North America: http://naphnetwork.org/designer-training/. You'll be relieved to learn that building high-rises, even using curtain-wall assemblies, is not as hard as you appear to believe... It's currently being done in much more challenging climates than Vancouver, where Passive House certification is now being offered as an alternate pathway for code compliance, in lieu of the step code. The CoV is offering a number of substantial relaxations in their zoning code for those opting to use the certified Passive House pathway. Here's their website with further details: http://vancouver.ca/home-property-development/build-a-passive-house.aspx

10.
Oct 13, 2017 10:33 PM ET

Bronwyn
by Malcolm Taylor

You have missed my point about the typical construction the development community currently builds in Vancouver. I probably worded it poorly. The construction industry, the largest generator of taxes and driver of Vancouver's economy (and arguably a constituency that few municipal politicians can survive without the backing of) has been used to producing high-end housing with poor envelopes. Getting them onside is what is going to be challenging.

You probably don't remember, but some time ago we had a discussion where I expressed my concern with the Passive House agenda of forcing people to adopt the standard by getting it adopted in municipalities or included as part of building codes - something you denied.

And now here we are with Passive House attempting to do just that in Vancouver. The consolation you are offering, rather condescendingly considering you know nothing about my professional skills, is to take the Passive House training. Forgive me if I decline.

11.
Oct 14, 2017 9:06 PM ET

Calm down to frantic, Malcolm!
by Bronwyn Barry

Malcolm, forgive my impertinence in suggesting you may benefit from some additional education... Rather than taking my word for it, I was hoping you'd be able to figure out yourself that "making that housing form meet very stringent new levels of efficiency will be extremely challenging" is not that challenging after all... Here’s an assembly high-rise architects will be familiar with in Vancouver, using a section profile just one pane different from those currently being specified: http://www.raico.de/en/Products/THERM/Passive-house.php. (It’s being offered through Unison Windows in North Van: http://www.unisonwindows.com/.) The Schüco curtain wall assembly used on the Bullitt Center in Seattle is now widely available across North America, with an easy option to select ‘to passive house standard’ here: https://www.schueco.com/web2/us/fabricators/products/facades. If that’s too limited a choice for you, here's a link to 38 alternate options, all certified by PHI for the cold-temperate climate of Vancouver: https://database.passivehouse.com/en/components/list/curtain_wall_system. Vancouver developers will have no trouble using these assemblies if it means their projects are fast-tracked or they receive other incentives.

I'd also like to address your "concern with the Passive House agenda of forcing people to adopt the standard by getting it adopted in municipalities..." (I remember our discussion.) Please rest assured that many smart municipalities, including those of New York City and the City of Vancouver, are impressively capable of recognizing the benefits of the Passive House standard all on their own. (No strong-arming required.) As far as I know, the Passive House standard is still voluntary in both those cities. Our community’s collaboration with the United Nations (https://youtu.be/f9VWTGjPLzw) on their building framework is also all based on member nation’s voluntary signing of the Paris Agreement. I promise not to strong-arm your city into meeting the Passive House standard. Despite your obvious disdain, I can also promise that the training will still be open to you and anyone else who’d like to learn how to design what will soon become the new code minimum performance targets, whether it's called 'Passive House' or not: http://naphnetwork.org/designer-training/.

12.
Oct 14, 2017 11:05 PM ET

Bronwyn
by Malcolm Taylor

Would you suggest that course to Martin? John Straub, Joe Lstibek? Bill Rose? Do you know more than them? Better than them?

The Passive House designers and builders I've had contact with seems well intentioned, but the closer you get to the centre of the organization, or its propaganda arm, the more ideological it appears. Despite your constant denials, Passive House itself makes quite clear it wants to get their standard accepted to the exclusion of others. The vehemence of your fratricidal battles with American Passive House also show you don't want a plurality of approaches.

There are a lot of well-educated practitioners who are interested in the same aims you profess, but believe they can best be achieved by other means. You have consistently shown no genuine interest in exploring an open examination of any topic here beyond a blanket defence of Passive House. Would it be fair to say your new message to me is that once Passive House has out-manoeuvred alternate approaches, you promise the door will still be open for me?

13.
Oct 15, 2017 11:11 PM ET

Hmmm... perhaps the ice needs to be 'broken' and not melted?
by Bronwyn Barry

Malcolm - let's just bury the hatchet, shall we? I hope you'll be hanging out with Joe Lstiburek's in his basement, smoking cigars, if and when "Passive House has out-maneuvered alternate approaches."

In the meantime, I look forward to seeing other ice-melting demonstrations happening all across the country, using the building assemblies of your own personal favorite path to lower carbon emissions.

14.
Oct 15, 2017 11:16 PM ET

Bronwyn,
by Malcolm Taylor

That's more than fair. Cheers.