Episode 2 – Alex Worden (StudioTJOA) – Curtain Wall Conversations

By Sean | Blog

April 5, 2022

In Episode 2, Peter dives deep with Alex Worden.

​​Originally from Calgary, Alex has lived in the states for over twenty-two years. Completing his Master’s in Architecture at Virginia Tech, he would go on to specialize in parametric workflows, digital modelling and fabrication techniques, working at several high-profile envelope contractor and engineering firms as well as co-founding Boulder based, StudioTJOA with his wife and business partner, Audrey. 

Since graduating in 2011, Alex has worked on numerous world-class projects, such as VIA W57th by Bjarke Ingels Group (BIG), the SoFi Stadium by HKS and Zahner, Lucas Museum of Narrative Art by MAD Architects, and closer to home, the 9th Avenue Parking Garage in Calgary by 5468796 and Kasian Architects. 

We had a great time chatting with Alex about facade retrofit considerations, embodied carbon, supply chains, the challenges of flame-spread testing, and much more. We hope you enjoy this wide-ranging conversation as much as we did!

Haven’t seen Episode 1 yet? We explored adaptive facades, durability, upgradeability and more with RJC’s Phil Parker!

Still curious about fibreglass-framed curtain wall systems? Check out our other videos on our YouTube page. Previous topics include Passive House, Embodied Carbon, “Combustibility”, Installation Partner FAQ, and more!



  1. Intro [0:00]
  2. Designing for Retrofits [1:18]
  3. Considering Carbon Impact [3:15]
  4. The Challenges of Flames Spread Testing [12:44]

Hi there, I’m Peter, Managing Director of GlasCurtain. Today we have episode 2 in our Curtain Wall Conversation Series where we talk to industry experts to explore new ideas of what’s possible with glazed facades. In this episode, we’re talking to Alex Worden. Originally from Calgary, Alex has lived in the States for over 22 years. Completing his Master’s in Architecture at Virginia Tech, he would go on to specialize in parametric work flows, digital modeling and fabrication techniques. Working at several high-profile envelope contractor and engineering firms, as well as co-founding Boulder, Colorado-based StudioTJOA with his wife and business partner, Audrey. Since graduating in 2011, Alex has worked on numerous world-class projects such as VIA 57 West by Bjarke Ingles Group, and cothe SoFi Stadium by HKS and Zahner, and the Lucas Museum of Narrative Art by MAD Architects and of course closer to home, the 9th Avenue Parking Garage by 5468796 Architects. We had a great time chatting with Alex about facade retrofit considerations, embodied carbon, supply chains, the challenges of flame spread testing, and much more. We hope you enjoy this wide-ranging conversation as much as we did.


ALEX: You have the over-cladding weight aspect


ALEX: and planning for future retrofits and things like that. Facade Techtonics 2020, I actually moderated the presentation that Daniel Kelso gave, who’s a friend and former student of mine, who went to Enclos. I told Enclos like “hey, he’s straight out of school, you guys need to hire him now because your competitors are gonna hire him” and they did. He gave a presentation on a topic called “Designing for Distance”. The paper is available on the website. So on Facade Tectonics, if you type in “Daniel Kelso”, K-E-L-S-O or “Designing for Distance”


ALEX: His proposal was: designing curtain wall mullions today for future retrofit applications. Right?


ALEX: And he created this really interesting clip system. You know how the American/North American style split mullions are…


ALEX: open web with the anti-buckling clip?


ALEX: He designed an anti-buckling clip system that could be toggled on and off by way of just a rotational tool and then you could take a unit out in situ, right? And then you could retrofit it and put it back in without having to deal with the – I mean, typically you have to take a reciprocating saw and cut out the clips and then move, and then poke around and do retrofits, he was proposing something different. So, I recommend anybody who’s interested in that, take a look at that paper cause it’s a really good paper that he did. But, the idea of designing for future retrofitting is something that’s hugely important to Audrey and I at TJOA.


ALEX: In fact, my statement of interest to get me into grad school at Virginia Tech, I wrote on systematic demolition of buildings and the architectural knowledge that is required and that architects need to be more knowledgeable of building construction methodologies in order to design for demolition.

Peter: Hm

ALEX: Now, demolition could easily be flipped to retrofitting and systematic or localized demolition for retrofits.

PETER: Mm-hm

ALEX: This is where that knowledge, the knowledge that Audrey and I gained working at Enclos, working as contractors, being in the facade space for 11+ years now, system design, facade architects, curtain wall specialists, parametric specialists and things like that too. The fact is, that’s what we’re trying to propose with this ETFE cladding system that we’ve put in our patent application for and are actually moving forward with it with this thermal switch MetLife Competition idea and making it more of a reality. That’s what we’ve found at the very least is, the weight aspect is huge and one of the things that helps us in our product exploration and system exploration is the fact that this over clad system that we’re developing actually is probably one of the lightest weight over clad systems that would be available.


ALEX: Due to the nature of framing and the fact that we are using an ETFE film. So when you can take the stress off of existing buildings and even the engineer, right? Taking the stress off the engineer.


ALEX: Trying to figure out the calculations of “is this brick anchor gonna hold up its panel system?”

PETER: (laughs) right.

ALEX: So anyway, I think that um…

PETER: Yeah and the weight is a big consideration too, and that’s a big consideration when we’re talking about these other kinds of retrofits, whether it’s replacing a curtain wall or it’s over top, like you were talking about, other tall multi-family residential buildings where you just have a punched opening…

ALEX: Yeah

PETER: and in most situations, the weight is very important. Who was it? Like Buckminster Fuller or something asked Norman Foster once, he’s like, “Norman, how heavy is your building?” or “How much does your building weigh?” and there’s actually a great YouTube video on that as well. But it’s like, it’s so rarely a topic of conversation like how much does a building weigh? I know that there are newer parametric techniques I remember recently Zaha Hadid had designed the Mexico City Airport or something that used 30% less concrete or something like that because they were trying to make it as light as possible to have as little carbon impact as possible. I think as we get better at all of the operational thermal performance things, next we have to look at the embodied impacts I think that’s something that is still…you know, LEED looks at very closely but Passive House, unfortunately, doesn’t for example, yet. But then, it’s gonna be things like weight. Especially in the world of supply chain disruptions, because weight is also logistics.

ALEX: Yeah

PETER: You know, weight is not just “how much can our existing building hold if we’re retrofitting it?” Weight is also moving materials across the planet and the environmental impact. You need that much more fuel to move these materials across the planet, the vehicles need to be that much bigger and heavier and stronger to handle it too. So it’s all the way down the supply chain.

ALEX: That’s funny that you mention – we’re talking about the weight of material


ALEX: And that’s actually something – the paper that Audrey and I are co-authoring with Kihong Ku, who is the Head of the PhD Department at Thomas Jefferson University, on these ETFE cladding systems. So, Thomas Jefferson University just did the Solar DeCathalon China Project it’s called the “Y-House” and it’s an entirely double-skinned residential project


ALEX: There’s not much on it yet, but it will be, it’s currently in 2nd place, judging will be June, but it’s a double-skinned ETFE outer sort of pillow system,


ALEX: Which is quite amazing. We were their facade consultant and then the industry advisor during design and it actually got built

PETER: I think I saw you post that on LinkedIn or something like that

ALEX: Yeah

PETER: That was super cool

ALEX: Yeah, so anybody who’s interested, type in “Solar Decathalon China 2021”, “Y-House” or “Thomas Jefferson University”, you’ll find it. But, what we’re talking about we’re using that project as a precedent and the MetLife project as a precedent and then we’re gonna move into, for the presentation in October that we’re gonna do, we’re gonna move into what we’re doing with the next-gen product that we’re developing and for retrofits. But we actually did a whole calculation on embodied carbon.


ALEX: The difference in embodied carbon in glass vs. ETFE. We had to go all the way down into, not just weight because you know how companies will like to kind of play with the numbers.


ALEX: It’s like meters cubed vs. metric tonne vs. …

PETER: Sure, the unit of count are all over the map, right?

ALEX: Right, so the EPDs, right? The Environmental Product Declarations of these materials especially ETFE, that one gets a little tricky because a lot of these companies, you can find like Texlon or Nowofol you can find the EPDs but they’re for meters squared of system assembly not of ETFE alone, right?

PETER: Uh-huh

ALEX: We ended up finding ETFE alone relative to a single sheet but then we had to do this calculation, it’s an easy calculation, Audrey was even saying, “Why are we even doing this calculation?” because one, it’s a film of like 250 microns thick, right?

PETER: Right

ALEX: Add up meter by meter by 250 microns thick equals “X” carbon emissions, right? Or embodied carbon, right?



PETER: Sure, okay, yep

ALEX: Multiply that by the thickness to get a meter is “X” number of sheets, so we can finally get an apples to apples and we realized very quickly we were like, “Oh my God”, the GWP on ETFE in a meter cubed vs. glass…

PETER: Is it through the roof?

ALEX: Yeah, it was orders of magnitude, it was exponentially higher

PETER: Orders of magnitude?!

ALEX:  Yeah, yeah, but…


ALEX: But here’s the thing, when you start actually going apples to apples going, “okay, what does this actually mean?” We ended up going into a term that we kind of coined for ourselves but I’m sure it’s being used or there’s probably another industry term for it but, “operational thickness”.


ALEX: What is the operational thickness required for glass?

PETER: Sure, 6 ml glass, 3 ml, triple-pane is 18mm thick of glass, standard unit.

ALEX: Exactly, to get “X” U-value.

PETER: Yep, sure, R10 or whatever, sure

ALEX: We did the same thing with ETFE to figure out operational thickness required to get “X” U-value comparable to glass.


ALEX: All of a sudden the ETFE system dropped, plummeted on the GWP


ALEX: Right? Now instead of – I think it was something like a glass double-glazed unit with the U-value that we wanted standard .3 or something like that, imperial units.

PETER: Yep, R3 – ish, right?

ALEX: Exactly. They were looking at something like 50 GWP or something like that

PETER: Hm-hm

ALEX: Don’t quote me on this, we have the numbers, we will present it at FTI 2022.


ALEX: It was reduced by a quarter not by a quarter, it was like 10 instead of 5. It was so much lower. But that was because of the operational thickness and the weight aspect of it, right?

PETER: Mm-hm, right

ALEX: But then, when you look at the weight aspect of it you know there are things with ETFE you gotta consider. One, there’s the internal stresses on the single skin that’s stretched and things like that. But the weight, the weight on the existing structure…

PETER: Right

ALEX: You know, so that’s what we’re when we saw that we were like, “we have something here” there’s something in the MetLife thermal switch proposal where we were taking these C channel frames and putting them over the precast.


PETER: It’s something we’re going through right now as well because we’re about to…we were originally thinking that we were going to re-test our new Passive House system to CAN-ULC and NFPA again but it’s now looking like we might be able to do…we’ll still have to do the NFPA test but we might be able to do an engineering assessment or a smaller scale mock-up…


PETER: because the difference between our existing curtain wall system and our new Passive House system it’s like 5% different.

ALEX: Yeah

PETER: Right? There are important differences to be sure, but it’s not like they’re night and day different like we’re testing some totally clean sheet design. It’s definitely an iteration of what we already have. So, it’s kind of crazy to have to go through this big $100,000+ test all over again if there’s a more economical solution that provides the same assurances. At the end of the day it’s like an exterior flame spread test, and we’re not really changing anything outboard for an exterior flame spread test you’re using the same aluminum snap caps, the same fibreglass pressure plates, and you’re making a few minor differences on the interior, the shape of the mullion a little bit, some of the gasket shapes…

ALEX: Right

PETER: and that’s kind of it. It’s like why go through the whole rigmarole again when there’s so much similarity? So, we’re in the process of doing that, and we should be finding out in the next few weeks, if not, few months, what we need to do to get that design listing updated with Intertek and then we’re hoping to actually do our NFPA fire test in April or May probably. Don’t hold me to that.

ALEX: Sure

PETER: But that’s our current timeline, so this is very pertinent, very relevant. So by the time this conference happens, we will have had experience we will have had lived experience with designing and testing to non-uniform assemblies, because these tests are also designed, at least in theory, at least originally, for uniform assemblies of whatever combustible cladding materials, right?

ALEX: Yep. Yeah, that was something that I found to be a little bit of a hurdle that was put on the manufacturers. Was that, it’s an assembly test, okay, so Cascadia, or GlasCurtain or whomever has to test with glass infill, with metal panel infill, and then metal panel infill could be changed to anything else: UHPC or…


ALEX: ACM paneling, etc. etc.. and it just bloats from there. And NFPA 285 is a destructive test


ALEX: So, you can’t reuse anything. It’s not like a cycling test where you go 50%


ALEX: 100%, 150% where at least you’ve got the first 50 and 100 before you do the destruction test or the destruction cycle. And even then sometimes those performance mock-ups still survive just fine. So you guys are using Intertek, are you guys doing that in the States?

PETER: Yeah, the only facility left in North America, so once upon a time we actually tested to CAN-ULC S134 in Canada, so there was a facility outside of Ottawa. That was in our very, very early days before I joined in 2013. So that was in like 2010 or something like that. Unfortunately, we actually failed that test at the time. Not from a design issue, I don’t actually share this very often, but maybe I should, because it was actually just to do with installation. So, there was actually just a small gap, on top of the combustion chamber before the first horizontal mullion came…

ALEX: Mm-hm

PETER: and the fire ripped in around the back side of the curtain wall and ate it from the inside. When the test is actually not supposed to test that at all, the test is supposed to be for the outside. We didn’t know. And the testing agency isn’t there to babysit you.

ALEX: Yeah

PETER: The testing agency isn’t there to tell you, “Hey, GlasCurtain guys, maybe you should crush that gap from an inch to a millimetre” because from their mind, they’re like, “this is just business”. And they’re also supposed to be impartial too. I get it.

ALEX: Yeah

PETER: They’re not supposed to help you pass because the point of the test is not to pass the point of the test is to install it as if you were actually installing it to determine if the product is safe or not for non-combustible building envelopes. Unfortunately, in situ, you would never have that gap.You would never have a non-firestopped gap, like a slab edge, you’d always have some kind of fire-stopping, you’d always have a secure space and there shouldn’t be a way for a fire to easily get in behind a curtain wall in situ. But, unfortunately, the way we assembled it, we didn’t know at the time, no one was there to tell us. So, when we re-tested it in 2017/2018, we closed that gap and we passed no problem. Right?

ALEX: Yeah

PETER: Literally the only difference. Closed the gap, passed the test. So we are now hoping we don’t have to make that same kind of learning mistake, or learning lesson,

ALEX: Mm-hm

PETER: There’s no such thing as mistakes, there’s only lessons, with our NFPA test. To your question about the States, so that facility outside of Ottawa closed, maybe 6/7 years ago, and now the only facility on the continent that can do CAN-ULC specifically, and then also do NFPA, there are other facilities that do NFPA, but not other facilities that do CAN-ULC, was with Intertek. And so, we’re going back to just outside of San Antonio, Texas to do that test with Intertek, that’s sort of THE facility for that.

ALEX: That’s cool to know, as I think you know, when I left Calgary, I moved from Calgary to Dallas, right?


ALEX: So, 15 years old, going to high school in Texas, I leave Calgary for “the big city”, you know, like I’m moving on up.


ALEX: And then I lived there for 10 years and then I realized as we were leaving, I met my wife there, Audrey’s from Texas, born and raised, but when I was leaving to go to grad school, I was like, “Oh my God, it was the exact same, not the same culture but it was like Calgary right? Cow town: cattle, cowboys, and oil. Texas, Dallas: cattle, cowboys, and oil.”


ALEX: But then you get the Bible belt sort of aspect to it, that’s really the biggest difference.


ALEX: But still, middle of the country type environment. But, I asked that just because I remember you saying that some of the testing you were looking at with Intertek I think was potentially at the DFW or the Plano facility, which is just north of Dallas. But that’s really good to know that the CAN-ULC can be done at the San Antonio facility


ALEX: I didn’t know they had a San Antonio facility.

PETER: I want to thank you very much, Alex, for taking the time today and yeah, Curtain Wall Conversations will be coming soon to a theatre near you (laughs) but yeah we’ll definitely send that out when we get that to share with your audience. As well as, thank you for sharing that with our audience. So there you have it! Our second episode of Curtain Wall Conversations featuring Alex Worden. Hope you enjoyed our conversation as much as we did. Be sure to follow us on LinkedIn, Instagram, Twitter, and Facebook to stay up to date on new episodes of this new series. Also be sure to check out our Spotify account, where this episode and others are now available, with Apple Podcasts coming soon. If you have any questions about our conversation today, or fibreglass-framed curtain walls in general, feel free to reach out to us on email at info@glascurtain.ca, with one ‘s’ in glas and you can also subscribe to our blog for all the latest updates, which we’ll link to in the description below. Thanks very much, we’ll see you next time.


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