Episode 9 – Ken Levenson (Passive House Network) – Curtain Wall Conversations

By Sean | Blog

February 6, 2024

In Episode 9 of Curtain Wall Conversations, we’re thrilled to welcome Ken Levenson, Executive Director at Passive House Network and a pivotal figure in the world of sustainable architecture. Ken earned his Bachelor or Architecture from Pratt Institute and brings over two decades of architectural experience from his tenure in New York City. His career took a significant turn towards sustainability after embracing the Passive House concept in 2009, leading to his certification as a Passive House Designer. 

Ken has played a pivotal role in advancing Passive House standards through founding New York Passive House, the National Passive House Alliance, and NAPHN. His contributions to energy efficiency standards, including advisory roles for Urban Green’s 90 by 50 report and the United Nations Economic Commission for Europe, highlight his broad impact. With a career that merges architectural practice, advocacy, and education, Ken brings invaluable insights into sustainable building design and Passive House evolution. Welcome, Ken. 

This episode delves into critical topics at the heart of sustainable design:

  • The unique advantages of Passive House standards over other sustainability initiatives
  • Adapting Passive House principles to various geographical conditions
  • The critical role of public policy in promoting sustainable building practices, highlighted by New York City’s Local Law 97
  • A closer look at the Winthrop Centre in Boston, the world’s largest commercial Passive House building
  • The significance of the Passive House Planning Package (PHPP) as a tool for architects
  • The crucial conversation around embodied carbon and its impact on the environment
  • And so much more!

Watch this episode now on YouTube!

Haven’t seen Episode 8 yet? Catch up now on our conversation with James Satterwhite, CEO of Advanced Glazings Ltd., where we discuss evolving trends in facade and glazing performance, the unique aspects of his company’s Solera product, global challenges impacting manufacturing, developments for vacuum insulated glass in North America, how innovation drives Stretch Codes, and more!

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



  1. Intro [0:00]
  2. Why Passive House? [1:32]
  3. Geographical Adaptation in Passive House Design [8:24]
  4. The Role and Importance of Public Policy [20:19]
  5. New York City & Local Law 97 [24:06]
  6. The World’s Largest Commercial Passive House Building, Winthrop Centre [29:37]
  7. The Case for Code Mandated Air Tightness [35:15]
  8. What’s the Big Deal with Embodied Carbon? [40:22]
  9. Wrapping Up [45:15]


PETER: This is our 9th episode of Curtain Wall Conversations! Today, we’re thrilled to be joined by Ken Levenson, Executive Director at the Passive House Network in New York and a larger than life figure in the world of sustainable design. Ken earned his bachelor’s degree in architecture from Pratt Institute and brings over two decades of architectural experience to his work, which took a decisive turn towards sustainability after embracing the Passive House concept way back in 2009 which is incidentally when we were doing actually our R&D at GlasCurtain and when we did our life cycle assessment in 2009, so, there was something about that moment, there was something about that moment!

Since that time, Ken has been instrumental in popularizing Passive House standards in the US market evidenced by his roles at the New York Passive House, the national Passive House Alliance and NAPHN which is the North American Passive House Network. His expertise also extends to his contributions on advisory panels for Energy Efficiency standards, including Urban greens 90 by 50 policy report and the United Nations economic commission for Europe. His diverse and impactful career combining architectural practice with advocacy and education makes him a compelling guest as we delve into the future of sustainable building design and the evolution of Passive House standards. Ken, welcome to Curtain Wall Conversations.

KEN: Thank you, Peter. It’s good to be here. It’s quite an intro very, very kind of you.


PETER: So, let’s start with the first question here today why Passive House? You become kind of the Passive House guy in many ways how did you first become involved in the PH movement and what continues to fuel your enthusiasm about this particular approach to sustainable architecture out of all of the available options out there?

KEN: Great question. I think that when I first discovered Passive House I was an Architect working in a range of projects and really questioning whether I was helping or hurting in terms of big picture sustainability particularly climate change and the climate crisis back in post Al Gore’s “An Inconvenient Truth” and having fire so to speak under us; that was 2006 so over the next couple of years it was like what am I really doing? What does it all mean? And I bumped into Passive House on the internet in 2009, and it was a revelation really. I was like, whoa, here is something that’s actually speaking to the magnitude of change, that speaks to the magnitude of the climate crisis. It’s not incremental, it’s like, let’s go, we can do this and make the difference. So that was super exciting.

The other part of it that just engaged me immediately was as an architect Passive House was driving architectural solutions to the problem, it wasn’t a techno-fix. Of course, innovation and technology is part of our modern lives but it was really about the fabric of the building, the enclosure, the structure, all the common elements that going back to vernacular architecture, that you’re just dealing with solar shading and all these things to passively drive performance and put the weight of the success of the building on the architecture itself. I found it very empowering, so often since World War II architects have been very disempowered, more consultants, more engineering, less architecturally driven results and it’s really about how the air conditioning system could get you out of any any problem right?

PETER: And we’ve been completely leaning on that since the War. I mean since we invented air conditioning, yeah completely leaning on it.

KEN: Yeah, so, this flipped the script and it put architects back in the driver’s seat. Although, I think many architects are nervous about that and feel the restraints of it but I felt like it was a very liberating force in a way and continue to this day and I think it’s a big part of the approach in engaging architects and builders, building owners and occupants. It’s also getting into the craft of building, we’re not going back to like 19th century handcraft. Iron work all that. It’s about the details, it’s about how the materials come together and you can’t fake it. And, so, it really requires everybody to understand building science and how buildings function.

But I think that’s the last part of this is, it’s so exciting to kind of like have building science explained in a way that you can change how you interact with everything around you, it wasn’t abstract like a textbook and you’re like how does this really relate? How do I make this all come together? Passive House gives you the methodology: I relate it to cooking, there’s this book on fat, acid, heat, and salt. Basically, these four basic elements of cooking, and if you know how to manipulate those four elements of cooking, basically anybody can throw ingredients at you and you’ll make a great meal. Passive House is a bit like that where you get a handle on what’s driving performance and then you can take a wide variety of ingredients, problem-solving design tasks and create the solutions that need to happen. So, it is really like revealing a whole lot about building, so there’s a lot there to chew on for architects and everybody in the industry. It’s invigorating to this day.

PETER: Well, hey, that shows the wisdom of your decision, or your intuition at that time – that there was something really there, and I love that you mentioned the vernacular and I think that that’s something that’s so easily forgotten about is that architecture is geographically contingent, right? We think, “Oh we’ll have these global standards,” you know? We’ve had this idea for a hundred plus years that we’ll have something that we can just copy and paste copy and paste, and the whole world will have the same building or something, right? But it has to be vernacular, it has to speak to its geography. The same kind of buildings that we do here in Edmonton or in Alberta or Northern Canada are not going to be the same kind of buildings we do in Florida, right? But we can still have the same principles and maybe that’s what you’re talking about with the cookbook?

Ken: Yeah, and the vernacular, right, I mean there’s a lot more as in many of this stuff, there’s a lot more in common than difference and there’s ways of tweaking things and looking at it, and there’s emphasis and there’s things that need to need to happen in one place versus another, but it’s still the same elements. It’s kind of like you’re still dealing with gravity, is not going away and the rules of thermodynamics are not going away.

PETER: No, they’re not. But, I like when you mentioned the vernacular as well because it made me also think of the Saskatchewan Conservation House and when most people think of the Passive House concept as having originated in Germany and that’s kind of the home of the International Passive House Institute, which is in Darmstadt, where it’s popularized by Dr Wolfgang Feist, starting in 1996. But, the real history buffs know that in 1977, the Saskatchewan Conservation House was actually built by the Canadian federal government and one of its agencies and played a key role in influencing Dr Feist.


PETER: With respect to how the Passive House system and ideology adapts itself to the different geographies of the world, what is the history of Passive House in the US? And how did the creation of the Passive House or PHIUS come about in 2003? And then, subsequently, the Passive House Network in 2013?

KEN: There’s a a good deal to unpack there, Peter. So, well, let’s start and go back and we definitely want to give credit to the
Saskatchewan House. I think those that have a depth of learning around Passive House know that and get it and the continuum of, the debt to vernacular to, earlier studies and work in high performance building and combining these components in Canada, in the US, in Scandinavia, Northern Europe, there was a lot being done and the Saskatchewan House is definitely a key player in all of that. I think in 2015, I was just looking back which I was at the conference, I think it might have been in Hanover, an award was given or was received by Harold Orr in recognition of the Saskatchewan House and that effort there. And, there’s definitely a long relationship and you see it – that continuum and it’s really nice to see one thing building on another.

Another tie back to North America is that when the first modern Passive House as we know it in Darmstadt was built as a physics experiment, really, to narrow it down, and it was a visit by Amory Lovins from the Rocky Mountain Institute that really crystallized the idea of moving this from mere experimentation and investigation to something that could be standardized and globalized and could have a market transformation effect. So, there’s a lot of indebtedness to go around and I think PHI is very happy to share in the credit for it. Regarding, its development here in the US and going around the world – International Passive House standard came to the US, through Katrin Klingenberg, and she built her home in 2003, which is the first building built to the Passive House standards. And, interestingly, though, the first certified building was a school building in Minnesota, and it was also the location of the first conference in North America for Passive House a few years later, or I think it was at that time was like 2006 something like that. And, so, it developed and in 2011 was the split between the two organizations.

For us, I’m in New York and we helped found New York Passive House and we worked with the PHIUS Alliance Organization and everything. It was important for a bunch of people across the country to maintain the international connection; that was another leg of what’s exciting about Passive House to me personally, is it’s as a global effort, and you’re working with folks around the world. We have a lot, of course, with Canadians, there’s a lot of back and forth… but also with the UK, with folks in Australia, New Zealand, English-speaking World in particular, but the Spaniards, to Italians, the Greeks, Chinese, really, a lot of interaction, which is, which is super important – global problem, global solutions. The kind of, confusion and uncertainty of the moment formed the North American Passive House Network, which became the Passive House Network – we rebranded it a few years ago, really, to know that we have that international connection. That time PHIUS was turning inward and doing its own thing, so, a lot of folks work across the standards and there’s a lot of interchange of information and learning and good works, so it’s exciting,

PETER: That split was a little before we started certifying because we started our process in 2017 and certified in 2019, but we certified, for those of us who don’t know, in the Passive House German standard there’s a certification for projects and there’s a certification for products, there’s what are called components. To my knowledge, is it correct that PHIUS does not also certify components or they do?

KEN: I’m not an expert on PHIUS by any stretch of the imagination but it’s my understanding that they do some component certification of a sort… but I’m not exactly sure what’s entailed. PHI certainly has it dialled down in terms of the different component classes and the performance within them so there’s definitely been a lot of development there. And it’s one of the things driving globally where we’re trying to see between window units, ventilation units and heat pumps and all these different ways of looking at key drivers.

PETER: Obviously that split happened, 15 odd years ago now between PHI and PHIUS…was that a good thing? Should every jurisdiction do that? Should there be a Canadian one? Should there be a Brazilian one? Should there be a Chinese one? What are the advantages and disadvantages to having that kind of model?

KEN: The international standards certainly can work and have worked around the world. They come with them certain constraints and certain capabilities. That is certainly powerful and we see it and with the larger firms that are doing work in a number of different areas, and we see its applicability across the United States, where projects are from Maine to Southern California, really stretching across the geographies. I think there’s always something good about having choices, and about having diversity, and, it’s a bit chaotic – I can’t tell you how many people come up to me and say, “Oh, are they getting back together? When are they getting back together? Oh it’s so sad that it’s all split up.”

PETER: Like Brad and Angelina or something, it’s like some kind of like TV romance.

KEN: Exactly, exactly, and I have two minds of it but at the end of the day it’s like it’s okay, the world’s a complicated place and we can deal with a couple of flavours of ice cream and we can deal with two of these Passive House standards. As you were saying, there’s a multitude of sustainability standards out there to begin with, so you’ve got to pick Passive House and then you’ve got to pick one of the Passive House pathways; and some folks will and some firms will be operating in both pathways, and depending on the project, they may run them through the different energy models and see which tweaks because some things are easier for one than the other and some things are harder for one than the other, and it can depend on the specifics of the project whether it’s the better fit for the project depending on how you define that.

The big regret that I see and have is that there’s not as much cooperative competition as there could be. That we at the Passive House Network and from the beginning, although, we definitely were bent towards the international scene and wanting that connection, we definitely wanted to be allied as an industry player, right? So, you have like your high-performance window manufacturers or other groups of players in the industry, your soda makers, whatever it might be, working finding common ground and working together in terms of public policy and making things happen in the world. It’s been very difficult, PHIUS unfortunately has shown no appetite to work together. We have on occasion a couple of times come together but really they’re to just, to put it out there, they’ve been very exclusionary; When Passive House Network puts like policy opinions or advisory or information forward in terms of how we’d like to see things roll, we put both standards in right from the get-go, and say, “have the choice.” Because, in that way, the choice is good, the policy makers are more apt to, we believe, knowing that it’s not a monopoly and knowing that the market there, is market diversity, and unfortunately the favour has not been returned. We uncover left and right where we have to go back and dig and correct things to make sure that we’re levelling the playing field so to speak. C’est La Vie, it’s unfortunate but we can, hopefully, we’ll find ways to improve on that and make a better working relationship, we certainly want to.

PETER: Well, we can always hope for more collaboration across the industry. I think we’ve seen in other parts of this sustainable buildings world, organizations that split off and then sometimes it’s 20 or 30 years like it’s a full generation and then they come back together. And, so, sometimes it takes fresh blood, it takes letting bygones be bygones for people to come back together. I’ve seen that, certainly, in the Canadian sustainable building industry where 30 years ago couple organizations split up and then they kind of come back together and they do joint conferences and they’re buddies again and sometimes it can take time though.

KEN: Yeah, I hope it happens.


PETER: You mention public policy and your role with Passive House Network in recommending public policy. How important is that? Why do we have to push public policy at all?

KEN: Yeah, no, it’s a good question and definitely we don’t want to undervalue all the individual strides and people that are making a big difference and it’s absolutely critical that these individual projects that are happening in all these different places happen because they’re setting the precedence and being the demonstrations of what’s possible; so, they make a big difference in that helping build the movement and getting things forward but honestly just to put it bluntly unless we can make Passive House code or something like Passive House code, it doesn’t make a difference at the end of the day. It needs to become code.

PETER: Thank goodness for the stretch code, right, Massachusetts?

KEN: Yeah the opt-in, the opt-in stretch code has made it for, I mean it’s for multi-family, above 12,000 square feet in the jurisdictions that adopt it. But you have Boston, Cambridge, Brookline, Newton, on and on and on, Somerville, and many, many other towns taking it on. And, it’s yeah it’s a sea change. And, it’s early days, I mean it’s just coming online and God, we do not want to see it fall on its face.

PETER: No, we’re trying to help support it in any way we can right?

KEN: Yes!

PETER: Because the architects are going nuts, they’re like what do? It’s like they’re doing BC, and it’s funny because they’re referencing BC, right British Columbia, Western most Province in Canada.

KEN: Of course.

PETER: They did the step code. The step code, which is a 15 year road map, right? We’re going to do the 15 year thing from 2017 to 2032 and we’re going to incrementally ratchet it up by 10 or 20% every three years, five steps. And Massachusetts looked at that and said, “Oh, you’re funny. You guys did that in 15 years, let’s do that in one!” And so everyone’s kind of losing their mind.

KEN: Which is brilliant,

PETER: Hey, you know, it’s fine I mean there’s there’s a lot of merit to both. I mean, I think there’s a lot of Merit to showing the BC model which is really showing industry and taking industry on a journey, right? And showing legislative transparency and guidance. And, there’s a lot of industry engagement, there’s a lot of workshops, there’s a lot of like community buy-in that was really, really developed. And then there’s also merit to just saying f-it, let’s just go. And, sort of, like do first, ask questions later.  You know, like shoot first, ask questions later.

KEN: I mean, I think the issue with the Vancouver and BC is, the 15 years, you’ve got all these years for the special interest to undo it all and it’s gets lawyered up and it’s happening with Local Law 97 in New York, and whereas it’s definitely a risk to be sure but one the climate crisis, is demanding the kind of action that Massachusetts is taking. It’s just everybody else is like being more realistic politically in their own way. And it’s basic and these buildings, it’s not that hard to hit it if you have the right training and pieces in place. So, there are some ifs there, some big ifs.


PETER: You mentioned Local Law 97, I wanted to touch on that because that’s something we haven’t talked about here on the podcast before but I just saw it actually Adrian Lowenstein of LinkedIn fame had a really good podcast about Local Law 97. And for our audience, we’ll link to that. But for our audience, Ken, what is Local Law 97? Why is it important? You’re obviously based in New York it is a New York thing, how does it differ from BC energy step code, Massachusetts stretch code, Passive House, LEED, etc., What is special about it? Why is it a buzz right now?

KEN: So, Local Law 97 was passed a number of years ago, not in 1997, it was the 97th law of the year that it was passed in. And, it addresses building carbon emissions. It’s addressing buildings over 25,000 square feet and it’s a stepped emissions cap on the buildings. So, it’s not necessarily saying exactly what you need to do but there’s 2024 cap, I believe, and then a 2030 cap, 2040, 2050. If I’m remembering correctly, they’re basically pushing it down to zero or close to zero at the end of it. You don’t need to do Passive House, necessarily, to do it, and they are, I’m not exactly, I don’t know, I don’t remember the details inside of it but it’s not focused on operational energy, it’s focused on carbon emissions and so there are lots of ways to get to that. One of them is certainly buying carbon credits and renewable energy, and a whole bunch of ways that don’t involve actually making a better building. There’s a lot of push back and there’s even more push back from the real estate industry in terms of the penalties that are involved if you’re not hitting it. So, they definitely need to improve and there’s also building grading that comes along with it. So, now. for the big buildings whenever you walk by a big building in New York, it has a grade in the window like you have for restaurants in New York.

PETER: A,B,C,D I love that grading system by the way. I mean, I actually used to be a Health Inspector in a former life. We didn’t have that standard, that rating system, we always looked fondly at New York like, “Ah they got it figured out – you shame them publicly!” And, so, that’s hilarious that they’re doing that. I mean, because, usually, we just have the little logo “Oh we’re a LEED Platinum building,” and you have a logo on it and that’s kind of your promotion. It’s your promotion on the upside but like how do you penalize to the downside; and, if you have a C-grade building and it’s not just that your real estate agent telling you, you have a C-class building. You have an energy performing C-grade building. And the penalties’ a really interesting idea. I mean, stretch code doesn’t have a penalty. BC energy step code doesn’t have like an explicit year, after penalty, right? That’s something special about Local Law 97, is you’re penalized every single year, is that correct?

KEN: Yeah, I believe so, I believe so. And so, one of the things that we talk to building owners, especially doing new buildings, but if they’re looking to do substantial retrofits, to do Passive House and employ Passive House strategies because that will lock in a lot of the savings and get you out of paying and paying and paying one way or another like do the investment, cut it, get it as good as you can and save that money.

PETER: No, it makes a ton of sense. I mean, this is the whole passive principle is that these active systems, it’s passive versus active, right? The active systems is how we’ve been building buildings for how many decades now, since we invented central ventilation basically. And these active systems, though, are getting more expensive to maintain, they’re getting more expensive to install, more expensive to repair, labor is getting harder, parts are getting harder. And, so if we invest again, once again in passive
building envelope materials, we future-proof ourselves.

KEN: It drives me crazy when people just look to renewables and the production side. It’s like, yeah well, you need to electrify and we need to go green but we want as little production as we can possibly have otherwise we’re just going from producing our way out of the problem with fossil fuels to produce our way out of the problem with renewables, which has a whole set of other problems that come along with it. And it’s like we need to minimize the production.

PETER: Making solar panels are not, they don’t grow on trees, they’re not leaves that grow on trees, I mean, I assure you, they come from somewhere, they come from the earth and there’s a cost to that. The earth pays a cost to manufacture those.

KEN: No. yeah, it’s massive. So, it’s interesting.


PETER: To run it back a little bit, you were mentioning about projects earlier and PHI certification. One project that definitely caught my attention, has caught many people’s attention in the last little while, and I know is featured on your website as well, is is the Winthrop Center by Handel Architects in Boston, which, in my notes to you, I was like it has to be PHIUS certified. It’s an all glass building, like surely it has to- it couldn’t possibly be certified by the Germans to be the Passive House standard certified building, there’s no way, but, it is! It is, they pulled it off and this building is occupied now, I believe?

KEN: Yeah, yeah, I think they’ve leased out, I mean, it’s amazing like in an environment where office buildings are struggling, they, I think. they’ve leased it all out to Blue Chip companies.

PETER: Phenomenal. So how? You know much about that? Do you know much about that, more that about the design?

KEN: I don’t know the technical, technical details but obviously it has a very good facade system It has- so, what you had alluded to when we were talking earlier about exchanging information about the all glass… it’s certainly wrapped in glass but the Vision Glass isn’t nearly, well there are a couple of things going on. One is that it’s the commercial floors of the building that are certified, not the entire building.

PETER: Interesting, and which is deceptive if you just look at a picture, it’s deceptive if you just look at a picture of this high-rise. I mean it’s huge, it’s what, a 40-storey building?

KEN: Well, It’s a huge portion of the building it’s like 800,000 square feet of office space, right? They’re big floor plates, It’s, you have a base, a commercial base that’s outside of it, and then you have the mid part of the building, which is the office. And then you have high-end residential at the top. And, they decided this was one of these projects that take a long time to produce. It’s almost planned in a different world and they decided they wanted to do Passive House, they wanted to do something pushing the envelope so to speak, and so they bid off the office portion of it. On the sides of the building that have views, there’s obviously spandrel glass, insulated spandrel glass, but there’s also vertical non-vision glass with it as well. I don’t know what the percentage is exactly, it’s still pretty high it’s probably like 70%, 75% vision.

But, then, you go around to the facades that are like up against other buildings and they don’t have views, the percentage drops precipitously, it’s mostly opaque with punched openings, it still may look like a glass curtain wall but it’s effectively a traditional proportion so they’re playing with that. And then, with the size and with everything else… when you get to a bigger building it becomes much easier to hit the performance. What remains difficult is the comfort criteria, like that inside face of the glass still needs to be a certain temperature. So, that’s where it’s driving that component performance irregardless of the overall heat demand or cooling demand numbers. You need to have a certain foundational comfort level.

PETER: It does make sense when you talk about weighing out all of the different aspects of the building. And, the larger building they have, the more chips you have to play with in a way to move them from one area to another to have these features that photograph very well and are iconic in their own right. And then also have the makeup of the building, the compensation in other areas of the building.

KEN: That’s the great thing about Passive House in terms of using the PHPP energy model as a design tool. So, you’re actively manipulating all these different factors – make the windows better, make them worse, make more insulation, make less insulation, more air tightness, less air tightness. All these things, the ventilation efficiency is a huge driver and it’s really an argument; since we’re talking, is like when you understand the power of high quality windows in the path in the energy models-

PETER: It’s a game changer.

KEN: You want them and it’s crazy when people are are struggling to make the models work and you realize that they just have mediocre windows. It’s like, come on, suck it up and it will pay for itself in a whole bunch of different ways.

PETER: In a whole bunch of ways, yeah it makes your models look better, makes comfort better, productivity, everything else that at the end of the day these buildings are for people and if people are having a better time and are more productive, well then the building will pay for itself.


PETER: You mentioned something as well about about airtightness. That’s obviously something that distinguishes PHI from kind of everything else, is that it actually tests the completed building. How far away are we from that kind of thing being code? To me, that’s the biggest kind of no-brainer, one of the best things that we can do. And, obviously, you have your work at 475 High Performance Building Supply, you’re always dealing with clients who are looking for innovative materials but there’s a big between specifying something and then installing something, right? So, what else can we do to make sure that installation is happening correctly? And then, how far are we from getting that into code? Because that seems like kind of the best litmus test, is test the completed building.

KEN: Yeah, yeah, so it’s encouraging, I mean, blower door testing, airtight testing is coming into code. New York, it is required, you’re still at three ACH, but it’s something and people need to start to acclimate with it. In Massachusetts, where they have the opt-in specialized code, they have to test to Passive House standards the completed building. It is, it’s less just a specification but actually providing the results and the exciting thing about air tightness is when people get it they realize like the power of it. One of the big things that was frustrating in the ramp up of Passive House was when the international standards came over and it was .6 ACH 50 and everybody’s like, “that’s ridiculous, you can’t ask for that!” They’ve gone from 3 to 1.5 and Building Science Corporation couldn’t even understand why it was that because they’re like, “We just cut it in half again! Why is this point six?!” and, “This is absurd, nobody’s going to do it.” And people struggled at first where the techniques weren’t there, the materials weren’t necessarily there and the experience, the community. But, now, still not nothing… you have to plan and make it happen but people are hitting it, people are going much tighter.

The beauty of it is, if you know that you can hit point you know, .4, .3, that frees you up a whole lot more. All of a sudden you have even more. It’s like picking a better window, or you have a higher efficiency ventilation system. It gives you options in terms of trading off one thing to another and it gives you insurance essentially. That’s one of the things that’s nice about Passive House too, is it’s inherently conservative. It’s not saying, people want the airtightness or these performance things to be like, you know, we’re just gonna make it and then everything’s going to be okay and it would be a bit like designing steel for a structure for a building and we’re just going to design the steel right to where it’s okay. Yeah, no insurance. But there’s no safety factor and Passive House is building in safety factors into the primary standards. So, there’s wiggle room there and still having performance, not that you don’t need to hit the numbers but then to hit them more and be able to know that you’ve got insurance redundancy, some room there to ensure yeah high performance is really important.

PETER: It comes down to the quality of installation right? It comes down to the fact that you can specify whatever you want in the world, if it’s installed badly, doesn’t matter, it’s not going to be a good product. And, this is why we send, actually, a GlasCurtain Installation Advisor to every project.

KEN:That’s great.

PETER: That’s relatively unique, I mean I’m sure there’s some someone else out there that’s doing this but it’s super important to us because it’s one thing to have the highest thermally performing curtain wall in the world but if it’s not installed well, who are we serving?

KEN: You see that all the time with Passive House too because if they haven’t taken in the care that needs to happen with certain things that are driving the performance, they’re like, “What?! This isn’t working, what the hell’s going on? This is garbage, this doesn’t work!” And, it’s like, well, you know these things are connected, actually…?


PETER: Measuring carbon, embodying carbon. Another thing that organizations or certain other sustainability certifications like LEED, I’ve heard rumblings through the grape vine that the Passive House Institute is going to start looking at embodied carbon and embodied environmental impacts someday? That they’re thinking about it, they’re working out, they’re aware of the issue. Why should we look at embodied carbon? What’s the big deal with embodied carbon and does Passive House have a role in that conversation?

KEN: Yeah, absolutely, good question. So, embodied carbon is incredibly important in that it’s a huge amount of emissions produced by merely making the building. If we can lower those initial emissions, it helps the overall emissions profile of the building. Now, it’s interesting with Passive House, it makes those initial embodied emissions, carbon emissions even more pronounced, right? Traditionally, you had huge operational emissions, absolutely disgraceful, and the embodied emissions were quite small in comparison. Now, once you’ve smashed the operational emissions, the embodied emissions are the elephant in the room so it behooves you to tackle those as well for sure. Whether it becomes a certification requirement or not, who knows what will happen.

I do say, I think the international Passive House perspective, in particular, is wanting to keep as narrow of focus as possible while still having that core impact, maintaining that core impact like not wanting to be everything to everybody. So, there are lots of good ideas out there, there are lots of things that we need to do, but it’s not necessary to have it within one standard. So, I think, the Passive House community, in general, because most of them are mission driven around the climate, are at the forefront of incorporating that. And, I could see embodied emissions becoming code very easily. It should be, I mean, I think it’s, along with Passive House level performance, you can codify requirements for embodied carbon. I think architects actually like the embodied carbon conversation more than the operational and I’ve seen it personally with different groups. I mean, architects are the driver of Passive House, to be sure, but many architects see it as cramping their style, right? All of a sudden they’ve got to think about all these things and they’re just not free to do whatever they want.

PETER: Aesthetically, especially, right? Especially that building envelope aesthetics, feature aesthetics, like where’s my window to wall ratio? Where’s my feature curtain wall? Right. Not so easy.

KEN: Right, but architects definitely successfully work their way through that and it becomes like gravity, you learn how to work with gravity. With embodied carbon, they’re changing the specification. It’s much it’s much lower impact on their actual vision of the building per se.

PETER: It’s an unseen cost or an unseen benefit, in a way too, which is one of the challenging parts about conveying it to clients, is like, what do you mean my building comes from somewhere? What do you mean I don’t just draw it and it appears one day and I give you some money and then there’s a building? That it actually comes from the earth, right, fundamentally, everything we’re doing is in one way or another.

KEN: Yeah, I would hope they could code requirements. I mean, it’s pretty clear what the big drivers are for embodied carbon in buildings. It’s concrete, and the mixes exist to have a low carbon mix and why not mandate it? And, unrecycled steel, new steel is- aluminum too, other alloys, other metals. More processed stuff and you can get into more but just those two things is a huge percentage. There’s many things to do and buildings have an important role to play in supporting a more sustainable environment, sustainable community, all aspects.

PETER: Absolutely, couldn’t agree more.


PETER: Two more questions as we wrap up here. One is, with respect to all the things that there are to do, what are you excited about with Passive House? Where are we going in the next decade? What are you looking forward to, as it seems that now there’s finally North American manufacturers who are getting into the spirit of things and North American components being certified, and we’re actually having some options that don’t just have to be imported from Europe or Asia or what have you. What are are you excited about though in the decade to come, Ken?

KEN: So, I think, the global manufacturing has always been a core component like when you talk to PHI, it’s their first question is like who locally can make these? It wasn’t about employing German industry as an exporter; they wanted and they knew, they understand, explicitly, the connection between local manufacturer, local training, local design, like it needs to happen on the ground. Coming out of that, I think two things that are particularly exciting.

One is process-oriented in terms of prefabrication, panelization of buildings and seeing bigger buildings, whether they’re mass timber or otherwise. You know, factory buildings at scale is fantastic. So, you have the high quality, you have speed, you have scale, and hopefully one day you’ll have cost effectiveness. It’s one of those things at the moment, I mean, I don’t know the gory details, but it certainly can be cost effective; whether it’s cost effective enough to really like take over the market, we may be a couple cycles away but it’s on the move and expect it to totally dominate, I hope it does. And then, the other part is going back to the materials, is this idea of bio-based materials, less intensive manufacturing. I know you can’t make windows out of bio-based materials, but, upcycling, waste-agriculture, waste material and thinking about real agricultural stock materials that you’d see out in the corn fields of the Midwest, and things like wood fiber insulation where you’re getting, often times, you can get waste stock and you’re upcycling it. So, I think that has a lot of legs in different applications. I think that’s another thing that’s just on day one and could really play a huge role in our building industry and sequester a whole heck of a lot of carbon along the way because the forest offsets don’t really work. The forests tend to burn down these days, but if we can lock the carbon in buildings, it’s much harder to have a whole bunch of buildings burned down. We can protect those better.

PETER: No, and thankfully we have have much better fire codes and sprinkler systems than we did 100 years ago and we don’t have the Great London Fire and the Great San Francisco Fire and those things, thankfully, seem to be a thing of the past by large.

KEN: I would say on the window side, just to be explicit, I mean, it’s exciting to see the technology and the systems out there and what you all are doing to make glass systems that people have real choices and designers can design any number of different ways and people don’t feel like locked in, is really, really important and I think having those, that will just accelerate going forward.

PETER: Well, thank you very much. It’s nothing better than being able to feel like you’re part of the solution and feeling like you can provide architects with fixes instead of constraints, with opportunities, I should say, opportunities instead of constraints. That’s always a fun place to hang out in the world of the possible. Before we wrap up, any last questions for me about what we’re doing or or anything else that we can share with you, Ken?

KEN: It’s always a pleasure, we’re so appreciate having Glascurtain in this ecosystem and environment and driving the market and we want to see more of it so, we look forward to working with you more and more.

PETER: Well, we’re going to make it happen, Ken. We’re going to make it happen.

KEN: When are you going to be in New York?

PETER: I’ll be there middle of February, in time for that New York Builds conference, so plus or minus a couple days around that.

KEN: Well, hopefully, maybe I’ll bump into you at the conference.

PETER: That would be a fantastic, we’ll grab a coffee or grab a sandwich together.

KEN: Yeah, absolutely.

PETER: Well, Ken, thank you very much for joining us for Curtain Wall Conversations episode 9 and it’s been an absolute pleasure. And where can people find you online going forward so if they have more questions about Passive House Network and your work.

KEN: Visit us at passivehousenetwork.org! We didn’t go into it but we’re really fundamentally about training and about education and knowledge sharing and connecting people. It’s really the network, it’s peer-to-peer knowledge sharing and so, stop by and feel free to ping me, my email is ken@passivehousenetwork.org.

PETER: Fantastic, well, with that we’ll say thank you very much, Ken, and we’ll talk to you soon.

KEN: Yeah, thank you Peter. Have a great day, this was a pleasure!

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