What Wall Assembly and Insulation Type Should I Use?

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Marcel Studer of Econ Group Ltd. joins the Passive House Live Construction Tech edition to discuss insulation strategies and wall assembly options. His presentation shares lessons learned over the past 18 years as a designer, builder and instructor focusing on energy efficiency, building science and construction technology. It's also a lovely fable about a virtuous young squire from the House of Passif.

You can watch the video above or read the transcript below.

Marcel Studer:
Thank you very much everyone for those kind words. All back to you, really been proud that I'm part of this movement, part of this great group of people, and have been for the last decade or more now. Wow, time flies when you're having fun with PH [Passive House] of course, and it's not going to be funky tonight, I'm going to put a different spin on it and try to keep all the technical stuff a little bit light. I know it's a little bit later for some of you in the Eastern time zones, so I don't want to bore you too much with technical details, but, as you know me, the ones who know me, I could talk forever and get into the depths of those. I'm definitely open to take it further if you have some more questions, and I'll start my slides here now. I hope you can all see that.

Shannon Pendleton:
Looks great.

Yeah. Good. Today, I'm going to tell you fairytale of the perfectly insulated building. And it starts, once upon a time in the Great White North, where most of us live, and there lived a princess called Gaia as well. Princess Gaia was always cold because her castle had no insulation, terrible form factor, lots of thermal bridges, and an ACH of 50, only single pane windows and no HRV. Her father Old King Coal was at the end of his resources, and after a lot of thinking and consulting with his court, he made the announcement. Whoever could form a plan to provide thermal comfort for his princess Gaia would have her hand in marriage. Suitors came from far and wide, among them, Sir Heat-A-Lot heat a lot from the country of Unlimited Resources, Herzog from Greenwash from the country of Hypocrisy, but none of them were good enough for our princess Gaia.

She had almost given up hope when along came a young squire from the House of Passif, only armed with his wits and good intentions, and he presented her with his plan. Five basic principles will guarantee thermal comfort, as well as high level of energy efficiency. And as most of us know, there's thermal insulation at high levels, passive house windows that are the high performance, orientated properly, using ventilation with heat recovery, getting high level of air tightness, and also try to avoid some bridging in design and construction. There could be a six that we could add, and that has to do with the form, the design of our building, how compact they are. But typically we talk about the five and today's focus is on the first principle, the super insulation, very important for those who are new to the standard to realize the key element that it is a performance base standard, so that means there is no prescriptive path, really. There is no rule of how much insulation do we need to put in our assemblies. A passive house in Vancouver looks difference in a passive house in New York.

And princess Gaia ask, "But where do we start and how do we figure out how much insulation we need for our projects?" Well, it can start with a model and that just goes hand in hand with our design, definitely at a stage where we have schematic design ideas, logometric ideas of our buildings. I highly recommend using design pH. It's a very easy to learn tool, it's a plugin to sketch up. Anyone can learn SketchUp in a few hours too, drawing off that it can use it to start modeling your design project, at an early stage, but it's goes further you can run different scenarios. So you see a little bit in the background here, a lot of the business from a project that worked on, I started out with the baseline. So this particular project, they came to me and everybody was designed not as a passive house, but they asked me, can you, can we make this a passive house?

And I said, "Yeah, I'll try and I'll model it and see what we can do." So it started out with a baseline and it was around 70 kilo hours of heating demands. And just by changing the quality of the windows that already dropped down to around 30 and then started looking at the assemblies and the U values of those. So definitely one of the first kick at the can, when you're looking at a passive house building and figuring out how much do we need, how much insulation do we need? What do we need to look at in terms of view values?

Another approach will be to look for projects in your climatic region and get a basic idea of the adequate U values. There is an international passive house database who you're familiar with passivehouse.com. We'll lead you there, look for your region. Look what has been done, I know passive house, Canada has their own one. Not sure what's happening in US in that regards, but take advantage of your colleagues in your area even if you walk around and see someone is building a passive house, ask them what they're doing and we are all sharing our lessons learned and the Passive House Accelerator is the perfect example for that we can learn from each other the most.

And remember that size and form do matter. And especially for smaller buildings, I would say they don't even have to have, a very intricate envelope that's has a lot of chalks and makes it bigger. It really depends also just on how many stories you have. I was looking at a passive house in Ottawa. I was a one story rancher with a courtyard in it. And I had to tell the client, unless you're adding another floor or a basement, it's not very feasible to get to the certification. So for us who are in the single family world, in the lane way in Phil house world, it's very tough sometimes to get to the full certification. Much easier to have multi-story unit residential projects or powers, et cetera, definitely gets easier in terms of what we have to do in terms of insulation values for our wall assembled particular.

And for example, a single family home in Vancouver could use six to eight inches of exterior insulation, a four or five story building that's a multi residential could use three or four. So it could be that drastic, so keep that in mind, it just got a node and know that you have to work extra hard if you're working with smaller buildings. And then don't forget about your site restrictions. When a lot of us are designing and working in city environments, there is setbacks there's fire regulations. And then also what's around your site. Are there any tall buildings or is there any tall buildings planned maybe across the street? On the south side. Vancouver has a lot of trees. It's always, that's a lot of the time, the main thing we factor in is the trees that are lining the streets.

And then some of us are in mountainous regions where we have a mountain range that's quite far away and the actually impact our solar gains quite a bit as well. So again, promoting design pH, particularly for this stage of your design, where you can add those in, you don't have to get fancy and draw a whole mountain range. What I did recently for a project in pamper tennis is figured out how far the tallest mountains away. And all I did was draw a plane in that direction and that already kind of acts as, it reads the program, reads it and realizes, "Oh, hell we don't get any solar gains after a certain time anymore because the sun is behind the mountains.

Princess Gaia is asking again, now that we have figured out what range of insulation values we require, how do we choose the right assembly and the right details? I really enjoy, or like this, I used some of these slides probably for some of you have taken classes with me, recognize them. And they don't necessarily come from me, that come from my colleagues as well. And I always try to kind of find an easier way to explain things. And this is one of the slides I really like, especially when we are talking about timber frame, with different, with non combustible commercial assemblies, but there's a lot of options always.

And again, the advantage of having a performance based standard is that there is no rules of how we're building our walls really, as long as we get the U value that we are modeling out of it and put the right values in there, anything really works. So this slide really talks about what frame and how can we add more insulation into our assemblies? So there's two major ideas, we either stuff more insulation into our walls. And at some point, we increase into the depths of those walls and we'll get more into the details of what that could look like. And the other idea is to start wrapping our existing structure with more insulation with insulation panels.

So I picked a few here. There's a lot of variations to this and don't think, again, this is kind of a rule book of what you have to do. It's just showing some of the commonly used assemblies that we, and most of them have worked with personally. And I can tell you some of the advantages and disadvantages of these. So in our cool temper climates, it's very important how we differentiate this, where do we build this possible house building? Because that will, how much insulation, is kind of the average will differ if it's a cold climate or a cool temper climate or warm climate. So for us, we are in the cool temper climate. And Vancouver happens to be the same climate as in central Europe, same as [inaudible 00:11:44] So a lot of literature is based on that climate zone.

If we are looking at the stuff it category, the easiest one we see in that is it two by eight or two by 10 wall that's insulated. And we are getting, I got close metric U value of around 0.1 to 0.16 or a Imperial R value of around 36 to 53. So that would be enough here, say for a single family home, medium size. One thing you notice here in the asymmetric is that something has changed from kind of what we are used to in our buildup of our stock frame wall. We the plywood door is sitting on the inside, and there's a few reasons why you can do that and the main one is really, if we are putting it into that position where it's on the warm side of our insulation, it can actually act as our vapor retire layer and the structural engineers, then not really care about where you get that strength from, if it's on the outside or the inside.

So that means you can get away without using a vapor tar membrane. So you don't need a poly what we use to do, but no Proclama Intel or Sega, you can just use the plywood and then if you want, you can also make that your primary air tight layer. So now you're adding another function to this material you're already having in your assembly that your structural engineers asking you to use because the building was fall down like a house of cards, if you wouldn't have it. So we making it the way control layer, and we can tape it air tight. So now we got everything in one plane, so happens quite often so because really it's an economic kind of question of spending more money on material and labor. And now of course you not talk too much about air tightness, but we always want to protect our air tight layers.

So we would add in a service cavity to the inside. That's that two by four framing. You see, I indicated on destroying where we can run our electrical, even plumbing now on exterior walls, because it's way on the warm side. So calling this the deep stall walls, sometimes the fat wall as well, it's one of the most preferred prefabricated panel systems as well. And I saw Jan in the audience there, Hey, Jan this is, you guys put those panels together for us collective carpentry. And this was actually quite a large passive housing built in outside of Vancouver, 7,000 square feet, completely penalized offsite, walls, roof, even intermediate floors.

So we used exactly that buildup. We can see the OSP already taped from the factory, and then the panels getting installed on site. The one on the right, a little infill house in Vancouver, we worked on that, we didn't have set up a crane, not putting any or staging any panels either. So we, you have to be deciding the end to hand frame it, but still went with that same assembly. One thing to note about this assembly, a lot of time, the floors are latchered in. So it's more like a balloon frame than a platform frame, just to kind of make that transition between floors easier in terms of carrying the air tightens through.

Now, if we are looking at a cold climate, then we're still in the stuffed category and we need more space than a two by 10. Once you get to two by 12, I think these pounds will get way too heavy. So I'll call this the original Canadian hype performance ball. And literally, some of you heard of Harold or, and the Saskatchewan conservation house, which was built in 1970s and was the first high, efficient housing, I think maybe north America, which was influential also for Wolfgang and who Adamson, who founded the standard anyway, they used this assembly there. So I'm pretty sure that this Herald do kind of figured this out. He's very humble about his multiple skills, but the double stop walls. So the idea is that you have one structural two by four and one that's non-structural and you move them apart, as much as you want to get the right amount of insulation you acquire.

So definitely something that's more suitable for a cold climate. Typically the cavity gets filled with dense, packed insulation, a little bit trickier to detail all the vapor and airtight layers. Won't get into that too much. Now, rapid is pretty self explanatory. You are using some form of exterior insulation panels and you wrapped them to the outside, or you put them to the outside of your structure. It's like putting on a wool sweater over top of your building. Obviously with that, there's less some of bridging, we don't have any stats anymore that are some of bridging every 16 inches. We could do this on top of a regular two by four or two by six frame. What I'm showing here in the illustration is a CLT panel, mass timber could be mass, anything. It could be mass concrete, mass block, definitely one of the most used assemblies for any building that has a bit of insulation really.

And in our experience, this is kind of what we used as our go to assembly that we do from new construction. And we are using between six and eight inches to the outside. So typically two layers of panels that are either three or four inches, and most of the time using mineral for this, but you could use wood fiber as well. We'll talk a little bit more about why would you choose one material over the other. The trick is really to attach the declining through it. So that's where it gets a little bit difficult, very easy to do on a CLT. It just, hit the screws wherever it's mass timber, right? Even the highest density mineral or with fiber, we'll have a bit of flexibility once you tighten, those screws in those patents will get sucked in you got to get off plane a bit.

So it becomes critical that you have some kind of a system in place to straighten out those walls. What we do is just string line it, plum the corners, and then work our way up just before we put the cladding on and to just it, or suck the screen a bit more or by it off, just to straighten it out. If you are going on top of a wood frame, you may have to hit the stats, or you may upgrade your sheeting to a three quarter where it's easier to support some lightweight planning. If we are looking now at the rapid for a colder climate, I think two panels is in my experience, kind of the most two layers it can do. I've seen people in illustrations of three or four, I think you'll get really cumbersome. You need really long screws and will get very practical on site.

So we have this exterior box that gets added on to a framing. So that could be either made up out of a Larson trust, which is in the top right, it's kind of a cheap, handmade trust, a TJI, which is a wood eye choice. That's just off the shelf. They're really designed for floor roof structures, but you can use them as a broken wood element to build this non-structural box to the outside of our structure. And then it gives you the chance to fill that with insulation, again. Bottom right, is UMBC that's a University in Prince George called climate. Wood innovation campus, a timber frame structure behind this and they actually used a full trust to build the wall and then insulate in between them.

Now we talked about how a few different methods to get that insulation in. There's a few things we always have to consider and one of them is our building science, so anything to do with moisture management. So having moisture inside the building, vapor drive can that dry out to the outside, very important to not trap any moisture between two vapor type materials. Also obviously looking at a exterior moisture, ambient humidity, rains, no wind driven rain, anything like that, that's what our cladding is for. So we always talking about the five critical layers that we need to have in our assembly. So they will look different depending on how you are building up your wall. And here's just an example. And again, for some of them, there is different approaches, even in this one, there's a few different ways to get your air tightness on that picture, on the right. But I always consider that, and if you are having some materials, you're not quite sure of maybe do a hydrothermal model where you figure out, I'm not going to have some issues with trapping moisture in this assembly.

We just talked about walls for now, but it really is all ties into a bigger picture. You need to have a grant plan for your assemblies. It doesn't make sense to switch from exterior insulated to interior insulated between foundation and walls above, and then to the roof. So really look at the building and more as a whole. And we typically put a uniform amount of insulation around the building. We don't just favor the attic versus a little under the slab and more on the walls, so it's a bit more uniform. And this is a nice example of where the architect really lines things up. If you're lining things up, it's easier to build and it's going to be cheaper. So it is definitely doable, it doesn't have to be rocket science.

Don't forget about the windows, the windows are the most critical piece in your assembly, in terms of everything coming together there, your air tight layer, your insulation layer. And just a couple of examples from our chop sites. One where we had that exterior TJI where we had to build a buck to put the window in, and then we are over insulating and the frames a little bit, the one on the right, there's an exterior insulated one where we actually pushed the windows out into the insulation cavities, so we're using fiberglass angles to support it. And then we are going to build the insulation around this once it's all waterproof,

Don't forget about thermal bridging. So first of all, thermal bridging can occur any change or direction at any change of material assemblies, so going through our section and figure out how we doing in terms of thermal bridging, and if using exterior insulation, we really got to pay attention to what is the cladding system? How do we tie that for SAP back to our wall without creating a thermal bridge? So the old metal set guard that was really like highly conductive, really kind of avoided the insulation value of that exterior insulation. So we have now nice clips made out of, or stainless steels. I really broken, or we can use bruise and minimize those thermal bridges.

Gaia obviously named after modern earth goddess is really concerned about modern earth as well. And she asked you, how do I minimize the impact on the environment with all these extra materials? First of all, if you have an existing building consider renovating it, doing a deep energy retrofit, use the passive house tool, ener-phit to certify it. Got some excellent examples out of Brooklyn, all those brownstone buildings. We have a few in Canada, not enough, in my opinion, yet one that comes to mind is the can tower, which is a multistory concrete building that got exterior insulated. Really, I have to start thinking about our resources and I was talking to a Swedish, actually a cycling friend of mine, but he was saying, oh, Sweden is already looking at that, they're running out of cement. They, they don't have concrete forever. They're already starting to look at alternatives to cement.

So I never thought of that. That cement is a resource that actually is going to run out, but we'll face this in our lifetime so we got to think the differently about what we do with our existing building stock and how can we reuse what we have keeping the structure if possible, reusing some materials. So I think that would be the first step, really to get into before we even look what the embodied carbon is of materials, which definitely is summing, I would do looking at new builds and something that actually is getting implemented already into the pacifier standard, pH ribbon is something that some of you may hear it of, it's a tool to look at what is the embodied carbon. And for some of you are not familiar with the term, this illustration really shows it's looking at the entire kind of life cycle of the material, looks at the extraction of the raw material, into the processing, manufacturing, transportation, and the use, and then also the recycling stage or the end use of the material.

So it obviously there's some materials that are just very high, intense in energy, when I went to school a long time ago, we just talked about embodied energy. How we basically just spinning that with carbon, because energy is carbon emissions if use fossil fuels. So the ones who are really bad are the ones who use a lot of energy and there's spray foam. All the plastics are there, there's made from oil, et cetera. And then as we are getting into the more natural materials, especially the ones that are grown, they actually sequester carbon, that means they're a plant absorb CO2 doing its growths.

And if we don't burn it and releasing that carbon again, we are locking that carbon into that material. So using woods most typical naturally grow material we work with actually is a really good thing to use that for construction in terms of low body embodied carbon, using mass timber and using light wood frame, using wood insulation, wood, fiber insulation, and obviously cell is a byproduct to that too, or cork, wool, all these different things we see. So definitely something I would consider,, it's always a question of, can you get the material, how expensive it is as well. And talking about expense guy says, that sounds all good, but my father has a budget. How much will this all cost?

I always like to explain it this way. It's an economic model, really, to explain why high performance buildings make sense in a very easy way. And it is called the cost of monthly ownership. So basically you're figuring out what is your premium to go to high performance, to passive house. And then you figure out the additional mortgage payment you're going to have to pay per month. So you let the bank carry that additional. And then you subtract the savings you're having from your energy bill. And then if you are basically even negative under the bottom line, it's a no brainer. You're saving money every month, right? So who wouldn't want to save a hundred, $135 each month, let the bank carry that extra premium to go high performance.

And you're having the savings. Now, this is a project of ours where we incorporated affordable take. So they're even generating and you see there's energy production. So there's even a bit of more, but obviously that costs quite a bit of money too. So even with that kind of scenario, it starts making sense for these clients, homeowners, building owners, to use the high performance standard and saving for the lifespan of the building.

The next thing I like this Panpina Institute or list here, they figured out how much does it cost to save a kilowatt hour or to produce a kilowat hour? And you buy it from hi from BC, hydro, whatever, from your utility, that's one cost, or you can buy all this equipment and put it on your building and you figure out how much did that cost and how much is the yield. And then you get a kilowat hour cost as well. The cheapest way to buy energy is actually to conserve it. So to buy insulation, to buy good windows, to buy an HIV, to buy membranes for airtightness is you start with that and you are much cheaper than anything else that you can buy any kilowat hour you can buy on the market. So this is another good way I find to really make an economic point for high performance building standards like passive house.

I did a presentation a few years ago, and we looked at a few different buildings with a colleague of mine, we were in Munich at the international passive house conference. And we looked at a few of our buildings and we looked at the spread kind of between where we spending money on passive house features like windows, insulation tapes and the HIV, and we compare it to a regular building. This is just a little snippet out of it. However, want to just draw your attention to how big that pie is. The pale blue, which is interior exterior finishes.

We have a lot of control of over that part of the pie, right? We don't have as much when we're doing a passive house over, the structure, the insulation, the windows, the HIV, but we can save a lot in using more, maybe off the shelf, not too super expensive interior exterior finishes. So this is a concept we do in our residential single family building a lot. We, and the owners get it. And I go, okay, I don't need this expensive tile from Italy. I can do something else or it's just being smart about their choices.

So both princess Gaia and king Coal were convinced. They hired the squire by the way, his name was Wolfgang, of course, to conduct an enerphit on the castle. And after the completion, there was a big party to celebrate the passive certification and the Royal wedding and Gaia and Wolfgang lived happily ever after in their energy efficient castle, full of summer comforts to the end of their life. And that's it with the official presentation. I hope you enjoyed it.