Good Walls Create Great HVAC

Added: 2026-06-01

[00:00:00]HEY, HEY, BUILD SHOW. STEVE THE BASIC ARCHITECT. YES, this week I continue my conversation with Ross Trthoule. Yeah, in the other video we talked a lot about the hydronic tubing and the radiant floor system and we kind of got off track. So, I said, "Hey, Ross, let's jump outside and let's continue that conversation about windows and the thermal envelope and that relationship to our HVAC strategy." So, yeah, stay tuned. I'm going to head outside and catch up with Ross.

[00:00:32]>> Come see Steve Basic at Build Show Live.

[00:00:35]Scan the QR code or click the link in the description for tickets.

[00:00:47]All right, so made my way outside. Ross, how you doing, buddy?

[00:00:51]>> Doing great. Good to see you, Steve. Um, you know, we got a little sidetracked in the last video there where we were talking about the thermal properties of wall systems, air tightness, windows, relationship to HVAC, and then somehow we went down the >> the radiant rabbit hole >> and uh we were down there for a while to talk about. So, yeah, it's uh well, like I tell like tell them you you get you here, it's like my mind just starts going crazy. Got a million questions.

[00:01:18]So, but let's get back on that train because we're sitting here, beautiful climate.

[00:01:23]>> This is a heating climate and we have some massive doors. Y >> and you don't I mean, >> you can say whatever you want. You don't buy this lot and not haveing, >> you know, 30% of the house glass >> cuz that's why you buy >> amazing views. You got to take advantage of that for sure.

[00:01:40]>> And so with that comes the luxury tax and the penalty of I have to put a lot of windows in and I have to make those choices. And >> yeah, >> all of that comes with it.

[00:01:50]>> Yeah. So when we look at buildings, you know, we think about, you know, where the heat's going to be lost, right? And so we do a manual J cal, right? That's a load calculation. And when we do that, we find often that air leakage is sometimes up to 50% of the heat loss of a building.

[00:02:04]>> Yeah.

[00:02:04]>> And so air leakage is so critical to make sure that building perform. The next one is window to- wall ratio.

[00:02:10]Because when we have a lot of windows that make up a lot of our walls and we know windows are not great performing um you know characteristics of of of a wall assembly um we got to deal with that.

[00:02:20]Right.

[00:02:20]>> And especially sliding sliding have gaskets they incrementally get worse and worse depending on how much more luxury you want.

[00:02:28]>> That's right. That's right. That's right. And so the more you want the window or door to do, say fixed versus an a casement versus a sliding door or a hinge door, they just get incrementally worse and more of a challenge.

[00:02:42]>> That's right. That's right. Yeah. When we look at windows especially, we look at, you know, double hungs versus casements, etc. And we'll look at the air leakage metrics from from the penetration calculator, right? Which and they'll tell us, they'll actually measure how leaky that window is. And so certain windows perform better, certain styles of windows perform better from an air perspective. And so um that's all part of the HC design, right?

[00:03:04]>> Yeah. And I mean up here, you could imagine there's probably some very windy days. So if if you had a casement window, it's going to try and pull that casement away >> from the the gasketing and introduce air tightness.

[00:03:18]>> Yeah, for sure. I'm going to jump back a second because I don't think maybe people don't realize we talk a lot now about things like thermal bridging, air tightness, and these concepts that are really, really important to a house.

[00:03:32]Absolutely.

[00:03:32]>> But when I started out 30 years ago, there was nobody that gave a damn about air tightness in a house.

[00:03:38]>> No. No. It was all about just put in a large gas furnace and a large condenser, oversize it, and just throw as much energy at it and as much mechanical equipment at it and walk away. And the HC guy just wanted to make sure, hey, he wasn't going to call back.

[00:03:52]>> And and going from a 2x4 wall to a 2x6 wall was like going to the moon.

[00:03:57]>> Yeah. Yeah. It was a big difference.

[00:03:59]>> Oh, wow. I I did a 2x6 wall. I always do 2 by six walls. I'm the best builder in town. And yet the house leaks like a sick. That's right. Or you're putting in windows that they're double hungs that rattle and the gaskets don't even touch.

[00:04:12]>> That's right. That's right. That's right.

[00:04:13]>> And yeah, I mean without the thing is now that the hubs are getting more and more airtight, the mechanical systems really need to be sized, right? If you oversize now, you're in trouble.

[00:04:23]>> Okay, >> you're in trouble because like if you think about it for like air conditioning, if you oversize an air conditioner or oversize a heat pump that's doing cooling for a building, if you oversize it, you don't get the run cycles that you do. It's on, it's off.

[00:04:36]It's on, it's off. So, you you blast the heat or blast the cooling into that house and then it shuts off. And so, you you know that same analogy of like would you rather have cruise control for your house, right? And just kind of set it and forget it and let it kind of modulate up and down to meet the loads of the house or would you rather have it be 100% on or zero, right? I think of a car analogy. You're either going 100 or you're going zero or it's on, it's off, >> but don't touch the brakes or gas.

[00:05:00]>> Don't touch the brakes. Exactly. Just let it rip, you know? But with with these modern systems now, sizing matters and sizing it with the right equipment makes all the difference from a thermal comfort perspective.

[00:05:10]>> Gotcha. And then on the flip side, you know, air tightness, it it can kind of hit you both ways because initially it's immediately a comfort issue, >> right? So if I have a window like this, I walk by and the gasket isn't really tight here. Yep.

[00:05:26]>> I get an air stream in there and it's like, wow, I feel cold draft. And and I hate that. But that cold draft is also allowing for heat to escape.

[00:05:35]>> Escape the other way. Yeah. The other way.

[00:05:37]>> Yeah. And so we could see it where you could have cold air infiltrating low and you can actually see warm air leaving xfiltrating crack.

[00:05:44]>> Out of the same crack.

[00:05:45]>> Yeah.

[00:05:45]>> So it's it's pretty amazing. You can actually see that with some of the smoke testing that we do. When you have the smoke pen, you can see the smoke pen where it's going in. Then you go up high, you can see the smoke pan where it's going out. And so you're right.

[00:05:55]when you have these cracks or openings in the envelope or in your window assembly or door assemblies, um it matters because it's going to affect the thermal comfort, the drafts and how the house is going to perform, right?

[00:06:05]>> You know, and so that's where the red door of truth also comes into play.

[00:06:07]>> Exactly. Exactly. How do you know? Well, you got to measure it and make sure you know and you know, speaking of measuring it, but I'm going to ask you a question that I can't believe I'm going to ask, but like people always say houses need to breathe, right? And both of us just cringe when we hear somebody because immediately, you know, they don't understand building. They might think they do. You might have been a builder for 30 years, but if you're asking that question, >> you don't understand. You don't understand it. No. No. We have mechanical systems like ERVs now that provide the proper amount of ventilation. It's filtered. It's preheated, prehumidified, pre-cooled, pre-dehumidified before it ever enters that house. And you breathe in for the occupants of the building. Right? That's the That's the most important part.

[00:06:54]>> And I and I think until you actually live in one of the houses, it might be a hard concept to capture because, you know, I I've had clients that, you know, we're we're sitting there designing and they want every window to be operable.

[00:07:08]>> And I was like, you probably don't want that because it's a really efficient house. You're not going to No, Steve, you don't understand.

[00:07:14]>> I'm going to open >> I'm gonna open all the windows because that's what we do. And I was like, no, I don't think you understand. And then I catch up with them a year or two after living in there and they're like, I didn't realize how great of a quality I can have inside a house.

[00:07:29]>> So they they're not operating the window.

[00:07:31]>> They're not operating the window.

[00:07:33]>> Yeah. And you know, we do I think that's slowly coming around because we do have some very smart clients now that say, let's just put in the minimum operable windows for egress in the bedrooms and stuff, but pretty much make it all fixed. I'm not going to open them.

[00:07:49]>> Right. Right. If you have a good enclosure and you have a good HVAC system, it defeats the whole purpose.

[00:07:54]Why are you opening up the windows?

[00:07:56]>> You know what I mean? Like it it just doesn't make sense. Like you have the ERV systems, etc. makeup systems working to provide all that proper ventilation to the house. You've got all this money spent in radiant floor heating and heat pumps and other things like that that provide an unbelievable amount of thermal comfort and temperature control within the house and humidity control.

[00:08:12]Why would you open up all the windows?

[00:08:14]Think about like all like in a hot humid environment, all the humidity is flowing in, right? In a cold environment, all that cold, dry air is flowing in and you're going to make things uncomfortable. So, window openings don't work to our benefit like people think they do. And how's the vault?

[00:08:26]>> In the old houses, it was like, okay, I'm not going to let the house leak through the walls. I'll open the window and just give it that easier of a path >> where that kind of mentality doesn't really exist now.

[00:08:39]>> Yeah. Yeah.

[00:08:40]>> In what we're building. And you know, the the windows certainly we we touched upon it in the other video, but they're a direct part of the calculations for heat load.

[00:08:52]>> Yeah.

[00:08:52]>> And and it's not only the fact that it's the size of this window or the operation, right?

[00:08:58]>> It's the makeup of the IGU here.

[00:09:00]>> That's right. That's right. So the size like you said, the IGU and the frame.

[00:09:04]>> Right.

[00:09:04]>> Right. So that whole system as an assembly has to be taken into account.

[00:09:09]Right.

[00:09:09]>> Right. And when we plug that into our model, we can figure out how much heat is gonna get through this and how much um co you know heating and cooling heat gain versus heat loss. How much is going to get lost on a winter day? How much is going to get gained on a summer day? And especially when you add solar gain into the mix. That has to be part of the calculation which is >> especially if you're down kind of in the in the southern states. That's going to make a really big difference because now you're asking not only your air conditioning system to cool off the house, but hey, let me heat it up even more and force you to work harder.

[00:09:41]>> That's right. That's right. Yeah. So, you value or you factor for the window and then slower heat coefficient, you know, the SHC ma matters so much, especially down south.

[00:09:50]>> Yep.

[00:09:51]>> And the thermal performance of the frames. Frames are always the worst part of the window. At least I'm told. Yep.

[00:09:56]that you know the center of glass is usually the best part of the window.

[00:10:00]>> I would agree. Yeah, I would agree. Yep.

[00:10:02]Usually when you have condensation inside the window, it's going to be right along here, which is a combination of the lowest part of the frame. I mean, it's the bottom frame and right where that glass meets that frame, right?

[00:10:12]That's always that weakest point is right there.

[00:10:14]>> You know, I I had one framer, you'll get a kick out of this story, he was telling me that he learned that he had a problem because the framing on the inside of the house um there was some condensation on it. And I was like, "Wasn't it on the windows?" And he said, "No."

[00:10:27]>> Yeah.

[00:10:27]>> And I was like, "Why would it it would be on the windows first, >> right?" Like, >> right?

[00:10:31]>> That's where you're going to find probably the coldest spot >> in the house. So, it it was again it kind of lets you know maybe this person doesn't quite understand where this conversation >> is uh is going or coming from. Yeah.

[00:10:45]>> But uh >> it is the weak point of the envelope right here. It is. Yeah. So, you got to get it right.

[00:10:50]>> And and and the the thermal properties of the wall system. I mean, these are pocketed doors, so they go in. So, you're really relying on this manufacturer to do a really good job in not only making the window, but all of the gaskets and the design of the window. That's right. The actual engineering of the window.

[00:11:11]>> That's right. That's right.

[00:11:11]>> Is is a whole another world, >> installation, and also use over time, too. You know what I mean? So, like getting the install right, getting it plum, square, etc. And then the, you know, the usage of it. Is this is this going to be used every single day all the time? Is it going to be used every once in a blue moon? That kind of thing.

[00:11:26]Like that does matter because the gaskets will wear down over time and you might might have some maintenance items >> and you'll have some air leakage. We've we I've been in houses where we we're doing some work and it has two sliders that meet and over the course of time the gaskets get worn, the door gets worn and the homeowner is like, "Yeah, every winter like we'll get a little pile of snow." Yeah, >> at that joint and it's like we can't make it go away. And hopefully these are, you know, better engineered now.

[00:11:57]This was years ago, but but still it's like there's there's a lot of uh trust that we put in the manufacturers um in terms of the windows andor insulation and you know the spacing that we put um on our walls and the amount of insulation that goes in. All of this is a direct tie to your work.

[00:12:20]>> That's right. It's weird for people to think that the windows are part of the HVC system. And that's kind of the mentality we're trying to get across that the building enclosure, especially the windows are really your first line of defense in the HVAC system designed to get the thermal comfort right. So when SP I think when people start to think about that um that if I get my enclosure right, I get my windows right, I reduce the size of those mechanical systems, I reduce the size of how much heating and cool I need to provide, I reduce the size of the duck work that needs to be provided, you know, a lot of good things happen when I get that enclosure right. So these are the unintended consequences of building airtight and awesome homes.

[00:12:56]>> And I'm I'm not the biggest fan of labels. Most of the time I say I don't find them very useful but I think with things like passive house coming to the US >> that it actually it just it created a conversation where people need to understand it's not about just putting in a big heating system like build the right house and then tune a very small heating and cooling system. Yep.

[00:13:20]>> To the house. And you can think about it from like if you have um a budget that you're working within and let's call that you know um so you know a bucket what portion of that bucket is going to be spent on the enclosure and on the windows and what portion of that goes to the HVC system directly and so now you're just switching right you're putting more money into the building enclosure and less money into the mechanical systems right in some cases >> and I would argue less mechanical systems smaller mechanical systems less maintenance less initial cost less replacement cost less headaches to try and figure it out. I mean, I see some of your videos. I absolutely love them, but I'm like, if that was the mechanical room in my house, like I would go crazy when the heat didn't work. Like, where do I even start with a troubleshoot?

[00:14:04]>> Yeah, exactly.

[00:14:05]>> So, it's a kind of like a sub like it gets crazy.

[00:14:07]>> Yeah. Those some of those projects gets gets nuts. We have clients that want have a high level expectation and they want to do some crazy stuff with pool heating, hot tub heating, radiant flooring, makeup air, you know, >> snow melt, >> snow melt. I mean, you name it. It's like wine sellers. It gets crazy.

[00:14:22]>> And you you have gas systems that are doing this and you have electric systems doing that.

[00:14:28]>> You have a 600 amp service at the house now. Yeah. And it it can >> it can get complicated when you want to do a lot of things, you know, on these projects. It doesn't have to be that way though is my point.

[00:14:38]>> Right. Right. Right. And and as a matter of fact, we did a we one of my first passive houses 2600 ft twotory. We heated it with one mini split and the one min split was twice the size of the load.

[00:14:54]>> Yeah. Yeah.

[00:14:54]>> And so it can be done.

[00:14:56]>> It can be done. It can be done. Yeah.

[00:14:57]>> You know, just distribution >> was the problem there. We ended up we we plumbed and wired for a second mini split because we were afraid distribution wouldn't keep up. We can handle the load, but we just can't get the heat where we need it or the cooling.

[00:15:12]>> Yeah. So my concern on those projects is that having two levels, trying to get the comfort right between the first floor and second floor, that can be challenging. And distribution, like you said, when bedroom doors are closed, they're not going to get the same level of air flow and, you know, passive air movement because the house will try to reach equilibrium, right? Like heat is always trying to go from hot to cold to try to equalize and humidity is trying to go from hot high to low to basically equalize. And so you have those kind of laws of physics helping us. But now if you close bedroom doors for long periods of time, you don't get enough air flow and enough air movement in those spaces in a non-ducted arrangement like that with just one mini spot doing the whole house.

[00:15:48]>> And I have to I remind a lot of our clients because I had an engineer tell me that, you know, we've had this conversation like when you leave in the morning, make sure all the kids bedroom doors, your bedroom door is open.

[00:16:00]>> Yeah.

[00:16:00]>> So that now the rooms can kind of speak to each other.

[00:16:03]>> That's right. That's right.

[00:16:03]>> And uh so we can get there. But >> anyways, I don't know. Any parting words? I mean, I th this is your show, man. I'm just trying to trying to catch up, keep up.

[00:16:12]>> We talked a lot about a lot of stuff. I mean, I'm just so happy to be here in Utah. I mean, I've never been here before. The the view here is amazing.

[00:16:19]You know, Stephanie's projects are amazing. So, always great to catch up with you and talk shop as well. So, I always enjoy that.

[00:16:25]>> Shout out to Stephen Dailyaly Construction and both Stephen and Stephanie. They've been exceptional hosts this week, taking us around to job sites, coming out to the symposium, bringing their team out there. but then spending a day taking us out to these >> awesome projects. Yeah. So, they're doing a great job. So, go follow uh Stephanie on the Build Show. Go check out her videos. Check out Ross's on Instagram, of course, if you're not a This Old House follower. Go follow this old house. Like just a bunch of guys doing really cool stuff still and they've been doing it for a very long time. But as for you, Build Show, Build Show Live, September 10, 11, 12. Get out there. You can get uh buildcholive.com.

[00:17:09]You can check out all of the educational stuff. I mean, I might be kind of biased, but me and Lexi, we do a hell of a job. But go check it out. Build Show Live. I look forward to seeing you there. We're in San Antonio, Texas.

[00:17:21]Other than that, this I'm Steve Basic, architect. This is the Build Show. Until next time, long live our buildings.