HVAC Strategy ft. Ross Trethewey

Added: 2026-05-23

[00:00:00]Hey Build Show, Steve Basic Architect.

[00:00:02]Yeah, I'm on the road again. Yes, I am somewhere in beautiful Utah with absolutely gorgeous views. And as you can see behind me, we have this very extensive whole house remodel. This is being done by Steven Daily Construction.

[00:00:19]They might sound familiar to you because of course Stephanie Daily is one of the contributors on the show and I've shot some videos with her out here. So, make sure you go check those out. But, I'm about to go inside. We're at kind of the perfect point to have a initial conversation to talk about what kind of HVAC, what are we going to put in a house like this? How do we solve for some of the problems? What are some of the concerns? And we got one of the best minds in residential engineering inside the house. So, we're going to go catch up with him. I'll introduce you to him when we get inside. But, uh sit back, relax. You're in for a treat here. Let's go on inside.

[00:01:05]Come see Steve Basic at Build Show Live.

[00:01:08]Scan the QR code or click the link in the description for tickets.

[00:01:13]>> [music] >> Hello, Ross.

[00:01:21]>> Steve, how's it going? All right.

[00:01:23]>> Good to see you, man. Always a pleasure to have a chat with Ross. Uh you might not know it. I I can't believe that if you're watching this video, you wouldn't know it, but Ross is on This Old House.

[00:01:33]Yeah.

[00:01:34]>> And uh he does the engineering there. We actually have a project or two that we're going to be working with Ross and and his group there Super excited about that.

[00:01:43]>> Engineering. Yeah, I'm very excited.

[00:01:45]>> But, you know, we're out here in Utah, beautiful country. This isn't Massachusetts.

[00:01:49]>> not Boston, yeah.

[00:01:50]>> But, both of us being from Boston, it's like you get out here and it's like, you know what? I can see more than a mile away.

[00:01:56]Um and in some case 100 miles away.

[00:01:58]Spectacular.

[00:01:59]>> But, uh uh, we're in this new house remodel and I thought, you know, what a great video. I have this whole house remodel by Steven Daily Construction out here and I had a couple it with having you inside it.

[00:02:11]>> Sure. And as I look around, you know, we have three bedroom suites down the way there. They're all 9-ft plate heights.

[00:02:18]Pretty common, you know, occurrence in a in a retreat type environment that they're building here. Yep. But, then that comes out into this large room >> I know, look cathedral ceiling going all the way up there, yeah.

[00:02:30]>> ceiling and we don't stop there with the complications cuz we then have a tuck under and a loft. Yep. So, as an engineer, you come in here and me as the architect, I'm going to look at you and say, where the hell do we go from here?

[00:02:44]>> I know. I know. Well, usually we're at a point where we don't We're looking at a piece of paper, Right.

[00:02:48]>> right, or a computer screen >> Exactly.

[00:02:50]>> So, the fact that we're here and we actually see it, you know, in person is great. When I think about building, kind of the first thing is loads, right?

[00:02:57]What's the heating load? What's the cooling load for this building and starting to think about the envelope, right? So, we talk about air leakage, we talk about, you know, wall insulation, roof insulation, you know, how well is this building going to perform, right?

[00:03:09]And what's the kind of goals and expectations there? But, once we digest that and we understand what those are going to be, now we can think about the actual HVAC design within the enclosure.

[00:03:18]>> Correct. And so, we to your point, we do have very complicated things going on here. This loft space here is, you know, is going to be, you know, roughly 10-ft above here. Right. I mean, that's heat rises, right? Stack effect's happening.

[00:03:31]So, to have the heating and cooling handled properly with its own zone up there is going to be something that we definitely would want to consider here.

[00:03:37]>> Yeah. No client wants to walk the stairs and feel a 10-degree temperature difference >> Exactly right.

[00:03:41]>> climbing the stairs.

[00:03:42]>> So, you got this large volume of space, right? And you got this all You got the east-west exposure here. So, the volume of this and the load of this is probably going to dictate also the size is going to dictate probably its own zone as well. So, I would say one zone for this main core, one zone for this loft space for sure just looking at it, you know, high level. And while it's common to have, you know, a large space like this with a large piece of glass, which is going to be the worst part of the wall, >> Absolutely. you know, it's it's not uncommon that you have to deal with these That's right.

[00:04:13]>> in in almost every project probably.

[00:04:15]>> That's right. We have We have a lot a lot of glass in these projects, you know. And it's great for the views and it's, you know, great to have, but you're right. The The window is going to be the weak point of any wall assembly.

[00:04:24]And so, we when we talk about the enclosure, we really do want to focus in on what that insulation package looks like, what that window package looks like cuz it does make a difference from a thermal comfort and from a load perspective.

[00:04:35]>> Got you. Got you. So, let's talk about, you know, and you tell me if I'm thinking about this the right way. We have the three bedroom suites, then we have this space, we have that space, and then we have this lower space that has another bedroom suite there. That's right. So, I kind of see zone one out there for those bedrooms. Now, we might consider taking those three and breaking that into multiple zones. And a lot of that comes with the comfort of the client, right? And their desire. That's right. That's right. So, you got three bedrooms down there. From an orientation perspective, the ceiling height, the assembly, the windows are all very similar there. When we do the loads out and the model will tell us that the loads are probably pretty close there in terms of orientation and how the building's going to respond being on the north side of the building, etc. So, I think you're right. I think you agree that is one zone. The question would be where does that thermostat live? Because you got three beds. Some clients may want a thermostat in every bedroom, so that's going to make it a little bit more complicated, a little bit more design.

[00:05:29]>> And would that be one system that then just has a bunch of zone dampers that are controlling where it's pushing the air through the ductwork? Yeah, so because the exposure is very similar, you could get away with one air handler system with three zone dampers, one zone damper basically controlling airflow to each one of the bedrooms. So, so you'd have three thermostats on one air handler to handle that. You could also go depending on style of system we choose, you could go with a more like a ducted mini split style system or just regular or ductless mini splits and then you could have one in each one of those bedrooms to give you the different zones there. And so that's going to come down to equipment selection.

[00:06:03]>> gives you direct control from each environment.

[00:06:06]>> That's right. Both of those Both of those systems would achieve the net same result. Yep. So, as we move into the larger room here though now, now we get this complication between these spaces and the fact that it's adjacent to some of those.

[00:06:18]>> That's right. Because as you heat and cool that space or heat and cool this space, there is some transfer across these walls, too. That's right. That complicate things. That's right. So, you have heating and cooling. We're in a cold climate right here in Utah, right?

[00:06:29]So, it gets 10 15° here or even colder.

[00:06:32]So, we have to be, you know, considered about what's the climate in this in this space. So, this is the answer to my question in this project in Utah is going to be different if this was in Phoenix, Arizona or in a different place.

[00:06:42]But, um you're going to use the ductwork to heat and cool, right? You could use radiant floor heat to also heat. Yep.

[00:06:49]So, now there's a question about what's the comfort and the expectations of the space cuz you could do a beautiful radiant floor heat system here to do all of your heating and you could do ductwork from above or below feeding up through floor registers or ceiling registers to do all of your cooling and maybe even supplemental heating. So, I've been asked this a bunch of times and you said above and or below, which I I find interesting because I think the above or below, there's probably somewhere in the country where that starts to skew to it's probably better above or it's far better or more okay to be below.

[00:07:27]Right. So, the way I think about this is that if you pull the high performance envelope aside and you just look at fundamentals, if I'm in a heating dominant market, meaning that I have more heating hours than I have cooling hours, the ideal situation is that I want floor registers to supply warm air over the exterior surfaces like the glass and the weakest performance part of the envelope and then have returns also in the floor because that will be the coldest air that would go back to get reheated. So pull the coldest air from this room and send it back to the exterior nice and heated, warm up the exterior envelope and bring it back to those floor returns. So that would be a more optimized system for heating climate. So in a room like this and you're talking about bringing that heat up and both locations near the wall, does that mean we want to have the return somewhere central?

[00:08:14]>> So yeah, I would look to put a I would look to put a return somewhere over in this area here if I could or potentially on that wall over there and I'd have supplies along the exterior.

[00:08:25]>> the air to kind of go up come around and Yep, so warm up the exterior envelope and then bring it back to the central returns. Those central returns could be in the middle of course you know not knowing the floor layout in terms of what's going on with furniture etc. But I would say here or there would be great locations for returns.

[00:08:40]>> For returns.

[00:08:40]>> Yep. And if this is a cooling dominant market, let's say we're in Phoenix, Arizona or you know pick another place and I we're optimizing for cooling, cooling operation would be optimized with ceiling returns and ceiling supplies. Got it. All right, so you're going to be blowing cold air down. The math is the same it's just inverted.

[00:08:58]>> Exactly. Take the hottest air off the top of the room, cool it and send it out to the supplies at the perimeter. And so you know, we don't live in just a heating or cooling dominant climate so in most cases you have both. You have heating and cooling. Uh but if I'm optimizing this for cooling, I would do ceiling fed systems and I would do radiant floor heat for really if I'm going for a comfortable place.

[00:09:19]>> So what So I you said heating dominated so I guess that's the reason you make the choice but if you're in a climate that's kind of a 50/50, it's like how do you kind of tend to make that decision?

[00:09:31]Yep, so you can go either. Okay. If it's 50/50, you go ceiling or you go floor.

[00:09:36]Both are going to work. Both are going to work just fine.

[00:09:38]>> a little bit milder, it's not as extreme where it needs extreme measures.

[00:09:43]>> And also with the envelopes that you do on your projects, they are so good that that it gives us a lot more kind of benefit and forgiveness.

[00:09:53]>> More control. More control of the space.

[00:09:55]So we have better forgiveness on the mechanical systems, meaning that if the envelope is really bad, I need to get those supplies out to the windows and out to the exterior because the enclosure is so bad.

[00:10:05]>> Or really bad windows.

[00:10:07]Cuz even in a wall, you have a window like that, the center of that glass is a lot different than the exterior wall over there. And so this is going to really require to have a lot more either heating or cooling depending on the climate.

[00:10:21]>> Right.

[00:10:22]>> With with that level >> Right. There's also we talk about in our conversations mean radiant temperature. And so if you think about the glass, because the glass doesn't perform that well, it wants to pull heat from your body on a cold day.

[00:10:33]Right. So it sees you as a cold object and it's pulling that heat from you. And so when you want to think about thermal comfort, the window is going to be the weak point, right? Right. And so it's so important that we try to put the emphasis especially on large window facades like this, that the glass really does matter. And you bring up a great point because being from New England, I'm sure you what I'm about I'm about to say you've heard no less than a thousand times, but when I meet with clients, they're like, "Yeah, I can't wait to get rid of that window. It's really drafty."

[00:11:03]But it's not drafty. It's the couch is in front of the window. The window is such a poor insulator, you have become the radiator. So the the heat leaving your body to try and warm that window is what they think is a draft.

[00:11:20]>> That's right. That's right. I think of it as surface temperatures. If it's 0° outside and that glass inner surface is 40° or 45° and our bodies are 70 to 90 degrees surface temperature, that window sees us as a heating object. Right. So, it's pulling heat from our bodies to that window, so you feel cold and it has nothing to do with drafts, as you And it's the same as when you walk down in a basement in a New England project in kind of the late fall or early spring, it's a nice sunny day, you feel warm, you go in the basement and you're like, "Man, it's freezing down here." Freezing cold. All that cold. Cuz you're trying to warm up the concrete >> That's right. down there and it's just basic physics.

[00:11:58]>> That's right.

[00:11:58]>> Right. That a lot of people don't understand. They think it's kind of drafty or whatever the case is. So, those three rooms, we talked a little bit about it. Let's continue with We have this big room. I don't How do we deal with it? Yeah, so I think the biggest thing will be what is the conditioned space start and stop. So, if we have conditioned attic space above us, I think we have and we have an open web truss design here, we have the perfect opportunity to bring ductwork above and overhead and we could feed this with nice registers along the perimeter there, some nice registers along the perimeter there, blow that air down if we're feeding it from the ceiling and have some central returns up high, you know, and so we could do a really good job doing it that way for this project here.

[00:12:37]>> Mhm. We could have a separate zone from the lofts for the loft space from above as well. Um and that's all predicated that we're we're optimizing for cooling.

[00:12:46]Um and that's, you know, also going to be dictated on what the space allow, right? We have a knee wall space on either side, so we could use some of that knee wall space, you know, to put um to put some air handlers or ductwork in. Um and then, you know, when it comes back to the radiant, you can do above floor systems, you know, tubing plate, you can do staple up, you can do thin crete, you know, the jib crete or thin slab systems. There's a lot of different radiant systems you could do here if that's the way that they choose. And because we have basement below us, are there considerations with you as the engineer? So, you said, "Oh, we'll introduce heat from above even though we're heating dominated climate." But, we also in this case here, the downstairs is going to get heated and that heat loss is going to help warm this floor and help warm the lower parts of this room.

[00:13:33]>> So, there's definitely trade-offs here and so, the way I think about it is that if I'm heating the basement space and I'm doing it with an air-based system, I need space for that ductwork down there.

[00:13:42]And so, if if this system was fed from the floor at this level, then I need two duct systems potentially in the same plane. So, it's going to get very busy down in the basement ceiling.

[00:13:52]So, sometimes we do a trade-off where we do just do the basement system from the basement side and we do the first floor in this case from above. And so, it helps complicate some of the ducting pathways which are always going to be the some of the most challenging things to deal with on these types of projects.

[00:14:07]Yeah, and this is a remodeling project so, this is an existing basement under us and my experience tells me we don't have a whole lot Yeah. room down there.

[00:14:16]>> No, not a lot of room in ceiling height.

[00:14:17]You're always fighting ceiling height as well.

[00:14:18]>> putting it up here. Yep.

[00:14:19]>> So, is there ever cause to say take that loft and make it its own environment?

[00:14:24]With that with that open face, is that even possible? Yeah, it is and we do that a lot. And so, um you could see a 10° rise from this level up to that level just cuz, you know, stack effect, right? Heat rising. And so, we would definitely want to have a dedicated zone up there because there could be a situation where you might have the radiant floor heat running down here and you might actually have solar gain through these windows that are going to be up there baking down in that room where that room actually might need some cooling. Right. Right? And so, that could happen especially in a climate like Utah where we get cold nights and then they get some really, really hot days with a lot of solar gain the next day. And you know, the other thing that people don't consider that I'm sure you consider is when you have a loft like that, right? You could potentially, like I could see myself if this was my house, I go up there and that's our little office space. So, now there's two or three people, there's computer systems, the two dogs come up >> Mhm. and so, just the heat load in that confined area is drastically different [clears throat] than putting two or three people in this large room. That's right. That's right.

[00:15:29]Yeah, so we're going to look at that floor plan and we're going to see, oh, they have a desk up there. They have got some computers up there. That gets factored into the model. We will put internal gains in where internal gains exist.

[00:15:39]>> Right. Right. So, those computers, you know, refrigerators, you know, appliance loads, plug loads, we want to know where those are going to be. And so, it's going to be really want to have a dynamic system that's going to be able to capture any of that heat gain up there before it becomes a problem and you don't notice it as you walk up those stairs to the loft space.

[00:15:55]>> Right. Yep.

[00:15:56]>> Right. Yeah, you don't want that. I mean, no, none of us on the team want to have the client walk in and say, "Wow, I can always feel the temperature difference." It's kind of That's their way of saying, "You guys kind of failed me." Right. Right. Right. You know, we >> [clears throat] >> we don't we don't want that.

[00:16:11]>> not want that. So, um any other parting thoughts before we close this out here? I mean, it's a pretty interesting space that, you know, they added on to and uh It's a really cool project and love love seeing it come together, you know, and the the views here are amazing and so, yeah, we'll talk about ventilation, we'll talk about some of the other stuff related to HVAC you know, as well.

[00:16:31]>> bunch more videos here with Ross today.

[00:16:34]So, uh stay tuned. A bunch more will be coming out, but Yep. first and foremost, thank you. And as you can see, it's I wasn't kidding when I said, "Man, this is the guy you want to talk to about this stuff because he he gets it." And and I think, you know, for me, having been in it for 30-plus years now, you know, it was really a big challenge when Joe brought building science to America in the late '90s because there weren't people like you or Allison Bales or you know, the like that concentrate on residential.

[00:17:09]>> That's right. Right. There were a lot of engineers that did big commercial projects and oh, well, yeah, we could do the duct layout for the house and it was atrocious.

[00:17:16]>> Yeah. Because it's it's a different animal. Complete different. Apples and oranges. You know, commercial engineering is commercial engineering.

[00:17:22]Different equipment, different duct design, different duct classifications.

[00:17:26]It's like night and day compared to residential design. And so, you're right. There are a couple of us that I'm familiar with and that do and focus on residential only. And and you know, there's there's definitely a market need from what we're seeing in the industry.

[00:17:39]And the hardship for you guys is that as time goes on, people begin to understand that wow, these guys are smart. They can figure this out for us. So, now their expectations have grown. That's right.

[00:17:52]Nobody wants to walk through this house and feel more than a a 4° temperature difference anywhere in the house.

[00:17:57]>> Yeah. Yeah. So, we have you We're in the comfort business. We are 100% in the comfort business. Everyone thinks like, "Oh, you're all about efficiency. You're all about this. You're all about that."

[00:18:04]No, no. We are in the comfort business.

[00:18:05]We want to make sure that these houses that are designed have the the comfort and meet the client's goals and expectations for what they deserve, right? What they're expecting, you know, when they're they're spending this kind of money to do this level of house, they want comfort. Yeah. The energy bill fluctuating 50, 60 bucks a month or something on a house like this, they're not going to care about that. Walking up to that loft and feeling a 10° difference, that's failure.

[00:18:30]That's right. But, the good thing about this type of project is it's proper planning, right? You've got the windows, you've got the wall insulation, you've got the air leakage, you've got all of that factored in. That's the number one thing cuz that reduces how much mechanical systems you need. It reduces a lot of the load. It reduces the complexity of the project. If I can get away with a 2-ton unit versus a 5-ton unit, hey, that's that's great, you know? Less ductwork, >> lower repair cost. Exactly. This is a domino effect.

[00:18:54]100%. All of that stuff flows downhill.

[00:18:56]We're going to talk more about that today. But, anyways, if you want more, come check out my catalog of videos. I'm going to shoot a bunch more with Ross, but I have over 500 videos on the Build Show. Go check them out and they're at your favorite price, free.

[00:19:11]So, if you want to see me out at Build Show Live, September 10, 11, 12, registration's open. Go sign up for Build Show Live. Look forward to seeing you there. Other than that, Ross, thank you. I told you you wouldn't disappoint.

[00:19:24]I'm Steve Basic Architect. This is the Build Show. Until next time. Long live our buildings. All right.

[00:19:33]>> [music]