Episode Description:
Episode 468 explores advanced airside HVAC sequences, offering building automation professionals an in-depth look at ASHRAE's Guideline 36. This episode unpacks strategies for optimizing energy efficiency through standardized control sequences, helping listeners understand how to achieve predictable and repeatable system performance. You'll gain insights into best practices and considerations for implementing these strategies across different building scenarios, with a focus on practical, real-world applications.
Key takeaways you’ll get:
- The Principles of Trim and Response: Understand how this control strategy minimizes energy use while maintaining optimal HVAC performance.
- Handling Zone Requests and Zone Groups: Learn about managing cooling and heating demands across multiple zones for better system efficiency.
- Implementing Economizer Control: Discover how to leverage outdoor air conditions for free cooling to reduce energy consumption.
- Effective Reheat Control Techniques: Explore how reheat strategies can improve comfort, especially in colder climates.
- Key Factors for New Builds and Retrofits: Get guidance on sensor calibration, system integration, and adapting strategies for project success.
Tune in to SBA 468 to enhance your understanding of Guideline 36 and elevate the performance of your building automation systems.
Click here to download or listen to this episode now.
Resources mentioned in this episode
- Free Technical Skill Assessments
- Smart Buildings Academy Workforce Development Program
- Smart Buildings Academy Courses
- Building Automation Training Guides
Podcast Video
Transcript
Phil Zito 0:00
This is the smart buildings Academy podcast with Phil Zito. Episode 468, Hey folks, Phil Zito here and welcome to episode 468,
Phil Zito 0:08
of the smart buildings Academy podcast. In this episode, we are going through guideline 36 and other advanced airside HVAC sequences. This will be part one of this two part series. And as always, everything can be found at podcast at smart buildings academy.com forward slash 468, once again, that is podcast smart buildings academy.com forward slash 468, so real quick, want to talk about what's happening at SBA, and then we'll talk about what's happening in this episode. And yeah, let's dive in so Workforce Development cohort 11 is starting in January. If you're looking to get new folks on your team who can do technical work, install, startup, point to point, checkout, functional test, graphics and the like. This is the quickest way to do it. We will have people who are literally working in a post office, working as hotel lobby clerks. And by week three of the program, they're out on a job site. They're 80% job chargeable by week four, and by week 11, they can be on their own doing those installed startup tasks. We've had 11 cohorts run through this program if you're looking to develop net new talent in the fastest way possible, this is it. You can find out more by going to smart buildings academy.com, and clicking on the Workforce Development link. Also our skill assessment, our free online Skill Assessment, which, by the way, I'm so excited, version 2.0 is going to be out in a probably about a month and a half. And so if you're listening to this in October, late October of 2024, if you're listening to this in the future, a month from and a half from then, that assessment is going to take our already existing assessment that 24,000 individuals have taken and improve it even more, but our current skill assessment will help you to pinpoint the exact gaps that your team has so that you can make your training decisions based on quantitative data and not based on feelings. So if you are looking to upskill your team, and you don't know where to start, the skill assessment is a great place to start. You can find out more by going to smart buildings academy.com, forward slash skills. All right, so what are we going to do in this episode? We're going to be covering age you control. We're going to talk about trim and response. We're going to talk about zones, zone groups, and we're going to talk about how the sequencing works on the air side for guideline 36 I will talk a little bit beyond guideline 36 just some lessons learned when utilizing these sequences. To be clear, we're not going to be talking about the recently added fan coils and exhaust fan controls. Those aren't going to be part of this series, if you and we're also not going to talk about fault detection diagnostics or advanced alarming if you'd like us to discuss those in a future episode, just let us know in the comments. Speaking of the comments, we do this podcast free every week, so please, if you're listening on YouTube, Like Comment. Subscribe. If you're on LinkedIn, please share this. You just hit repost and share with your comments. If you're on Spotify or on Apple podcasts. Please consider giving us a five star review if you are listening to the audio version of this. I encourage you to go to podcasts at smart buildings, academy.com, forward slash 468, so you can see the video and PowerPoint presentation. So what's guideline 36 guideline 36 is a comprehensive set of standardized, energy efficient sequences of operations. We've all been in a project where we get one sequence from an engineer, and then we go to the next project, same engineer, same kind of building, completely different sequence, and it's like, man, if we only had standardized sequences, standardized, pointless, standardized ways of controlling our systems, then we could have standardized point to point. We could have standardized functional tests. We could have standard programs, and we'd be able to deliver a standardized, repeatable, predictable installation. Well, that's one of the hopes and visions of guideline 36 note, it's a guideline, not a standard. So guideline is like, Hey, you do this. Standards are more you know, like ASHRAE, 62.1 you have to meet the standard for minimum outside air into occupied spaces. Or 90.1 you have to meet the energy performance requirements. Those are standards versus guidelines. Now I will say that a lot of what we're going to see here is stuff we're already doing is just done a little bit differently, primarily on the treatment, response side of things. This is going to be primarily about a use and VAVS. So let's go through here. Uh, guideline, 36 purposes, optimized energy usage. This is why you're seeing a lot of adoption in the federal and state space, as well as in the higher education space. This is a way to control your set points and temperature resets, especially in the air side. Control strategies that should, in theory, reduce the need for custom programming, because you're going to be doing it the same way. And I will say that once again, we're not covering this, but the system monitoring and error detection. Just brief segue, I promise, very brief. I've been to so many large owner operated sites, and they have 3040, 50,000, unacknowledged alarms because they're nuisance alarms not properly calibrated, not properly set. Guideline 36 looks to get a handle on this, because they recognize that that is a big issue, because if you ignore alarms, systems get degraded. You miss actual faults and failures, and the next thing you know, you've got all sorts of issues in your facilities. Okay, trim and response, or trim and respond, depending on who you look at it, right it, it's, I like to call it trim and response, but some people whatever, essentially what this does, and it works not only on duct static pressure. I've also seen it on a supply slash discharge, air temperature reset, but essentially, what happens is, you have a VAV box air handler, and so it serves multiple zones, or worse, spaces, which we'll get into zone versus space in a second, because for some of you who maybe have a lighting background, that can be confusing. But what happens is, we're going to trim our duct spat, duct static. Oh my gosh, it's Sunday morning. So first off, if you hear people running around, it's because my daughter has friends over, so I apologize for that. And two, it's early Sunday morning, so I if I misspeak, I apologize. But like I said, we trim duct static pressure in a response to a issue that's going on in the building. As far as like there's no call for cooling, things are satisfied. We're going to start to trim our static pressure, and we respond. So there are calls for cooling, or dampers are open, we're going to respond and increase our static pressure. So this is going to reduce our fan energy, reduce wear and tear. We've all been on those really large air handling units. You know, we're talking like 100 ton air handling units, where you fire that bad boy up, all the boxes slam open. The PID Loop. Looks like you're on a roller coaster. It's up down, up down. It's crazy. You're trying to get this dialed in. So you put a ramp block, or you put some sort of kind of just constraining block after your PID loop. This aims to eliminate that by really starting to dial in your duct static pressure set point. So what's going to happen, essentially, and we're going to look at a bunch of sequences now. We could do this two ways. We can look at the most open damper, right? We're going to lower our static pressure set point. It's typically done on a time period basis, and it's typically done in my experience, point one inches water column, or point 05, inches water column. So we're gradually stepping that set point down right until the most open damper reaches approximately 90% so basically, we're reducing air flow, and our VAV box dampers are opening up to their max cooling set point, right? And or whatever set point they're driving to, they're opening up. And then once we see the most open damper at 90 95% we're like, Okay, this means that we're at a good place to pause and hold that static pressure set point. And so we're really not over ventilating. Now, once that damper reaches that steady set point, we sit there and maintain but what happens right when we start to see more boxes open up? Well, once we see more boxes open up, then we're going to respond right right by increasing our static pressure sub point. So we're trimming responding, trimming responding, and that also is a step up, right? So what does this look like from a logic perspective, depending on your vendor? Some vendors have pre program guideline, 36 response trim and response blocks. Others, you need to use like a Totalizer or an average or a high select, and then you use a count block, and then you use, like a latching timer.
Phil Zito 9:45
There's a variety of ways to do this. I'll tell you the big things in this. Three things I found aren't really covered in guideline 36 I mean, kind of covered, but just lessons learned for me. One, have a way of throwing out. Bad values. Either look at your controller health, look at the value, throw out bad values that aren't realistic. If you get a 200% damper command that's probably not real, throw that out. If you get something that's offline, especially if we start looking at calls for heating and cooling, throw that out. So that's the first thing. Two, be very conservative with your step up and step downs, especially. And it depends on the vertical market, right? So for in an OR I probably wouldn't do trim and response in an or that's just me, something with 18 to 30 air changes an hour, that's not where I would want to implement trim and response. I want to, like, really dialed in, and that's actually probably where I would use, like, PID, and not just pi, but something like an office space where you've got three to four to five air changes an hour in a space good application for term and response, in my experience, but it all depends on your calibrating of your sensors so your duct static pressure sensor calibrated. Also hugely important your vav airflow sensors, especially if you're implementing this on a retrofit or TI and they do rebalance, usually, right? They they usually do a good job on test and balance and rebalancing, and make sure everything's calibrated. But really make sure those air flow sensors are calibrated on those vav boxes, especially if there's something that been sitting in there for 510, years. Okay, so fans modulate. You all know how PID loop works and how we track to duct static pressure. I don't really need to tell you all this, but one thing we do want to talk about is this concept of zone requests. So this is slightly different. Instead of us looking at the most open damper, we're actually looking at calls for cooling or calls for heating. So either the zones you're going to totalize that up, or you're going to use the zone group concept. Let's talk about zones for a second, because this is something that trips a lot of people up. Okay, so if you're from a lighting background, you know that zones can comprise multiple spaces. Back when I used to do a lot of system integration, this was something that would trip a lot of people up, because AV and lighting have zones, and zones can track across multiple different spaces. Give me one second here, I gotta sneeze. Ooh, man, the beauty of recording versus being live is you don't have to be subjected too much to my sneezing or coughing. Sometimes it sniffs out. It sniffs sometimes it sneaks out. The joys of living in a extremely low humidity world. And yes, I know you all have been like, we'll get a humidifier. Phil, I have one. It's right over there. I just always forget to fill it up. I apologize. Okay, so back when I was doing a lot of integration, the really tricky concept was you'd have AV, right? You'd have access, a fee access control, like I said, Sunday morning audio visual systems. So I'd be working with like Crestron system, whatever, and I'd be mapping that in, I don't even think it's called Crestron anymore. I think they got bought by someone neither here nor there. So I would map in the AV system, or I'd map in the lighting system. And a zone was actually multiple spaces, and so trying to get it to work with Bas schedules, it was a nightmare. You had to do all this fancy programming stuff. It was a pain in the bot. But now when we're talking about zones, just take zones. Anytime you see zones, make it space. Zone groups, those are like zones in lighting or AV. Zone group comprises of multiple zones that usually are serving the same purpose. Maybe they're cooling, maybe it's an open floor plan, and it's like the office area versus the zone group for, you know, the the conference rooms, etc. So what happens is you get these zones, and they're either totalized at the zone level or zone group level, and you get these calls for cooling and calls for heating, and when you pass a certain threshold, that is your ratchet to either trim or respond. All right, let's keep going. As I mentioned, I'm not going to go super deep into this. This is just more stuff that you can pause and read if you're interested. But as you increase pressure, right? So if you need more cooling or more heating, because remember, we have a minimum heating, CFM, right? We have our min cooling, Max cooling, and our heating, CFM. And so if you need more airflow for this, you will get a call for cooling or heating. Once you have enough calls will increase pressure. And then, if the system detects these zone dampers are open wider than necessary, we can reduce it. Or if our calls go down. We can reduce it. Couple different ways. We can do it all right, let's talk about economizer. Okay, everyone should be familiar with demand control ventilation. If you are not, please go read the most current standard of ASHRAE, 62.1, understand demand control ventilation. It's one of the most powerful ways that. For you to save energy on a mixed air system, because with demand control ventilation, you can take your outside air damper down to zero, depending on CO two levels, and you can really reduce the amount of fresh air that you need to condition. Because remember, economizer, right? We're only going to run that when we're in certain temperature and humidity thresholds, the outside airflow, minimum outside airflow. We're going to run that when we need it, regardless of our outside air conditions. That's why you see up in the upper Midwest, you see these air handling units with these giant steam preheat coils to condition that outside air that had to be brought in for fresh air. So what's going on here? We're talking about economizer. Economizer is different because economizer is free cooling. So we have mechanical cooling and we have free cooling. Mechanical cooling is chilled water coils or our dx cooling, and then free cooling is actually bringing in unconditioned outside air that will be brought in to act as cooling right, mixing with the return air and that free cooling right, is going to then reduce our energy consumption. So guideline 36 goes through how you can do this. It goes through a couple things. You've got your baseline dry bulb lockout, temperature. You've got your enthalpy control. You've got your return air versus outside air comparison. You've got return air versus outside air enthalpy comparison. There's a variety of ways to do this. The important point is that we're implementing this and that we have outdoor air and humidity sensors, so they really aim towards that enthalpy based control, which is like, what's the heat energy in your return air versus your outside air? Because remember, if you have a lot of moisture in your air, it takes more energy in order to then cool that air and remove the moisture from it. So economizer control definitely something that you want to consider for guideline 36 supply air temperature reset. This is something that you'll see also in guideline 36 this is basically term and response, but it's on the discharge air slash supply air temperature side, instead of the pressure side. Now I do see people who combine pressure and discharge air temperature reset. You can, in theory, do that. I don't like to do it because it makes it difficult to troubleshoot and control. In my experience, maybe I'm just bad programmer. Maybe you all have figured out how to do it great, and you're like, Phil, you just suck. We're able to do this awesomely. Me, personally, I find when I hand this off to an owner operator, it just makes it more difficult for them after the fact, because they're like, is it the discharge error reset that's not working? Is it the static pressure reset? What is causing the issue? And so I personally like to do discharge error reset on constant volume, and then I use pressure reset on variable volume. So variable volume units, I'll do pressure reset on the actual constant volume units, I will do a temperature reset. Still same theory, right open dampers, call for cooling, call for heating from the space, Vav boxes, reheat control and duct static pressure. I'll probably going to skip over the duct static pressure, because I'm basically just recapping terminal response for you here. But let's talk about reheat control real quick. So reheat control, what this is going to look like this quite simply, is you have a series of zones, either zone groups or zones, and they're going to request reheat when the space, like gets really out of whack and isn't able to heat up, keep up with the heating load, then you're going to get a reheat call. And if you have reheat at the air handling unit, it's going to kick on and reheat accordingly. Pretty simple, pretty basic. It's just a way of looking at the zones with the highest demand during peak conditions, and really firing up some additional heat at the unit. You see this a lot in the upper Midwest and more colder climates. I should know this, because I'm into gardening. What is it like? Zone one is warmest, right? So this would be like zone nine. Zone nine is coldest. Am I right? Those of you who do gardening, you're gonna be like, Phil, no, you're wrong. It's the reverse. I should know this. I think it's the higher the zone number for gardening, the colder the area, so those colder parts of the US, and I know I just probably confuse people, because I'm talking about zones and spaces. And then I went into gardening, it's Sunday, all right. So like I said, we're just going to do some basic reheat based on the demand of the systems. Pretty straightforward, pretty easy,
Phil Zito 19:46
not terribly difficult. And then right here, I'm just talking about some basic things of turbine response. You could pause this if you want to read it, but I'm going to skip over it because it's not terribly different than what I had earlier. All right, so let's talk through a couple things here real quick. So when are you going to use this new construction? Especially if you're doing federal, local, the higher ed, I'm seeing them require guideline 36 sequences, depending on your OEM. A lot of the OEMs are now building in a guideline 36 selection block. So you just select that and it automatically writes it for you. Not terribly difficult. What do you need to look out for? First off, if you're doing this in a retrofit scenario, you need to make sure you have the sensors. So you need to make sure that your VAV box sensors are calibrated. You need to make sure that your outside air and enthalpy so humidity sensors are calibrated. Need to make sure that your pressure sensor at the air handling unit, your two thirds static is calibrated. You also really want to dial in how many calls for heating or cooling cause you to do a tick up or tick down so a response or a trim accordingly. Additionally, I highly recommend you start at like point 05 instead of point one for your trim and response on your actual pressure, temperature is much more forgiving than pressure. Pressure, it can get out of whack pretty fast with big changes and big leaps. So I typically recommend points. Recommend point 05 over a five, three to five minute time period, and then dial it in if you find it's not responding fast enough, or if it's responding too fast, then you know, back it off even further. Be aware that a lot of these sequences, they require the ability for the controller to communicate to the air or the space or zone controller to communicate to the air handling controller. So however you in, you develop this, whether it is a hard wire or, sorry, not hard wire, hard coded map from the controller to the actual from the zone controller to the actual air handling controller. Or whether it's, you know, you do a totalization in your supervisory device and then you push down, or whether you do some like server level control. Just be aware that if you have a network outage, or if something is brought offline, or you get bad values, if you haven't accounted for having failure scenarios, which, anytime you write code, especially if you write code where it is an integration between field level device and another field level device, you need To have failure scenarios. What happens if I lose the data I need in order to do my calculations? You need to think through that, and you need to have a way to address that. Like I said, most OEMs are up to speed with guideline 36 and their blocks and logic handle that. They already have a way of throwing out bad data. So with that being said, this is the very high level overview of guideline 36 if you have read guideline 36 then you know that there are some really detailed calculations that go into this. When we're calculating, how do we drew our trimmer response? How do we do our reset? How do we determine at which point we switch from mechanical cooling to free cooling and economizer. So I encourage you. ASHRAE does make all their guidelines and documents freely available. So go read that I've been telling you all if you've listened to the podcast for any amount of time. ASHRAE 55 ASHRAE 62.1 ASHRAE 90.1 ASHRAE 111 guideline 36 highly encourage you to go read those standards and guidelines. It will make you a better technician. It'll make you a better operator, it'll make you a better engineer, it'll make you a better salesperson. Because if you go into a customer site, you're trying to sell a retrofit, and you notice, like things are all out of whack, you become immensely valuable. I'm a big fan that how you sell is by being people like yeah, they love liking people, but you're more important to them if you're able to solve their problems. So understanding this enables you to do that. All right. With that being said, I really do appreciate you all being here. I tried to keep this under 30 minutes. Next episode, we're going to be going through waterside systems. I really don't see how we keep that under 30 minutes. So just be aware that's probably going to be a 4045, minute episode, because there's a lot of concepts, because it goes through decouplers and things like that. So we're going to be going through that another change you're going to be seeing in the near future is maybe bringing on some other podcast hosts to the episode. I know you all really liked when we had our instructors teaching some episodes. We're trying to make some internal changes to see how we can get them doing more episodes. Because I know you all found that very valuable. Example, some of our most listened to episodes are the ones where we have our instructors do them, and so we're going to try to include more of that as always. If you found this valuable, please like, comment and subscribe on YouTube, please hit the repost and share this on LinkedIn with some notes. I mean, this really helps. This is really a free service we provide to the community every week, and that just helps us share it. If we can do anything better, if you'd like us to cover something, if you're like, hey, Phil, cover this or cover less of that, please. I will tell you, after doing 460, episodes, just like moment of transparency here, it becomes hard to figure out what I'm going to talk about next. And you all just saying, hey, Phil, talk about this. Talk about that. You have no idea the amount of pressure you relieve from me by going and giving me ideas. Because it's really easy once I have an idea to go and create an episode and create an outline, but it's hard to think, because I have so many different things I could talk about. So that would be super helpful. As always, everything will be available at pockets, at smart buildings, academy.com forward slash 468, once again, that is podcast. Smart buildings. Academy.com forward slash 468, and I look forward to seeing y'all in the next episode. Have an awesome rest of your week. Take care. You.
