16 min read

SBA 214: Creating your own Pandemic Mode Part 2

By Phil Zito on Aug 10, 2020 6:00:00 AM

Topics: Podcasts

In this episode, we discuss control strategies that allow us to address viral spread within our building.

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Phil Zito 0:00
This is the smart buildings Academy podcast with Phil Zito Episode 214. Hey folks, Phil Zito here and welcome to Episode 214 of the smart buildings Academy podcast and in this episode, we are going to be completing part two of creating your own pandemic mode. So last week's episode Episode 213, we started to dive into what pandemic mode was, how it works and how to go about creating it. We ended up getting through most of the sequencing all the way to where we were starting to talk through pressurization and we were starting to talk through some sequences around pressurization. So in this episode, we will be diving deeper into that if you find yourself listening to these episodes, and not really understanding a lot of the sequencing we're talking about, then I encourage you to go check out our course control sequence fundamentals which will be linked at podcast dot smart Buildings academy.com forward slash to 14. Before we dive into this week's episode, we are going to be starting something a little new with each week, which is our question of the week. So our question comes off of our Facebook smart buildings Academy group, there was a discussion around actual integration pulling in an existing supervisory device into a new supervisory device. How would you do it? What would you need to think about so what I want to talk to you about is this concept called dual coding. And it's something that a lot of people don't think about when they first start to do integration. And the concept of dual coding is where you have global logic, that's logic that sits within the supervisory device. And then it's usually stuff like averaging of box positions or average pressure across the building so that way you can create some sort of global logic. Well, when you're doing dual coding, you're Keeping that global logic in the supervisory device, and then you're duplicating it in the new supervisory device. This is especially prevalent when you're doing integrations from systems before kind of circa 2005, because most of the time, you don't have the tools to actually see what code is in those controller, or rather, in those supervisory devices. So whenever you are doing integration, and you're pulling an existing supervisory device into a new supervisory device, I encourage you to make sure that you are accounting for that dual coding phenomenon. I see so many people who they start to get these kind of ghost issues in their system, they can't figure out why at night, or at random times, certain things are being overwritten, or they send commands to their field controllers, only to have those commands overwritten, and they can't find where these overrides are coming from. And quite often it is from this dual code scenario. You've got code and your new supervisory device but you still have code in your old supervisory device in that old code is overriding the new code. So just something to be aware of. Alright, so as I mentioned in our previous episode, we started to go through the sequencing of our actual hv AC systems. In response to this quote unquote pandemic mode. We talked about increased filtration, we talked about achieving standards of ASHRAE 55. By being more cognizant of our indoor temperature and our humidity, we talked about those new ranges. We talked about the impact i q primarily through increased air change rate and through increased outdoor air. We also kind of hinted at how this filtration strategy actually can have some really compounding effects. Because most of these systems are designed for what are called design days and those design days are designed for maybe like

Phil Zito 3:58
Merv 11 Something you know something lower than birth 13. And what happens when you have that lower like Merv eight or Merv 11 filter versus a Merv 13 filter is you're designing for much less pressure drop across the filters, which means less fan power. And when you introduce this new filtration, you are reducing your fan power, which means on your design days, where all your VA v boxes are going to be fully open because they're trying to cool down the building, you're not going to be able to adequately supply temperature or sorry, air conditioned air to the spaces. And you also see that when we start introducing a ton of outdoor air into an air stream, especially in southern or humid climates, if you don't have a dedicated outdoor air system or a doe as as it's called, then what will happen is you won't be conditioning the outdoor air prior to it hitting your air handling unit. So these coils that were sized for mixed air not sized for 100% outdoor air, are now not able to achieve their full Delta across the coil. So maybe you've went from a 12 degree delta to a seven degree Delta. And once again, in design day conditions, you're going to be unable to properly condition those spaces, you won't be able to cool the discharge air enough. And you'll basically just start to build up as you continue to research air in the building, you'll just start to increasingly build up hot air in the building. All righty. So that being said, let's start to read through and I know it's kind of dry when I read through stuff. So what I try to do is kind of read it but then give you my interpretation. Alright, so we went through air conditioning and ventilation systems. We talked about continuous operations of the systems being recommended. However, they also say if you do a flush of two hours before and after occupancy times, then you may not have to go an hour. operate your systems constantly. And also something that I don't see being communicated. And this is a really important insight like if you get anything out of this episode, I think this one inside right here is going to like save you a lot of money. Because you hear everyone talking about with pandemic mode, we need to bring in more outdoor air, and you would naturally assume that you would operate the building 24 seven, with optimum with optimal outdoor air right bringing in as much outdoor air as possible. If you thought that though you would be wrong, because according to these recommendations, you actually should only be operating your outdoor air when the building is in a flushing mode or it's in an occupied mode. So if you have a building that's unoccupied, then you should be using minimum outdoor air settings and that is a significant difference, both in moisture buildup and cost of system like cost of running your system. So Just be cognizant of that. Alright, switching to our VA v systems, you want to be able to use the VA v systems that have capacity to run 100% outdoor air, you want to run them at that if they do not have that capacity, then you want to run them as much as you can bringing in as much outdoor air as you can while prioritizing humidity controls, so you don't want to go above 60%. And if you don't have any way of introducing humidity and you're in a very dry climate, you don't want to drop below 40% you want to be in between 40 to 60%. So what's going to happen if we're thinking about this from a programmatic perspective, we're going to be actually picking a humidity setting and driving our outdoor air damper based off of that indoor humidity slash temperature. So we want to look at temperature and we want to To look at humidity, and we want to look at the delta between those two, and then use that. So one way you could go about doing this is set a setpoint for temperature or humidity, and have both of those go through a p ID loop and then take the greater of the P ID loop outputs to drive or sorry, the lesser of the PD outputs, to drive your outdoor air damper you could be doing that. That's personally how I would do it. Because here's the thing, you can just simply do a humidity setpoint and drive off of that. But the problem with doing that, and this would be like a reverse acting loop, right, just like you're we're doing heating, we're doing the same thing. As we get closer to 60% humidity, we start to close down our outdoor air damper.

Phil Zito 8:50
The problem with doing that is because you're not controlling dry bulb and so dry bulb of like 8555 so 85 degrees 55% relative humidities can be miserable inside the building, so we want to be cognizant of Dr. Bolt as well, that talks about floor by floor control. It says in floor by floor vv systems that have only minimum outdoor air damper positions or openings open the outside air damper to its maximum position. Now if the outside air is supplied centrally from outside air handling units like dough as is right, then you can divert the air to the units that have occupied floors. Rather than having to open up each vv air handler also talks about potentially raising your discharge air to 60 degrees. I get where it's talking about raising your discharge air to 60 degrees but when you're introducing much more humidity, and then you have 60 degrees so you're not really hitting saturation, so you're not wringing out that humidity. It just seems like to me in humid environments, that would be a bad idea. If you've understood, well, if you've seen a psych chart and you understand psychometrics, then you would kind of understand how these systems could keep fueling one another as far as right you bring in humidity, but you're not hitting dew point. So thus, you're not wringing out the humidity and the humidity just kind of starts to build up in the building. Now, it says by raising the discharge air temperature setpoint to maximum, you are going to have boxes that are going to open and try to satisfy cooling loads, and it's going to increase air changes in the spaces being served. So that's one way to increase your air changes is you keep us constant exhaust and you increase your supply artificially by raising that discharge air temp. I hope you just tracked what I said right, you raise your discharge air temp to 60 instead of 55. Which means the v v boxes since they're not getting the same amount of cold air are going to have to actually go and increase their airflow. And because your exhaust typically is constant, you're going to have an influx of pressure and ultimately air changes. Now, where this won't work is where you actually control building static pressure. And you have variable speed exhaust fans, because those will adjust accordingly as well. However, another way of doing this without decreasing your discharge air is simply decrease your exhaust rate. So if you decrease your exhaust rate, you're also going to get increased air changes. Now granted, if you decrease your exhaust rate that could have some negative effects because you aren't removing air as much as you could be. Right. So you could have or sorry, I meant to say, increase exhaust rate. It's been a long weekend I was on a Boy Scout camping trip with my son and I did not get any sleep for two days in a row. And I'm like thinking to myself, as I just said that I'm like, but that doesn't make any logical sense. I decreased excited Straight air would build up and I actually would get less no increase exhaust rate and that will start exhausting more air so thus forcing more air changes. Alright, man tell you end of the day recording a podcast, something it's not necessarily the best idea alright so as I was saying vv systems now if they have heat or energy recovery, so if they have fop wheels like what's used in a das system, then you want to go and make sure that energy recovery is being taken advantage especially entropy is being taken advantage of, to control to that entropy setting. Now, here's one of the things that they say some energy wheels have the potential of cross contamination between the intake and exhaust stream I'm not going to get into that because I am not an expert on that. I will tell you though, if you have the Right filtration in place that should take care of that.

Phil Zito 13:03
They talk about other heat recovery devices that decouple the intake and exhaust streams such as coils, plate heat exchangers, they can operate just fine. Their main concern with recovery wheels is are you introducing contaminants into the air stream. So just be cognizant of that know where your recovery wheels are, know where your filtration is, and just be aware of them. Okay, so cooling coils can become contaminated as well. And therefore, they talk about doing UV on the coil surface. So I've heard of UV I've heard of negative ionization, the jury's still out as to which one necessarily works better UV tends to work good for solid or for objects that are static like a coil. And ionization tends to work well for things that are in motion like an air stream. So it may be combination of the two, where you have UV for static objects and you have ionization for objects that are in transit like airflow, because if you think about it, UV is not going to have enough exposure time to airflow in order to actually go and decontaminate it. Whereas ionization basically what that does is it charges the virus particles that are in the air, the virus particulate matter, which then causes it to stick to surfaces, thus making it less likely to spread through the air stream. All right. And then it talks about operable windows. I'm not really going to get into that. Because there's, you know, let's be honest, most folks aren't going and opening windows in their building, especially this time of the year in the United States. I mean, yeah, there are some areas But if you do happen to do that they talk about interlocking your air conditioning system to shut down. If the windows are open, I'm not quite sure why you would do that. If you've got the right filtration of the air stream, you'd probably be better off just using filtration rather than opening windows. And then it goes into the general stuff that you expect, right? Keep your hot water above 140 degrees to avoid microbial incursion. I mean, yeah, obvious, right? Everyone knows keep your hot water above 140 degrees for multitude of reasons, one of which is microbial incursion, exhaust systems, they talk about running them 24 seven, do not have operable windows in the toilets. Garage exhaust systems should be run two hours before occupancy and two hours after and run them continually during occupied hours. So basic, Lee, what we're seeing is we're adding a flush to anywhere where there's going to be populations of people. And those flushes are going to be two hours before occupancy and two hours post occupancy. And then they talk about special exhaust systems in rooms that may accommodate infected people. So where they're talking about or you know, those little waiting areas where you wait for the elevator, those kind of spots that potentially people could gather and be present among one another, there's where you might want to implement some exhaust strategies. Okay, and then when we get into pressurization, we start to talk about how we want to go about doing pressurization. They talk about doing slightly positive pressure as compared to outside and both single multi storey buildings shut off return air to the central air conditioning system in spaces where infected people may be present and use exhaust fans to discharge the air outside from outdoor public gathering spaces. All right, so let me give you my thoughts on that? And what is practical and what's not maintaining a slightly positive pressure in a building? That's practical, right? We can do that we already do that in a lot of cases, going and shutting off the return air to air spaces where infected people may be present. I mean, that's like a giant guessing game, right? I mean, do you just assume everyone's infected? Because we're talking commercial buildings. Right now, we're not talking hospitals where it's obvious who's affected. But at this point, you have to make a decision Do you just not use return anymore, exhaust everything and bring everything in from outdoor air. I mean, you can do that that's going to be much more costly. It's going to put a strain on your system, especially in design day conditions, which we're still in design days. So you've got to make a decision as to what your

Phil Zito 17:47
risk and comfort level is. And ultimately, a lot of these sequence adaptions are risk decisions. You are basically weighing out what you perceive the risks to be. Have someone being sick and what you perceive the risks to be someone then being sick in your building and spreading through the air stream. And you yourself have to make a decision based on what could be your potential liability exposure and then control accordingly. So in tall buildings, they talk about pressurization and they say, Hey, take it take consideration of stack effect and wind effects and everyone knows what stack and wind effects are basically the buildup of pressure as you get higher, and then wind effects of infiltration and exfiltration of air and both the heat as well. So just be cognizant of those tenants and visitors should use revolving doors properly designed vegetables and buildings that have these types of entrances rather than single swinging doors to enter the building. I'm not quite sure what their logic is on this because personally, I guess They don't want people to touch the door. But then at the same time, you have these people, potentially multiple people standing in the same door at the same time. So my wife and I went on a trip with our kids. And we went to Yellowstone and we went to Denver, we went to Badlands. And you know, one of the things we noticed when we went into some hotels were that like, people were in your space, like it said, you know, one family at a time through the revolving door, one family at a time in the elevator, yet you get in the elevator and people get in with you. And it's like, dude, I don't know where you're from. I don't know who you are. You know, I'm trying to keep my space from people. So why are you in here? So I get what they're saying. But honestly, I'd rather just sanitize my hands and use my elbow to push open a door like have a double sided door right, it opens to the inside and it open. To the outside and use my elbow or use a foot. You know, I saw it a lot of McDonald's, they had these little foot hooks where you could open the door with your foot and not have to touch it was kind of neat. So I personally would rather use those just my own two sons to talk about basic elevator control, which I'm not really going to get into, they talk about access control, which I'm not going to really get into. And then they talk about disabling demand control ventilation, but in a nutshell, at the end of the day, basically what you're trying to do is make sure you've got humidity level, at as high as you can reasonably get at while staying in that 40 to 60% range, the higher you can get it, supposedly and I say supposedly because no one really knows. I mean, it seems like every single day there's different news coming out but supposedly higher moisture content will reduce the effect of the virus to spread because the moisture will bind to it and force it to the ground. Additionally pressurization to push air out of the building, and using high air changes to drive the air through filtration. Also the use of UV lighting and the use of ionization with filtering to take care of virus particles that are within the air stream within systems. And so these are kind of all the big things that you as a controls person can be doing. So to recap from last week's episode, figure out what you have in your building, figure out what you can reasonably change and then make adjustments based on your risk profile. So if you feel that you have a ton of transient people coming into the building that you don't know like it's not a predictable group of people, then it may make sense to really focus on exhausting the air stream 100% outdoor air building flush Hire changes. However, if you have a very predictable set of people and you feel that these people are a low risk set

Phil Zito 22:08
of people, then it may make sense to do less of these control mechanisms. So it's not one size fit all. And that's kind of why the recommendations here are recommendations. They're not really no one yet has put into place standards. I am still waiting to see standards being pushed by municipalities not quite sure what they're going to measure. As far as standards probably maybe standard air changes, maybe you'll see like ASHRAE 62.1, but yet for IQ and not necessarily for just outdoor airflow. So it'd be interesting to see what flushes out. So folks, that is it for this part on pandemics. I hope you enjoyed this as always feel free to go to podcast smart buildings Academy calm slash to 14. Feel free to ask anything you want to know about the podcast topic. And for the next several weeks, we are going to be diving into managing your VA s team. We're going to look at all aspects of running a VA s business. We're going to look at structuring your team. We're going to look at training your team, we're going to look at developing your team. We're going to look at talent assessments, we're going to look at how do we drive profitability through our projects. So it's going to be very manager focused over the next couple weeks, you know, that's some content that we really haven't done a lot of, and it's something I'm really frickin good at. So I want to make sure that I'm sharing that information. I mean, I took a $60 million PnL that was hemorrhaging cash. I think we had $2 million that had been owed to us for two years and I came on board, turned all that around, got the cash flow flowing and made up One of the more profitable operations teams. So I've got a lot of personal experience turning around poorly managed operational teams. And I'm going to be sharing that with you. Over the next several episodes, we'll look at how do we drive some cash flow through our team? But more importantly, how do we develop the talent in our team? How do we know what makes our employees tick? How do we go and keep them satisfied, because you're only as good as your team, and so we'll be diving heavily into that. That being said, Thanks a ton for being here. If you haven't yet, I encourage you to go check out our new website at smart buildings Academy comm check out our courses, we've got over 17 courses now. I really encourage you to go check those out. They are the best online training that you are going to find for building automation in the world. Thanks a ton for being here. I look forward to talking to you all again next week. Take care

Phil Zito

Written by Phil Zito

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