5 Common Humidity Problems & Solutions

Miss Kendra Seymour. And I'm joined today by a repeat guest, Carl Grimes. Thanks Carl so much for being here again.

You're very welcome.

Now for those who don't know Carl, you know, today I asked him to come on because we're going to be talking about something that I think everybody needs to listen to. We're going to be talking about condensation and humidity in your home and five real life examples that I see happening all the time and what you can do about it, what it might mean for your health. But a little bit background on Carl first. Now Carl, he's an. Excuse me, I keep losing my voice here. Carl is an HHS cic. He has direct experience consulting with those who experience complaints indoors and as a leader in the industry intended to fix those causes. Because he also originally experienced the harm in his personal life, he has a unique perspective and approach for understanding and communicating the complications and confusion between them. He is the past President of iaqa, Vice President of Practice of the isiaq. He chaired the IAQA Healthy Home Committee that wrote the Healthy Home Assessment Principles course. He has served on committees writing the original S520 mold remediation standard, medical practice parameters for Allergists, Office, official policy, position statements for ASHRAE Policy, plus several peer reviewed and published papers. He's currently the Director of the Healthy Homes for the Hayward Healthy Home Institute and Hayward Score in Denver, Colorado. He is the Chair of the ASHRAE TCI 12 on Building Dampness and Chair of the ASHRAE SGPC 10 Committee. Interactions affecting the Achievement of Acceptable Indoor Air Quality Carl, you are everywhere and doing amazing things. I absolutely love it.

Well, thank you.

So thanks for squeezing us in today. So let's jump right in. So let's talk about humidity. How and when is humidity a problem and how does temperature affect our humidity?

It's a very simple question with a very complex answer. Because it's interactive. We know what temperature is and we know that there are certain things that are feel too cold and other things that are feel too hot. We also have a general sense of humidity, of when it's really, really dry. Like in the winter when the forced air is on, it gets dry. Or where I live in Colorado, it's dry year round or when it's too humid it's very uncomfortable and there's a range in there of temperatures that are comfortable in a range of humidities that are comfortable and uncomfortable. And there's actually a science behind it. So I'm going to get really geeky with everybody up front. So if you can put up that first image, that first photo. So this is what is called a psychrometric chart. Not a psychometric but psychro metric. This is a very simplified version. But what I will, the reason I put this up here is that you notice at the bottom it says dry bulb temperature and then up upper left on an angle it says wet bulb. Don't worry about that for right now. I can explain that if you need it. But basically that's how humidity is actually measured. You don't need to know that right now. What you need to know is, is that along the bottom with the temperature there from 40 degrees Fahrenheit up to over 120, and then humidity, see those curvy lines left to right that go. Yeah, 20% humidity, 48, 60, 80, then 100% humidity you can find on here. It's not inconsistent at all. If you go to like a hundred degrees up to 20% humidity, you now have a lot of information that it, the, the wet bulb is over there. Whatever that is on the right hand side is like vapor pressure, there's dew point involved, all kinds of other numbers involved. What I'm pointing out is that if you have a hundred degrees and seventy, 20% humidity, that sets a number, a specific number of things in play. Go to the next image. Now this is a more complicated chart and you don't have to understand all the numbers and colors and everything else. What I want you to focus on though is if you could make it just a little bit bigger. Yeah. That green place in the middle that says comfort zone. Out of all of these temperatures from 0 up to 50, in this case Celsius 22 to 27, which is about 70 to 78 degrees roughly, that is a comfortable zone in general for people. The comfortable humidity, which we've all heard about, is 40% and 60%. So the bottom of that green area is 40% and the top is 60%. So in that set of combinations from about 70 to 78 degrees with a humidity of 40 and 60%, that is a comfortable zone in general. Now some people can't tolerate as much, or some people can tolerate more, but it's not going to zoom all the way up to the right hand corner, it's going to be a little bit in there. So what all these other numbers mean is they apply to something else in all that range of all that complexity. This helps to simplify all that complexity because when the temperature is really low, like along the left side and the humidity is as high Low to high even. But the temperature mostly, that's the heating zone. That's when you're heating furnace people. That's when your furnace turns on and all the measurements for how do they design a furnace? How do they design heating in a commercial building or a school? It relies on this chart. And there's that green comfort zone again. Now, if you go over here to the upper red, that's cooling in high humidity. That's when you need to cool and dehumidify. The yellow area is that's cooling and it's low humidity. You need to cool, but you also need to add humidity. So it's not a case of high humidity is bad always. It's not a case that low humidity is bad. It's not a case of any one of those things. It's always that dynamic combination of the two. So without understanding all the details of it and fully comprehending it, I wanted to show these images to get the point across that, number one, it is complex, but number two, it's known there's a science to it. And there are people that spend their entire life studying, analyzing, applying this psychrometric chart to the point that they become psychometric. What all this means also is that with the really high humidity, I'm going to enter another concept here, and that is, if you have high humidity in the air, what's the effect upon materials? Not just people. Well, uncomfortable, but on materials. For example, we've had high humidity here in Denver, higher than I've in the 40 some years that I've been here. And my favorite cookie is crisp, but not this year. It's a little soft and sometimes a little soggy. Why? Because the extra humidity in the air is being absorbed by that cookie. It's a concept in building science and in thermodynamics, if you will, that wet always goes toward the dry. If it's wet, it's going to move physical scientific pressures. It's going to move from the excess moisture to where there isn't as much moisture until it equalizes. Okay. Similar with temperature. Temperature, for example, one of the things that I recommend for people in new buildings with high VOCs is to do a bakeout. And what you do is you warm. I won't go all the details, but you warm it up so that it will evaporate VOCs in the building materials and the furnishings so it evaporates out into the air. And it will continue to do that until it equalizes, till there's as much of the chemicals coming out as is going back in. There's no deficiency, there's no change. Similar with the humidity. It's going to go one way or the other, wet to dry, whatever is wettest. If you have high humidity and dry house, it's going to be absorbed by the house. If you have a damp house, like from a flood or something, and the air is drier, it's going to move from the wet building into the dry air. And if it's closed up, it's going to reach equilibrium to where it's back and forth, back and forth. Then that case, then like if you've got, say it's 80% relative humidity in your house and it's closed up and tight and it's in equilibrium, then that's going to be 80%, the equivalent of 80% in the building materials. That's when mold can grow actually about 70, 75%, but certainly 80%. And then you got to get up to about 85 to 90 before Stachybotrys spores can actually sprout and germinate and sprout into active mold colonies. So, I mean, it is complex, but I, I'm trying to get, if not the details, at least the concept and the understanding that it's not as simple as, oh my God, my humidity 70% and I'm gotta have mold or I'm gonna, I have 70% humidity and it's, it's gonna condense on things and make, make things in my house wet or it's going to get clothes in my closet damp enough to grow mold or something like that. It's a balance in there that helps to understand and hopefully will reduce some of the uncertainty about what is going on with humidity in our house and what can grow mold or not, what can cause water damage or not. So let me stop right there and see if Kendra, if I've just messed things up and made it confusing or if you maybe have a question.

No, that's a great. Because, you know, I'm going to be honest, Carl, I used to only care about humidity in relation to what kind of hair day I have was going to be having. I live in humid Virginia, is very humid out this time of year. And that's the extent. But over the years and one of the reasons, you know, for this interview is I had reached out because we had some issues. We're going to talk about that when we get to scenario five. So you're going to want to hang on to that. Something that really happened to me and it was about humidity and, you know, Some of the things that we were seeing, and when does it become an issue in your buildings? And you have, I think, done a nice job explaining that there is that. That connection between the moisture in the air, the temperature, and the amount of time. Am I understanding all that correctly? Before we are at risk for mold growth, which is what I think a lot of people are listening, are worried about. They want to make sure that they're comfortable in their homes and that their building is protected and their belongings are protected.

That's right. That's right. And when they should become concerned and when they can become not concerned, which.

I love, because the information is power. And we don't want you needlessly worrying or freaking out. I've been there. You know, I called Carl a couple weeks ago. He's like, calm down. It's okay. And, and so we're gonna go through some five scenarios. Do you think now is a good time to transition to those? Or is there another point or two you want to make before we do that?

Go ahead and transition to that. There's another point, but it's, It's. It's germane to the scenarios.

Okay, all right. So. So Carl, here's the first scenario that I see come up all the time, and people have questions about. They notice that maybe condensation is forming on the outside of their toilet. So what might be going on and what do they do about it?

Okay, so here's the other concept that has to be brought in, and that is that combination of temperature and humidity. When the humidity is at or near 100%, whether the temperature is 40 degrees or 140 degrees, there's an amount of moisture in the air, and it is relative to the temperature. So you can have a set amount of moisture in the air, but if you raise the temperature, the percentage is decreased. So like 100% at 40 degrees, could be 20% at 100 degrees. But it's the same amount of moisture. The amount of moisture didn't change. It's just how. How it compares to the temperature that's important. Because when the temperature and humidity combination reach or approach that 100%, 80, 90% relative humidity, 100, the air becomes saturated and it can't hold it anymore. If it's outdoors, it's going to rain or snow or have fog indoors. I've seen it in crawl spaces. I've seen it rain in crawl spaces. Okay? High humidity and it's cool enough. It reaches the. That dew point temperature, that saturation temperature, that condensation temperature technically called Dew point temperature. And that's when the moisture falls out of the air because it can't hold anymore. It goes from the wet air into the dryer into a dry space. So if the air temperature and the humidity are at that dew point, you get that dew, or condensation, if you will, the rain. Now, you can have low relative humidity in the air, but if you have a really cold surface, that combination then will condense moisture on that surface. The simplest example is a glass of ice water. You know, and the east coast and high humid areas, in a restaurant, they always have. Not on a coaster, but on a coaster that has a little reservoir down below because the water gets on it and drips. Here in Denver, I almost never see that. But my water bottle right now has condensation on it because we got high humidity. Right now it's raining outside. The dew point outside, okay? Dew point temperature. So if the surface temperature, even if the air and the mass of the building is low, or if the humidity is low on that surface, it can condense. Like that bottle of ice water and the cold toilet tank. The cold, particularly once you flush the toilet and the cold air comes in, it cools off that tank. Then it's like that glass of ice water. It condenses on the outside. That doesn't mean your whole house is full of moisture. It means that cold surface, it has moisture on it. Now, the other part of that is when you have a dehumidifier, that's what a dehumidifier does. It takes that metal plate and chills it so that reaches that dew point temperature. So that humidity in the air condenses on that cold plate, that cold surface drips down into the bucket or down the hose. And that's how a room dehumidifier works. When you get into air conditioning, you got your hot, humid air coming in. What we all think about is, oh, that the, the coils, the cooling coils are cold. It chills the air. Yes, it does. But it does something else too. It condenses the moisture out of the air. And that is the major cooling factor in air conditioning. Not chilling the air, because humidity vapor has a lot of stored energy. Think of it this way. You have a pan of water on the stove. You heat it up and boil it. Look at all the heat and how long it takes to get that water to evaporate up into steam and then disperse into the air as you increase as more humidity. All that energy is stored in that humidity. Then when it cools because of a Cool surface or cool air and condenses, it releases that energy. And that's one of the driving forces of hurricanes and thunderstorms. It's that energy release. That's what happens on a small scale in a house.

So let me. Maybe this is oversimplifying to make sure I'm following along though. So is it, could you say that warm air holds more moisture before it hits that dew point and.

Absolutely.

Cooler air holds less moisture.

That's right.

So you're going to hit that dew point sooner when the temperature is lower.

Yes. So if you move the temperature from high to low, then that's when you, that's when the air can hold less and less and less. And that's why humidity, relative humidity goes up and up and up as you cool the temperature until you hit that dew point temperature, the condensation point, and then it releases the moisture from the air onto the surface, the cold surface, the water bottle, the ice water glass of ice water, or the dehumidifier plate or the AC coils in your air conditioner.

Or the toilet tank.

Right, or the toilet tank.

So what do you do about that? Let's say your toilet is sweating. I think that's what sometimes people say. What, what do we do now?

Don't flush the toilet. That's a, that's a smart ass remark. But in a sense that keeps the temperature from going down to the dew point. So one thing you can do is they some you can sometimes buy these insulating blankets that will fit on a toilet tank. So you now have insulation between the air and the humidity and the toilet tank so it never reaches that dew point temperature, so it doesn't condense. The other way is to use like a dehumidifier in your house or at least in the bathroom. Okay. To remove humidity. Or you can increase the temperature so that the air, the warmer air will hold the moisture instead of condensing out on the toilet tank. Now I realize sometimes that's not easily done, but those are the dynamics that you can use to control that.

So it sounds like we're really paying attention here to dew point and what we can do to influence that so we can keep that condensation from forming. All right, let's talk about another one because I've seen this a lot lately. It's summer. At the time that we're filming this, I'm in a humid area and I see, I was in a friend's home and she has condensation forming on her windows. What does that mean? What do we. What can we do about that? Especially when the condensation's on the inside of the home.

Yeah. That means she's got very low efficiency windows. And there's a big temperature difference. Okay. So in the winter time, the outside cold air will chill that window glass to below the dew point and form fog on it. Or if it's really, really cold, it freezes, and now it's frost. Okay. If you have the double pane windows or the higher efficiency windows, that's like that insulation on the outside of the toilet tank in that the. The outside pane of glass may be cold, but it doesn't have the humidity of this inside. And because of the insulating value of the double pane or triple pane window glass, you keep that inside window above the dew point. The other way it can happen in summertime is if the air condition, if you got the air really, really cold. And sometimes people say, okay, I have high humidity, so I've got to run the air conditioner to get the humidity lower, lower, lower. Well, you get the air colder, colder, colder, and then that air can't hold as much, so the humidity stays the same or actually increases. But that really cold air can chill like the. The AC vent where the cold air comes out and chill that to below the dew point so that it drips, or it can chill. Other surfaces that have hot, you know, heat, it's called heat conduction. They're really conductive of temperature like a window, and it can chill that window or it can chill a mirror or can chill other surfaces to below the dew point. Let me give you an example. I was in North Carolina shortly after Hurricane Hugo went through, and years ago, I don't remember how many before pandemic sometime, and it was humid outside and hot. I go into my hotel room and it is freezing cold. I mean, the thermostat is down below 60, and it's still running and it's cold, it's frigid. So what do you do? You open the window, right? Get some warm air in there. I opened the window just that much, about an inch and a half or two. And I stopped because the fog rolled in. Just all that air coming in, it hit that humidity outside, that was clear air, okay? But it hit this cold air. It hit the dew point, it started condensing in the form of visible fog. And within a minute, while I'm standing there dumbfounded and watching this and saying, God, I wish I had my camera take a picture of it, I turn around, the walls are dripping the frames, the doors, the. The. The vanity, the comforters on the bed are already wet because there was so much moisture in the air outside and so cold inside. It immediately condensed it into fog and condensed it onto surfaces. And we just had a big. A huge dehumidifier. A room as a dehumidifier, we just didn't have a bucket to drain into or hose to run out, and everything was wet within a minute or so. So obviously, I got a different room.

That. That's why. I mean, on a smaller scale, I've noticed, like in. In the. Especially in the summer when there's just huge differences. Like my glasses will sometimes fog. I'll walk from inside to outside in a building. I go from really hot to really cold, and I'll sometimes get that on my glasses, but I can't. I can't believe that. So for.

For windows, because that's the difference in the temperature conduction of the. Of the lenses in your glasses.

Yeah.

Right.

Yeah. It's crazy. So. So for the window case, it sounds like either newer windows would be needed or maybe there's some installation issues around the window. But you. You. I'm so glad you brought up something, because people will say I have to control the humidity, and they turn their. Their air way down and it gets very chilly. And that can actually add to your problem. So you would maybe want to either not drop your temperature so much, add in a dehumidifier, replace your windows.

It would. Yeah. And replacing windows is good, but it's very expensive and it takes a while. So a dehumidifier would help. And, you know, you can increase the temperature also, but it's already summer and hot, so you don't want to do that. But if. If you're really desperate, particularly if you're in a situation like with an absentee or uncooperative landlord, if just moving air over that surface, it'll take the warmer air of the room and blow it over the cold. The chilled window glass. So it'll slightly warm that up and also move moisture off of it so that it doesn't drip. That isn't itself isn't a problem unless it's actually dripping down onto the floor or down the wall from the window. But it's an indication that you have conditions in the house that can cause this. So what other cold or cool surfaces are in the house that may be having this problem also? So it's a clue.

Yeah, I love that. And the clues are important. All right, then here's the next Scenario. And actually this happened to me. This isn't the story I was alluding to, but people notice their H vac ducts are sweating. What do you do? What does it mean?

Wow. Yeah. This is where that psychrometric chart comes in with the experts that have to deal with it because it's very complicated. Because the, the way air conditioning is set up, the air, it chills the air to about 55 degrees. You can't control how cold the air comes out. Just like in the winter. How hot is the air that comes out? That's set. In fact, it has an upper limit switch in there that it cannot go beyond a certain amount of heat. Okay, so those are fixed, but with the air conditioning, with the ducts are getting, are sweating. That means that you have more humidity than the air conditioning is able to remove. So you've got high enough humidity with the cold ducts because those ducks are now chilled like that window glass we talked about or your eyeglasses we talked about. That's below that dew point temperature, so it condenses. If you can put insulation on the outside, please, not on the inside, but on the outside of the ducting, like on the outside of the toilet tank, then that will keep that temperature. There won't be a surface temperature below the dew point. You won't have that condensation. But you may need to have an air conditioning specialist come in to look at the size of the air conditioning unit and the efficiency of it, the ducting system, the airflow, that sort of thing, that, that all can be a factor in there too. So this is another example that I experienced. I was in Hong Kong a number of years ago in August, where it was so hot and humid. I had a three block walk to the conference and I was sweating after half a block. So the air conditioning in my room, the, the duct was sweating and dripping. Okay. So I did, counterintuitively, I opened the window just a bit and I experimented with it just enough to warm up the air enough so that it, that vent wasn't condensing and dripping, but the room was still comfortably cool. So going back to the very beginning, it's this balance, this complex dynamics between temperature, humidity and surface temperature that governs all this. And it's all known. Sometimes it's hard to figure out and the experts have to go back to that psychrometric chart maybe to figure it out and compare that. That's, that's the ideal. Then they have to measure what is actually happening in your house with that system and say, okay, what adjustments do I need to make and how do I make those to stop this problem? So some of these things have really simple solutions and you can do it yourself. You can experiment and try. And sometimes it, it's much more complex.

Yeah. Just another example that happened to us about two years ago. I noticed a small, very faint stain in our ceiling. And I'm obviously hypersensitive to that kind of thing. And I thought, well, there must be leak. It was near some bathroom plumbing and. And I ended up having my remediation company come over and they remediated a small amount. And it turns out we had a. We have an H vac duck there. It wasn't a plumbing leak. So I was like, yay. But I'm like, what's going on? And it was only in the summer and in probably the hottest part of the summer. So that's why it wasn't year round. It's probably why it took a number of years for me to notice. We had a little breach in our building envelope. It was near an exterior wall where that warm air was coming in. And then it was meeting the cold duck. And it took a lot of investigating and different people to remedy that situation.

But it was, it was the humid air coming in.

Right.

The moisture coming in. That's really interesting because that's the simple kinds of things that sometimes can cause big problems.

Yeah, yeah. And it required multiple people. We had to bring in different people to solve. And it wasn't as easy of a solution and unfortunately very expensive. But that's an example of one of those things where, you know, any other season it wasn't necessarily an issue. It was that just the occasional thing over time.

Yeah. I want to digress for just a moment. This is where the type of inspection and analysis becomes important because it took several people over a period of time to figure it out. But if they would go back to that psychrometric chart and the principles involved and say with some curiosity and say, why is it dripping here? Well, it has to be because it's only in the summer when it's air conditioned and the humidity is high outside. Why is it the humid air only in this spot? Well, the only way that could be happening is from outside. So how does it get in? And with just that thought experiment, if you will, with that curiosity, you go very quickly to looking. Okay, I need to find somewhere in the vicinity where high humidity is coming in. Can I find that? And if I can, it's like, oh, but that's Such a tiny spot. What's the big deal? I don't block it and see what happens.

Yeah, yeah, and you're absolutely right. We did. We kept it open for a while and experimented with different things. But, you know, that, that's part of, you know, the, the building really is this complex system of all these inner working parts. And so you have to, you can't approach it with a singular focus. You know, you have to kind of really think about it as, as a system. So let, let's talk about another one, because I actually, I see this happening a lot and it definitely freaks people out. They open up a closet. You know, we, I have kids, we tend to pack our closets, you know, full. It just happens and you don't get to it for a while and you come back and all of a sudden maybe you notice some, you know, white fuzzy mold growing on your items or people underneath the bed where maybe they're storing things and there's stagnant air. What's going on and what do you do about it?

Oh, it's just mildew. And some people say, yeah, mold on cloth is mildew. It's not mold. Well, mold and mildew is the same thing. Other people say mildew is what grows on plants, on the leaves and stems of plants, but it's still mold. It's all fungi, the taxonomic kingdom of fungi. So there, that's another type of dynamics, if you will, where in this case, materials that don't have a lot of conductive value, like glass and metal, temperature, conduction, but you reach that stable environment that I mentioned earlier of wet goes to dry until they equalize each other. You've got a closet that's closed up, that's a stable environment. And if there's moisture in there or if temperature drops, because a lot of these are, have an exterior wall. Okay, not always, but usually an exterior wall. But the, the, the, the dynamics is that it's like a closed mason jar, a closed jar, a bell jar, so that whatever's in there, it all equalizes temperature and humidity wise. And VOC exhaust or outgassing or whatever, everything goes from excess to deficiency until it all equalizes. If that equalization point for humidity is at the temperature, the dew point temperature, then it's going to grow mold, even if the clothing isn't, doesn't feel really wet. The available moisture. And here's another concept that complicates it even more. It's the available moisture on a surface that grows mold. It's not humidity in the air. Mold doesn't grow in the air. Spores don't germinate in the air. They're on a surface that has enough water, enough moisture for a long enough period of time. And that is called. And there's a scientific term and a scientific measurement of it. It's like the psychrometric chart. It's all there in formulas. And that's called available water or specific humidity on that surface. Not relative humidity, but specific. It doesn't change with temperature. It's the amount of moisture that's on that surface. If that is sufficient for germination of spores and mold growth, then you get the growth. The remedy for that is to basically leave the door open or periodically or sometimes people will do something simple like put a. Well, we don't have incandescent bulbs much anymore, but a 60 watt incandescent bulb and put it in the closet and leave it on. And it warms the temperature just enough that it stays above the dew point. The temperature is so that you don't get that condensation, you don't get the mold growth. But that is an example of a closed system where everything is reaching that equilibrium point of wet to dry to dry. And it all equalizes. The temperature equalizes. And in that situation, it all equalizes at the dew point.

Yeah, so you're decluttering your closets helps with that because I think that is really important that you were to reiterate that point. You said, you know, the mold doesn't grow in the air, it's going to grow on. On the surfaces. And so when the moisture content of that material is high enough, and this is just a good general housekeeping, because sometimes people wait to clean out their closets until they go to move. And I just had a friend who had this happen. And then there was like, you know, a spot of, you know, mold growing in the corner or whatever. You can have closets often back into bathrooms or where there's plumbing or, you know, if it's exterior and your sprinkler is watering your siding, it's a good idea. If you're listening, when was the last time you cleaned out your closet? Maybe put that on your to do list just to see. See what's going on.

Right.

Because we definitely saw that. I know there was news stories, you know, during the pandemic where, you know, I remember a picture of a mall I think was in India, and they shut off the H VAC systems. Save energy. This happened at a school. I told you this story before. To save energy. And then they had mold growth all over items and walls and things like that. And you know, that's not something anyone wants to deal with.

No, so, but you mentioned schools and I, I want to just make a quick mention of that. All right. Please, while we have some time. This is a well known phenomena that people deny they don't understand. They don't know how to control it or manage it or whatever. And it's somewhat less now with year round schools, but used to be schools shut down for the summer. They got two and a half, three months or so, hot, humid weather even in dry, semi arid Colorado. Okay? You now have the closet effect. Everything in there reaches an equilibrium of temperature and moisture, humidity, and it'll change somewhat based on the outside, how it affects the building envelope and those surfaces. And it warms or cools the air inside. So it does change somewhat. So the, the brilliant person on moisture, humidity and so forth, the name of Lou Harriman, who's a guru at ASHRAE and former chair of the, the TC112 committee that I'm now chair of, he and others wrote the masterful books on all this stuff, okay? And it was through his leadership and that of others that that they address that issue with a summer school problem, the version of the closet, by addressing not the relative humidity which the, the old standard said of keep the relative humidity below 65%. Well, as we talked about, that changes with temperature, okay? And the temperature can change and you can't keep the humidity at 65% because it's cooler now, okay? The humidity, the relative humidity goes up, the dew point, point changes even though the amount of moisture stays the same. So they rewrote that and just over a year ago. The standard now says to maintain in, in summer, in the cooling season at below 60 degree dew point temperature. So control the dew point and then the schools won't have that problem and your closet won't have that problem.

So all you teachers out there, pass that on to your administrators and the people who manage your building.

It is in Ashrae 62.2 or and I believe 62 point. If you want to have a source for it, get it. There's an ASHRAE standard, it's written in code language and it's by the international experts on all this. And go by dew point temperature.

Yeah, thank you, that's super helpful. All right, so we're gonna go to scenario five, folks. We're gonna get real because this, this is a scenario that just happened to me and I have a feeling it's happened to some of you listening, and we're gonna go through everything that happened in my house, what we did, full disclosure, I did freak out for a moment because, you know, when things go wrong in your house, nobody loves that.

It was more than a moment, Kendra.

It was more than a moment. It was. There was a lot of moving parts, as you'll see. So here's the gist. It was August. We're in the worst heat wave we've had. Temperatures were in the 90s. It was very humid, and our H vac system stops working. Now, I won't get into details of everything that went wrong there, but hang on, because there's a little tidbit we're going to share with you at the end about H VAC systems. And my first thought was when we found out we had to get it replaced and it was going to be at least a week to get parts. And I called around to multiple companies was, well, the temperature was quickly rising in the home. I worried about the humidity rising in the home, and what was I going to do about this? So the first thing I did is I bought a bunch of dehumidifiers and I had them going in a bunch of different fans. I was lucky enough I was connecting with Carl about something else, and so I got his opinion. So what happens if your H vac system goes out? It's a heat wave. You're facing rising temperatures, rising humidity. After you're done freaking out for a moment, what should. What should somebody do? Take us through a scenario from start to finish.

Well, and your question to me was, how do I do that and not create mold because the humidity is so high? So what you don't want to do is when that new air conditioner turns on, is to turn it on as cold as you can get it and freeze dry your house. It's like freeze drying food. It's a flash freeze. Okay? Because what you immediately do is chill those surfaces while the hue before the humidity can be reduced. So you're going to get condensation just like in that hotel room that I described. So what my recommendation to you was to bring it down gradually. Yes, I know. You'll out of the house. You're in a hotel, you want to get back in. But if you can bring it down, like if the temperature outside and without the air conditioning going back to equilibrium, the temperature of the house, outside and inside is going to be roughly the same as outside, along with humidity levels. So what you need to do is to gradually reduce the temperature inside slow enough so the surfaces also gradually reduce, keeping it above the dew point. So it'll take a day or two depending, so that you can get that back down to the comfortable in that comfort zone, in that psychrometric chart, into that yellow crooked square thing there, without creating the condensation that could grow mold. Because if you do it really quickly, it can condense the liquid moisture on surfaces absorbs into sheetrock, absorbs into. Into wood, into carpet and other furnishings, and then it can hold that until it gets warm enough to evaporate out or dry enough to evaporate, but it's not going to get warmer to evaporate because you're cooling the air. Okay. And it. The air is getting drier, which increase that equilibrium, move from wet to dry. So you can't just do it all at once. And, you know, tab A into slot B, you. You do it gradually, and that way you can get it back down without creating all the side effects. So my question to you, and I haven't asked you this yet. Okay. You haven't. You haven't called me yelling and screaming. So did it work?

So it did. We've been back about 10 days. We. We brought it down slowly. So the. The first day it was fixed, we actually stayed in the hotel another night because we knew it would be. We have a kids and a puppy. And it, you know, even with fans going, which we kept fans going because I was in and out of the house a fair amount, it was still uncomfortable, but it took. It took about a day and a half. And I will say during the meantime, we were very good. We were running dehumidifiers anyways and monitoring the humidity. I have a little hygrometer. I mean, it was 10 bucks on Amazon. You know, there's a plus or minus in terms of accuracy, but it was pretty close. We were able to keep the humidity low. We slowly brought it down because that was my concern to you. I was worried about. I was like, am I going to start seeing condensation on my toilets or on other windows and things like that, my belongings. And I did not want that to happen for obvious reasons, but, you know, knock on wood. So far, so good. And despite my humid hair, that's because I was outside earlier. It's quite comfortable inside. And, you know, our humidity is managed, and I feel quite comfortable, so.

And you don't have mold growing on everything. Like, you did it like, like a. In a closet.

Right, Right.

You didn't turn the whole house into a closet or your whole house into A school in the summertime.

Which is why we started with those examples, guys. We were building up to this one where I knew, you know, I wanted to avoid the closet effect. I'm just going to coin that right now. I wanted to, you know, make sure.

I like that. I like that. I wish I had thought of it.

Well, I appreciate your help on that because it's easy. It's very overwhelming. And actually, the reason I called Carl to tell him about that wasn't necessarily initially to ask him for his help, although I plan to do that, is because I wanted to share something funny. At least I found it funny, but actually frustrating and infuriating for you as the consumer, because I talked with three H Vac companies and when I was going through the process, if you talk.

To three H Vac companies, you got five opinions.

I did. But you know what drove me bonkers? The one thing they all agreed on is they all told me, you know what? You're concerned about indoor air quality. I have this UV light I can sell you. 3 for. 3 told me to install a UV light, and this is what they said. This is not correct, folks. But I'm going to tell you what they told me. That by installing this UV light that it will kill anything and everything in the air. So any mold spore would go through. Zap. That's what one of them said, and it'll be destroyed. Now I know enough to know I've. I've followed Carl for many years and asteroid. That. That's not true. You can imagine when I tried to push back on this, they didn't love that. But I felt pressured as a consumer, even with all my knowledge that, well, you know, maybe. But I. I stuck to my guns. The. The sales tactics were hardcore. And I can see if it's been 10 years ago or even five years ago, I probably would have fell for it. I would have spent a thousand dollars installing one of these things. So, Carl, what are your thoughts on UV lights for H VAC systems?

You were smart to resist. So couple things. A UV light shining directly onto the AC coils, not in the shadows, but directly onto the coils, can prevent mold and especially bacteria from growing on those damp surfaces. Because the AC coils are damp, Remember, it's below the dew point. It removes moisture from the air. It drips down, it condenses and drips down into the drip pan and then out the hose. Okay? So if the coils are dusty, if you got a MERV 11, MERV 13 filter, you're going to drastically Reduce that or prevent it even. But if you got dust on the coils and then that unavoidable moisture, it can grow mold. But especially bacteria. It's more bacteria than mold, actually. So the UV light shining directly on clean surface will prevent that from forming, but it's not. Well, let me back up again. If the, if the, the coil is like this and the light is over here, it's not going to shine here. It's in the shadow. So that's why they have on an, a shaped coil, they have a light here, a light here and one in the middle. That's minimum. And it's still not going to get everything out of the shadow. It helps, but not that much. You really need at least two lights on the outside and at least two or three in the middle in order to cover all surfaces to prevent that. In dusty, very, very humid climates with a long dehumidifying season, a long cooling season. Now, UV light can kill live mold, but spores are not alive. They'll seeds, they'll either viable or not viable. Viable means they can become alive. They can germinate. Under the right conditions, non viable means no matter what you do, they're not going to, they're not going to germinate and grow into mold. And there's 50 times more non viable spores than there are viable spores, according to Tina Raponen, University of Cincinnati and others. Okay, so you've got spores flying through the air at about 30 miles an hour. Okay. And they've got about a foot and a half of UV light and they go through less than a second. So then the question becomes how long does it take? How much of UV light to kill? Well, there's no live mold in the air going through there anyway. Once it's off the surface, it dies. Okay? It's not even a zombie anymore. It's, it's dead, it's not alive. How long does it take to denature it, to change it so that a viable spore can't become, will become non viable or fragmented or the proteins on all the spores and particles are now denatured to where they aren't mold anymore, they aren't those proteins. So UV light can do it, but it takes a light that's much stronger than what's in the, in, in the H vac systems. And it'll take anywhere from 3 to 30 minutes of exposure in order to do that.

Not the fast half second that it flew by.

Yeah. Now, small bacteria, small light colored bacteria can be killed in that amount of time. And that's important because if the bacteria is infectious, okay, then that stops it from being infectious. But the larger bacteria or the darker colored ones take not just a half a second or a third of a second, but maybe a full second. And that's not enough time. So it can't even kill the larger darker bacteria. And it's not. It's basically going to have no effect on any spores going through there. So number one, it doesn't kill mold because the only mold going through there is dead mold. It cannot be alive. It is not live mold. But there are fragments and spores with the proteins and, and glucans and proteases and other factors that can and will cause reactions whether it's all dead or alive or whatever. But that UV light is going to have negligible to zero effect on that. So the reason the H Vac companies do this is H Vac contractors. This is a profit center for them. Okay. They can sell you. I don't know how much these cost. A thousand, two thousand, whatever it is. And that's high profit to them. So Zelda. And they actually believe they've been trained and they actually believe this. However, one company, and this goes back 10 years trane t r a n e stopped selling UV lights in residential systems. And they put out an official position document saying that they will no longer do it because it's not effective in residential systems.

This is not enough dwell time. Right. The mold spore is traveling too fast through the air. So, and, and I. You brought up something. Those, they're not living, so they can't be killed. They're non viable. So that's. Those are still health hazards. So really, if you're talking about reducing the exposure, that's when we get into filtration. Right? That's right at the filters. We have a great. And I should have mentioned at the start, Carl did an interview with us. It was all about understanding air purifiers and air cleaners. I'll include the link below with this interview because he gets into all of that and it was really nicely done. So. Okay, any final thoughts, Carl, as we kind of wrap up here about condensation, humidity takeaways, anything you want people thinking about?

I guess what I'd like to leave people with is I got really geeky at the beginning and referred back to that later. You don't have to understand. There's formulas out there that describe all this. This is how fixed it is and how well known it is. There's actual formulas out there that can predict. Okay, and do predict the, the, the, the, the difficulty is it predicts if you know the conditions. The challenge is what are those conditions and what is affecting it. Just like that little hole in the wall in your attic that brought in moisture into one specific point on the AC ducts to cause condensation and drip down onto and through the ceiling. So the, the, the, the, the logic of it, the physical properties are known. The challenge is what's going on in your house. And what I hope I imparted in a way that's somewhat understandable, at least, is that there are some simple understandings of wet goes to dry temperature and how it changes the relative humidity, but not the amount of moisture in the air. But it does alter what's called the dew point or the condensation point, the point at which things get wet or damp. And that you can manage that by altering humidity, temperature, and even air movement, sometimes using insulation. And then starting out with the toilet tank example is a perfect example of that because that's the way you stop that, that's the way you stop it on ducts, that's the way you stop it on windows. The insulation value of double pane rather than single pane windows. So in one sense it's really, really simple. We don't need to freak out about it. We just need to stop and think and ask some questions and consider and look at what is, what is going on and not freak out.

I think I'd add to that and feel free to like jump in and correct me. For anyone listening, I think a really affordable, handy tool that anyone can get is the hygrometer. And they're 10 bucks on Amazon and it's going to be a good start. And you can, you know, check out the, the relative humidity in your basement or your main level because it does change throughout your home. And that's just a good way as a consumer that you can start to think about what the humidity might be like in your home, what that might mean for you.

That's a great suggestion. And two things. One is get several of them and put it in the middle of the room and put it near that window with the condensation on it or the bathroom mirror or whatever and see what the humidity is. It'll be hugely different from the middle to a cold surface that has condensation on it. And get the ones for 10, 10, $12. The digital ones that also have temperature.

Yep.

And if you can get a lot of them now have the dew point on there also.

Yeah. Mine even has a smiley face when it's good and then like a, like a middle face and then it frowns too when it gets too high.

Yeah, I want one with a zombie face.

Maybe somebody out there will make that. You know, I actually give hygrometers out for Christmas presents. You don't you want to be a friend of mine, isn't it? I mean, I'm not nerdy, but hey, I like that.

Yes.

Yeah. So, so that, that has been so helpful, Carl. Thank you so much for, for your time. If somebody had any follow up questions, is there a way they could get a whole in contact with you, with you if they wanted?

Yeah, you can get a hold of me @grimes Hayward score.com.

Yeah, or just drop shoot me an email@kendra changetheirfoundation.org if you're watching on Facebook or Instagram, feel free to drop your.

Questions wherever you are. Yeah, and, and we go through Kendra. She's a fantastic.

We try to get you the answers that you need. Thank you everyone so much for listening. If you found this helpful, please do me a favor. Head on over to changetheirfoundation.org Sign up for our newsletter because it really is the best way to get great helpful interviews like this directly to your inbox.

And send me smiley faces or frowny faces, not just the humidity meters.

Yes. All right, Carl, you have a great rest of your day. Thank you.

Thank you.