Hello everyone, and thank you for joining us for today's webinar on Managing Moisture in Non-Mechanized Environments in Disaster Situations. My name is Jessica Unger and I am the Emergency Programs Coordinator at the Foundation of the American Institute for Conservation. I will be serving as technical support for today's program, and I'm happy to address any questions you may have. Today's webinar has been organized by the American Institute for Conservation's Emergency Committee. The Emergency Committee aims to promote awareness and increase knowledge of the AIC membership in the areas of emergency preparedness, response, and recovery for cultural heritage. Thank you to all the committee members who have worked to make this program possible, particularly the committee co-chairs Becca Kennedy and Howard Wellman, and Chair Emeritus Katie Wagner. Before we begin the program, I wanted to share some technical notes. On your screen you'll see several boxes including one labeled chat on the left hand side. You can use this chat box to say hello as many of you have. You can also use it to ask questions and share any information that you'd like as well. If you post a question in the chat box, you'll receive a written response from me. Any questions will be noted, collected, and then I will verbally ask them of Jeremy at the conclusion of his presentation. This program is being recorded and it will be hosted on AIC's YouTube channel. All registrants will receive an email with a link to the recording as well. With that, I'm very pleased to introduce you all to today's presenter. Jeremy Linden has been the principal and owner of Linden Preservation Services Incorporated since 2017. He is an active educator and consultant with two decades of experience in the cultural field, the last eight years of which have been focused on enhancing preservation environments and sustainability. He is taught and consulted for institutions around the world, has been a pioneering researcher on methods and strategies to reduce energy consumption and preservation settings, and is an active participant on national and international standards committees. His passion is helping institutions preserve their collections in the safest, most economical, and environmentally responsible way possible, finding solutions appropriate to individual buildings and diverse climates and geographic regions. And with that, I'd like to turn things over to Jeremy. All right, everybody. Thanks for joining us today. I hope this is coming through clearly. Thanks, Jess, for the introduction. I appreciate it. And to all of you who have joined in, thanks a lot for saying hi over on the chat board. We'll get started and kick this off here just by means of introduction. I'm sure most of you noticed when the announcement went out that this is actually going to be a two-part series. So if most of you have or folks have heard me talk about systems in the past and mechanical solutions inside of buildings, we're not really going to be touching that too much today. We'll save that for next time. The idea behind today is really to get in on the base level and start to understand some of the psychrometrics of what happens with interior environments, especially as we're looking toward moisture. How does the moisture gets into buildings? What it is that we can do about it, especially in non-mechanized is what I put in the title, but I'm really going to talk a little bit here about non-mechanized and if we may partially mechanized environments. And the idea basically being that we don't have a lot of moisture control within the institutions that we're talking about today. This is a topic that is near and dear to a lot of our hearts, especially given some of the events last year. For the folks that are joining in from Puerto Rico that I noticed over on the board, thanks a lot. I just got to be there a couple of months ago, kind of helping with a few of these very questions. So we'll go through this. And as I said, not a lot on systems today. We won't talk much about humidification dehumidification, but we will be going through and addressing things like natural ventilation toward the end. We'll be looking at some different structural types and starting to understand a little bit more about how it is that moisture works its way into structures. As Jess said, if you guys have any questions as we're going through, please do send those in. I'm happy to answer, at least give a shot at answering whatever I can toward the end. And one thing that I'll just mention right now is we're thinking this through because we have the liberty of a second session here in about a month or so. As I'm going through in the slides today, if there are aspects that I haven't addressed to what you were looking for maybe, or if you're curious about something in particular, if there's something you'd like to make sure that I try to address in the next session, please do feel free to send that in and put that as a comment either in communication with Jess right now or in the evaluation at the end. And I will do my best to make sure that I include at least some discussion of most of those in that next session as we're going through kind of a more mechanical side of things. So without any further ado, let's get this party started. And just to go through and set the stage. You know, this is a topic that's near and dear to my heart and it's one that I think for as many different times and ways and locations and settings as I've talked about this over the years in terms of thinking about moisture and preservation and collections and structures and buildings. It never really ceases to change that I always learn something new every time I go out to a new site or work with a new institution. Sometimes we are learning more even in terms of research when it comes to preservation, what moisture levels impact things and how it is that we can practically apply some of the science that we're discovering. So it's, it's always fascinating to look at this and even go back just five or seven years ago and recognize how much more has changed what it is that we've learned and I'm always going through and trying to update talks. So the goal today is to think about what are the primary things that we need to understand regarding moisture and cultural institutions. We're going to talk about cultural institutions writ large, but you know throughout most of this you're going to see a lot of pictures of historic buildings, historic structures. Some are small historical societies some are parts of larger institutions. There's kind of a broad swath in that regard that I tried to bring in here a little bit. But what are the typical challenges that we run into when it comes to moisture in these types of environments and settings. And really what options do we have for managing and controlling them is there we're going to talk a little bit about more about that concept of control here in a few minutes. But the other part of this is how do we go about choosing the right moisture management approach for our own individual situation. It's a critical component of this because every institution every building every site is a little bit different. And as we're going through I'm hoping that some of the ones that I'm giving as examples may show up and say, oh, yeah, we've had that problem in the past or boy if I got a story for you or something along those lines. But as we go through, keep an eye out hopefully we'll be introducing some concepts or ideas that will be familiar to your own situation. Finally, how is it that we actually respond to looking at moisture incursion when we do get into a disaster scenario. And this is one that there are a whole lot of levels of response, many of which have to do with human safety first and foremost I'm not really going to get into that today. My role in talking about it is really to discuss the concept of when we have limited power availability when we have a structure that already is shall we say missing any sort of mechanized solution. What is it that we can do from a natural or passive solution that may help us either avoid the worst of things start to dry out the building. How do we think about rerouting some moisture. And I think most importantly in most of these settings how do we avoid growing mold. So we'll go through some of that and we'll have some suggestions and some talking points. And hopefully that's a little bit more than we can discuss toward the end of the talk here today. So first and foremost I've tried to choose my language fairly carefully and the reason why I say management is because we are working with non mechanized environments here at least only partially mechanized. Meaning that we really don't have mechanical systems or powered solutions and a lot of cases to really talk about fine tuned temperature control let alone humidification and dehumidification. So as we as we go through and talk about that you know there's a very key difference here between the concepts of management and control. In partially mechanized environments we might have ways to do some temperature control think about historic structures with a little bit of heat. And I would even take that so far as you know if we look at modern applications. There are plenty of small institutions out there are historic structures that have gone the route. More often than not looking at kind of localized air conditioning solutions whether that's a window unit or something else. But there are situations where a few of these institutions have gone toward a centralized system for air conditioning. We're not going to touch on that too heavily I will address kind of the mechanics of that in the next session coming up. But it's just to say that you know really when we talk about non mechanized that also applies to really sort of lightly controlled environments where we're not really talking about fine tuned control. It's more about temperature control and we get a little bit of moisture impact on the side. As we go through this a lot of the strategies that we talk about are going to appear really more passive in nature. So talking about rain and groundwater management how it is that we understand and think about vapor flow and structures. Thinking about passive ventilation which is a really key one especially when we get into disaster situations and a few other things here and there. So just a reminder for everybody to keep in mind we're not going to go in really carefully to different types of preservation conditions and what is safe and what isn't safe. But I always like to keep these at the beginning of most of my talks just to give folks an idea of what are the things that we really want to be careful of here. So this first page is looking at general temperature safe and risk zones and even though this goes down to if you will very fine tuned numbers. The basic idea behind this is that it's using the four categories that are laid out in some different resources including the international standards organization. ASHRAE chapter the American Society for heating refrigeration and air conditioning engineers working with some of their materials as well as some different preservation guidelines. And just talking about basic categories of temperature here where the risks are what is good for most materials as usual for talking about the concept that cooler is better when you can pull it off. And that cooler really depends on what it is that we can do from moisture control. And when we think about general RH safe and risk zones. Yeah these are just kind of my highlighted targets again from multiple resources so don't consider them the Bible by any means by any means please. But places where we kind of have to start watching and being careful for things to start to go wrong. So up there at the top you know anywhere above 70% when we're talking about moisture 70% relative humidity is kind of that magic panic number if you will. When we start going above there especially at room temperatures and above we're getting into situations where more risk becomes a serious threat. And you know we're talking about disaster situations this is often the first place many of us go in terms of not just what we're responding to but also what it is that we're trying to prevent. But on down the line as we reduce relative humidity we need to keep in mind that there are various threats at different levels that 35 to 55% relative humidity is really probably the safe range that is agreed upon by the majority of material science right now. There are a few exceptions in there for media specific situations but that's a pretty good guideline for most of us that have mixed collections and whether that's thinking about library materials archival materials photographs museum objects artwork that 35 to 55% range is going to be safe for most of it. We're not going to be talking quite as much about the low relative humidity conditions today. And interestingly enough that's something that if you I will be touching on the next webinar when we look at humidification. But as far as that lower age condition goes, more often than not for a lot of us that is not usually the panic point when we get to issues of disaster and power outages. There are some exceptions, and if we want to talk about that at the end I'll try to go back to that. So, practically speaking, and I mentioned this before, but when we're talking about non mechanized and partially mechanized cultural heritage structures, really at the end of the day the primary goal is avoiding mold. We recognize that we can't necessarily control moisture as such, what we're trying to do is manage and mitigate as much as possible, so that we can stay away from that biological growth scenario. And when we're talking about different preservation metrics or when we're talking about different decay functions, everything else, chemical decay, mechanical damage, physical shape change, oxidation, corrosion, looking at metal corrosion is, is certainly something to be considered and we want to be aware of. But it really is secondary oftentimes to that situation. So that's kind of what's in the back of my head as we're talking through this and I hope you'll keep that in mind as well. So, getting started, welcome to the first step into technical world here, but we're going to talk about dew point and a little bit of psychrometrics here for a little bit. Now for those of you who have heard me talk about this before it will hopefully be a little bit of review for anybody who's new to this. If it's not entirely clear the first time around don't feel bad. I've had people come up to you before and say you know what I've heard you give this talk three different times, and I think I have it now. So if it takes a little bit of going through or if maybe I'm not giving it the best explanation this first time through, let's do it another time sometime and we'll keep at it. So, let's see here. Getting into dew point why why do we really care what's important right. The first thing is that it actually gives us a good representation of the actual moisture content in the environment. Even though it's not necessarily what it is that the engineers such would say is the technical moisture content. For those of us on the collection side it really is a nice place to refer to and think about how is it that we can imagine the amount of vapor or the amount of moisture that's actually in the air surrounding us. And we look at conditions that have a high dew point temperature if we see a dew point temperature above 50 degrees 60 degrees here in upstate New York 60 to 65 degree dew points are very very common in the summertime. That's a fair amount of vapor in the air. If we get to the Southwest US, hopefully somebody is joining us from that area. But when we get down to the Southwest and we see outdoor dew points ranging the 20 and 30 degree range. We know that we're working with an environment that has a lot less available moisture, even for the amount of heat that we sometimes see. The other thing about dew points that is really critical when we start talking about preservation is that that moisture content really does determine the preservation environment we can achieve. As you'll see basically choosing your dew point using that vapor content tells us where we're going to wind up when we start looking at the balance between temperature and relative humidity. And if we understand how it is that our environment especially outdoors behaves for moisture contents over the course of the year. We really start to get a better idea for what types of conditions we should expect, especially if we know that we only have limited or maybe in some cases very little temperature control at all inside of destruction. It does help us understand whether or not we want outside air in the building and when. And what it is that we have to worry about in terms of vapor moving in and out of the building. There's Joanne. Thanks for chiming in. I'm glad somebody joined us from the Southwest. So correct me if I say something that's wrong for you guys. But going through when we get to next month's talk for mechanized solutions, the one thing about dew point to keep in mind is that from a system design and capability perspective. It really is oftentimes that limiting factor of what the system is able to provide. So if the system has a good dew point capacity or good capability of providing a shall we say do point control, whether it's depending on how low you're going. It gives us that very immediate information of what type of interior environments we can maintain. If we're looking at a system that was designed only for temperature control without really addressing moisture, then it goes the opposite direction. We can really identify what the possibilities are, but unfortunately we may not always be very happy with them. And finally, this is something that we run into a lot, especially for anybody out there that has ever gone through a renovation project or worked with a contractor to look at a new mechanical system. Or anything involving really the mechanics side of things is the dew point is a really nice unit for us to work in in terms of finding that common vocabulary to work with a lot of our shall we say more engineering architectural oriented colleagues. They use a lot of different measures we won't get into humidity ratio and things like that today. The dew point is usually a nice common ground for us to work with. So I promise this is the last time I will show you the psychrometric chart. This is never a fun one, especially to try and teach through webinars. I try to try to keep this only for live applications. But for anybody that is going through and looking at a psych chart if they're curious, the dew point curve that we're talking about there is at the far end looking at the saturation temperature. And I think we'll cover this in just a second, but 100% relative humidity is the same as the dew point temperature. And here we go. We'll move in a little bit and maybe some of you have seen these diagrams before. But when we're talking about temperature relative humidity and dew point, I think the first idea, the first concept that we want to get a hold of is this idea that when we're talking about air temperature, that temperature is what determines the environment's capacity to hold moisture. So if you look at, I kind of fondly call these buckets as we look at that diagram. Notice that as the temperature goes up, so does the capacity to hold water. In other words, the warmer the temperature is, the bigger the bucket it is that we're working with. And as we cool down, the bucket shrinks and gets smaller and smaller and smaller. The key to remember here is that this is entirely independent of the actual volume of moisture that is in the air. So when we're thinking about temperature, we're just talking about the capacity and the overall size of the bucket, not yet what is in the bucket, if you will. When we get to the actual moisture content or if you will more specifically humidity ratio, and this is where dew point comes in. The actual amount of moisture in the system in the air does not change even as the temperature changes. So the water present is always going to be the same with one exception here that we'll get to in a second. But even as the temperature goes up, whether we're at 55 degrees Fahrenheit on up to 80 degrees Fahrenheit, we do stay at that same moisture content with amount of vapor in the air does not actually shift. And this is a really critical component to think about because when we a lot of times it's interesting. We use language like things are dry or there is very little moisture. And there's a difference between the actual amount of moisture in the air and the relative saturation or the relative humidity of the air. And that's the concept that we really want to cover in this slide is talking about that idea of what is relative humidity and essentially what it comes down to is its relative saturation. So if we're looking at that 80 degree Fahrenheit condition over on the far right hand side, we see that the environment has a very high capacity to hold moisture. There's a lot of room in the air and this goes back to kinetic energy and how much energy we have to bounce water molecules off of one another before they actually condense. But we have a lot of kinetic energy and a lot of, if you will, space available in the air in order to hold vapor. But at that particular vapor quantity, we still have a lot of room left in order to fill it up. So we're only partway full at that point where 42% full or the relative humidity in that case is going to be 42%. And as we cool down the air, notice that the volume of moisture doesn't change, but the relative humidity does go up. So as we drop down to 75%, our same volume of moisture has the bucket more full now that the bucket has shrunk. So we're now down to 50% relative or up to 50% relative humidity. Let's see, I didn't have to catch myself sometimes. And we drop down to 70 degrees, the RH continues going up to 59% and so on. So this is a really critical relationship to remember. And normally I have a slide in here that points it out and I think I actually left it off of this particular talk. But the rule to keep in mind is that when we have a constant moisture content within an environment, as the temperature goes up, the relative humidity will go down. As the temperature goes down, the relative humidity will go up. And it's that inverse relationship that we want to keep in mind because it kind of helps us understand on one hand the danger of cooling without dehumidifying. And on the other hand, sometimes the advantage or the shall we say tool that can be heating in order to lower relative humidity, even though we don't have any capacity to actually remove moisture. Those are things that we'll talk about a little bit more when we get to the mechanized section. Those are concepts just to keep in mind. And again, remember that relationship, given a constant moisture content as the temperature goes up, the relative humidity goes down. And as the temperature goes down or cools off, the relative humidity will go up. And that brings us to this a little more involved diagram over here on the right. But we want to keep in mind that concept that the key here is how much moisture we have in the environment. So if we have a lot of moisture available, we're kind of locked into this line where we have an actual amount of moisture at a 55 degree dew point. Notice over on the left at the top, we use the arrow here. Here we go. So looking right here where we have 55 degrees in our bucket is 100% full. Notice that we are at our dew point condition in that particular instance. So we're at a 55 degree dew point with 100% relative humidity. Now, looking over here to the right, if we're talking about preservation conditions in this case, notice that if we wanted to maintain an interior temperature 65 degrees for the sake of preservation, we're going to be at a 70% relative humidity, which is not a terribly good idea. We talked about before that's going to start introducing that risk for eventual mold growth for us. So instead of looking at that, we know that we're locked into this moisture content at the moment, so we can't use that cool temperature. The key then is to think about how it is that we can dehumidify or remove moisture from the system in order to bring the relative humidity down at this particular temperature. And that's where we get into the concept of dehumidification. There are multiple ways to do this, but in this particular example, we're looking at something that's called subcooling. So if we're 100% full at 55 degrees, we know that if we drop the temperature to 50 degrees, we're going to shrink our bucket. And that's this illustration here. As we make the bucket smaller, there's no longer as much space or room in that air, if you will, to hold the moisture that is present. The result of that is that some of it is going to have to condense out. As we drop the temperature below the dew point temperature below the 100% relative humidity, we condense some of that moisture out of the air until we hit the temperature we're looking for, at which point we are still 100% saturated. So looking at that 100% relative humidity and moving back, now we're going to reheat the air, reheat the environment. And as we warm up that air with that moisture content, notice now that when we get to 65%, we're down to 58% relative humidity, which for some collections is perfectly fine for a few others, we want to be concerned or watch for things like corrosion. But in this case, that might be one option for you, especially if we're working within a library setting. And on down the line, we're not going to spend quite as much time as this, but if we're looking on this, but if we're looking for cooler temperatures yet, we could further dehumidify, we can drop that subcooled temperature down to 45 degrees, reduce some of the moisture content again, condense that out of the system. And as we bring the temperature back up to the set point we want in the space, notice now that we can maintain 65 degrees at 48% relative humidity, which is just fine for nearly any collection that we would run into. So this is that relationship between temperature relative humidity and the moisture content in the system. And when we're talking about non mechanized environments, recognize that we don't always have a lot of control or a lot of option, in terms of changing the actual amount of moisture that the air in the building is containing. And what we're looking for are ways to mitigate it and other means, right? We can't add moisture to the air in terms of humidifying. We can't take it out in terms of dehumidifying. But we can try to slow the rate at which moisture comes into the building to begin with. And that's what we're going to go through here for the next little bit is talking about structures themselves. Where it is that the moisture comes from, how it gets into the building, whether through a roof or through a leak or through a wall via the fusion, take lots of different pathways here. But talking about how to try to mitigate and minimize that moisture movement in situations where it's critical, and then we'll get to the concept of where do we want to actually take advantage of some of these ventilation aspects when we're worried about particular things. So moving on here for a second. So conceptually, and New York City is just one example, right? We can do this through Take Your Pick, any particular site or location that we want to around the world. But if you put a plot up of dew point for your outdoor conditions, I think the idea here is that we want to get a feeling for what it is that outdoors is giving you, right? Now, in the past, I try not to talk about this too much. But in the past, there's been this, if you will, former guideline, if you will, if anyone has heard about the 70 degrees and 50% rule. Trust me, we're moving away from that very, very quickly and hopefully very steadily throughout the unified professions. But looking at that, that 70 degrees and 50% condition is requiring a 50 degree dew point. And we'll go back and show you where this is right here. Notice here at our 50 degree dew point condition, let me get those cursor back up here. Here's my 50 degree dew point line. With that moisture content, when I raise the temperature to 70 degrees, I'm at a 50% relative humidity. So looking back outdoors at New York City again. If we look to see how often outdoors gives us that 50 degree dew point where we would achieve that indoor environment of 70, 50, the answer is not very often at all. In fact, I would say virtually never and it certainly doesn't stay there. And this is something to keep in mind, especially for anyone who lives in a seasonal environment. And that's that the outdoor moisture contents are going to constantly change typically over the course of the year. The summer months when we have warmer conditions, at least in the Northern Hemisphere, in the summer months when we have warmer conditions, we are going to see a lot of instances where dew points go up because the air can hold more moisture. And the winter months with New York using here as the example is the outdoor temperatures drop and we can't hold the same moisture due to the size of the bucket. We noticed that the dew points drop significantly. And this is the amount of outdoor moisture that we're actually working with. There are a lot of other places where this curve looks quite different. For those of you who are joining us from Puerto Rico, your dew point curve is entirely different. You're almost always up there above a 55 degree dew point. So imagine that if this entire graph were capped off right here and your moisture contents were always in this range, that's a little bit more what we expect to see in Puerto Rico, South Florida, portions of Southern California. That's what we're looking at. So be aware of what your outdoor moisture patterns do look like. I will if it's, hopefully I don't get in trouble for this, but I'll put a plug in here for eClimate Notebook through the Image Permanence Institute. They have really great resources for outdoor weather data that you can pull into your account and have different options for plotting and looking at what's going on outside. But oftentimes you can also find this data to import in through a CSV and just run your own graphs, whether through NOAA or some other weather providing service that will keep this, keep this record for the long term. So keep in mind, right? And hopefully nobody's storing their collection in this particular pavilion, but you get the idea that anything that is truly lacking in any mechanical intervention, let alone any envelope intervention in this case, eventually your collection or your interior is going to feel exactly what the outdoor dew point is. If you give it long enough, nearly all buildings will come into complete equilibration with the exterior moisture content. The key, and this is where we get into building envelopes, is that they provide the buffer and can slow down that process. So in this case where it's just completely open and whatever is going on outdoors is what we feel indoors. That's kind of a worst case scenario, but there are a lot of instances, even in historic structures where the design of the original building, the way it was meant to breathe, the way it was meant to interact with its environment, means that even though it does fluctuate, it does help to buffer the extremes and we can maintain or at least contain to a certain degree the worst of the conditions over time with the right amount of buffering and provided that we use the envelope the proper way. So we'll get into that a little bit more as we go through. Alright, so to talk about envelopes and get into this. So as we talk about building structures and building envelopes, what we're really looking at for the most part are the physical substances that actually separate the interior of the building from the outside environment from the outdoor weather. Whatever it is it's doing, most of the time we tend to talk about this in relation to thinking about air, water, heat, light for some folks, although I don't get into it too much, noise transfer does come up actually, especially when we're talking about gallery situations. Oftentimes it's less of a thing or less of a discussion point with historic structures, but it is something to keep in mind that the envelope does serve a purpose there. And as we're thinking about what it is that comes into play, it's really every part of the structure from looking at the vertical walls to the subgrade foundations or subgrade floors, looking at penetrations that might include doors or windows or vents, anything the chimneys that we see here on the roof of this particular building, looking at drainage on it, looking at how it is that we move moisture away from the building, that is part of the envelope system. And when we're thinking about that physical structure, the relationship that we want or the takeaway that we want to have is recognizing how it is that each of these factors interplays with what is outside. In other words, are my windows going to keep things out for me or are they going to let things through on particular occasions? Do we want air to come in? Hopefully the roof is always keeping at least the moisture out, but recognizing that we do also use roofs and at least different roof structures for natural ventilation. So there's a little bit of a variant on every one of these particular factors, but it's that idea that we want to look at all of those surfaces that interact with what is outside of the building. And again, don't forget the subgrade portion, especially for places that have a lot of instances, either of basements or even crawl spaces. When we think about those interactions and the directions that things can move, we recognize that it goes both ways, right? There's a lot of interplay here. There's a lot of, shall we say, relationships that can change either on a daily basis, on a seasonal basis, even so often is just a particular weather event coming through. So at a roof, we can see a lot of thermal gain from solar radiation through the course of the day. But when we're looking at nighttime, that's also a place for that heat to be given back off. And that's part of what helps cool down a structure at night. As we're going through and talking about thermal gain, windows, doors always come up, especially windows. It's one of the nightmares of my own existence is looking at glass construction in modern buildings. But when we think about the moisture component of it, oftentimes we think very easily about leaks or about water coming in from subgrade situations. But the important thing to think about also is that the skins of the envelope itself in terms of construction allows oftentimes water vapor to pass through at varying rates. And we'll get into detail with that here in a minute. But that can both go in and out depending on the season, depending on what's happening inside the building. We do get thermal gain and loss through the exterior envelope of the building. And when we go through and just talk about air exchange itself, whether we're talking about the opening and closing of doors and windows, or if you've ever heard buildings described as drafty, I live in one. So you might, you know, many of us might have that example. But when we think about draftiness, it's not just the air that is moving in and out, but oftentimes that air is helping direct moisture. One of the things to keep in mind is that airflow air pressure and vapor pressure are two entirely different concepts. They do behave together, but they can, if you will, behave independently of one another. So even though we may have positive pressure, pressurization going outside of a building or flow going in a particular direction for air, that doesn't mean that vapor still can't come in or go out against what that air direction might be. Subgrade, we do have thermal loss to the soil and more importantly for most of us, we have moisture being from the soil for anyone who's ever dealt with water in a basement or issues of rising damp up through a foundation or up through exterior walls. So that envelope, when we're talking about it from a non-mechanized solution here, and it really is the key part of that system, and it absolutely does play into mechanized solutions as well, but that envelope allows us to moderate those effects of the exterior climate and try to, where possible, especially if we use it to its proper design, try to mitigate slow or the very least buffer, if you will, the rate at which the interior environment changes along with the exterior changes. So the other portion here to think about is that the capacity of the envelope, the construction and the way that you use it is really for non-mechanized buildings, the primary factor that we have at play in terms of thinking about what we can manage inside. And it really is the interplay of how the envelope works and where it is that we allow vapor and moisture or vapor and airflow, whether on purpose or whether it's sort of accidental or part of the nature of the construction, if you will. We need to understand that well enough because that's where we begin to understand what our limitations are and what it is that we have to be careful of in terms of risk. All right, so when we think about zones, interior versus perimeter, one of the things to keep in mind is that depending on the construction of an organization or of a building itself, interior spaces can be some of the best ones that we are looking for on a day-to-day basis from the perspective of where to store collections. We talk about this a lot, especially in mechanized environments, that we're trying to keep the influence of the outdoors away from what we're doing for a preservation mission. In other words, minimize the amount of interplay with the bad things that are happening outside. We don't want too much moisture. We don't want not enough. We're trying to find a happy medium in here somewhere and kind of get ourselves to a relatively steady middle ground. And we talk a lot about interior zones as a solution for that. They do have their own energy gains when we look at lights and equipment and people. And as well as when we talk about moisture, anytime we have a kitchen, a bathroom, or just an occupied space, we have to accept that we are actually bringing moisture into that interior zone. Anything that's on the perimeter, we have, and this is really a good thing and a bad thing on what situation we're in. We have walls and windows that are exposed to the outdoors, which means that we automatically have a way to achieve natural ventilation. And this is something that I want to caution us, as we're all thinking through, that concept of interior spaces really does often rule the day when we talk about mechanized environments. But one of the things to keep in mind is that, especially for historic structures, and when we start talking about non-mechanized environments, disaster response, the access to outside air, the access to natural ventilation can be one of our biggest allies in this entire process. So if you're working in an institution that is, that does have or is working with an historic structure that has limited mechanical intervention in terms of whether you're heating and cooling, or if you don't have any moisture control at all, think very carefully about how tightly you button up a particular collection zone or preservation zone. Because there are a lot of circumstances where we might actually want to use that outside or that natural ventilation to work for us, especially when we're running into instances of not having a lot of otherwise powered air flow. I hope that was clear, but I think it'll become a little bit more so as we go through. So as we're looking at any particular building envelope, the way that we think about assessment is looking for how it is that it interacts given both temperature and moisture in our particular case. So we want to understand what it consists of, how it's constructed, what its characteristics are, and within reason what its performance limits are, right? Can it mitigate temperature? Can we actually, is there insulation present that just varies on the type of building? Thermal insulation is something that we did come up fairly, shall we say, quite a while back, if you will, when we're talking about building construction, we understood the value of keeping cold temperatures out and the value of really also keeping hot temperatures out in the summertime. Insulation works both ways. When we're thinking about air movement, what is the natural air movement that we might have in a space, but also what is the air movement that is natural ventilation just due to the construction of this, of your particular building? Is it something that is mechanized, in other words based on duct work and you bring in outside air from a particular location? Or there are a lot of institutions that really do still rely on, shall we say, wise use of windows or opening doors and vents at particular periods of the day. So understanding how your building was designed to work in that regard. Moisture control, we'll talk about what it is that, how it is that we manage moisture on an overall building site, but then also vapor pressure, what it is that we're doing from moisture inside of a building and how that interacts with what's going on for outdoors in terms of vapor pressure. So a few examples to go through, just some building examples as we're looking at it. And again, as I said before, hopefully there are a few places that are going to sound a little bit familiar in terms of the institutions that we're working with. So for open structures, right? It's kind of like that pavilion that we looked at before. Limited to no envelope. Let's see here. I've got a note here to make sure that I speak up. I hope everybody can hear me okay. But here when we're looking at open structures, limited to no envelope, right? Really no intervention in terms of how it is that air and moisture or temperature are moving through the structure. At the end of the day, what it is that you're relying on is a roof structure to keep the actual precipitation off of the collection, whether it's rain or snow. And you accept the fact that in these cases, oftentimes you're going to be dealing with whatever the environmental conditions are that outdoors is giving you. And we see these a lot at different historic sites. This is something that we run into quite a bit in terms of living history museums. So don't consider this to be disadvantageous in any regard. This is part of history too. This is part of cultural preservation. And I think the decision always comes down to what are the right ways or right materials to display and right ways to use these structures. And making sure that we're keeping that in mind in terms of not only the integrity of the structure itself, but also keeping the material that we are housing within it safe. And then we talk to kind of the next step up from there when we're thinking about it is looking at, if you will, primarily post and beam structures with just a very basic sheathing envelope around it. And the easiest thing to think of when we're talking about this is really kind of a traditional barn structure that plenty of people are familiar with. But looking at frame barns, mills, cabins is here in the slide, but also a lot of just basic residences and houses are quite similar in their construction, especially when you're talking about a cottage or something along those lines where not a lot of need was not originally a lot of consideration for thermal insulation. You'll just run into very basic cladding on the exterior of an envelope. These may have earth or wood floors. There could be a crawl space beneath. We're not usually talking about masonry concrete in these structures. Most often, more often than not, when we're looking at this type of an environment, there is obviously no vapor barrier, but no thermal insulation either. The building is truly designed to breathe. Again, it is just that one step above that sort of covered space where we have a roof, but those walls and that sheathing is also there to sort of keep the exterior elements out. In some cases, we do get to a point now for both historic structures as well as modern structures where we do have fans and attic venting moving in some of these buildings to help aid the natural ventilation processes. So don't be surprised if you see that. The good news in those cases is when we do have ventilation that is powered, most of the time, even in a situation where we have a power outage, the ventilation process will still occur passively, just not quite as quite a rapid rate, if you will. And what we have to accept at the end of the day is that these buildings do have a very high air and moisture exchange rate. We really don't expect to control these in any sort of definition of the term. So next step up is when we start to notice that we're kind of moving into, if you will, kind of beefier structures here moving on. But this concept of uninsulated masonry or framed inside of wood structures, we're getting into a little more of a category that might include some residences, might include anything from older office buildings in some cases, historic structures, older mansions, historic houses, depending on how tightly or how strongly they were built. We're not often usually into church range yet, but that can include some of these. So when we think about modest houses, early industrial buildings, a lot of these in certain parts of the country will have basements or will have spaces that are subfloor that we do have to keep in mind, especially as it plays into moisture. For these buildings that are on grade, if they, most of the time they're not dirt floor, but they are just slightly raised up in terms of a crawl space and being aware of what's going on underneath the structure is really critical, especially in terms of how your moisture floor works on site. For windows, oftentimes it's just single glazing, in other words, single thickness. We're not getting into modern window structures and they really provide very little in terms of any sort of thermal barrier, let alone vapor. Generally lacking in insulation, but we do run into some instances where portions of these structures are insulated. Oftentimes where these have been renovated or moved into sort of a more modern usage, you'll see especially some insulation in the wall structure as time goes on. So that salt box below, for example, I've seen plenty of these through the years that have had insulation added over the years. Most of the time when we run into mechanical installations in these sorts of buildings, there's not a lot here in terms of vapor or moisture control. Really the envelope itself is far too leaky to try to control the interior environment for moisture. We're looking more at temperature control, and this is where we talked about before when we're trying to manage relative humidity. If we can't actually dehumidify or manage the amount of moisture in the air, what we can do is manage the relative humidity based on temperature. So a lot of these structures, especially that salt box below as an example, is where we see some examples of using what's called conservation heating, or that concept of heating at various times of the year in order to bring the relative humidity down. This is particularly at least for the US. It's a little bit different when we get into the UK and Europe. But in the US, we see this a lot in the spring and the fall where these structures are. And the other thing to keep in mind for folks that are in hot and humid environments, thinking about, again, South Florida, Puerto Rico, anywhere in the Caribbean, South America, Central America in particular, that there are actually different strategies we can use in terms of heating in order to reduce relative humidity. Oftentimes in repurposed historic structures, we don't have heating capacity, but we have to use that as a strategy in some newer structures as a way to bring the relative humidity down when we simply can't attain what we're looking for with dehumidification. So in these structures, again, we're looking at moderate air and moisture exchange rates. We know that air is going to move through these buildings, and one of the things especially with this, you know, kind of where we're getting into what we would call inhabited buildings is that, you know, we'll talk about it a little bit more, but the concept of staying true to the original design intent for the structure. I'm going to try to put this as, you know, plainly as possible, but our ancestors weren't dummies when it came to construction. Oftentimes they chose their construction methods and the way it is that they put up buildings very specifically for the region that they were in. And that goes for throughout the United States when we're looking at the Southwest, on up to the Northeast. Spanish construction and architecture in Puerto Rico is very common along these lines in terms of recognizing that they understood how the building should work passively with the environment around it. And the trouble that we get into sometimes, especially when we're looking at modern preservation and how it is that we try to control buildings for the sake of preservation of materials on the interior, is that we have a tendency to try and seal these structures up. In other words, block every air gap, block every leak, make sure that air can't come in and out, try to block all of the moisture from coming through the building. And what we wind up with is a situation where the building can't actually flex and breathe the way it was supposed to. And the real downside to this isn't necessarily just the problem that we might have in an interior preservation zone or if you will let's just say a collection storage room within the building. Oftentimes the problems that we run into are with the structure itself where certain elements of the way that the building was constructed were meant to be able to flex and breathe and when we start to seal those or when we start to lock those down or restrict them we start to cause damage to the historic structure itself because it can't move, flex, expand and contract the way that it was originally intended to. That's something that goes a little bit more into historic preservation but for anybody whose structure or building is part of their collection where you're looking at a situation with an historic structure or an historic site especially do be very careful and cognizant of how it is that you are using these envelopes and what it is that we do to change them over time. Not only is it required oftentimes from historical integrity to make sure that we keep them similar to their original intent but from the preservation purpose alone in terms of the physical nature of the structure making sure that we allow that building to perform the way that it was intended to is usually one of the best preservation steps we can take. We'll talk a little bit more about that here in a minute. And finally this is about as far excuse me this is about as far as I'm going to take it with structures today because we are talking about non-mechanized to partially mechanized buildings as we're going through this but we still do get up into this category I would say of if you will sort of the heavier or slightly tighter wooden and masonry structures that we see around us every day. Picture down below New York Public Library is just one example of a Library of Congress through its original construction actually falls into this category. Tighter wooden structures in terms of modern if you will colonial architecture or something like that. As we're going through and talking about it we have a lot of these sites and a lot of these structures have become aspects of our cultural organizations over the years whether it is the home to the particular organization whether it's an historic house that we are trying to preserve both the structure and the collection on the inside. These are really really common to many of us and as we look at their construction we look at what they're intended to do we're kind of at the midpoint between what we would think of as a modern new construction and what we might think of as a completely uncontrolled historic structure. We oftentimes have very thick walls that often many times with insulation on the interior of that wall. Wood frame on the inside quite often plaster and lath and a lot of construction. We may see attics that are insulated but also a lot of ventilation through the attic. Storm windows are more and more common on these structures and what we also see quite a bit of is moving away from single glazed onto if you will double pane windows and looking even at if you will more energy efficient installations that have been designed to appear accurate for the period but to perform on a more modern efficiency sort of grade. As we go through most of the time these structures had very limited mechanization to start with and in most cases it was really just a heating system, nothing in terms of moisture control. That still may be the case for a lot of these that we run into but there are quite a few over the years that have been renovated either by a prior occupant or by the cultural heritage organization that sits in it now to have some degree of central conditioning or central control that often does have a moisture control component to it whether it is humidification or dehumidification. These can cause some pretty serious problems. We'll go through this just in a couple of seconds in terms of what happens with the envelope but we'll also keep in mind very carefully when we get to the systems perspective of this that there really are right and wrong situations to talk about applying humidification and dehumidification to a lot of these buildings. When we're looking at this in terms of just natural air movement and moisture movement through the structure it's relatively low especially when we start looking back at what the earlier examples were. These aren't necessarily tight structures in the term of not letting anything through but they are very heavy and what does come through when we're talking about air exchange when we're talking about moisture and heat transfer is that they will equilibrate to the exterior condition eventually but that process is often quite slow and that's why in a lot of these structures we'll notice that in the summertime on a hot day the interior buildings like this often times stays quite cool and if you've maintained the building properly and let it run to its original intent often times we'll find that air conditioning really isn't necessary especially from the human comfort perspective getting into collections is a slightly different ball game. So when we look at all of these envelopes and when we look at all these structures where does the moisture come from? Do we pour it down the chimney? Do we let it come in through the front door every time we open it up? Actually I'm joking but the answer to both of those is yes but as we go through there are a lot of different ways that moisture gets into structures that we really want to talk about and understand so that as you're going through and doing your own assessment on your building or working with someone to assess your building you understand where those risk potentials are and what it is that you have to learn how to mitigate or learn how to strategize in order to manage the way that moisture comes through the structure itself. As I said before when we look at those historic building envelopes these were truly designed to breathe. They were meant to allow some degree of moisture to move in and out of the building. They were designed to allow some degree of air flow in and out of the building. When we start to change these over and renovate these and in effect when we trap that air moisture either on the inside or the outside the inside is really the more critical part of this. What we wind up doing oftentimes is damaging the envelope. These envelopes I don't have a good diagram in here because of creative commons issues or in terms of permissions issues but I apparently need to create one myself. When we're talking about envelopes we want to think of these as basically a sandwich with multiple layers and one of the great things about historic envelopes is each of those layers was designed with the intent of allowing either moisture or temperature through and sometimes depending on the layer both. But as we go through and we start to seal those up there's a danger that if you seal it in the wrong location that you can trap especially moisture into the wrong part of a wall cavity or into the wrong part of a building envelope where now once that moisture is contained there without any means of escaping or evaporating to a different location we run into some real serious problems especially with temperature changes looking at condensation issues high relative humidity there are a lot of buildings where we've gone if you think about historic structures that have been resided especially in today's day and age of vinyl siting would help me. When we look at if you will renovated structures along those lines oftentimes you're blocking that vapor transfer and when there's moisture inside of the building looking to diffuse or work its way out of the building if it hits that impermeable portion of the envelope and can't get through all of a sudden you're looking at situations with high relative humidity in that micro environment potentially condensation and the next thing you know unfortunately and sadly for a lot of these buildings is you wind up with issues of mold growth inside of wall cavities you wind up with issues of mold growth underneath an exterior sheathing layer oftentimes that is just due to poor planning in terms of how it is that the psychometrics of the building actually function and as I said there below keep in mind that if your structure is part of your collection then it really does limit our options for what we can do in terms of moisture management and we have to think about site activities and how it is that we can mitigate rather than oftentimes going with mechanical solutions and upgrades so for moisture gain and loss is we're going through that building envelope and thinking about how it is that moisture moves across the structure we recognize that part of our issue is simply just the moisture that is contained in the air right what it is that's surrounding our buildings at all time all at all times whether it's the winter months or whether it's summer months or a dry season or a wet season depending on where we are we recognize that rain plays a huge part in this for anyone who's ever had a roof leak you know exactly what I'm talking about issues of condensation thinking about not just condensation with what is going on with daily temperatures and moisture contents but also thinking about condensation on the interior of your structure the classic example is anytime you take a shower in a cold month and you notice condensation forming on a bathroom window that's the classic example of where does that moisture go if you're not careful if you're lucky it gets evaporated back into the air in the building if you're not that condensation runs down the window into the sash into the sill and then down into your wall and can really create some problems over time surface water and runoff and thinking about how it is that we are going to deal with water on the exterior of the building and this includes drainage, gutters downspouts from the roof and then also thinking about groundwater what is the height of the water table in the area where you're living a lot of places that don't have basements the biggest reason is because their groundwater level is so high that the instant you start going sub grade you're actually digging into water really quickly so instead of having to pump out a basement we'll just build on a slab instead so thinking about those groundwater issues as well and if you do have a basement or any sort of sub grade construction how it is that you contend with that how it is that you can mitigate it or if you will evacuate that water over time moisture movement in and out of buildings from their perspective really is moving via two different media the first one that we're going to talk about here is the concept of vapor diffusion and basically what that is is it's the movement of moisture of water molecules through a media in this case we're talking about the envelope or the walls of the building from an area of high vapor pressure to an area of low vapor pressure so for these purposes this is not a completely accurate representation but it works for what we're talking about for these purposes think about vapor pressure in terms primarily of relative humidity generally what's going to happen first of all is that moisture vapor likes to equilibrate in other words if we have an area with a lot of moisture that is connected in some way to an area without very much moisture it's going to want to go from point A to point B from the area of high concentration to the area of low concentration and if we think about that in terms of relative humidities if we think about the fact that outdoors in the summertime we might have a high relative humidity of 65, 70%, 80% depending on where we're at and inside of a building if we have either let's say looking at some form of mechanical intervention with dehumification or if we just haven't equalized with the exterior moisture contents yet we're going to see with a lower relative humidity inside we're going to see that water want to go from outside to inside and this process of diffusion it's not coming through the open door it's not coming through the window it's actually soaking into the structure itself and moving through the structure through the media from the exterior surface to the interior surface and for a lot of us that are listening in and talking about this today this really is a seasonal pattern typically for us moisture will move into a building in the summertime and out in the wintertime that's not always going to hold true there are certainly some exceptions we have to watch those shoulder seasons and for folks that are dealing with again, hot and humid climates really it's not a matter of ever going out most of the time moisture is almost always coming in so it's thinking about okay, how big of a surface are we dealing with and how much moisture is going to come through the wall so we've got diffusion on one hand and when we think about measuring diffusion this is just to get you into some of the technical terms that if you're starting to work with building contractors or starting to work with your facilities colleagues within your organization one of the things to keep in mind is that we're talking about permeance and basically in the U.S. a perm is the amount of water vapor that will move through the structure end of the particular rate so a perm in the United States is one grain of water vapor we're not going to get into defining grains versus the difference between humidity ratio and dew point today the quantity of water going through a square foot of media per dependent upon the pressure of the entire system so that permeance is basically how well the material is rated to keep water out one U.S. perm is equal there to the conversion for metric perms for anybody who's joining us from Europe just as a heads up and when we're talking about the total permeance of an envelope basically what you're doing is you're adding up the perm ratings of all the different construction materials that live within the envelope so if we're looking at historic envelopes we're looking at the permeance of the brick layer whatever so we say cellulose based insulation maybe in the building if we have a lathe and plaster structure on the interior wall and finally a paint layer every one of those has a permeance rating that you can actually look up and that will give you an idea of how quickly moisture is going to move through the structure when we're looking at modern envelopes in shall we say a newly renovated or more modern building we get a whole lot of different layers that also start to play into this we have an exterior layer that might be wood siding or vinyl siding or brick or masonry depending on the type of building we usually get behind that some type of a vapor barrier or vapor layer whether it's a Tyvek house wrap which isn't a true vapor barrier but it is a vapor retarder we can look at insulation whether that's rigid foam insulation or foil backing that foil backing has an excellent permeance rating so as we're going through this we start to again add up all of those different surfaces that the moisture has to get through and we get a feel for how quickly moisture is going to move in and out of your particular structure and the thing to keep in mind is that when we're looking at those different construction materials thanks John Luke thanks for pointing that out Canada is metric also through those different perm numbers the thing to keep in mind is that the lower the number the better we're really looking for numbers that as low as we can get indicates that that is a very slow moisture movement through the structure as we start to get into higher numbers you get the feeling really quickly that there's not a lot there to block or to buffer the movement of moisture through the envelope itself again in modern we really want those little permeance numbers so that the diffusion process as we have moisture moving through an envelope right I'm sure we've all seen this in one case or another wherever we are but we get this evidence of as that moisture moves through the structure what it's doing is it's actually picking up salts and picking up minerals along the surface of the structure and that's where we're going to get that moisture to move through the structure and that's where we're going to pick up salts and picking up minerals along the way and once that vapor gets to the other side of the structure and evaporates it leaves that salt or that mineral behind and a couple of things can happen that in particular is efflorescence so that image there at the lower left is basically salts that are left behind as the moisture moves through the brick masonry evaporates at the surface but leaves that salt behind you'll see that efflorescence on the exterior buildings you'll also see evidence of efflorescence on the interior building as we go through oftentimes and this happens quite a bit especially when we're looking at really two examples come to mind in basements for one example where oftentimes the vapor pressure when we're looking at the surrounding soil is much greater than the vapor pressure in the basement itself as the moisture comes through that wall any paint layer obviously will typically pop up you'll get a lot of left behind salts and efflorescence on the interior wall this also happens an awful lot above grade for anybody who does have a mechanized structure mechanical system that is dehumidifying as we dehumidify and remove moisture that lowers the vapor pressure on the interior of the building and really just increases the rate at which moisture comes through the envelope if you don't have any other sort of vapor barrier in place these are the two most common ones that we'll see efflorescence on the exterior buildings oftentimes is associated either with humidification if you do have the ability to humidify within a particular building environment but it oftentimes also shows up a lot as a symptom of a leak issue or of a water drainage issue that photo in the lower left is actually poor drainage where that downspout that you see coming down off the side of the building the top where the drain was was actually blocked and as the water came in it would pool right there along the top of the building and seep its way down into the wall and that's the efflorescence that you see as a result spalling, cracking also happens as a result especially with masonry surfaces as that moisture comes through it can weaken the exterior surface of the material that we're working with so you will see sandstone in particular is particularly susceptible in my experience but as that physical structure is weakened because of the movement of the water you'll start to see sheets or flaking of that external structure begin to fall off as the moisture moves through and understanding the other part of thinking about this is we're looking at how moisture moves into or out of buildings depending on the case is when we're thinking about the concept of air leakage and this is really one that I want to be careful with because it's very easy to get these conflated over time basically what it comes down to is air that enters the building can certainly bring moisture with it and from the perspective of interior environmental control we're thinking about limiting air movement in and out of a building so making sure as we're going through and recognizing that this is oftentimes one of the things we'll go through and seal windows, we'll seal doors add weather stripping, gaskets and seals to different exterior entrances this particular example is an overhead door on a loading bay that there's an air gap in place so when we're looking at that those are obvious places for air to move in and out of depending on whether or not the pressurization of the interior is positive or negative to the exterior air pressure one thing that is obviously problematic is that if we have air pressure going in the wrong direction and outdoor air is automatically coming in to a negatively pressurized interior it brings a lot of moisture with it very very quickly regardless of whether it is going to be a summer situation where we're dealing with too much moisture for the interior environment we're also for a lot of places for a dry season or a dry season situation where we have a very low outdoor moisture content and that negative air pressure coming into a building brings the lack of moisture along with it and eventually will dry out the structure faster than what you're looking for when we're thinking about preservation needs but the one thing to keep in mind is even though we can combat pressurization or at least air pressurization by looking at system control by thinking about some ventilation and at least purposefully bringing air from different locations air pressure alone does not defeat the physics of vapor pressure and diffusion so what it comes down to is that air and moisture do equilibrate differently or if a better way of putting it is independently of one another so when we're looking at air pressurization even though we're blowing air out of the building and this is something where from an engineering perspective we often have made mistakes in the past sadly but we'll think that positive pressurization on a building is enough to keep the moisture from coming in the recognition is even though you have pressurized the building and the air is pushing out if there is a low vapor pressure inside the building moisture will still come in against the flow of air not only through diffusion on the surface but also even against airflow when we're talking about leakage so always remember that if you're working with professional colleagues and engineering and architecture to make sure that as they're explaining to you how it is that they're going to combat air movements in and out of the building or at least control air movement inside of the building and how they're thinking about vapor movement in and out of the building they are addressing both of those separately and not simply describing the control of vapor or the control of vapor movement as a function of air pressure the two truly are separate points additional places or areas to just keep in mind in terms of where moisture comes in and I think we've probably all experienced these in one way or another seepage, subgrade, basement walls coming up through the floor and basements there are a lot of circumstances where for whatever reason we have decided to a lot of places have built on filled land that were initially wetlands or were initially in some cases even a lake or a reservoir if we want to talk about Manhattan there are a lot of instances where we do have underground streams or aquifers or springs that may be below institutions or below certain buildings within an institution so keep in mind the amount of moisture that comes up through even in my own home I have to run a dehumidifier in the basement because of groundwater when we're looking at water that is coming down off of a roof and drainage thinking about gutters and downspouts drainage issues not just up at the roof in terms of whether or not that gutter that downspout works but as that water is evacuated down the building you need to make sure it makes it out away from the building and not just let it drain right against the foundation of the structure again thinking about groundwater and underground streams one of the ones that comes up quite often and this is just something to keep in mind is when you're looking at building plantings and landscaping this is really a balancing act it's one of those things that we oftentimes encourage folks to do because it can take some of the load off of the building and can help mitigate some of those changes but vegetation in particular will also hold moisture in close to a structure and really inhibits the amount of drying that we can experience so be aware of that leaks at the perimeter through the roof the walls and windows and especially porous exterior walls keeping in mind as walls become damaged if we have evidence of spalling over time or cracking that really is just going to increase the rate at which moisture can move in and out of the structure and again when you're looking at repairs for that it's not about sealing necessarily as it is thinking about what is the correct repair for the historic integrity of that building and getting that original envelope back to its original operating capacity you know just a few examples of these you know water stain carpet in a basement looking at seepage and rising damp drainage issues this is the one that I had mentioned a few minutes ago coming down off the side of a building there's a downspout off of a gutter at the rooftop that doesn't move away from the building at all it just dumps right down in against the structure in this particular case and while that one isn't my image there are a lot of examples of these where you notice that when that happens and the moisture comes right against the foundation if you look about five or six feet away on either side of that all of a sudden you notice the symptoms of rising damp and some of the signs of diffusion is the moisture is wicked back up through the building so this it really does come into play and it has multiple implications as we're looking at that moving water away from the building is critical making sure that those gutters and downspouts do move away from the structure oftentimes is by as much as 10 feet if you can move it further away that's even better especially given the drainage that you might have on site certainly do keep in mind and watch for any perimeter leaks especially sub grade this is one that comes up quite a bit not always within historic construction but as people are making renovations and shall we say what they think are improvements to historic structures they'll go through some landscaping processes and all of a sudden you realize that the exterior ground is actually sloped in the wrong direction that when you're looking at ground level you're encouraging water to move back against the foundation instead of making sure that you're sloping away from the building structure in the direction again trimming vegetation especially not just shall we say low plantings or low landscaping but even looking at trees keeping in mind not just how close the tree is coming to the building and whether or not it's holding or retaining moisture in place but also thinking about the concept that we really do need as much air flow if we don't have sun exposure on a north wall again at least for the northern hemisphere if we don't have sun exposure we really do need as much water to be able to allow moisture to evaporate in that area of the building and this is one thing that trees often times will unfortunately work against us in that regard it's part of the reason why we talk about always seeing most of our biological growth on the exterior buildings on the north side of structures at least as well as long as we're north of the equator understanding the building sites this is a top down view of a particular site in Maine and when we're looking at it again think about and this is with the advent of Google Earth and other tools as such it's a really nice way to look at your overall site and think about where it is that moisture is draining and running not just in terms of looking at ground levels surrounding the building itself but also looking at in terms of if you have a drainage situation where you can't evacuate it away from the building on one particular side let's say for aesthetic purposes or because of a patio keep in mind what your options might be in terms of even routing it by a pipe underneath the building or in some other direction away from the building to evacuate it not right against the building structure itself and again making sure that we are directing drainage lines whether from primary roofs or secondary roofs into lines that go out into the surrounding area rather than directly against the foundation when we're looking at those historic structures and thinking about what the moisture content is inside you know this is just a good example this is a non-mechanized structure no moisture control at all notice that the red plot in this case I'll bring that arrow back up here that the red plot there's a lot of fluctuation not only daily but through this but through the entire season where the outdoors is really showing the extreme and what we're looking at from moisture content and moisture availability in the environment but when we look at the interior of the building and talking about that historic envelope it certainly does, it certainly is influenced by what's going on outdoors but in a lot of cases what's happening inside is significantly muted against what's happening inside notice how the blue plot in this particular case which is the interior room never feels the full movement or fluctuation of what's happening outside so in these cases as we're looking at the interior environments this is the influence of the envelope there's no mechanics at work here this is really just what those walls look like in the roof as well in terms of mitigating moisture flow in and out of that structure give it enough time and eventually especially as things start to get a little damper the interior does catch up but oftentimes, here's an example over here where we get some bad exterior examples or some bad exterior conditions and the interior really never quite hits that extreme so think about especially if you are working with a building that doesn't have any mechanical intervention looking at environmental data logging on the interior structure and then comparing that against what's going on outdoors it may give you a really good idea for what it is that you're capable of doing from a buffering perspective and also thinking about whether or not you can make some of those corrections concerning moisture runoff roof issues thinking about mitigating groundwater how it is that you can actually go about trying to move some of that moisture away from the building itself choosing appropriate repairs we've talked about this a little bit and meeting the historic integrity of the structure again, not just for historic preservation purposes but for the actual functionality of the envelope itself so just a few examples here for anybody who is looking at it the key part is we're talking about making sure that we are repairing historic envelopes appropriately is making sure that you work with experts there are people out here and I'm not a historic preservationist by any means those of you who know me know that I work primarily with the mechanical world but when we're talking about historic preservation and historic structures make sure that you're consulting the people who work with these envelopes every day they understand what the original design intent was they understand what the original construction was and can oftentimes help you choose the right materials or the right repairs to make that will bring that building back to its original functionality or its original operation and again, this is especially critical to remember if your building is part of your collection and I'll add a little note here that's not on the slide but just something that folks should keep in mind inside of the historic structure is not always the best place to preserve the rest of the collection we get a lot of discussion about that not just in terms of standards and in terms of thinking about how it is that we're working with different organizations and institutions but there is this oftentimes limitation that people experience or that they're concerned about I have to preserve my collection inside of my historic building there will always be limitations sometimes you can create box and box construction on the inside of an historic structure that will provide for a controlled environment for preservation purposes sometimes it's better to look at some sort of an exterior solution even if it's just looking at the construction of a small box elsewhere on site that is on the outside going to be period appropriate but on the inside is your box and box construction that serves as your overall collection storage rather than relying on the historic envelope to provide your preservation environment that you want for the rest of the collection oftentimes it's very good to separate those two different missions keep in mind that when we're looking at building closure that has a lot of impact especially if there are not people moving in and out one of the things to watch for when you are closing down places will do this and not really just thinking about weekend closures but more specifically looking at seasonal closures a lot of organizations especially here in the northeast will close down during the winter months or have very limited occupancy in the winter months always keep an eye come spring what it is that's happening in terms of temperature and moisture contents in the spring and the fall because as we're looking at structures that have naturally cooled or stayed cool and have allowed moisture to seep up through the structure all season long we usually do run into problems with mold growth in a lot of these and it's just a word of warning that we don't want to have a situation like this where notice that our absolute worst relative humidity conditions are right here kind of in the end of mid to end of winter moving on into the beginning of winter over here in this particular setting the summer isn't great as it is but the absolute threats really do come from these conditions so disaster response and thinking about non impartially mechanized buildings and I realize we're getting a little bit low on time here so I do apologize I will say that as I go through this I'm happy to stay a little bit late to answer a few questions for anybody would like to stick around just as long as that's okay with you but let me go through this real quick and we can hopefully get to a few questions so as we're talking about disaster response especially with non mechanized structures at the end of the day that original construction is our friend we really want to think about breathability and it's very much about ventilation the first key in any disaster setting is to make sure that the structure itself has enough integrity that A it's safe to work within and that B you can actually begin to go in and if you will manage for the interior environment so I absolutely follow the direction of whatever emergency crew or whatever emergency personnel you're working with obviously do not enter a building until it has been declared safe by authorities but when we're looking at those historic structures or non mechanized buildings this is not necessarily ironic but I think it's a good lesson for those of us who are sort of attuned to a more mechanized world to keep in mind and that's looking at it and thinking realizing historic structures oftentimes make it through from an interior environmental perspective make it through disaster situations much better than modern buildings because they have the natural architecture and the natural ability to let the space breathe and to allow for air and vapor flow one of the biggest problems that we run into especially in modern construction is that if we lose power or for some reason we lose capacity to mechanically move air in and out of a particular space and now that space is just sitting there and moisture is slowly diffusing into that environment over time that's really beginning to rise we oftentimes have no built-in means for natural ventilation without electricity, without power so in a lot of circumstances and this applies to recent things that we've seen in Puerto Rico recent problems that we've had in Florida some of these structures that have been without power have sustained damage to the building systems in a modern setting oftentimes those spaces did not actually make it through the storm as well as some of these historic structures in terms of the period after the storm itself because we had no way to evacuate the moisture we had no way to provide ventilation without power and what happened was just the unfortunate circumstance of a true micro environment inside of a building where moisture was able to make it into the space temperature was able to continue rising in accord with the outdoor temperature and mold growth occurred because we had no means of combating it either by moving vapor out or by allowing for ventilation in order to retard or restrict mold growth over time so we'll talk about a few different strategies for how we can achieve natural ventilation especially in historic structures I'm going to touch on this again when we get to the mechanized portion of this next month because actually as I've been looking at this more and more in particular last fall in the spring it's making me realize that there might be some aspects of design that we would want to consider in the future even for modern buildings or buildings that we've renovated to use mechanical systems I think I'm starting to change my own outlook on how it is that we should look at those designs so moving into this first of all where's the moisture source is it coming from the roof it's coming from groundwater this particular image is looking at a ground floor level wall in an historic structure in San Juan, Puerto Rico and if you notice the thermal image over on the right I'll pull the pointer up here again there you go so we've got warmer temperatures here in this area of the wall that appears to be registering as a cooler temperature by almost 5 degrees C this actually that temperature difference that the thermal camera is picking up isn't solely temperature this is actually the influence of moisture coming up through the wall into the structure and we see evidence of past diffusion over here and efflorescence on the side of the wall where evaporation has occurred and a little bit over here on this side and as we look at it through the thermal image we can see that there's active moisture still in this wall so this is one option in terms of looking at tools when we're talking about especially historic structures and figuring out where the moisture is coming from this along with the moisture meter can be some of the tools in your arsenal to figure out is the moisture coming from below are we worried about groundwater content or is this a case where we have a steady roof leak every time we have a rain pattern or any sort of precipitation event we still get we're reloading that leak in the roof and having moisture come through the structure itself so constant sources this is just keep in mind right constant sources of moisture in an enclosed space where the moisture can evaporate and escape welcome to micro environments and mold so this is what we're trying to avoid now the slides that I'm going to get into here we're going to talk about ventilation for a minute I've been posed this question a number of times over the last six or eight months and one of the things that I want everybody to keep in mind at least as far as I'm aware of the science right now so my awareness nobody actually knows exactly how much airflow and ventilation we need to keep mold from germinating in an environment that would otherwise eventually lead to mold growth but what we all accept from a science perspective is that ventilation and airflow does inhibit germination or germination of mold over time so this is one of the circumstances where if you're going to ask how much airflow do I need my response is sadly it's a good question and usually they're usually the kind of off the cuff answer is as much as we can get the idea is that we want to be able to circulate and move moisture in and out of the building we don't want it to sit in any particular pocket or micro environment and we do recognize that agitation airflow over surfaces again without being able to quantify we do understand that that does slow the rate of germination for mold so if it's a case where we're looking at 75 or 80% relative humidity and warm temperatures that we know will eventually cause germination hopefully ventilation and airflow can help stave that off for a little bit until we can come up with a different solution so there are three different forms of passive ventilation that we want to talk about and looking at these in mind that there are various impacts on these including wind direction pressure and temperature but generally when we're talking about passive strategies for ventilation we're looking at it in one of three shapes if you will one is single sided ventilation when we only have one exterior surface available in the building that we're looking at and this is actually quite common I'll use San Juan again as the example where we have row construction with different buildings that are butted up against one another the oftentimes of the if you will four sides of a typical building three of those will be shared with another structure and you only actually have one front that is exposed in the case oftentimes of historic architecture in San Juan we do have the I think the best way to put it is the advantage of the original courtyard construction that does give us additional exterior surfaces to work with so that is something to keep in mind anyway when we're looking at single sided ventilation what is your exterior surface and if you only have one to work with then you're going to be trying to figure out how it is that we can induce natural ventilation through one exterior surface cross ventilation is when we have multiple exterior surfaces we'll talk about that a little bit more but most of the time it's air moving either across a room or across an entire building depending on construction and finally looking at stacked ventilation this is using that natural tendency of cool air which is denser than warm air to sink down warm air exits out the top by event this is something that happens quite a bit in a lot of different forms of construction and something that we can very easily use to our advantage for a lot of historic structures single sided ventilation I apologize for the limited graphic here I promise that if you tune back into this in the future I will do my best to draw my own diagram for what's going on in this particular process but this is really one of the most difficult things to pull off because you are fairly limited the idea of single sided ventilation basically says that we need openings for venting both high and low on a particular wall and the easiest way to achieve that is when we're looking at a double hung window if we have that already in place then life is fairly simple you open the bottom pane just enough to allow some ventilation through the bottom cool air is able to come in settle to the lower portion of the floor and if we open the top top pane of the window and allow that warm air to escape out that top side we have just enough inducement therefore for air to move through via just natural convection so in that regard that's a very easy way of looking at it one thing that doesn't work and this is unfortunately just the realistic truth is a single wall with two windows at the same height that open at the same height when you do that you're bringing in air at the exact same level and you're not able to encourage if you will the less dense air to evacuate the space almost always if you're looking at two doors on one exterior wall or two windows of the same height on an exterior wall without this double hung configuration you have to look at some method of being able to induce that ventilation or power that ventilation and some other means via a fan on one side or the other to create positive or negative pressure or some other aspect some structures that I've worked in before and that I've talked with people about we've actually discussed the concept of in situations where the threat is bad enough especially looking at biological risk of actually opening up an additional hole higher up on that wall in order to allow or induce natural ventilation if it's the difference between putting a hole in the wall of the structure temporarily mold inside of the room for which you have no ventilation a lot of us I think would choose the let's put a temporary hole in the top of the room up at the higher part of the wall and let the air flow through the space so something to keep in mind in that regard this is a tricky one to pull off cross ventilation is a lot easier generally a lot of buildings were naturally designed with this for this when we look at historic architecture so up at the top there you see a diagram of just what we would consider a single wide space window on each side and depending on what the air flow is and where pressurization is we're going to move from the direction of positive pressure on one side of the building to negative pressure on the other side of the building and if you will it's that natural cross breeze that we like to experience that's the difference between being in a room with two windows open at either end or that previous example living in the efficiency apartment in Washington DC in the summertime with only one window and realizing it's pretty well stocked because a breeze is not existent for buildings that are kind of two rooms wide or looking at other circumstances looking at those transoms across the top of windows on the interior doors those were there for the historic purpose of allowing cross ventilation and allowing air flow if you're in a structure where those have been painted over for some reason or otherwise sealed up and you're in an area that is prone to power outages or prone to disaster situations I might suggest actually bringing those back to their original capacity and their original functionality cutting through that paint layer working on those hinges a little bit and making sure that when the time comes you're able to use those for that natural ventilation if required finally going through here looking at the last example stack ventilation the concept is really that we are bringing in the cooler more dense air at the lower portion of a building or at the lower level of a building and allowing that to displace the warm air up through the top of the building this can take place either up through a multi-level building up out of shall we say a roof vent or a chimney vent up through the upper structure this is also by the way the same concept with which you would have fireplaces in cabins you would have air that came in and would allow the warm air to be displaced up through the chimney in these cases more often than not where you'll experience it in common everyday construction is looking at soft vents on buildings and then looking at ridge vents along the roof and the idea of that the physics in that particular case is that it allows air to move from the lower soft vent up through the ridge vent and circulate air within that attic structure of a particular building but we do see this quite a bit not only in terms of historic construction being able to utilize it for natural ventilation but stack effect or stack ventilation is also something that we're very aware of from a mechanized perspective as well it's something we have to consider in our historic buildings so moving through and this is just to wrap things up when we're talking about moisture management and control I hope what everyone will remember is that every one of these solutions is truly unique to the institution and unique to the situation the key is that we keep in mind what it is that our external climate is doing what type of building we have and what it is we're working with how it's been intended to use originally but also maybe how changes to it over time have impacted that use do we still have the functionality or the ability for ventilation that we used to have or has that been blocked off because of renovations or insulation or some other factor that's been in the play keep in mind how it is that we use spaces whether or not and what type of preservation we want to expect in interior environments especially in historic structures what the needs of the collection are and not overstating what the preservation requirements are coming back to some of those examples at the front of the talk when it was giving safe ranges for temperature in RH think about what your collection actually requires and whether or not those conditions can be allowed to flex over the course of a year and again finally mechanical capability if you have some what is it can you do just temperature is there moisture control involved or if you're working in a non-mechanized structure then what can we do in terms of looking at buffering, passive control, site management and how it is that we work with moisture in this construction itself and just to wrap it up that's why we talk about management and next week when we get into next month when we get into talking a little bit more about mechanical solutions why we'll get into a little bit more on the control side so for everyone who is able to stick it out thanks a lot for joining us I really appreciate it if you need to get in touch please don't hesitate I'm happy to answer questions anytime like I said is you're going through the evaluation I'm happy to take some questions here but as you're looking at the evaluation do keep in mind that if there are things that I maybe didn't cover that you were looking forward to or hoping that I would write those in as part of the evaluation Jess and I will talk and I will do my best to try and include those in next month's talk for anyone who's registered so with that Jess I will let you take any questions that we may have and I'll do my best to answer those for humans for whoever wants to stick around presentation I'm going to go ahead and mute you real quick just because I think we're having some feedback issues but if anyone did have questions please feel free to drop those in the chat window there there are a few folks asking about the power point there were some questions early on about specific slides the general temperature safe and risk zones just to remind everyone this presentation is recorded and it will be available online so we'll all be receiving a link to that before too many of you I do want to go ahead and pull over this link to evaluate the program as Jeremy mentioned at the end of this evaluation there's a question of anything else we should know so if there's other topics that you would like for him to address in next month's webinar please be sure to drop those in there so we do have one question from Rachel about if you have any suggestions for dealing with sorry I'm going to mingle this in a historic house basement so I'm going to mute you real quick okay I'm back hopefully everybody can hear me Rachel thanks for sending the question and that is a really good one so the question again was any suggestions for thinking about or dealing with efflorescence in a historic house basement there are a couple factors at play here usually Rachel and if you don't mind typing back in I'll just pose the question real quick do you have any air conditioning cooling or dehumidification in the basement right now because that will impact the answer that I give you but one of the first things when we're looking at basement efflorescence when we're thinking about substructure moisture is to think about what is the primary source of that moisture that we're working with so one thing to keep in mind is things that are not necessarily easily dealt with but first places to look go back to drainage looking at how it is that your roof is shedding water making sure that that is directed to gutters that are clean and that are open and that those gutters come via drain or downspout either draining directly to if it's allowable in your area in some cases a storm drain but in many cases just making sure that you move that out away from the building and again by as much as possible is one key factor there now there are some instances where we run into problems if it's not a matter of moisture coming from the roof or roof drainage okay Rachel did write in we do have air conditioning in the attic that flows down through the house so when we're thinking about it in terms of sources of moisture again not just where the roof drains necessarily but when we're talking about groundwater one of the other things that we can do and this is this is a little bit more of this is a little more intensive response depending on how bad the efflorescence is or whether or not you're seeing structural damage in addition to the efflorescence one of the things to keep in mind is that oftentimes depending on soil types we can really suspend or entrain a lot of moisture directly against a subgrade foundation and one of the solutions that is often used in different types of construction is to pull away some of that soil level or some of that earth away from the foundation itself fill in against the foundation with a gravel structure or more of a gravel material that will allow moisture to actually fall out of the substratum before it makes it all the way to the foundation so rather than moisture being entrained against the exterior foundation it can drain through the gravel to below that foundation structure in some cases especially residential will even go so far as sealing the exterior foundation on the building especially where we have not just efflorescence but a lot of groundwater seepage coming into a structure that's oftentimes a little bit extreme and may not simply not be possible depending on the nature of the foundation of the building but those are options to consider from an exterior perspective from an interior perspective one of the things to watch for is just what those conditions are in your basement and what it is that is driving that efflorescence so if there's a way to do environmental data logging in the basement space and understand what the temperature and relative humidity are and recognizing that especially after rain events whether it's just shall we say water from precipitation or whether it's a constant source of groundwater recognizing what the difference between those vapor pressures are going to be interior to the building and exterior and upside and downside if the basement is heated at all and you are lowering the relative humidity in the basement that is going to increase the pressure differential and is going to encourage moisture to come through the wall the problem with keeping a basement cool in the summertime is that oftentimes that does mean high relative humidities and the introduction of a mold risk so there's a balance there in terms of thinking about interior our age conditions and you know letting the basement cool down but dangerous we run into mold perspective or mold possibilities even though we are if you will minimizing the vapor differential but more often than not when we're looking at that exterior moisture can exterior moisture entrance through the building we try to deal with that as much as we can on the exterior level first looking at those ground levels outside making sure that pitching away from the building is appropriate making sure the drainage is appropriate again improving the drainage along the foundation if possible interior solutions often times don't work depending on the structure that you're in I'm sure many folks have run into this before you run into buildings that will say that they will seal the interior of basement walls by and large that is not a viable long-term solution because it doesn't actually keep the moisture from coming into the foundation structure itself it's just a surface application that is actually keeping it from coming through the surface and over the long term you may actually cause more damage to the foundation by not allowing the moisture to move anywhere so be very careful about how it is that you're thinking of it in those terms for some organizations especially if you're using a basement storage some folks have gone the route of building interior walls against the primary foundation wall and creating an air gap within that space so that as the moisture comes in at least the efflorescence is contained and is contained to a space where the moisture can come into sort of an interstitial space and that built-in wall may serve as both your thermal and vapor barrier in some cases but again for your local area I would consider consulting carefully with the construction expert or historic preservation expert for that area again all of this is very determined or is very much determined by what outdoor climate conditions are and how your seasons behave so I hope that is at least a little bit of information but that's a start anyway I'm sorry I can't go further into that Jess was there another question or anyone else that had written it? Yes there were a couple of other questions that came in I think we might have time for just one more and that's unfortunately because I have to duck off and join another call but so Jeannie was wondering what's the best way to care for collections of tropical climates when you don't have air conditioning Puerto Rico type climate is air circulation the best one can do and there's the magic question Jeannie it's a really good question and it's one that I think we're all still struggling with a little bit because unfortunately the answers that we have are not entirely satisfactory and I'm of a couple of different minds about this and I really truly do believe in managing your expectations first and foremost I always approach preservation in hot and humid climates as my first goal is to inhibit or control mold growth and my second goal is to achieve whatever degree of good preservation again from there and that really varies from institution to institution so the first part of that is absolutely circulation and if you're in an historic structure my response to that is to say depending on what your institutional capacity is do not sacrifice your ability to naturally ventilate or allow for passive ventilation in the effort of creating what we may consider to be a quote unquote good preservation environment I think at that perspective and when we're thinking about it we really have to keep in mind what the greater risks are to the long term of the collection now that being said there are a lot of institutions in Puerto Rico that I've met with and talked with and worked with over time and we can achieve modern mechanized environments in Puerto Rico the same way that we can in the continuous 48 so looking at things along those lines it is possible to do box and box construction within Puerto Rico especially if you have the wherewithal in sort of the institutional capacity whether it's looking at a generator situation to get you through the power outage periods my own opinion on that construction is that I'm still certainly willing to consider that as a good long term solution for some organizations and some institutions again depending on capacity but I think what I've what I'm even starting to kind of adjust my own perspective on this a little bit is that quite often we think about box and box or preservation environments is being tightly not only tightly controlled in terms of maintaining certain ranges of temp and RH but also tight in terms of air flow and I'm actually kind of trying to rethinking my stance a little bit and I'm not sure that there's a right or wrong here but as I'm going through and thinking more about the need for passive ventilation and what are those scenarios where we have no power and even your generator isn't available because of lack of fuel going through that and really saying you know what if you're going to go through that route and look for a mechanized environment in a hot and humid environment build your backup in build your louver dampered opening so that you can achieve natural ventilation through the space so whether that is looking at something that you have an insulated panel that is blocking it maybe 98% of the time for that 2% of the time you take out the insulated panel you open up the louvers and you allow ventilation and airflow to move on through the space and one of those things that we really have to watch for and this is something that we need to learn a little bit more from a research perspective is that there's a really fine balance between how long you keep a space closed up and try to let it kind of maintain that refrigerator effect of if you don't open it materials will equilibrate more slowly and when that tipping point comes that it's time to open it up and accept and allow and encourage natural ventilation so that we don't wind up with with air trapped inside of a micro environment this is I've been like I said I've been doing a lot of thinking about this and I think this is something that we as a profession need to talk about a little bit more and really you know work with colleagues in hot and human environments to try and think about what some of these design considerations especially in the light of disasters and unfortunately sadly weather events that will continue to happen thinking about these of how do we find that balance between mechanized environments if you will you know spaces that are mechanically controlled but how it is that we can revert to a more natural or a more passive ventilation system when we need to you know that's that's not an answer I think it's more of a perspective but that's something that I hope to be thinking about here in the future and I'd love to join and talk with other people about it too great well I just want to jump in here and say thank you again to Jeremy for this wonderful presentation and also for taking a few extra minutes here to address some of the questions I know that there were a couple we didn't get to I will encourage those of you who had unanswered questions to be sure to join us for the next program which is going to be on August 21st correct let me just double check August 21st at the same time so 2 p.m. eastern time and going until 3.30 as well so please do feel free to add any comments for additional topics you'd like addressed in that evaluation link in the final question be sure to get those over to Jeremy I want to thank everyone who joined us for the program today for taking the time to educate yourselves on this important topic and again thank you so much Jeremy for your generosity and sharing your wisdom alright thanks everybody have a great rest of your afternoon I hope you can all join us here again in a month and I'll look forward to talking with you then and certainly go through and add some of these comments that are coming in we will talk about standalone dehumidifiers and industrial dehumidifiers there are right situations and wrong situations to play with those so we'll talk about that a little bit and certainly please do if there are other topics that we can address feel free to write those in even if I can't fit them into next month's webinar I'm sure that there are things that the emergency committee will consider in terms of thinking about future programming so if you include those it gives us something to talk about thanks again so much for joining us and I'll catch you all in a couple of weeks bye