本系列播客节选自为期两天的“建筑科学基础”课程，由建筑科学公司的Joe Lstiburek博士和John Straube博士教授。

上周，乔博士概述了一种观察建筑空气质量的简单方法:人、污染物、路径、压力。本周，他描述了自己的室内空气质量诊断程序:相信你的直觉，跟着你的鼻子走，惩罚年轻人和首席执行官。＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿___________________

一个常见的室内空气质量噩梦:砖砌建筑，天花板下垂

我们有一个吊顶空气处理装置，对吧?你在一个下降的天花板上放两三个空气处理器;补给系统已经完全连通了，但回程系统还没有。你只是把空气从下降的天花板中抽了出来。所以整个下降的压强变成了负压。所以空气被注入，空气被拉进下降的天花板上方的负压场，我们有空气循环。但是这个负压场在屋顶和栏杆的连接处与外部相交。室内的石膏板很少与顶部相连。就算你知道，也不是密封的。有人就往里面塞了一点矿棉。 So whatever is in that exterior wall or parapet is being sucked right out of that exterior wall, into the return system, and ejected out the supply system, into the breathing zone of the occupied space. You’ve actually coupled your building enclosure to the occupant. The parapets are often the fresh-air intake for most buildings. And if it’s hot and humid outside, what kind of air are you bringing in? Hot humid air. And if it hits a cold surface — say a chilled water line — what’s going to happen? It’s going to condense and it’s going to drip.

谨防潮湿空气

机械工程师不考虑湿度负荷。这是一个隐藏的负荷，潜在的负荷，湿度负荷，他没有意识到。你知道，他会知道它在那里。它不是在计算中 - 它在现实世界中，但没有人思考它。这是一个大问题。现在，如果你很幸运（你很少是）你会得到足够的冷凝，它实际上滴过了，所以你实际上可以看到污点。但是，您通常可以获得足够的冷凝来导致湿度升起下降的天花板，但不足以通过材料染色。当湿度上升时，你注意到的是它开始发臭。并且有几种不同的气味。有多少人记得呕吐闻起来的味道？ Well, puke has a distinctive odor, and it’s actually called butyric acid, which comes from the fermentation of starch. Well, butyric acid is emitted from ceiling tiles that are made from cellulose and a starch binder. When the humidity goes above 80 or 85 percent, the butyric acid is emitted, and you have the odor of vomit. So one of the most common things you do when you lose control of the relative humidity because of the coupling of the negative pressure plenum to the outside wall is you get a whiff of vomit.

你的鼻子是一个很好的诊断工具

现在，当我走进一幢大楼，我——[吸气]——我不会让客户知道我在用我的鼻子——我的内置气相色谱仪——来弄清楚到底发生了什么。但如果我闻到丁酸的味道，我知道我已经失去了对相对湿度的控制，我知道那是该死的天花板瓷砖。它就像，你知道的，确凿的证据，如果你曾经闻过它，你现在知道其中的联系，你知道发生了什么。这是第一种独特的气味。它们通常会保持更长时间的湿润，因为那里有没人预料到的水分。你经常会在线圈上长出红色细菌，它散发出约翰袜子的气味。我们不叫它约翰袜子综合症;我们称之为脏袜子综合症。有一种独特的气味，就像一个更衣室。所以你走进去(嗅嗅)，如果你闻到呕吐物的味道，或者闻到脏袜子的味道，你会立刻集中注意力在什么? Dropped ceiling return plenum negative pressures coupled to the exterior wall. So you smell mold, or musty odor, you smell vomit, or you smell a dirty sock, and those are distinctive. I mean they’re not there all of the time, but eight out of ten times — you’ve pretty much got it sourced out that you’ve basically coupled your return plenum to the exterior wall. Remember, I’m talking as an engineer; I’m not talking to you as a scientist or a physicist. I’m just telling you my experience has taught me when I walk into a building and I’m thinking what? People, pollutant, path, pressure, hot wet, UV, ozone — this relationship is true. This is so common I don’t go to the projects anymore. Or I don’t want to go. I’m bored, I’m tired. I send the youngsters in the office. But they don’t want to go either cause they’re bored too. And so, you know, the client gets all annoyed because John or I get the work, but we don’t go out there. They get all pissed off they say, “We hired the great Oz and they sent us Toto.” So sometimes I have to go and so I take a youngster with me to abuse them.

你的眼睛和直觉可以告诉你关于一座建筑的很多信息

我们接到电话就走，我不想在停车场下车。我没必要在停车场下车。我当时和柯塔在一起，他说:“乔，你得下车，下车，快下车。”“我不下车!”我不需要从那该死的车里出来!这是愚蠢的!看!”柯塔说"什么，什么，什么?“你不需要下车!”我有砖块，所以我有什么?储层包覆。我不需要在墙上开个洞就知道我得到了什么? Mortar droppings. You know that it’s steel studs cause they’re all friggin’ steel studs. You know that they’re Dens-Glass Gold cause they’re all friggin’ Dens-Glass Gold. You know that they all have Tyvek and if they don’t they have tar paper. You know they’ve got friggin’ fiberglass in the wall cavity and it’s a fifty-fifty chance that I’ve got a plastic vapor barrier or vinyl wallpaper on the inside. Now, what kind of a mechanical system do I have? Nine times out of ten I’m going to have what? Dropped ceiling return plenum. So before I get out of the darn car, out of the parking lot, I have a nine out of ten certainty that whatever’s in that wall is not going to be good, and is in the breathing zone of the occupied space. But they’re paying me, and so I have to get my fat ass out of the car, and go in. So I’m not happy about it. So the first thing you do is you pop the ceiling tile, but you do it in the corner office to piss off the CEO who made you go there. And what do you see? There’s no connection between the gypsum board and the underside of the roof. You can actually see the exposed fiberglass, right? We knew that! And it’s dusty. Why is it dusty? You’re pulling the air through it. So we’re just actually sucking on it. You know? Because I knew it was a problem, because after it rains, three or four days later we always get this musty odor. You know? So, “Well, OK, we’ll send somebody out.” “We want you!!” “Well, OK.”

首先，密封空白

所以我走了，我下车了，我笑了。那么我们该如何解决这个问题呢?好吧，我们把石膏板放到下面，现在我们试着通过喷PVA(聚醋酸乙烯酯)和一些pookie来建立积极的连接。但我们要的是不会烧坏的便便。要找到不烧着的小屁孩可不容易。所以你要用一些东西，比如FireDam从3米开始，导致它是一个不会燃烧的pookie。

然后，均衡压力

我们做完了吗?不。那我们该怎么办?我们在空气处理器上加了一个回风管道。这是工程师们不知道的。它不是很大，它非常非常短。它只需要附着在单元上，然后直接穿过天花板。你明白我的意思吗?那我从哪开始不吸了?我不是在吸天花板，我是在吸空间。 So then I take every fifteenth tile and I throw it away, and I put in a grille. And what’s the function of the grille? Well, to equalize the pressure. I don’t want to suck on the wall any more, so I’m bleeding the negative pressure field. I’m bleeding it two ways: One, I’m putting a return duct on it, and two, I’m perforating the ceiling. Well, why won’t the return duct itself work? Well, because you know the air duct, the air handler, and all of the pieces are going to leak no matter how good you are. And you don’t know where that leakage is going to be — on the return or the supply side. You just know what? It’s going to leak, and so by perforating it, it means you’re going to equalize the pressure regardless of what’s going on. Because what you’ve done is you’ve put that thing in the middle of the room. If you put it in the middle of the room, from a pressure-field perspective it’s doing only what we wanted it to do in the first place, which is to circulate the air without causing a pressure difference. So that’s it! So, you disconnect, you fill the hole, you bleed the pressure field, and you’re done.

如果你只是填补空白呢?

如果我刚刚运行石膏板来制作连接，我没有做任何其他事情，那么会出现问题吗？答案是：这取决于我在天花板和石膏板之间做出的连接有多好。这是非常非常困难的。所以我们仍然有被拉出墙壁的东西。我们只是不会被拔出墙壁。好吧，现在它成为一个稀释问题。什么是去除通风率，与我们吸入它的速度？这不可能确定，除非你现在做什么？措施。但测量并不容易。 What are you measuring for? See, do you measure the tiny particles? Or the medium-sized particles, or the big-sized particles? And are they viable, or non-viable? Well then, you have to plant them, and grow them, and nurture them like a farmer, you know? And depending on what relative temperature you incubate them at, is going to determine what you get. Anyway there’s about forty-two different combinations that you’d have to do for each sample. At that point it’s more difficult to figure out what’s going on with sampling than to just say, screw it! I should just take the ceiling tile out, and put in the return and bleed the pressure — because the cost of the diagnosis is going to be more expensive than the repair, you know? The big decision should be: is my wall getting wet and soggy, and should I intervene and fix that? And more often than not, we don’t get a shot at that. Why? Well, I’ll talk to you about the politics. Who called me into the space? It was usually the tenant, not the landlord. So I’m fixing what I can within the tenant’s control.

在你解决了湿气问题后，发霉是一个问题吗?

在湿润建筑物的乙烯基壁纸后面是我们经常找到可怕的黑色模具。所以？那么吓坏了什么？这不是 - 哪里？里面！我可以把它留在吗？是的！那么，将它留在那里的后果是什么？嗯，取决于水分的进来程度。在某些时候，石膏板可能会得到 - 什么？柔软的。 And so you’re going to have to intervene in the places where you have an actual breakdown of the product. That’s not usually everywhere. It’s usually on the south and west exposures. You only rip it out if you have access to — what? OPM — other people’s money. And so if you have access to money, the conservative, safe bet is to do what? Rip it out, because the world is filled with stupid people that think it’s dangerous. If it’s not coming out of the wall, I don’t care. If I have access to money, I’m going to take it out because someone’s going to think it’s going to affect the real-estate value. You know what? That in itself is a justification to take it out. If you have access to what? Money. But if you don’t have access to money, leave it there. We get all kinds of people who have moldy crawl spaces . And they’re poor. They don’t have twenty thousand dollars to decontaminate a friggin’ crawl space. Which we scare them about — “you’re all gonna die!” Well, you friggin’ close the crawl space vents, put in a hundred-dollar exhaust fan, or radon fan, and suck on it and the air moves in the other direction. What have we done? We’ve left the mold in place. Big friggin’ deal. But that’s not a popular view, because there’s an awful lot of money available to do — what? Mold remediation, and scare people. Now, what do I do? Well, at the end of the day, you have to solve what? The mold problem. You solve it by solving the water problem that caused the mold problem. What you should probably do is take the vinyl wallpaper off. Now what happens is, when you take it off you have to be careful, because what’s going to be behind it? Mold. And one of the ways you should deal with mold is deal with it like you deal with drywall dust, right? Because if you rip it off, that’s when you trash the rest of the building! Right? So you ought not to have it spread around. So if you’re going to take it off, you may as well hire someone to take it off correctly. But you only do that if you have access to people who can actually pay for it. Otherwise you’re going to do what? Leave it alone. So, a pretty fundamental example of people, pollutant, path, pressure.