60. 负载计算速成课程

《ASHRAE期刊》为您呈现

ASHRAE Journal presents

您好，

Hello, and

欢迎收听本期《ASHRAE期刊》播客。

welcome to this episode of ASHRAE Journal podcast.

今天由我，马特·普赖斯，担任主持人。

I am your host today, Matt Price.

感谢您的收听。

Thank you for joining us.

今天我邀请到了内森·凯格尔。

I'm joined by Nathan Kegel.

我和内森在东田纳西州CTTC担任主席期间已经认识好几年了。

Nathan and I have known each other for several years as CTTC chair in East Tennessee.

内森是我最早邀请来参加分会活动的演讲者之一。

Nathan was one of the first speakers I brought on for chapter meetings.

这么多年下来，他依然是我们邀请过的最顶尖的嘉宾之一，也是我见过的最出色的演讲者之一。

And after several years of doing it, he's still in the very, very top tier of who we brought in to our chapter and one of the best speakers I've seen.

今天我们要聊的话题是商业暖通空调的负荷计算。

So today's topic will be load calculations in commercial HVAC.

Nathan，你算是那种在我们行业里几乎干过所有重要岗位的稀有人物了。

Nathan, you're sort of one of those rare people who've worked in most of the visible roles in our industry.

能不能跟我们的听众简单介绍一下你自己？

Can you tell our listeners a little about yourself?

是的。

Yeah.

当然可以。

Sure.

谢谢，Matt。

Thanks, Matt.

很高兴能来参加。

Good to be here.

我在这个行业已经工作了二十五年多，担任过各种不同的角色。

And I've spent over twenty five years in this industry in a variety of roles.

我最早的工作是为全国各地的项目做负荷计算，包括加拿大。

My first jobs were working doing load calculations for projects all over the country, including Canada.

所以不只是在美国，而是整个北美地区都做过。

So not just in the country, I suppose, but all over the continent.

我接触过各种各样的设计条件和项目类型，花了很多时间去复盘这些负荷数据。

So I saw a wide variety of design conditions, a wide variety of projects, and had a lot of time starting to review those loads.

像我们很多人刚入行时一样，我当初是跟着资深工程师学习的。但在深入了解负荷计算的方法和原理后，我开始对一些学到的东西产生疑问，这也促使我转向了下一个角色——在北美各地的建筑、工程和施工领域，支持建筑性能模拟工作。

I was trained like many of us are at that age or new in the industry by more senior engineers, And through the course of learning more about load calculations, the methods, etcetera, really started to question some of the things that I learned, and that kind of led me to my next role, which has been to support simulation, building performance in a variety of roles across architecture, engineering, contractor spaces across this continent as well.

那怎么

So how

当然可以。

can Absolutely.

我觉得每个人进入暖通行业的方式都不一样，这其实挺有意思的。

And I think all of us have a path to HVAC that's different, you know, and I think that's pretty cool.

我的职业道路也不是直来直去的。

So also my path is not completely direct.

我大学毕业后先当了汽车制造商的工艺工程师，但并不喜欢那份工作。

So I started as a process engineer at an automotive manufacturer after college and did not love that.

后来我想搬回老家，就开始参加ASHRAE的会议。

And then I wanted to basically move back to where I grew up, and I started going to ASHRAE meetings.

第二次开会的时候，我已经找到了工作，还在想去的城市买了房。

And then in the second meeting, I had a job and was buying a house in the town that I wanted to come to.

所以，如果你想在某个地方安家，ASHRAE真是个不错的途径。

So, basically, if you wanna live somewhere, ASHRAE is an excellent way of getting to it.

我和内森都积极参与ASHRAE的活动。

So Nathan and I are both very active in ASHRAE.

我的暖通空调背景是做设备制造商代表，负责销售。

So my HVAC background is as a manufacturer's rep in HVAC equipment sales.

那是一份特别棒的工作。

It was a fantastic job.

现在我经营一家教育公司，专门帮助建筑行业的新人。

And now I run and own an education company for new professionals in the construction industry.

比如实习生、预算员、销售人员、设计师、工程师在训人员等等。

So interns, estimators, salespeople, designers, EITs, etcetera.

这就是我目前的工作内容。

So that's what I do now.

换句话说，我现在不再每天整天做负荷计算了，而你一直在做。

So in other words, what I do not do now is deal with load calculations all day every day, and you do.

所以我是主持人，你是这方面的专家，内森。

So that is why I'm the host, and you are the specialist here, Nathan.

今天我们要聊的是负荷计算。

So for an introduction, we're gonna be talking about load calculations today.

我觉得最好的方式是先讲清楚为什么要做这件事。

So I think the best way to get us there is to sort of explain the why first.

因为《ASHRAE期刊》播客的听众群体很广，我们需要兼顾新手和有经验的人。

As the ASHRAE Journal podcast has such a broad audience, I think we need to consider sort of new people to experienced people.

那我们先从为什么说起。

So let's start with why.

为什么需要做负荷计算呢？

Why are load calculations needed?

是的。

Yeah.

这是个很好的问题。

It's it's a great question.

负荷计算几乎是所有暖通空调系统设计的基础。

Load calculations are probably the foundation of nearly every HVAC system design.

因此，从这个角度看，负荷计算也是设计过程中一个非常关键的风险来源。

And so load calculations, by extension, are also a very significant source of risk in the design process.

简单来说，除非你清楚负荷是多少、负荷的构成如何，否则根本无法确定需要多大的制冷量，或者该选用哪种暖通空调系统。

In short, you really can't figure out how much cooling you need or the type of HVAC system potentially until you understand what the load is and how the load breaks down.

所以，制冷和制热的情况是不一样的。

So that's different for cooling versus heating.

不同气候下情况也不同。

It's different for different climates.

不同类型的建筑也不一样。

It's different for different types of buildings.

影响因素多得去了。

There's all sorts of factors that go into it.

虽然说负荷计算的重要性听起来挺简单，但其实热量在建筑里怎么传递、怎么分布，复杂得很。

And load calculations, while it's easy to sort of describe their importance, are actually really complicated in how heat moves and is transferred in a building is is very complex.

这一切的基础，我相信我们后面会详细讲，主要是《ASHRAE基础手册》第18章。

The foundation for all of this, and I'm sure we'll get into this more, is really chapter 18 in the ASHRAE handbook of fundamentals.

那个部分还有很多其他内容我们会谈到。

There's a lot of other things that we'll talk about in that space

也都包括在内。

as well.

你能描述得具体一点吗？

Can you paint a picture?

我们有些代表虽然不直接做负荷计算，但对负荷计算的结果非常关注。

Like, we have reps listening who don't do load calculations but are very involved with sort of the outputs of load calculations.

所以在设计流程中，工程师和顾问什么时候会进行这项工作？

So in the design process, where does this occur for the engineer, for the consultant?

这个环节在流程里具体发生在哪个阶段？

When does this occur in that process?

对于顾问来说，理想情况下，只要了解了建筑的三个基本信息，我们就会开始做初步的负荷计算。

For the consultants, ideally, we'd start doing a preliminary load calculation as soon as we know three things about the building.

首先得知道建筑的位置，这样才能评估供暖和制冷的设计条件。

We would want to know where it is so we can get an assessment of what the design conditions are going to be for heating and cooling.

我们还需要知道这是什么类型的建筑。

We do want to know what type of building it is.

是办公楼吗？

Is it going to be an office?

还是医院？

Is it going to be a hospital?

这样我们就能大致估算出需要多少新风量。

So we can get an idea of things like how much ventilation do we need.

而地点还能帮我们判断外墙应该做哪些合理的假设。

And the location will also tell us things about reasonable assumptions we should be able to make for what the envelope is going to look like.

比如墙体的R值大概是多少？

So what's the r value of a wall, for example?

太阳得热系数又是多少？

What's the solar heat gain coefficient?

这些在早期阶段都得靠推测，或者至少是基于经验的合理预估。

And all of those things are going to be assumptions very early on or at least educated guesses in a way.

随着设计推进，理想情况下，那些基于规范或经验做出的假设会逐渐变得清晰。

As you the design progresses, hopefully and ideally, some of those assumptions that you're making based on code or based on just, you know, experience are going to come more into focus.

我说理想情况，是因为现实中并不总能如愿。

And I say ideally because realistically that doesn't always happen that way.

而且就算很多细节后来都明确了，总还是会有一些未知数。

And also, you know, even in the case where you do get a lot of those blanks sort of filled in, there's always going to be unknowns.

在建筑建成之前，你永远无法知道实际的空气渗透率是多少。

You're never going to know what the actual infiltration rate is until after the building is constructed.

你可以做一些有依据的推测。

You can make some educated assumptions.

你可以参考ASHRAE 90.1或者国际能源节约规范这样的标准，来了解该预期什么、现实点能预期什么，但说到底，工程师并不亲自盖楼。

You can refer to standards like ASHRAE 90.1 or IECC, the International Energy Conservation Code, to get an idea of what you should expect or realistically expect, but, you know, the engineer doesn't build the building.

建筑师也不盖楼，所以我们总会遇到这类未知因素。

The architect doesn't build the building, so we will always have those sorts of unknowns.

但有些事情是工程师能掌控的。

But there are things that the engineer can control.

比如，工程师可以选择用哪种方法来做负荷计算，这完全在他们的掌控之中。

For example, the engineer can and does have control over which method they choose to select for doing load calculations.

他们也能调整一些输入参数。

They have the ability to change some of the inputs.

手册第18章说得对，输入参数对结果的影响远大于方法本身，我觉得这个观点非常中肯。

You know, the handbook in chapter 18 rightly points out that the inputs are the bigger delta in terms of the result than the method itself, and that's I think a very valid point.

我还想指出，手册里也提到，热平衡法是最准确的方法。

I'd also point out that the handbook also states that the heat balance method is the most accurate method.

所以在做负荷计算时，要权衡的事情很多，包括选择哪种方法，以及哪种方法最符合项目需求。

So there's a lot of things to weigh in the process of setting up the load calculation, but also determining which method to use and what's the most appropriate one for the project.

你之前稍微提过，能给我们讲讲什么是负荷计算吗？

So you spoke about this a little bit, but can you tell us what is a load calculation?

那我们先从什么是负荷说起吧？

So what is probably starting with what is a load?

在暖通空调领域，我们一般不谈导热、对流和辐射这些术语。

So what we in HVAC don't talk about conduction, convection, radiation.

虽然有些情况会用到，但更常见的说法是围护结构负荷、内部负荷或新风负荷。

There are certain situations where you do, but it's actually much more common to hear envelope load or internal load or ventilation load.

这些分别指的是什么？

So what are those?

能举几个每种负荷的例子吗？

And could you give a couple of examples of each one?

从技术上讲，得热和负荷是有区别的，这一点在基础手册里也有说明，对吧？

So technically speaking there's a difference between gain and load and this is also described in the fundamentals, right?

通风有时候算作负荷，但通常属于得热；围护结构通常也是得热，而不是负荷。

So the ventilation can be a load but it's typically a gain, the envelope is typically a gain not a load.

得热呢，比如阳光照进窗户，照到地板上，把地板烤热了，空气通过对流把地板或者被照到的墙面的热量带起来，最后这些热量积聚在空间里，就得靠空调系统把它排出去。

So gain is what you get from, you know, the sun shines through your window, falls on your floor, warms the floor, convection picks up the heat from the floor or an internal wall wherever it's striking, whatever surface it's striking, and then that eventually becomes a load in the space that has to be removed by a cooling device.

负荷呢，用最简单——可能简单过头了——的方式来解释……

So load is what in very simple, probably overly simplistic

我就是要最简单的说法，内森。

I need overly simplistic, Nathan.

得热是你得面对的东西，负荷是你用来应对它的手段，如果你愿意这么理解的话。

Gain is what you have to deal with, and load is how you deal with it if you wanna think about it in those terms.

总的来说，你能举几个围护结构负荷和内部负荷的例子吗？再讲讲通风负荷是怎么融入整体负荷计算的？

Overall, could you name a couple of envelope loads or internal loads and then explain how the ventilation loads integrate into the overall load calculation?

明白。

Yeah.

我这里引用一下ASHRAE标准183，它其实是《基础手册》第18章的一个精简版。

There's you know, I'll reference ASHRAE Standard one eighty three here, which is sort of a a condensed reading of chapter 18 in the handbook of fundamentals.

顺便提一下，标准183总共只有八页。

And just for reference, Standard one eighty three is eight pages.

内容非常紧凑，但很好地梳理了房间和区域负荷的最低要求，而且明确说明它不适用于系统 sizing。

It's it's very condensed, and it it does a good job though of of laying out what the minimum requirements are for room and zone load and not and it explicitly states it is not for system sizing.

所以我也会在后面把这些区别讲清楚。

So I'll I'll make those distinctions here as well.

你通常会遇到的围护结构得热或负荷，主要是传导传热。

The Rumin zone gains or loads that you would deal with would typically be conduction.

比如一堵墙或者一扇窗，两侧有温差，热量就会因为这个温差而传递。

You you have a wall or a window and there is a temperature differential across that across that surface and heat is moving because of the temperature differential.

还有太阳的辐射，直接加热了墙面、地面这些表面，再加上前面说的对流——空气流过这些热表面，把热量带走，传到空气里。

You have the radiant component of the Sun which is warming up the surfaces themselves, and then as mentioned you have convection which is picking up air moving across that warm surface, picking up the heat and bringing it into transferring it from the surface and into the air.

这些就是围护结构方面的主要负荷来源。

So So those would be some of the like envelope based loads.

还有内部热源，比如照明设备会散热，人员也会散发显热和潜热。我们还没细讲显热和潜热的区别，但这些概念其实很重要。

Then you also have the internal gains, which you have your lights which give off heat, you have people which give off both sensible and latent heat, so we haven't talked about sensible and latent heat here but those are important distinctions as well.

另外还可能有一些零散的热源，比如电视、电脑，或者冷藏柜之类的设备，它们要么散热，要么吸热，做负荷计算时都得算进去。

And then you may have miscellaneous gains, like you may have televisions or computers or some other, you know, refrigerated cases or any number of devices that are either giving off heat or absorbing heat themselves that you have to account for in the process of doing a load calculation.

通常来说，负荷计算都是针对某个特定时刻进行的。

And typically your load calculation is done at sort of a moment in time.

供暖计算确实是这样。

For heating that's true.

但制冷计算就不一样了，我们会看一整条设计日的总体情况。不管哪种情况，你都只考虑一年里一两个最极端的小时，其他时间建筑的负荷基本远达不到这个峰值。

For cooling we move to looking at the totality of a single design day, And in either case you're looking at only one or two hours of the year and the rest of the year the building is you know probably nowhere near that peak condition.

我们知道还有很多其他因素需要研究，但在做负荷计算时往往暂时不考虑这些。

So there's a lot of other things that we know are needing to be studied but don't necessarily consider when we're doing load calculation.

很好。

Awesome.

这样我们就很自然地过渡到输出部分了。

So I think that takes us pretty directly to outputs.

没人是为了好玩才做这个的，大多数人也不是出于兴趣。

So no one's doing this for the fun of it or most people aren't doing it for the fun of it.

当工程师、EIT 或设计师坐下来做这个计算时——我们待会儿会讲到方法，这也是我们频繁讨论方法和设计的时刻之一。

So if an engineer or an EIT or designer, they sit down to do this calculation, and we'll get to methods, and this is one of the times that we do talk quite a bit about method and design.

他们坐下来做这个，最终想要得到什么结果？

When they're sitting down to do it, what are their outputs?

他们真正想通过这个计算达成什么目标？

What are they actually sitting down to do to get out of it?

是的。

Yeah.

这还得看情况，如果你在计算房间或区域的负荷，通常是为了确定这些房间或区域的设备需要多大的容量或风量。

So it depends again on your if you're looking at room and zone load, you're typically looking to figure out what those room or zone level device needs in terms of capacity or airflow.

比如说，我们以一个变风量多区系统为例。

So if we think about I'll just pick a VAV system, a multi zone VAV system, for example.

如果我们提前跳到什么是多区变风量系统，先向您道歉。

And if we're jumping ahead to what a multi zone VAV system is, well, my apologies.

我们今天不谈这个。

We're not doing that today.

所以我们得把范围定下来。

So we gotta scope it.

我们有时间限制，内森。

We have a time requirement, Nathan.

所以别记这个。

So don't note.

我们不会深入这个部分。

We're not gonna get into that.

但没错，你就从这儿接着讲吧。

But yes, take it from there.

对。

Yeah.

在房间和区域的条件下，对于VAV系统，你要弄清楚的是，假设送风温度通常是55度，那么需要多少风量，单位是CFM，也就是美制单位。

In a room and zone in the room and zone condition, the VAV system, you're you're trying to figure out, you know, given a certain supplier temperature, typically 55 degrees in a VAV system, what quantity are CFM in American units Yeah.

每秒多少升，或者其他单位，我需要多少空气才能维持设定温度？

Liters per second and other units, how much air do I need to maintain a given set point?

比如说，通常设定在75度左右。

Typically, let's say 75 degrees.

然后我这边有20度的温差，也就是室内温度和送风温度之间的差值，这样就能算出需要多少风量。

And then I have a 20 degree delta T or temperature differential between the space temperature and the supply air temperature, so I can determine how much air I need.

在房间和区域负荷层面，通常都是这么算的。

And that's typically what you're doing at room and zone load levels.

到了系统层面，你得考虑比如需要多大的盘管。

At system, you're trying to figure out things like how much coil do I need?

是用六排的、八排的，还是四排的盘管？

Do I need a six row coil, an eight row coil, a four row coil?

这些条件具体是怎样的？

What are the conditions of that?

我的显热比是多少？

What's my sensible heat ratio?

我需要让盘管从气流中去除多少潜热？

How much latent heat do I expect or do I need the coil to extract from the airstream?

这些盘管之后可能会连接到某个中央设备，或者在风冷直膨系统中，直接连到各自的独立机组上。

And then all those coils would then be connected to some other central device potentially, or they may be connected to their individual contained, you know, box in the case of air cooled DX.

你其实也在估算整个系统的规模——虽然我这里用‘系统’这个词有点宽泛。

You're also effectively trying to size that plant, if I can use that term a little bit liberally there.

但要确定所有这些容量后，自然会牵涉到电气工程师的问题：需要多大的电力负荷？风管该多大？保温层要多厚？

But to figure out all of those capacities need to be and then that by extension has ramifications for the electrical engineer, how much power draw do they have to have, how big the ductwork does the ductwork, how much insulation on the ductwork do I need?

所有这些都源于一个关键点：为了满足房间温度需求，设备的峰值容量到底该定多大。

All of those have cascading effects from figuring out or determining what the peak size of the equipment or the maximum capacity of the equipment needs to be to satisfy space temperature based on Yeah.

这直接引出了输入参数的问题，因为你展示的输出结果会直接影响建筑设计和施工，涉及预算、风险、复杂性这些因素。

And that takes us directly to inputs because you are showing that the output would be directly applicable to the building design and construction, which means budget, risk, complexity, things like that.

那么在输入环节，一个理想的场景应该是什么样的？

So in the inputs, what would a good application look like?

设计师在设置输入参数时，其实是在配置最终会用于热平衡计算或其他计算方法的条件。

So when the designer's putting in inputs, they're going through and setting up what would eventually be heat balance method or whatever the calculation ran is.

他们向软件输入了哪些数据？

What are they inputting into the software?

其次，软件运行计算时，是从哪些数据库里提取信息的？

And the second part of that, what is the software grabbing from, you know, databases when it's running that calculation?

对。

Yeah.

市面上有各种各样的软件平台，也有多种仍可使用的负荷计算方法。

I mean, there's a wide variety of software platforms available, and there's a wide variety of load methods that are also still available for use.

不过从根本上说，我会先从负荷计算方法讲起，再回过头来看输入数据，因为这些输入内容在各类方法中大体相似。

But fundamentally, the load methodology that you I'll start with the load methodology and then I'll work back into the inputs because the inputs are probably largely similar across all of these.

这些不同方法之间确实有些细微差别，但我先从方法说起。

There's some fine tuned details between some of these different methods, but I'll start with the methods first.

正如我之前提到的，热平衡法在《基础手册》第18章中有详细说明，被认定为最精确的方法。

So as I mentioned earlier, the heat balance method is described in the Handbook of Fundamentals, Chapter 18, and it is stated to be the most accurate method.

任何看过我章节演示的人都知道，ASHRAE做出这个结论是有研究依据的。

As anyone who's seen my chapter presentation knows there's ASHRAE research behind how ASHRAE has made that determination.

另一个目前有描述的是辐射时间序列法，它是热平衡法的简化版本。

And then the Radiant Time Series is the other one that is currently described, which is a simplification of the heat balance method.

我觉得很重要的一点是，这两种方法之间有不少关键区别。

And I think a really important is there's a bunch of distinguishing factors between those two.

但对我来说，最大的区别是：你不能用辐射时间序列法来做小时级的负荷计算。

But the biggest one for me is you can't use radiant time series to do an hourly load calculation.

你只能用它来找峰值。正如我提到的，热平衡法更准确、更灵活，比如你可以用它来计算热泵系统——像地源热泵——全年每小时的负荷，看看有多少小时落在某个温度区间，这样你才有把握去平衡地源热泵的环路负荷。如果你想为热能储存罐做 sizing，也得用热平衡法，辐射时间序列法根本做不到这些，所以它更精准。

You can only use it to find the peak, just quoting the And so heat balance method is being the most accurate and being more flexible in that I can use it to say, do like a heat pump system, like a ground source heat pump system, figure out the hourly load throughout the year, how many hours am I in a given range it's going to have the confidence then to do more of a balance of the loop load for example on a heat pump system or if I want to use it to size a thermal energy storage tank I would use the heat balance method I couldn't use radiant time series for that so it's more accurate.

它也更灵活。

It's more flexible.

不过代价是需要输入更多参数。

The trade off is it does require a few more inputs.

通常的输入包括室内热源。

So typical inputs are going to be your internal gains.

我们之前已经讨论过这些了。

We talked about those earlier.

高尔夫模拟器。

Golf simulators.

高尔夫模拟器。

Golf simulators.

你有棒球击球笼啊，那些东西全都有。

You have baseball batting cages, you know, all all all of those things.

是的。

Yeah.

所有这些。

Everything.

我真想买个高尔夫模拟器。

Just wanna golf sim so bad.

对。

Yeah.

快到年底了。

It's the end of the year.

你知道的，那些顶级的输入参数。

You know, the masterpiece inputs.

这需要更多的输入数据。

It it takes more inputs.

其实输入里头有些细节需要微调。

Well, there's some fine tunes in the input.

比如内部得热负荷这些，大家一般都挺清楚的。

So, you know, like the internal gains are well understood or they're generally well understood.

当然，也会有一些特殊情况。

And there's, I mean, yes, there's unique cases.

这正好说明了例外反而印证了规律。

So, you know, this is the case where the exception proves the rule.

手册里头给了不少数据，可以参考这些特殊场景下的内部得热值。

And the handbook gives you a lot of numbers that you can refer to for some of those unique cases of internal gains.

我觉得输入的差异主要在于你对内部表面的细节描述有多精细。

I think where the inputs vary is how detailed are you with your internal surfaces.

咱们先暂时把围护结构放一边。

So let's just set aside the envelope for the moment.

这个我留到最后再说。

I'll leave that for last.

如果看标准183，它明确要求我们必须考虑所有内表面，因为得弄清楚太阳照在哪些内表面上，可能把热量传到房间深处或者建筑内部。

If I look at Standard 183, it tells me I need to include the interior surfaces, all of them, because I need to understand where the sun is hitting an interior surface and potentially transferring heat into the further into the spaces or into the building.

另外，所有内表面都有热容量。

But it's also because all of the internal surfaces have thermal mass to them.

换句话说，它们吸热和放热的速度都不一样。

In other words, they absorb and release heat at different rates.

所以，要是再翻回手册，你会发现，各个峰值加起来，通常根本算不出实际的冷负荷，甚至从来就对不上。

So the peak, if we're going back to the handbook again, the sum of the peaks does not equal the cooling load frequently or maybe even ever.

因此，这些时间延迟效应，是负荷计算方法里最难把握的部分之一。

And so the time delay effects in those aspects is one of the trickier bits to get right in the load calculation methodology.

现在，热平衡法在输入参数上的特别之处在于，光靠墙体的R值是远远不够的，要想充分发挥它的精度和优势，你得提供更全面的数据。

Now, where the heat balance method differs on inputs specifically is you need more than just your R value for a wall, for example, to really leverage the capability and the accuracy of the heat balance method.

你的墙里有保温材料吗？

Do you have insulation in your wall?

如果有，是哪种保温材料？

If so, what kind of insulation?

用了多少厚度？

How much of it do you have?

还是你用的是混凝土、砖块，或者其他密度更大的蓄热材料？它们的热延迟效应和轻质金属板可不一样。

Or are you using concrete or brick or some other heavier thermal mass material that has a different time delay effect than, say, lightweight metal panel?

所以你看，辐射时间序列这个方法能简化这些计算。

So, you know, the radiant time series simplifies those calculations.

你没必要去一一详细定义每面墙的热特性。

You don't necessarily have to get into it and into all of the details of defining those surfaces.

它的代价，前面已经说过了。

The trade off with it is as has already been described.

输入的数据大体相同，但具体细节会因你选择的方法和软件而产生显著影响。

So the inputs are generally the same, but the finer details can matter significantly depending on the method you pick and the product

看情况。

depending on.

从外往里看，我过去是代表厂家，现在更偏向设计方向，感觉负荷计算的方法总是被反复讨论。

Outside looking in, again, formally as a rep and getting more into design interests, it seems like method is so constantly discussed for load calculations.

这几乎是个老生常谈的话题。

It's like a common discussion.

我们涉及风管设计、吊顶设计，还有设备选型。

We're in ductwork design, popping design, equipment selections.

讨论具体方法的情况其实并不常见。

It's not super common to to discuss method.

所以从历史角度来看，我觉得大家一直在简化那些理想化或者有趣的概念。你知道的，我们明明知道可以这么做，但当时没有相应的能力去实现。

So over time or historically, I guess there's been simplifications of what was ideal or interesting, you know, sort of we know we could do this, but we don't have the capacity to do this.

这主要是因为在过去，也就是一百年前，大家都是用笔和纸计算，而现在电脑的计算能力非常强大，基本上想怎么算就怎么算。

Is it mostly in your mind because it was pencil and paper a hundred years ago, and then now we have calculation capacity in computers that's like we can do what we want.

那么，用热平衡法进行的计算量，大概比一百年前用经验法则进行的计算量多出多少呢？

Like roughly how many calculations is occurring using heat balance method versus the rule of thumb that would have been done one hundred years ago?

当然有很大差别，技术的发展让更复杂、更精确的方法变得更容易使用了。

Oh, there's certainly a huge difference and technology has played a role in the availability of using more sophisticated methods or more accurate methods.

所以直接回答你的问题，如果我们想想以前大家桌上还没电脑的时候，其实都不用追溯到一百年前，对吧？

So yes, to answer your question directly, if we think about how load calculations were done before everybody had a PC on their desk, we don't have to even go back a hundred years, right?

只要回溯到大约五十年前，所有计算都是手工完成的。

We can go back probably fifty years and everything was done.

那时候有工作表，ASHRAE还发布过负荷计算的工作表。

You know, there were worksheets and ASHRAE did distribute load calculation worksheets.

人们都是手动一步步算的。

People would work through the problem by hand.

各种系数。

Factors.

你还能看到等待因子、莱曼时间序列这些内容。

You can still see the time waiting factors, the Riemann time series.

如果你好奇这些方法的来源，现在的手册里依然能找到。

They're still published in the handbook if you're curious about how where those come from.

你完全可以手工完成所有这些计算，但一旦有人做了修改，你就可能得从头再来一遍。

You can do all of those calculations by hand and then somebody makes a change and now you got to go through that process potentially all over again.

所以整个行业过去都是靠手工计算，也信任自己的手工结果。

So we learned as an industry by hand and to trust our hand calculations.

因为看得见整个过程，也就更容易发现其中的错误。

We could see the work and we could find errors in that work.

随着转向软件，我觉得这里还有一个类似的转变，可能对大家理解有帮助：就像从丁字尺和绘图板转向CAD一样，手工计算转向负荷计算软件也是类似的。

So with the move to software, and I think, you know, a parallel change here that I think might be helpful for people to understand is moving from T squares and drafting tables to CAD is sort of analogous for moving hand calculations to load calculation softwares.

软件里头涉及的数学运算更复杂，结果就有点像黑箱，没那么透明，不像手工计算那样一目了然。

So there's a certain element of the more sophisticated mathematics that's occurring in the software routine or the software program that lends itself to be a little bit more of a quote unquote black box or a little bit less transparent than, you know, manually doing it by hand.

不过好处是，计算机算得快得多，也不会出错，因为它完全按程序执行。比如现在用热平衡法，要解微分方程，这种事靠人手根本搞不定。

The trade off is, of course, the calculator, the computer, can do those calculations much more quickly and doesn't make mistakes because it's So coded as we get into like the heat balance method, now we're doing sophisticated like differential equations.

除非是我自己，否则我绝不会去手算微分方程。

Unless me, myself and I would not want to do

你别替我说话啊，

diff eq by having Speak for yourself here,

内森。

Nathan.

多次迭代。

Multiple iterations.

特别喜欢做这个。

Love doing that.

每小时好几次。

Multiple times per hour.

因为实际情况是，计算会以六分钟或十分钟为步长进行，有时甚至更短，目的是精确捕捉时间延迟，而不是像热平衡法那样简单地加一个等待因子。

Because what actually happens is the calculations happen in a six minute or ten minute time step or even smaller in some cases to resolve exactly the time delay or calculate the time delay rather than to apply a waiting factor the time delay in the heat balance method for example.

所以没错，数学更复杂了，计算更频繁，过程也更严谨，结果也就更准确。

So yeah, more sophisticated math, more frequent calculations, more rigor to the calculations to get a more accurate result.

这也改变了我们审查负荷计算报告的方式。

So this also has changed like how we think about reviewing like a load calculation report.

归根结底，用老式手工方法时，你最后在页面底部看到一个数字，经过质量检查确认无误后，再加个安全系数，诸如此类的操作。

So at the end of the day, you know, the old hand method, you'd get a number at the bottom of the page that was, you know, once you went through the QA process, made sure that was right, that was what you had, you know, you'd apply a safety factor, all of those sorts of things.

现在用的计算软件里还是会有安全系数，但审查的方式已经不一样了。

You still apply safety factors in the calculation softwares that are available, but the way that those are reviewed is different.

辐射时间序列法更接近于内部得热加上围护结构负荷再加上通风。

So radiant time series is probably more akin to internal gain plus envelope load plus ventilation.

把这三部分加起来，就能得出一个数字。

Add those up, you get a number.

这种算法比较好懂。

Kind of easy to understand.

基本上就是算术运算。

It's arithmetic more or less.

而热平衡法就不同了，因为它的计算量大得多，而且各个计算环节本身通过微分方程紧密关联。

With heap bounce method, it's different since there's so many more calculations happening and the calculations are inherently more interconnected with differential equations.

要解这些方程、拆解它们，再做质量检查确保结果‘正确’，整个流程都跟以前不一样。

Solving that and pulling that apart and how you do that QA to make sure it's quote unquote right, is a different process to go through.

这时候，光靠报告、数字和一页页的表格已经不够了，真正能帮上忙的是用图表这类可视化工具，尤其是当你想全面理解一整日的设计工况时。

And this is where I think transitioning from relying only on reports and numbers and like a spreadsheet around a page and using more visual tools like graphs and charts really comes into play to understand the physics, especially when you're looking at a totality of a design day.

我真的很喜欢负荷报告。

And I love loads reports.

别误会我的意思。

Don't get me wrong.

负荷报告确实很有用。

Loads reports are great.

它们以一种我这种人通常很熟悉的方式提供大量信息。

They give you a lot of information in a format that is usually pretty familiar to someone like myself.

但它们无法展现一整天内发生的所有变化。

They fall short of being able to show you what happens over the entirety of the date.

不管生成多少份报告，最终都只给我一个数字。

No matter how many reports they generate, it's only going to give me one number.

这个数字在纸上是静止不动的。

That number is static on the page.

但计算过程中实际发生的事情远不止这一个静态数字。

And what's happening in the calculations is so much more than that one static number.

所以我们不得不适应的一个转变，就是从CAD转向BIM。

So we have to, I think one of the transitions that we've had to adapt to is that moving now from CAD to BIM.

从原本基于代数的简单计算，转向更复杂的数学模型，这让我们不得不改变质量控制的方式，而且……

So moving from calculations that are algebraic and basis and moving into more sophisticated math encourages us to do QAQC differently as And

到了这个时候，它更像是一种模拟，而不是单纯的计算。

at that point, it becomes more of a simulation and less of a calculation.

对吧？

Right?

它比单一的计算要密集得多。

It's like more dense than just a single calculation.

你面对的是多个反复迭代的计算，最终得到的是一组选择丰富的可能性，因为你有了更多输出结果。

You're getting multiple calculations, iterative, and then you're arriving at an optionality heavy set of choices that you can make because you have more outputs.

是的。

Yeah.

某种程度上是这样。

In a way.

我的意思是，模拟还是模拟。

I mean, the simulation is still simulation.

对吧？

Right?

我教这个的时候，是这么理解的：如果我想看一天的情况，那就是一个计算。

So simulation, the way that I kind of when I teach this, the way that I kind of think about this is if I want to look at one day, that's a calculation.

没错。

Yes.

但在这一天里，我可能会模拟很多东西，最终得出那个计算结果。

I might simulate a lot of things within that one day to arrive at the calculation.

我觉得你讲的正是这个意思，我同意。

And I think that's what you're kind of driving I'd agree with that.

不过我想强调一下区别：我要做的是整整一年的模拟。

But I want to be careful to draw the distinction here of I'm going to do a simulation over an entire year.

这个模拟里会包含大量——多得多的计算，远不止一天或者几组计算那么简单。

And that's going to contain those calculations, you know, exponentially more of those calculations than just doing the calculation for one day or a series of calculations for

一天。

one day.

我想问一个具体的计算问题，就是通风量的计算。

A specific calculation that I wanna ask about is ventilation calculations.

在我看来，通风量的计算是实际工作流程中必不可少的环节，虽然我们不会深入展开，因为这本身就能讲一整期节目了。

Because to me, it seems that ventilation quantities, which we will not get super into detail for because that could be multiple other podcasts, of course, but there is within the practical application based workflow a need to calculate ventilation.

通常在做负荷计算的时候，大家也会顺带考虑通风量的计算。

And that is often wrapped in when we're talking about load calcs, people are also thinking that's the point at which you sort of think through the ventilation calcs.

是这样吗？

Is that correct?

设计工程师在实际工作中，一般是不是都在这个时候一并处理通风量的计算？

Is that when that's typically happening in the workflow of the design engineer?

是的，通风量的计算——确定需要从室外引入多少新风到暖通设备里——是整个流程中非常关键的一环。

Yeah, ventilation calculations, figuring out how much outside air you need to pull through your HVAC equipment is an essential part of this.

我觉得我们之前漏掉了这一点，没好好聊聊。

I think we neglected to dig into that.

我们刚才在聊输入参数。

We were talking about inputs.

我好像一直卡在房间和区域的层面，没往前推进到系统层面。

Think I still got stuck on room in the zone and never transitioned the system.

不过没错，要准确计算通风量确实有难度，尤其是如果你遵循62.1通风率标准——这在北美应该是最常用的方法。

But yes, certainly the challenge with getting ventilation right is that, you know, if you follow the 62.1 ventilation rate procedure at least, which is probably the most commonly used one, at least in North America.

难点在于，很多时候你必须清楚自己的系统类型，才能确定整个系统的通风需求。

The challenge with that is you really do need to understand your system type in many cases to figure out what the system level ventilation is going to be.

不过话说回来，即使还没选定系统，你也可以先根据各个区域的通风需求加总估算一个大致数值，这样心里就有数了，后续设计再慢慢调整。

Now that said, you can still estimate it reasonably well by looking at your zones and adding them up before you've picked a system so that you have some reasonable expectation what that's going to look like, and then fine tune that as the design evolves.

但如果你连通风量都不清楚，根本没法确定盘管的尺寸。

But you can't really cannot pick a coil size without understanding your ventilation.

对。

Yeah.

我刚才想表达的就是，你得先有通风量，然后负荷计算又会影响系统选型，中间可能得来回反复调整。

That's what I was kind of getting at is you need it, and then the load calc also informs the system top, and then you might have to iterate back and forth through that.

所以，除非像你说的，你特别喜欢做

So unless, like you said, you love doing

一定要做得扎实。

Definitely do a good job.

除非你特别喜欢解微分方程，

Unless you love doing differential equations,

否则最好用一种可靠的计算方法，比如热平衡法，反复进行计算。

it's much better to have a robust calculation method such as heat balance method to do that over and over.

而且，我觉得你说得对，这真的很重要。

Well, it's also, I think to your point, like, think it's really important.

能省下不少时间。

It's a big time saver.

我知道在咨询工程行业，大家总是面临费用压力。

And one of the things I know is happening across consulting engineering is there's always pressure on fees.

所以，只要能节省时间的地方，都能帮我们控制费用，提高利润。

So any place that you can save some time helps your fee and helps your profit margin.

所以，如果你的负荷计算工具还能可靠准确地同时完成通风计算，那就非常有帮助了，不用在不同工具之间来回切换。

So it's really helpful if your load calculation tool can also do your ventilation calculations reliably and accurately in the same tool, And you don't have to have multiple things to manage across those bits.

当然，你得搞清楚通风计算是怎么运作的，因为通风不足可能会带来法律风险。

Of course, you have to make sure that you understand how the ventilation calculations are working because there is legal risk about under ventilating So space,

对于

for

这里面容易出错的地方太多了。

there's a lot of points where you can go wrong.

因此，有很多关键检查点，工程师和正在学习这些流程的人必须充分意识到。

And therefore there's a lot of points of checkpoints that happen that I think engineers and people who are training on how to do these processes need to be aware of.

没错。

Right.

当我们快结束这个话题时，我觉得，理解通风计算至关重要。

And as we sort of turn toward closing this out, I think to me, understanding the ventilation calcs is critical.

这是我更熟悉的世界，然后你就会说，这里需要多少冷吨数。

And it's the world that I lived in a little more, and then it would be, here's the tonnage you use.

但通风这块我确实想了很多，因为它对设备成本的影响太大了。

But ventilation, I thought about quite a bit because, you know, it swings the cost of equipment so, so heavily.

你得保证通风量足够，避免风险，但也不能过头，否则会买一堆根本用不上的设备。

And you really you wanna go heavy enough that it's not a risk, but you wanna go light enough that you're not buying a ton of equipment that you don't need.

所以从我的负荷计算经验来看，常见的误区就是通风量要么过多要么过少，我们真该停下来问问自己：这个计算到底对不对？

So I would say in my load calculation view, that would be a common mistake or misconception is we're overdoing or underdoing ventilation, or we just need to really stop and think, are we doing this calculation correct?

因为通风的计算结果对整体输出影响太大了。

Because it has outsized weight on the outputs.

最终得出的结果要么设备贵得离谱，要么尺寸不够，这是两种完全不同的问题。

What you're getting out of it is gonna be very expensive or undersized, which are two different problems.

那你平时常遇到哪些类似的情况吗？

So are there any that you regularly see?

你去各个分会做同样分享的时候，是不是总被问到同样的问题？

Or when you give this similar talk at chapters, are you getting the same questions over and over?

就比如在2026年，负荷计算中最常见的痛点或问题是什么？

Like, what is a common friction point or issue with load calculations in 2026?

天啊。

Oh, man.

这些问题五花八门，太多了。

There's a lot of them that are all over the map.

而且

Well and

这其实也是一个机会，可以谈谈你还想补充的其他方法。

and this can be an opportunity to also say any more methods things that you would like to say.

还有没有我们没提到，但你经常想强调的重要内容？

So any more things that we didn't cover that you commonly are interested in hitting because it's an important thing?

是的。

Yeah.

我举几个例子，你在演讲里见过，可能其他听的人也见过。

I mean, a couple of examples that I use in in the talk that you've seen and maybe others who are listening to this have seen as well.

比如用热平衡法时，混凝土或混凝土砌块这类材料能长时间蓄热，缓慢释放，容易导致温度峰值出乎意料。

You know, with the heat balance method, the ability for materials like a concrete or a concrete masonry unit to hold heat for an extended period of time and slowly release it can lead to unexpected peaks.

我拿一个大型西南向玻璃幕墙的表演艺术中心作为例子。

I use a performing arts center with a large southwest facing curtain wall as an example of that.

结果室内空间在半夜突然出现温度峰值，因为一整天阳光把混凝土砌块都烤透了，热量花了好几个小时才慢慢散出来——这就是为什么在1983年版标准里，必须考虑内表面的热特性。

And then the interior space is unexpectedly peaking in the middle of the night because that the sun essentially cooked that CMU all day long, and it took hours for the heat to work its way back out of that, which is why in standard 01/1983 you've got to have your internal surfaces.

你不能想当然地觉得内表面对负荷没有影响。

You can't just assume that they don't have any bearing on your load.

另一个常见误区是，很多人假设设计日是全天24小时满负荷运行，但其实我的建筑是办公楼，根本不会24小时有人。

You know, another one is, you know, if I, you know, a common assumption that I've seen used is the design day is a 20 fourseven period even though my building is an office and it's not going to be occupied 20 fourseven.

如果按照183号标准，我得用实际的人员使用模式，而不是默认这个空间类型全天满员。

If I follow standard 183, I need to use an occupancy profile and not assume that it's 20 fourseven for that space type.

而且如果建筑有温控 setback，比如早上把温度调高到85度，而室内实际是75度，就会导致意想不到的峰值出现。

So and then and then if you have setbacks in there, can have unexpected peaks occurring due to morning cool down where you have a setback say of 85 and a space temperature of 75.

我们在审查这类情况时，通常会发现一个规律：很多时候，其实是软件算错了。

And then you know what triggers in our sort of heuristics when we review this is we say all that the so you know, I see a lot of times the software is wrong.

我经常看到软件出错，但人们总觉得自己不可能错。

I couldn't possibly be wrong, I see a lot of the software is wrong.

有了好的软件平台，你就能深入查看，发现原来确实有道理。

Then with a good software platform, you can actually dig in and say, oh, actually, that does make sense.

我只需要调整一下输入参数，因为热平衡法比其他方法更精细。

I just need to tweak my inputs because heat balance method is more sophisticated than the other methods.

要是靠手算，我根本发现不了这一点。

And I wouldn't have seen that with a hand calculation.

这并不意味着手算对或错，也不代表软件对或错。

It doesn't mean that the hand calculation is right or wrong or that the software is right or wrong.

这说明我们在继续之前，得先退一步，搞清楚基本原理。

It means that we need to take a step back and understand our first principles before we proceed.

上大学时，计算机课老师教我的第一件事是：电脑只会执行我们给它的指令。

First thing that I was taught in college for a computer class was the computers do what we tell them to.

它们不会思考，虽然我们一会儿可以聊未来，但它们大概还是不会思考——真正该负责的，是我们输入的内容，以及最终输出的结果。

They're not thinking, and we can get into the future here in a second, but they're probably still not thinking and that we're responsible for what goes into them and really, therefore, what comes out of them too.

我觉得你说的，正是我想表达的——职业责任问题。

I think you're you're getting at what I would get at with that is professional liability.