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Building Science

The Four Laws of Thermodynamics

We often talk of the second law, but what are the other three?

The laws of thermodynamics allow us to understand heat and energy.
Image Credit: Energy Vanguard

Building science is an odd subject. Few colleges and universities teach it. The majority of those who work on buildings call themselves engineers, architects, and contractors, not building scientists. And many of those who do invoke the term can explain at least one implication of the second law of thermodynamics (we’ll get to that below) but may not know what the other laws of thermodynamics are, why their numbering is so peculiar, or even how many there are. Do you?

Well, today let’s address this deficiency. If you’re going to speak of one of the laws of thermodynamics, it’s your duty at least to know the others well enough to tell a curious person what they are and which ones have some bearing in the world of building science. Before we launch into this subject, though, let’s get a little perspective on thermodynamics from the physicist Arnold Sommerfeld:

Thermodynamics is a funny subject. The first time you go through it, you don’t understand it at all. The second time you go through it, you think you understand it, except for one or two points. The third time you go through it, you know you don’t understand it, but by that time you are so used to the subject, it doesn’t bother you anymore.

With that, let’s begin at the beginning, sort of. The first of the laws of thermodynamics is not the first law of thermodynamics. (I told you it was peculiar!) It is…

The zeroth law of thermodynamics

Let’s start with the obvious question: Why isn’t it called the first law of thermodynamics? As it happened, this law was discovered after the first and second laws but considered to be more fundamental. So we have a…

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One Comment

  1. Jonathan Beers | | #1

    Thermodynamics humor
    Ever since I read poet Allen Ginsberg's version, I've enjoyed funny versions of the Second Law. C.P. Snow has been credited with this very similar version. I'm not sure which came first.

    Zeroth: You must play the game.
    First: You can't win.
    Second: You can't break even.
    Third: You can't quit the game.


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