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The Human Body is a Radiator

This goes back a bunch of years but the horror remains as raw and smelly now as if did then, and I can’t blame the airlines. It was the alphabet’s fault.

But before we get to that, a bit about your body:

If you’re sitting while reading me, this means you are currently alive. Your heart is pumping blood; your diaphragm is operating the wonderful bellows that are your lungs; your brain is hard at work, considering my words and all else that you are sensing. To accomplish all of this, your body at rest requires just 100 Btuh and isn’t that amazing? You are indeed a very efficient machine, in spite of what your colleagues may have to say about you.

But wait, there’s more. Your body at rest is actually producing 500 Btuh right now. That extra 400 Btuh is a safety factor, which means that Mother Nature would have made an excellent mechanical engineer. Those of the folks who figure out what’s needed and then add four times more, just in case.

Now to stay comfortable, you have to lose those extra Btus, and you will do it in a very specific way. You’ll lose 100 Btuh by evaporation as you breathe and sweat. That’s because when water evaporates it takes heat along with it. You probably know that already because you are in the heating-and-cooling business.

Another 100 Btuh leaves your body by convection. When air moves across you it turns your body from a radiator into a fan-coil unit. When you sit under a ceiling fan you feel cooler not because the ceiling fan changes the temperature of the surrounding air, but because the air moving across your body causes Btus to leave your body. Fans are only effective when there are people in the room. Remove the people and the fans become useless. In fact, their motors actually add heat to the rooms they serve.

Okay back to your Btus. The rest of them, a big majority of 200 Btuhs, leave your body by radiation. You are hot stuff, even at rest, and you will send heat toward anything around you that is cooler than you are. If you touch your skin with a thermometer, you’ll find that your surface temperature is about 85°F. Stand next to something cooler than that and notice how you start to feel chilly. And the reverse is also true. Stand in front of a campfire and notice how you feel warm on one side and not so warm on the other side.

Which brings me to this late-March flight from Frankfurt, Germany to New York City.

I was at the big ISH show with a bunch of friends, some of whom do not know when t o push back from any table that supports food of any kind. And I mean ever. We were flying home on a very-full Boeing 747. I had my seat assignment, which was alphabetical based on the first letters of the last names of our group (which is why I blame the alphabet). I boarded the plane and walked down the aisle toward my seat. I couldn’t actually see my seat because (let’s call him) Mr. H had the window seat and Mr. G had the aisle. I had the invisible middle seat. It was in there somewhere between Mr. H’s fat upper arm and ham hock of a left thigh and Mr. G’s equally blubbery right arm and thigh. They saw me and smiled.

Now I am not a small man either, but next to these loads I look like a runway model. I did not smile back. “Put down the armrests,” I said.

“Ah, Dan,” Mr. H said. “Don’t be like that.”

I reached in and pulled down both arm rests, which went more in than down. They were overflowing the metal and not at all happy. I worked my way in (these men don’t rise easily) positioned my rear between the two mountains of lard and wiggled my way down into my seat. Their bulk closed over me like waves on the beach.

After a few moments, I felt like I was in a steam room. I shoved my elbows in both directions, having more luck with Mr. G, who was on the aisle. There wasn’t any place to shove Mr. H’s mass because he had the window. I have two words for you guys,” I said. “Jenny Craig.” They grunted.

It was a very long fight and when Mr. H reclined and fell asleep, he spread like sewage over me. So did Mr. G. I sat for hours under that blanket of flesh and thought about how much there is to learn about human comfort on an airplane.

First, we have this situation, which has to do with our bodies as radiators. I’ve probably said more than enough about that at this point so let’s move on.

The next thing you’ll notice when you’re flying high is the way your own body gives up lots of heat to the wall of the airplane if you’re sitting in a window seat. At cruising altitude, the outside temperature is about minus-50°F. You’ll use your blanket and perhaps an extra pillow to insulate yourself from that cold, even though the airplane walls are insulated. The colder it gets outside, the more difficult it is to keep the heat inside, and that speaks well for good insulation. And don’t you think that’s a wonderful analogy? Use it when you’re speaking to non-technical customers about heating systems.

If it’s daytime, what side of the plane will you be sitting on? Do you like the sunny side or the shady side? There are lessons there as well. Do you know the origin of the word posh? It’s actually an acronym, standing for Port Out, Starboard Home. It was the preferred side of the ship that rich folks requested when sailing from Europe to America. A POSH cabin meant you always had the warmth of the sun, whether traveling west or east.

So let’s say you’re sitting on the sunny side. It gets hot because the sun’s rays have a short wavelength that can pass through clear plastic. But once through, the waves hit things (like you) and become longer. As you pick up that radiant heat, you continue to lose heat in the ways I described before, but now you may have too many Btus within your body so you start to feel uncomfortable. You close the shade.

The next thing you notice is that the shade is getting very hot. That’s because the radiation is heating the air that’s trapped between the plane’s plastic window and the window shade. And if you’re paying attention you’ll realize that what you’re experiencing there is exactly what you experience when standing upon a heated floor that has radiant tubing stapled to its underside, with an air gap between it and the insulation below.

Feel free to use that example when talking radiant to your non-technical customers. They’ll get it.

And now that your brain is considering all of this, and as you continue to lose heat to the cooler things around you and to the air that moves across you, see if you can come up with some more ways of comparing the relatively complex aspects of heating and cooling to the ordinary objects and events that surround us. The everyday things.

That’s how you get folks to understand. That’s how you get them to nod. That’s how you get them to buy.

And for what it’s worth, Mr. G took my Jenny Craig advice and lost more than 100 pounds after that miserable flight.

Mr. H, on the other hand, continues to be a hopeless, but charming, load.


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