WEBVTT - Short Stuff: Yakhchāls - Ancient Fridges

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<v Speaker 1>Hey, and welcome to the Short Stuff. I'm Josh, and

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<v Speaker 1>there's Chuck Jerry sitting here free Dave, and so this

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<v Speaker 1>is short stuff. How do you say this again?

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<v Speaker 2>Edition, Yeah, I'm gonna say it's pronounces spelled y ak

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<v Speaker 2>h you know, as most words are h A L.

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<v Speaker 2>I'm gonna say yakuls.

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<v Speaker 1>I'm going with the straight ahead yakh chaws. All right, Okay,

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<v Speaker 1>so you say your way throughout. I'll say it my way,

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<v Speaker 1>and I'm sure all inevitably unconsciously start saying it your way.

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<v Speaker 2>We'll see. But what we're talking about is the promise

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<v Speaker 2>from our refrigeration episode. A little bit more on these

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<v Speaker 2>ancient basically ancient refrigerators or cooling systems. They were found

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<v Speaker 2>across ancient Persia at least as old as four hundred BC.

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<v Speaker 2>This is modern day Iran, and this is these are

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<v Speaker 2>places where, I believe it or not, the climate enables

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<v Speaker 2>freezing of ice when you would not think you should

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<v Speaker 2>be able to freeze ice.

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<v Speaker 1>Yeah, it's pretty amazing and apparently still today in Iran,

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<v Speaker 1>Afghanistan and to Jikistan, to jeek Stan. Yeah, I said

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<v Speaker 1>it right. The first time they called the refrigerators yak Chile's,

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<v Speaker 1>which is how I would say it if I were

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<v Speaker 1>in Iran. But that's the name for the fridge, which

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<v Speaker 1>means that at some point someone in Iran has gone

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<v Speaker 1>into a store and said, you got a smeg yak chaw?

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<v Speaker 2>Yeah, exactly. And these have been the fascination of like

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<v Speaker 2>everyone from engineers to historians to physicists over the years

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<v Speaker 2>because they're just so kind of confusing and how they

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<v Speaker 2>actually work. And I'm still not entirely sure how it works.

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<v Speaker 2>It seems to be a little magic involved. One thing

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<v Speaker 2>I know goes a long way toward keeping this ice.

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<v Speaker 2>And we got to say some of this ice is

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<v Speaker 2>mined from the mountains, brought down and preserved. Some is

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<v Speaker 2>made on site. We'll get to that, but one big

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<v Speaker 2>factor is the insulation of the structure itself, which is

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<v Speaker 2>made from a mortar called serrouge.

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<v Speaker 1>Was that how you're saying it?

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<v Speaker 2>Sand, clay, egg whites, lime, goat, hair and ash quite

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<v Speaker 2>a mixture.

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<v Speaker 1>Some of these were several meters thick. Some of these

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<v Speaker 1>yak chaws were. There was a study. We got some

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<v Speaker 1>of this information from the engineering for Max Fordham and

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<v Speaker 1>they did an analysis from twenty eighteen of yak Child's

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<v Speaker 1>and just how effective they might have been. And they

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<v Speaker 1>found that the walls of a yak chaw had the

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<v Speaker 1>same insulative properties as a wall of concrete three inches

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<v Speaker 1>thick surrounded by a one foot thick wrapping of styrofoam insulation.

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<v Speaker 1>That's how effective these things were.

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<v Speaker 2>Sand, clay, egg whites, lime, and goat hair and ash.

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<v Speaker 1>I was gonna say, like the secret egg whites, but

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<v Speaker 1>who knows you throw goat hair in there, and yeah,

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<v Speaker 1>who knows what the secret? I think the secret is

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<v Speaker 1>the whole thing together, the whole say rouge mysture?

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<v Speaker 2>Yeah, probably so so I mentioned that sometimes the ice

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<v Speaker 2>was brought in from the mountains and kept there throughout

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<v Speaker 2>the year. But usually what would happen is is they

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<v Speaker 2>would make ice, They would bring in water. They would

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<v Speaker 2>divert water from an aqueduct through these underground water channels

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<v Speaker 2>called cannots, and they would channel them to the north

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<v Speaker 2>side of this wall. It's another thing we haven't mentioned

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<v Speaker 2>yet is they have these very very high walls that

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<v Speaker 2>act as shade for these channels to keep you know,

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<v Speaker 2>the wind off of it, because stuff isn't going to

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<v Speaker 2>freeze as fast if it's moving, so to keep the

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<v Speaker 2>water still and to keep it cooler away from that sun.

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<v Speaker 1>Yeah, And so the channel has a little diversion into

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<v Speaker 1>a trench or a pit or like a very shallow

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<v Speaker 1>like rectangular pond usually, and it they'll divert water in

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<v Speaker 1>there to fill it up, and then they let it

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<v Speaker 1>freeze overnight. Over the course of a few nights, it'll

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<v Speaker 1>continue to freeze and freeze and freeze in layers. And

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<v Speaker 1>the what they're taking advantage of, you know, like when

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<v Speaker 1>it snows and then the temperatures heat up and all

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<v Speaker 1>the snow melts, but there's a little pile of snow

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<v Speaker 1>like in a shaded corner of your yard that never

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<v Speaker 1>gets direct sunlight. Yeah, and it just takes forever to melt.

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<v Speaker 1>There can be advantage of the same thing. They're building

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<v Speaker 1>that big old that big old wall to keep it

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<v Speaker 1>shaded and to just let this ice grow and grow

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<v Speaker 1>and grow. And then once it reaches I think fifty centimeters,

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<v Speaker 1>which is like about a half a meter thick, then

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<v Speaker 1>they'll cut it into blocks and they put it in

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<v Speaker 1>the yac shell and they store it through summer. Like

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<v Speaker 1>this stuff will stay frozen for an entire summer. So

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<v Speaker 1>in in that sense, these yak chails are built to

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<v Speaker 1>store cold throughout the course of a year, even when

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<v Speaker 1>the summer comes around still cold.

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<v Speaker 2>Yeah. Another way that helps us out is that dome shape.

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<v Speaker 2>It's not domed because they like domes, even though domes

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<v Speaker 2>are nice. It's conical because that optimizes what's called the

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<v Speaker 2>solar chimney effect. Is that's when you create a convection current,

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<v Speaker 2>letting that heat go up, up, up and out through

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<v Speaker 2>these openings at the top and bringing in that cool

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<v Speaker 2>air from the bottom.

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<v Speaker 1>They also have wind catchers that they call bad geers,

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<v Speaker 1>and they actually take win and direct it downward into

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<v Speaker 1>the yakchaw dome. And so the air that hits it

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<v Speaker 1>is cooled by that ice, and the air that's not

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<v Speaker 1>cool by it, or cooled enough, like you said, that

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<v Speaker 1>chimney effect takes it up along the curve sides toward

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<v Speaker 1>the hole in the top, and it says, see you later,

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<v Speaker 1>don't come back.

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<v Speaker 2>That's right, And that feels like a good time for

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<v Speaker 2>a break, and we'll come back and talk about what

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<v Speaker 2>the heck they're doing with all this ice. This all right,

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<v Speaker 2>So they're making ice, they're preserving ice. What are they

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<v Speaker 2>doing with all this ice? One of the things they're

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<v Speaker 2>doing is using it as a refrigerator. You know, they'll

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<v Speaker 2>store food in there that they don't want to go bad,

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<v Speaker 2>and just using it as a as a cold house.

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<v Speaker 2>They will also just use the ice to eat in

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<v Speaker 2>a treat. They have something called Feluda over there, to

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<v Speaker 2>Persian traditional dessert has thin vermicelli noodles made from cornstarch,

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<v Speaker 2>and then you mix that up with a little semi

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<v Speaker 2>frozen sirr of sugar and rose water, and then serve

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<v Speaker 2>it up with a little lime juice and maybe some

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<v Speaker 2>ground pistachios. And it's like a little Persian icy.

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<v Speaker 1>That has to be better than it sounds, don't you think?

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<v Speaker 2>Oh I think it sounds great.

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<v Speaker 1>I think the pistachos are where of throwing me off.

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<v Speaker 2>Oh yeah, you don't like pistashios.

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<v Speaker 1>Or I do like pisachos. It just they don't seem

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<v Speaker 1>to go with the rest of the ingreen eent. But

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<v Speaker 1>like I said, I'm sure it's delicious. I mean, it's

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<v Speaker 1>a traditional Persian dessert. It's got staying power. So yeah,

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<v Speaker 1>who am I to question for luda exactly?

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<v Speaker 2>I bet it's delicious.

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<v Speaker 1>One of the cool things about this is that yak

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<v Speaker 1>charles I mean, and there's some still around. I think

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<v Speaker 1>there's one in Kerman, Iran that's about the size of

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<v Speaker 1>a five story building. So you would think, of course,

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<v Speaker 1>obviously this was reserve for royalty. You would be dead wrong,

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<v Speaker 1>because not only were yakchels open and available to the public,

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<v Speaker 1>there are some that people just built for their houses

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<v Speaker 1>that were a private use of as well.

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<v Speaker 2>Yeah, for sure, they would make those delicious falluda. They

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<v Speaker 2>would make surbets and preserve them and then nuts, fruit

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<v Speaker 2>and ice and they would put them on a donkey

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<v Speaker 2>and go sell them at market and stuff like that.

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<v Speaker 2>They would sell ice directly from those places sometimes. And

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<v Speaker 2>you know, one of the things they're also taking advantage

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<v Speaker 2>of is the greenhouse effect. You know, the earth is

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<v Speaker 2>going to stay fairly warm at night because of the

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<v Speaker 2>greenhouse effect trapping those gases in the atmosphere. But if

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<v Speaker 2>it's low humidity and if it's a really clear night,

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<v Speaker 2>that effect is going to be weaker and that heat

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<v Speaker 2>can dissipate and disappear more readily. And so that's when

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<v Speaker 2>they discovered, like, hey, we can make these little thin

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<v Speaker 2>layers of ice and kind of build, you know, day

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<v Speaker 2>by day, night by night on these clear, low humidity nights,

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<v Speaker 2>eventually to get you know, some pretty significant ice.

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<v Speaker 1>And once they figure that out, someone said, go get

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<v Speaker 1>the donkey. Exactly, it's time to sell some Subert and

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<v Speaker 1>harvesome goat hair. One other thing I saw in that

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<v Speaker 1>Max Fordham analysis, they figured out that they could make

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<v Speaker 1>about what would be equivalent to three million ice cubes

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<v Speaker 1>a season.

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<v Speaker 2>Wow.

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<v Speaker 1>Yeah, which is a lot. But they were like, you'd

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<v Speaker 1>think it'd be more, and I was like, it seems

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<v Speaker 1>pretty good to me, especially in four hundred BC.

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<v Speaker 2>You know, it depends on how big those cubes were.

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<v Speaker 2>Were they big fancy cocktail cubes. That's a lot more

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<v Speaker 2>ice than a ice nugget.

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<v Speaker 1>That's right, You're absolutely right. I expect that they're probably

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<v Speaker 1>all donkey head size. So three million donkey head size

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<v Speaker 1>ice cubes, that's big. Think about the poor donkey that

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<v Speaker 1>had to cart those around. I know, no fun, you

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<v Speaker 1>got anything else?

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<v Speaker 2>Yeah, I mean these went away obviously because of modern

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<v Speaker 2>refrigeration came on the scene. And also one thing that

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<v Speaker 2>was happening was they were making this ice kind of

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<v Speaker 2>out in the open, and a lot of it would

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<v Speaker 2>get contaminated with dust and it wasn't like the healthiest

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<v Speaker 2>ice in the world. And so that combined with modern

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<v Speaker 2>refrigeration coming along, they're like, maybe we should just not

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<v Speaker 2>have these much anymore. But like you mentioned, there is

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<v Speaker 2>one still around, at least in Kerman, and there are

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<v Speaker 2>groups there that are trying to preserve this way of

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<v Speaker 2>life and at least keep it, you know, not like

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<v Speaker 2>a chief refrigerating method, but like, hey, we can't lose

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<v Speaker 2>our culture, and so let's work to take some of

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<v Speaker 2>these old ones and restore them at least, even if

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<v Speaker 2>only for like museum and touring purposes.

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<v Speaker 1>For sure, but also there's a lot to learn from them,

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<v Speaker 1>especially when we're trying to advance like passive cooling and

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<v Speaker 1>other things that require less energy to cool things down.

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<v Speaker 1>Yak Chaal's are something to turn to and say how

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<v Speaker 1>do we do this? And someone says, go get the

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<v Speaker 1>goat here.

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<v Speaker 2>That's right, we'll get some egg whites too. No one

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<v Speaker 2>likes this.

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<v Speaker 1>What do we do with all these yokes? Yeah, well,

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<v Speaker 1>I think that's it for short stuff, right, Chuck?

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<v Speaker 2>I think so?

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<v Speaker 1>Well? I mean short stuff is that.

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