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ezmack ,

Lotta old Victorian homes and factories from that Era did the same thing (without water obviously just a big tower to catch the wind). More like an attic fan than an AC in those cases, still a pretty clever way to move air without electricity. Always impressed by how clever people were back in the old times

Lazz45 ,

I cant speak to other parts of the U.S. but where I am from, people would design their farm houses so that when you opened all the windows, the natural wind direction wanted to blow through your house and naturally “cool” it. Coming from a house with AC, it seemed like a shit system lol, but i guess compared to being roasted in your stuffy house, it was probably pretty nice

grue ,

Frankly, ceasing to design homes and factories that way was a mistake. Stack effect ventilation is no less of an important part of green building technology today than it ever was.

SpaceCadet ,
@SpaceCadet@lemmy.world avatar

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    yesimprogun ,

    I think the areas these were used in were fairly dry so they worked like swamp coolers.

    Jilanico ,
    @Jilanico@lemmy.world avatar

    I’ve read that these wind catchers were used to keep ice frozen in ice pits during summer.

    en.m.wikipedia.org/wiki/Yakhchāl

    Fun fact: Ancient Persia had ice cream like desserts enjoyed year round.

    min_fapper ,

    Your link is broken

    Jilanico ,
    @Jilanico@lemmy.world avatar

    Works for me 🤔

    obinice ,
    @obinice@lemmy.world avatar

    Works great 👍

    DarthBueller ,

    Amazing - I had no idea that anyone was making ice in the desert in BCE times. The wikipedia article seems to indicate that they did a lot of storing of ice in the Yakhchal structures - but it is confusing as to how they made it. It seems like they either gathered the ice from the mountains, or made it in outdoor shaded “ice pools” that were situated next to the Yakhchal. Surely the ice required winter desert temps to form? Otherwise how would the thermal mass of the ground ever get cool enough to allow ice to form, even with the magic of physics? The permanent shading helps, but year round-ice making surely wasn’t a thing, was it?

    Jilanico ,
    @Jilanico@lemmy.world avatar

    Seems like the ice pools were used for year round ice making at night. See the section on “Nocturnal ice making in early India and Iran”: en.m.wikipedia.org/wiki/Radiative_cooling

    MeanEYE ,
    @MeanEYE@lemmy.world avatar

    It’s called evaporative cooling and it’s quite potent since water takes enormous amounts of energy when changing states. It takes around 5x the energy to convert 100°C water into 100°C vapor than it takes to increase temperature of said water from 0 to 100°. This energy has to be taken from somewhere and that is from the environment, dropping the temperature as a result. Problem with these is that the humidity of the air increases. Not much of a problem in desert, quite a bit problem in other places.

    Here’s a great video explaining science behind evaporative coolers and how it can be modernized. www.youtube.com/watch?v=R_g4nT4a28U

    Just wind tunnels without water, I agree with you.

    JohnDClay ,

    Wind powered swamp cooler. Basically a humidifier, but it does lower the temperature. I’ve heard people call swamp coolers air conditioning, so I don’t think it’s wrong.

    boonhet ,

    No, calling swamp coolers air conditioning is definitely wrong.

    If it’s 100% humidity in your room, the swamp cooler is going to do absolutely nothing, but AC will cool it down and can even dehumidify a bit if you run it enough.

    Swamp coolers are awesome, but they only work in dry climates unfortunately.

    jerrimu ,

    No, it’s a swamp cooler, which is still used today in drier climates. This is a desert, so yes the air is not humid, and yes the water is cool because it’s underground. Stop being so pedantic.

    SpaceCadet ,
    @SpaceCadet@lemmy.world avatar

    deleted_by_author

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    Comment105 ,

    On the point of calling eachother names, you two are acting like redditors.

    Now you should really feel insulted.

    jerrimu ,

    Pedantic isn’t an insult, my bad. Really felt like you were just nitpicking, sorry.

    hamid ,

    LOL Your comment makes it seem like you don’t think that it could possibly work, except that these things are still there and you can go visit them right now and feel how cool it is inside the buildings.

    boonhet ,

    The water doesn’t actually have to be all that cool for swamp coolers, because it’s the evaporation that cools the environment and warm water actually evaporates quicker.

    Wilshire ,

    Iran used to have AC. They still do, but they used to, too.

    chili1553 ,

    All-encompassingly!

    ultimate_question ,

    I remember using something similar to that in college but if I recall correctly it was for weed

    hark ,
    @hark@lemmy.world avatar

    I love passive systems. The more passive the better.

    SpaceCadet ,
    @SpaceCadet@lemmy.world avatar

    deleted_by_author

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    hark ,
    @hark@lemmy.world avatar

    I assume the water here is doing the work. I didn’t say anything about a closed system, just passive. Maybe that doesn’t count as passive, I don’t know physics all that well.

    monz ,
    @monz@pawb.social avatar

    The person that replied to you is probably being scientific-literal and obnoxious. I understood what you meant just fine. :}

    Lazz45 ,

    I wouldn’t call it obnoxious, it’s just pointing out that they are using terms that don’t align with what they stated. If nobody ever mentioned the difference, how can they ever learn? Not saying everyone needs “taught” but it really didn’t seem malicious like you seem to believe

    Lazz45 , (edited )

    The water does not perform work in this instance.

    I do not think you’re trying to say the water “does work” in the physics sense, but to clarify, the water is just a large heat sink that has a much higher heat capacity than air. You can heat the water with air (which in turn cools the air), and that water can hold MANY times the heat (per unit mass) that the air can. Water also has a higher thermal conductivity than air. Allowing it to absorb and pass heat very well. This water is in the ground which also acts as a massive heatsink.

    The air passes heat to the water which then passes the heat to the ground effectively cooling your air feed. A quick look online says current soil temp in Iran 21 inches deep is 35C or 95 F. That is your lower temperature limit. It’s physically impossible to become colder than the soil temperature (in this instance, as that is your lower temperature bound for heat transfer, in reality you wont even get there, because your driving force for heat flow is gone at that point) without putting in mechanical work (which is what a compressor does in your air conditioner) to compress your cooling fluid so that it may be evaporated repeatedly to exploit the tranfer of heat into an evaporating substance

    Rodeo ,

    Why only 21 inches? Soil temps aren’t stable until like 6 feet down, and then it’s closer to 12 C.

    Lazz45 , (edited )

    That is the deepest depth I could find being actively tracked on the website I ended up on. I did not wanna do a deep dive into “great” average soil temp data lol. If you have a good source of data I will gladly change my comment to include the updated numbers. I wanted to say the average soil temperature at depth is ~50-55 degrees F, but I hopped online to make sure that was not a number that I know to be true due to where I live. Good to know that its roughly 6 feet where it stabilizes

    Rodeo ,

    If you go down deep enough the earth temperature is stable at 12 C. But I’m pretty sure that’s like thousands of feet down. Geothermal rigs drill 500+ meters (1600 feet) down. Having a hard time finding a source on the stable earth temp though.

    I mentioned 6 feet because it’s well below the frost line where I am, but I guess in that part of Iran they probably don’t have to worry about that.

    Mostly I was just wondering if you had found something on how deep those waterways were actually built.

    Lazz45 ,

    Yeah thats exactly the issue I ran into. I started googling stable soil temp to confirm what I thought, and rapidly ran into a lack of answers lol. Any data I could find for free on websites didn’t seem to go very deep.

    In terms of depth of the Qanats, yeah I was wondering the same. Without any modern tools I’m not sure how deep they would be willing to dig out (although I bet it’s easy digging in Iran, likely sand/dry dirt vs. clay and sopping wet boggy soil).

    I am at work but I’ll see if I can dredge up info on Qanat depth

    bouh ,

    The wind provides the work here. Wind and air flows.

    hamid ,

    These things are still there and if you aren’t an American you can go to them. They are very nice and cool inside.

    Eikichi ,
    @Eikichi@jlai.lu avatar

    Passive system doesnt mean u cannot play with thermodynamic laws, understand them and then cheat them (like they did) to make your passive’s system works.

    Smart vs Facility (and the scramble who go with it)

    Gork ,

    Smart vs Facility (and the scramble who go with it)

    My dude, I have no idea what you’re trying to say here.

    Eikichi ,
    @Eikichi@jlai.lu avatar

    Oh sorry, i meant “the destruction” bound to the facility by you know, capitalism. Because in my imagination an complex system would need more resources than the passive one, to be made.

    Is it clear now dude ^^ ?

    sci ,

    Not really mentioned in the picture but Qanats are basically underground aquaducts, bringing water from nearby mountains to the cities. They can be up to 70km long. We went into one when I visited Iran.

    argh_another_username , (edited )

    deleted_by_author

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    Gangreless ,

    A modern home ACs can only cool about 20f below the outside temperature. 50c to 35c is 27 degrees so that’s pretty damn good for a fancy unpowered swamp cooler

    Norgur ,

    Yeah, the thing is the "unpowered" part. Look how much energy an AC chugs to achieve that cooling. This tower uses wind power to do it's thing.

    janus2 ,
    @janus2@lemmy.sdf.org avatar

    well technically it is powered, just directly by wind and water kinetic energy, probably(?) much more efficiently than if it had been converted to electricity first

    Shikadi ,

    Do we know it’s more efficient? Has anyone done the math?

    irmoz ,

    Are you joking?

    Shikadi ,

    No, I’m being genuine. It’s theoretical and all, but if you were to put up a windmill in the same spot instead of a tower, it’s possible traditional air conditioners would be able to cool the building to the same degree while also providing surplus electricity. It’s also possible that you wouldn’t, and I don’t know the answer. It would also be interesting to compare it in different ways as well, like rather than asking “If a windmill was here” we could ask “The energy removed from the wind by the tower”, because that would indicate scalability problems if one windmill was indeed able to cool one building, but maybe 100 wouldn’t be able to cool 100. All hypothetical, but air conditioners/heat pumps are actually very efficient, so it’s possible an active design could be more efficient than a passive one in this situation. At least, until someone does the math

    hamid ,

    Another thing to note, to your point, is that a windmill breaks down and requires energy to repair. These wind towers in Yazd are still there and doing the same thing from hundreds of years ago

    janus2 ,
    @janus2@lemmy.sdf.org avatar

    Very true. The best machines have the fewest moving parts

    Shikadi ,

    True, and it wasn’t meant as an attack at all, just a question out of curiosity. The towers are super cool

    janus2 ,
    @janus2@lemmy.sdf.org avatar

    Exactly, I have no idea. The “probably(?)” in my comment should have been a “maybe,” probably maybe.

    Duder167 ,

    The AC is also small compared to a literal building with a sewer underneath and doesn’t require a windy day. Trade offs

    Lev_Astov ,
    @Lev_Astov@lemmy.world avatar

    AC really doesn’t consume that much if designed and sized properly. It’s nothing like the energy consumption of standard heating. The problem is all these people going out and buying the cheapest floor unit or undersized window unit they can find, then the wheezing thing just sits there chugging 100% of the time because it can’t keep up with their space. That’s super wasteful.

    manillaface ,
    @manillaface@kbin.social avatar

    What’s your source for this? It routinely gets over 100 here and buildings aren’t 80 degrees inside.

    sab ,

    We're talking celsius, I hope for your sake it doesn't routinely get to 100 C where you are. :)

    Edit: The user actually said 20 F, I got confused by the mix of units. "50c to 35c is 27 degrees" didn't make sense to me, but I figured I'd let it slide. No idea what's going on here. :)

    argh_another_username ,

    deleted_by_author

    •
    sab ,

    Yes, that sounds about right - the relative effect of the tower probably depends a lot on various factors like how windy it is, if extreme heat occurs only for a day or if it has been ongoing so that the water under ground is heated as well, etc.

    These comments were in response to @Gangreless, who stated that a modern AC "can only cool about 20f below the outside temperature". I didn't catch that it was fahrenheit first, and now that I know I am happily backing off rather than having to think in terms of freedom units.

    Dark_Arc ,
    @Dark_Arc@lemmy.world avatar

    They’re full of it, that’s it. Maybe in their house which lacks sufficient insulation. Heat pumps (i.e. air conditioning) are/is extremely efficient at moving heat around, there’s not really a practical limit on it, particularly if you go geothermal.

    ezmack , (edited )

    20 degrees is just a rule of thumb most ACs have a specific temperature change they’re designed to do. You can go past it, that’s just what the intented to do and it might not work as well or be able to do it. Fwiw I’d always heard 30 degrees farenheight for most window units. Had an hvac guy explain it to me years ago but fucked if I remember how it works

    E: not sure why I’m getting downvotes this is like a very common thing. Google it frederickair.com/…/reduce-the-stress-on-your-ac-w…

    sci ,

    pretty sure 50c to 35c is 15 degrees

    pfannkuchen_gesicht ,

    I wonder how he got his number, it makes no sense.

    EDIT: oh, he just randomly mixed °C and °F, because why not…

    yeather ,

    Fucking Americans

    MrBakedBeansOnToast ,

    It’s the Mars Climate Orbiter all over again.

    Duder167 ,

    50c is 122f, 35c is 95f so he went 50c-35c = 122f-95f = 27f because why the fuck not.

    hairinmybellybutt ,

    ok, but the cost of building a quanat is still pretty high and is not trivial to achieve.

    Can’t have water flowing everywhere in a country for this to work.

    egonallanon ,

    Most countries in the world quite literally have water flowing everywhere already.

    dingus ,

    But don’t “swamp cooling” systems like the one in the OP not work well in humid environments? Sure, I have running water at home, but I also live in an incredibly humid climate.

    egonallanon ,

    I was more imagine something like the opposite of a district heating system and then using colling ponds or towers to disappate the heat from the system…

    bouh ,

    Don’t you have water to drink at home? Or in the bathroom?

    grue , (edited )

    Modern plumbing uses pressurized pipes that are completely full of water, and can thus flow uphill, as long as the elevation gain doesn’t exceed the head pressure from the water tower or pumps. That makes such pipe systems relatively cheap and easy to build.

    In contrast, qanats require large conduits with space above for the air to flow through, using open channel flow. That means the entire system needs to be designed with a gentle downhill monotonic slope. That’s doable (the wastewater and stormwater sewer systems are designed that way, for example), but it’s more expensive and would require a lot of re-work if you wanted to convert over the existing water distribution system.

    monz ,
    @monz@pawb.social avatar

    What do you mean modern AC can only cool by 20F?

    I’m in Florida and it’s routinely 95-98F outside. My AC is set to 65F.

    Did you mean 20C? Either way, that’s also false. AC units are limited to their rating and BTU. Many may not cool below 60F, but there’s no delta limit.

    RBWells ,

    Heat pump doesn’t do that for us. We set it at 78-79f in the summer and it feels cool enough & keeps the house from molding.

    Evaporative systems like the one pictured only work in the desert though. So if you have lots of water, it’s humid and you can’t use evaporation to cool, but in places you can use evaporative cooling, water is scarce. It’s still very cool tech, and everywhere can benefit from more intentional design of buildings.

    Zron ,

    Your heat pump will definitely do it, it’ll just take a long time.

    The 20 degree figure everyone is throwing around is actually supposed to be the difference between the return air temperature and the supply air inside your home

    If you have 80 degree air in your house, 60 degree air should be coming out of your vents. Once the 60 degree air has cooled down the house to 70 degrees or so, 50 degree air should be coming out of your vents. And that’s about the theoretical limit for home air conditioning, as anything lower means the cooling coil is below freezing and will get damaged by ice, there’s usually a safety switch that prevents things from getting too cold.

    Now the outside coil needs to be hotter than the surrounding air to actually push that heat out of the coil and cool off. Most places around me are designed for a 95 degree summer day, so will have a refrigerant temperature of about 120 degrees, in order to move that heat. Your compressor needs to be able to compress the refrigerant from your cooling coil until it’s about 30 degrees F hotter than the outside air. The hotter it is outside, the harder it is on the compressor. But it will eventually do it if you let it run long enough. Whether or not you want to pay for all that electricity is another thing entirely.

    dingus ,

    Are you my brother? Whenever I go to his place I feel like I’m going to get hypothermia lol

    WhiteTiger ,
    @WhiteTiger@lemmy.world avatar

    That’s just not true, a modern home can be at 70f or below when its 110f outside. Air comes out at 50-55 even at those outside temps.

    Aux ,

    You’ve got a lot of great replies on how you’re a wrong. But it is even simpler - your freezer works the same way as air con. And it’s at -18°C even if your room is at +35°. That’s all you need to know about air cons and their capabilities.

    WhiteTiger ,
    @WhiteTiger@lemmy.world avatar

    And get it has way more upvotes than down, just like reddit.

    Aux ,

    Reddit is sipping here at a rapid pace…

    sab , (edited )

    10 degrees is incredible though.

    These days in Yazd the average warmest temperature in July is 40 degrees, so if what you're saying is correct they'd be able to cool it down to a liveable 30 degrees even in the warmest part of the day. And at night temperatures still dip to 26, so the indoors temperature probably wouldn't quite reach 40 even without this system. So it might make the difference between 40 degrees outdoors and high 20s indoors, which is fantastic.

    Would be interesting to know if average temperatures got up to 40 in the summer around the time they were built as well, or if average temperatures in the region have been rising.

    SloppyPuppy ,

    I do wonder what the humidity is. The drawing shows that the new air is mixed with air coming from the water canals below which I assume is very humid.

    Looks like its essentially a swamp cooler.

    So I wonder how the 30 with humidity feels compared to 40 without.

    Im now at a 32 but with the current humidity it feels like fucking 38!

    deus ,

    Well, Iran is mostly a desert so I assume the air must be very dry.

    Swedneck ,
    @Swedneck@discuss.tchncs.de avatar

    That would be another benefit of having the water underneath evaporating up, increasing air moisture.

    luthis ,

    And what wind strength is required to achieve 10C decrease

    pfannkuchen_gesicht ,

    What a bunch of idiots! They should’ve just installed AC units.

    Mereo ,

    I hope that was a sarcasm, if so, add /s.

    Shikadi ,

    I think at some point the /s isn’t needed

    Aux ,

    Muricans and their need for /s…

    Mereo ,

    It’s the internet, you never know. In person, by how the person behaves, you know if he’s being sarcastic or not. On the internet, not so much. It’s just text and I’ve seen people who were quite serious.

    Steeve ,

    Oh man, I can’t believe ancient physics powered cooking techniques weren’t as efficient as the electrically powered cooling that we have today, those idiots

    BlazeMaster3000 ,

    Iran’s traditional desert architecture masterfully navigates extreme temperatures through a combination of smart design and local building materials like mud-brick or adobe, which possess low thermal conductivity similar to sand. The thick walls of these houses act as a thermal mass, absorbing the intense daytime heat and slowly releasing it during the cooler night, regulating temperature swings inside the dwelling. This principle, paired with the utilization of design features like wind towers and qanat systems, helps to maintain a comfortable indoor climate. Some structures are even partially or completely built underground, using the earth as a natural insulator and benefiting from the surrounding cool sand. Consequently, it’s this strategic interplay of materials, design, and the desert environment that enables these homes to remain cool during scorching days and warm during chilly desert nights. This is a gross oversimplification of thermal dynamics but it’s the gist of it. It would be quite comfortable inside is what I am getting at.

    Szymon ,

    Might not be a shivering 16 Celsius inside, but if it’s the difference between dead and alive then it’s probably good enough.

    bouh ,

    There is a note where I work that says the AC will not cool lower than 10C below outside to save on energy…

    notenoughbutter ,

    35 is livable while you would be cooked alive in 50

    hamid ,

    You can literally go there and witness these for yourself. It works. People live in Yazd right now in these old buildings. Newer constructions have air conditioning because building huge thermal mass retaining walls out of mud bricks is expensive. They keep ice all winter in buildings there from a thousand years ago cooled like this.

    grue ,

    Wikipedia claims “greater than 15 °C.” Besides, even if you supplement it with air conditioning, that’s 15 °C less ΔT worth of electricity you have to pay for.

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