Ancient Persian Technological Inventions | Iran

Windmills were first invented and used in ancient Persia in what is modern day Iran. Those Persians man, they made the wind catchers which is a form of ancient air conditioning in the city of Yazd more than 3000 years ago. Then they made the first freezers known as Yakhchals around 400 BCE and now they also have invented the windmill. Hot damn they're good at inventing. How did the inhabitants of the hot Iranian desert keep themselves cool during the intensely hot summers where even being in the shade is very uncomfortable? Well besides the wind catchers that is that they had in their homes that we spoke about a while ago. Think about being in the middle of a hot dry desert, it would be a blessing to be able to drink a cold beverage or to eat some ice cream to cool off. Or to keep your meat, dairy, fruits and other foods fresh for longer periods of time by cooling them. But I'm hearing you ask yourselves, ice, how would you be able to provide ice in the middle of a hot and dry desert? The answer to that is simple yet innovative, build a Yakhchal. No I did not sneeze, I said Yakhchal. A Yakhchal is an ancient Persian invention that literally means ice pit, Yakh meaning ice and Chal meaning pit. My name is Kayleigh and today we're going to look into the Persian invention of ice houses in the middle of a hot Iranian desert. I do want to note that in the southern parts of Iran where the temperature rarely gets below zero there were no ice houses and along the Caspian shores there were never ice houses as well. The climatic conditions didn't lend themselves for ice to form nearby, therefore ice houses were not an option there. For this particular video we're going to focus on Yazd again, which we covered in the ancient air conditioning video. We're going to look into this type of architecture, the materials used here and how these ice houses work. There are many forms of ice houses found in Iran and other parts of the world, I might look into the different architectural styles in a separate future video, but for this particular one we will focus mostly on the Yakhchals from the area of Yazd. We don't know for sure where the first ice houses were built on the planet and we're also not sure of when the first ice houses were built. We do know that around 400 BCE the Persian engineers were already mastering the art of storing ice in the middle of the desert, it was already a widespread phenomenon around this time. This shows that the actual invention of the Yakhchal happened much earlier as you don't master something by doing it for a short amount of time, but it's unfortunately unclear for how long. The practice of storing ice itself was already long established by the time of 400 BCE, we know for a fact that the Mongols were already storing ice for quite some time, although again it's unclear for how long but there are accounts of them doing it before 400 BCE. Ice was also mentioned in older texts in Iran from before 400 BCE, but there was no mention of how it was produced, which doesn't allow scholars to interpret that as Yakhchals already being used for very long before 400 BCE, although it is of course hypothesized as I said earlier, you don't master something by doing it for a short amount of time. There is always a difference in evidence pointing to something which leads to a hypothesis that may or may not be proven to be true, but this same evidence should not allow to be interpreted as anything factual without the proper investigation and corroborating evidence pointing to said interpretation. This is to me personally my favorite type of historic investigations, I love hypothesizing and theorizing a lot, but you will never hear me say that I know the answer or that I'm certain beyond a reason of doubt, because there will always be doubt until proven otherwise. In the traditional architecture of the Persians in Iran it was incredibly important to them to create safe living conditions for the inhabitants, the climate in this part of the world can be absolutely brutal. We've seen with the wind catchers they were great engineers with a lot of skills and they knew how to survive the climatic conditions. So let's take a look into what materials the Persians used to create these yakchals. The walls of the yakchal are made from a special kind of mortar called Saruj, this special mortar is made from sand, clay, egg white, lime, goat hair and ash, the ash actually acts as an insulator. These walls can be as thick as 2 meters, this makes the temperatures inside stay as low as possible. You can see a large dome shape above the ground, but this is only part of the yakchal, the rest of it is underground where a storage space is located. This storage space is mostly used for ice and sometimes used to store food, although food really isn't stored in it often. The Yakchal has a shading wall running east to west and a canot that runs all the way from the mountains to the north side of the wall in the shade. As I explained in my ancient air conditioning video, a canot is an underground aqueduct which transports water to the surface. In the case of these yakchals it transports water from the mountains to the yakchals. In the winter a few inches of water is then collected in a pool each day that by morning will be frozen due to the cold night temperatures. The villagers break the ice in the morning and bring it inside the yakchal to store it. This is repeated each day during the short winter time until the yakchals are full. Another way to fill the yakchals with ice was to collect the ice straight from the shaded parts of the mountain, transport it to the yakchals and store it inside. The ice stored inside could be kept cold throughout the year, even in the hottest summer days it would still be incredibly cold inside the yakchal. The combination of the thick walls, the cool waters that ran down its side and sometimes the combination with wind catchers and wind towers kept the stored ice frozen throughout the entire summer. Inside at the bottom of the yakchal would be a trench, this is where the melted ice would be caught and during the cold desert nights it would freeze again. A yakchal usually had 2 entrances, one was located between the pitfall and the frozen area on the north side with a sloped surface, making it easy to transport the ice into the yakchal. This northern entrance was almost exclusively used in winters to fill the ice house. The other entrance was at the south side and was almost exclusively used in the summers. It had a staircase leading down into the yakchal, making it easy to access the lowest parts of the pit and to serve and sell ice. During the hot summer days the ice from the yakchals would be used to chill food and treats like for instance a traditional frozen Persian dessert known as Falude. These ice houses weren't just for the upper class but most of them were actually public, everyone was able to use them during the hot summer days. Shops and villages would use the ice from the yakchals to keep their fruits and sherbets cold and huge chunks of ice would be transported by donkey and sold in the province. We know of yakchals still being in use in the 1960s, but unfortunately since then they've all fallen out of use. A true shame that when industrialization became widespread in the area and people getting common refrigerators at home these yakchals became an abandoned eyesore to many. The ice from a yakchal wasn't as clean as the modern techniques, the ice was often tainted with dust and soil because it was created in open areas in the middle of a desert. So it's not that strange that they've fallen out of use, although it is of course a shame that most of them are now deteriorating rapidly. Some yakchals have been restored as we can see in the cities of Kerman and Orumi, this is to show visitors of the city the uniqueness of these ice houses and the ingenuity of the Persian builders thousands of years ago. Once again Iran showed us it's traditional architecture which originated from the harsh and severe climatic conditions in which the inhabitants survived for thousands of years. Their architectural style evolved due to climate being the most important factor for their evolutionary building styles and inventions. They were masters in keeping themselves cool in a place that could be considered uninhabitable without the knowledge they possessed. The best part is that everyone in the village was able to benefit from the ice houses, they would all come together to make and harvest the ice in the winter that they then could all use in the summer. In our modern day and age we can still use the invention of these ice houses and try to make them function once more with a modern twist. It would be a great way to be able to provide ice without the use of energy like we do in modern times. Scholars and researchers are actually trying to figure out a way to make this viable in the future. Before I end this video I would like to note that the 3d renders that you've seen throughout this video were created by the creator behind the channel found and explained here on youtube. He also made the 3d renders and the blueprint for the windcatcher video that I think most of you have seen. I want to thank him for creating these renders for me to use and if you'd like to see more of his work which I highly recommend checking out his channel is found and explained and I've put a link in the description down below and his latest video is in the end card. It's really kind of him to create these renders for me and for all of us to enjoy his work. Someone asked me that I can do a cross eye with one eye, I can do a cross eye with one eye but like with both eyes so I can do that and that. Could a 3000 year old invention keep us cool in modern times? The answer to that is yes, ancient technology could play a huge role in our modern lives if the researchers, engineers and architects figure out a way to make this doable in all locations. Of course we have to take microclimatic conditions into account and it does rely on local weather but it could possibly be that windcatchers may be the air conditioning of the future. My name is Kayleigh and today we're going to look into the ancient windcatchers of Yazd, a city in Iran with some unique Persian architecture. The nickname for the city of Yazd is the city of windcatchers, but it's also well known for its underground channels transporting water called Qanats, its ice houses known as Yakhchals and its traditional reservoirs storing water known as Ab-Anbars. These are the features that made the inhabitants of this city survive the hot desert climate. On a yearly basis there are only 23 days of precipitation with a total of 49 millimeters making this the driest major city in the entirety of Iran. In this particular climate it's extremely important to keep yourself cool, luckily the Persians were masters in keeping their heads cool it seems. The inventions of ancient windcatchers may have happened in ancient Egypt around 3100 BCE during the early dynastic period. But Yazd is the city with possibly the most windcatchers in the world as they were one of the biggest reasons this part of the Iranian plateau became inhabitable. It's a shame that many of the city's windcatchers have fallen out of use over time, but the city did draw scholars, engineers and architects to it to possibly aid in our modern dilemma of air conditioning use and how that is affecting the climate. Because windcatchers don't need electricity to function they could be incredibly important in areas where the electrical grid is unreliable and expensive. It would even make air conditioning available in places where there isn't even electricity. Windcatchers can look vastly different depending on their location and the climate, they can have one opening on one side without internal partitions when there is a prevailing wind direction. But in areas with variable wind directions there may be openings on all sides with radial internal walls, this divides the windcatcher into vertical sections. These vertical sections may reduce the flow rate of the wind, but they do increase the efficiency at poor wind angles. If the wind hits the opening full on it goes in, but if it hits the opening at a wrong angle it can bounce off the corner and flow around the tower instead of going in. Areas with regular strong winds have small cross sections while areas with hot winds have smaller shafts to cool the incoming air. The windtowers with horizontal square cross sections are more efficient than round ones. Sharp angles make the flow less streamlined which encourages flow separation. The tall windtowers catch the higher winds that flow stronger, are cooler and are less dusty on average. Although with some windcatchers dust can be dumped at the bottom as the air slows down, with added mesh or plants more dust can be filtered out if needed. In areas where the wind is dusty or polluted or if there are insect borne illnesses like malaria for example, the air filtering may be a necessary part of the windcatcher system. Actual filters will reduce and disrupt the flow, unless it's harsh winds. Of course there are ways to close the windcatcher off partially or completely, you can see that system right here, it's quite fascinating. Some windcatchers are octagonal but their shape might be chosen for aesthetic purposes rather than efficiency. The shape of the tower, the layout of the house, how many openings the tower has, the internal blades and sections, the height and the direction in which the tower is facing are all specifically adjusted to improve the windcatchers ability to draw the wind down into the rooms of the building. Some buildings have a subterranean pool where the air flows over for further cooling, which I personally think is a smart option if you have the room for it. Now that we know what these windcatchers can look like, it's time to look into how they work. The short answer is that they don't have one particular function, but a whole array of functions. I will probably make a video in the future where I will take an in-depth look into all the different functions and workings of these windcatchers, but for this particular video I like to keep it short and simple. To explain the workings in the simplest way possible it goes like this. A windcatcher is never alone, it always is accompanied by another windtower on the same building. The windcatcher catches the wind which is then funneled down and will flow throughout the building. The cool air will flow underneath the warm air and the pressure will push the warm air upwards, which then rises and flows throughout another windtower which in turn releases the warmed up air. Then there is the so cutely called night flushing. Now I know that night flushing doesn't necessarily sound very cute, it sounds like you just woke up in the middle of the night, walked up to the toilet, took a pee, flushed and you know, did your business. That's not, that's not this type of night flushing, thankfully. Night flushing means that the cool air outside will increase the ventilation inside as the cool air gets dragged inside replacing the warm air and pushing the warm air out of the windtowers. In a windless environment a windcatcher can function by using the stack effect due to the differences in density from the air inside and outside. As the warm indoor air rises throughout the building and escapes through the windtower it reduces the pressure at the base of the building, drawing in cold air through open doors and windows. The stack effect is reversed during the cooler seasons although a lot weaker because the temperature differences will be lower. And lastly we will look into evaporative cooling mostly used in hot and dry climates for instance like Jast. With this type of cooling there is a body of water near the air intake where the air has to flow over the water before it reaches the inside of the building. Fountains in hot and dry climates are actually the opposite of fireplaces in cold and wet climates. Usually windcatchers that are used for evaporative cooling are combined with a canut, an underground canal. This particular windcatcher will be facing the wind head on, they might be adjusted by opening or closing directional ports on the top, this draws the air inside. There will be a larger windtower at the end of the directed flow that will pull the air out. This suction will make the wind travel through the canut where it's by coming in contact with the cold earth and cold water. The air is evaporatively cooled at the same time when some of the water evaporates when the hot and dry surface air flows over it. This humidifies the dry surface air before it flows through the building. It's then sucked into the building where it decreases the temperature inside before it flows out through the large windtower. Possibly the largest windcatcher in the world stands at Dolat Abad Gardens in, you guessed it, Yazd. This is an 8 sided windcatcher with a height of nearly 33 meters. Windcatchers have been gaining some slight popularity in western architecture over the years. Some of these modern windcatchers use sensor controlled moving parts and some use solar powered fans to switch between ventilation and cooling systems. There are some unusual looking ones that are being constructed in modern times, like the windcatchers at the University of Doha in Qatar as you can see here. It may very well be possible that we can replace a huge percentage of modern air conditioning systems with windcatchers. It would not only be more environmentally friendly, but it would also be cheaper in the long run and you don't need an electrical grid to rely on. If power were to suddenly go out, the buildings will keep being cooled by the ancient technology behind the windcatchers. Best part of this all, designing and constructing a windcatcher will cost approximately the same as our modern air conditioning systems and after that would only need some easy regular maintenance. In the long run it would definitely be a lot cheaper, so I would personally know which one I would choose. But then again, I live in a country where air conditioning is not really a thing for people at home. Before I end the video, I would like you to know that all the 3D renders that you've seen throughout this video, and the amazing work behind it, were created by the creator behind the Found and Explained channel here on YouTube. I want to thank him a lot for creating these renders for me to use, and if you'd like to see more of his work, I highly recommend checking out his channel Found and Explained here on YouTube. I matched with the wall, good enough right? I could put a dinosaur here. I could put a pyramid here. A while ago I created a video about ancient air conditioning that was invented approximately 5 and a half thousand years ago. This video did incredibly well on my channel and I got hundreds of comments. And reading through the comments in a couple weeks time, I noticed a couple questions kept popping up and some misconceptions. My name is Kayleigh and today we're going to look into just that. The most asked questions and misconceptions about the wind catchers in Jast. So first of all, let's look into a misconception that I saw pop up a whole lot. As a lot of people were telling me that this isn't considered air conditioning because modern air conditioning removes the humidity from the air, which is of course something that these ancient wind catchers aren't able to do. But I never claimed that these wind catchers are the same as modern air conditioning. What I claimed was that these wind catchers are the origins and the basis of modern day air conditioning. We perfected the technology over time, but it all started in Jast, in Iran. More than 5000 years ago, this was an incredible invention and saying that this isn't air conditioning takes away from the grandeur of the people who created it. And that's a shame in my opinion, because they were awesome. Really awesome. Probably more awesome than you and me. Especially more awesome than me. But moving on. I also saw a whole lot of comments that said that termites have been doing this for way longer. And yeah, you're right. They did. And we humans often get our inspiration from the nature surrounding us. So that's not weird. We probably saw termites do it and then decided to create our own. Going into one of the most frequently asked questions is what temperature would you get it inside? What inside temperature would you be able to create? And the answer to that is it varies. It's not like modern air conditioning that you set to like 20 degrees Celsius or whatever that is in Fahrenheit, because I'm not very well in Fahrenheit. I think it's like 60 something Fahrenheit. I don't know. But yeah, no, you can't do that with this. You don't have the technology to say I want it to cool down to these numbers. The only thing that you can do is make your house cooler than it is outside, which makes it more habitable. I've seen people who were from Jast or have visited Jast in my comment section, and they said that it can be a very comfortable climate and temperature inside while outside it's scorching hot. That doesn't mean that 34 degrees Celsius is cool in any way, shape or form. But when it's like 48 or 45 Celsius outside, then yes, that's really cool. So these wind catchers are still very cool. I like them. I wish I had one because yeah, I do live in a country without air conditioning. Like I mentioned, the Netherlands has no air conditioning and I'm moving to England in the new year. And England is also known for having no air conditioning. So I'm fucked. So the temperature inside depends on many variables, like how hard is the wind blowing? What temperature is it outside? What temperature is it during the night? Is there a canot or a fountain or a body of water over which the wind through the wind catcher travels? All of these will eventually have an effect on the inside temperature of the home. What we do know for a fact is that in the dry, hot desert climates where these wind catchers are found, they work extremely well. And you can see that when you look at the University of Doha, because they use the modern version of the wind catcher system. It works at least well enough for a university to have the wind catcher as their main air conditioning system. Universities aren't small and there are a lot of people walking around in universities. And I don't know if you know, but if you walk around in a building like a university or school in the summer, you sweat and it's hot. And lots of people with lots of sweat and heat means even more heat. And they can have it very comfortable there. They can have the temperature comfortable, which means that it works really well. It just doesn't work in humid climates, which isn't strange. I remember when I was in high school and we got these heat waves during the summer. So we would open windows in our classroom to maybe hopefully get rid of the heat that was trapped inside. But the problem when you open two windows on the same height is that it does nearly nothing because there's no cool air coming in or being dragged in. And the hot air, yeah, I mean it went out, but not really. We would just suffocate slowly until class was done and finally we could go outside and sit in the shade and breathe. Because sitting around 30 sweaty kids, it's not fun. I wish I had air conditioning in high school. Damn it. Then there were a whole, whole lot of people telling me that this doesn't work in humid climates. And yeah, you're right. It doesn't work in humid climates. And I even mentioned that at the start of the video where I said that it all depends on the climatic conditions in which these wind catchers are located and how good they function, how well they work. Not much works in humid climates except modern day air conditioning. And when I said that researchers are trying to make this work in all climates, I meant that. They're trying to figure out a way to make these wind catchers and the basis of these wind catchers, meaning you do not need electricity for them to function. They are trying to make that work and they are researching that. I don't know how they do it, but they are. I would also never claim that this would work in humid climates or in all climates. That would make me a liar and that's something that I don't do. Sorry. The fact that this is some sort of form of passive cooling or evaporative cooling, that isn't something that I needed to be told. If you look at air conditioning and the way it was eventually developed into the modern system, you can put two and two together to figure out that the basis of it was of course the wind catcher. Thankfully there were a whole lot of people who actually work with the modern air conditioning systems and or studied it or want to become one or have retired that told me that they enjoyed the video and that it was very accurate and they didn't know that their job or future job was that old. Because essentially it's a really old job to, you know, be responsible for the cooling of a house. It's a very old job apparently, 5 000 years old. The system of wind catchers and wind towers of course work like a giant house fan. They move the air throughout the pulling in the cold air through the wind catcher and maybe open windows on the lowest floor of the house and releasing the hot air through the wind tower that isn't facing the wind. Therefore the wind pulls out the hot air from the wind tower. Of course there were many people that told me that bugs and dust would collect and spread through the house and I mentioned in the video that there is a section below the wind catchers that will collect the dust. But to be completely honest, by the time I explained that in the first video, I feel like 90% of the people who left that comment had already left. Because I did explain it and when it comes to bugs, I mean, can I ask you, have you effectively kept mosquitoes and spiders and fruit flies out of your house? Because if you have, please in the comments down below let me know how that works because I've been unsuccessful and I'm now 30. I have not managed to go a few weeks without a new spider or a bug inside my house. So thanks. Can they all just bugger off? So under the wind catcher there is a section where the dust and the sand is collected and that it falls down and just stays there until it gets cleaned up. And to be completely honest with you, I personally don't believe that people who live in the desert are that faced by a little bit of sand inside their house. I mean, for god's sakes, they live in a desert. Everything is covered with sand. No, I don't think that sand was a real big issue for them. You get used to it. Just like when you live in a snowy area, your doormat inside will always be covered in moist and snow. It's just the way it is. They do have a type of mesh to keep the bugs out. Although I have explained in the previous video that when you put up some mesh, you can actually reduce the functionality of the wind catcher because the wind won't flow as great as it could. There can be like some greenery that you can put in the place where the wind will enter the house, near the wind catcher, and that will also reduce the functionality of the wind catcher. So I mean, in places where malaria is a thing, yes, put up mesh. In other places of the world, I mean, you can handle a mosquito when it's not a tiger mosquito, I think. I think. I hate mosquitoes. And of course, I had many, many, many, many, many, many, many, many, many, many, many, many, many, many, many, many, many, many, many, many, many, many, many people telling me that this it's just a swamp cooler. And yeah, yeah, you're right. I don't disagree. But the fact is that But this is a 5000 year old swamp cooler, it doesn't need electricity and it was used in ancient times. Somehow I feel like the people leaving such comments have zero understanding of life in ancient times and how much that differs from life in modern times. Like they forgot that the invention of the television happened less than 100 years ago in 1927 by 21 year old inventor Philo Taylor Farnsworth. The wind catchers in combination with wind towers, sometimes combined with the evaporative cooling method with the canuts, was such an ingenious thing the ancient cultures in the middle eastern Egypt invented. It's easy to gloss over the magnificence of the invention and to pretend that it isn't an amazing feat of engineering when you compare it to our modern technology. But it shows skill, knowledge and intelligence that most people never expected from people living in ancient times. So by making this video I hope that I was able to clarify some misconceptions and answer some of the most asked questions about these wind catchers. To me it shows the magnificence of the ancient inhabitants of this planet and I love looking into this type of ancient technology and I will absolutely keep doing that. My name is Kayleigh and as most of you watching me here on YouTube will know, I am Dutch. Now one of the most iconic things about the Netherlands, my country, is the windmills. Whenever I tell people that I'm Dutch I often get asked if I live in a windmill or wear clogs which are surprisingly comfortable according to my old neighbor. Even though I truly have never worn clogs in my life, it's not really a thing that we Dutch people do nowadays. Getting off track, back to the windmills. Because windmills are such an integral part of Dutch culture I was wondering, when was the first windmill invented and used? And where did they come from?