September 9, 2019 • 49 mins
Air conditioning has had a profound impact on modern life -- and in more ways than you might realize. In this trio of Invention episodes, Robert and Joe explore pre-AC cooling methods, the invention itself and the many ways it changed the shape (and temperature) of our lives.
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Episode Transcript
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Speaker 1 (00:03):
Welcome to Invention, a production of I Heart Radio. Hey,
welcome to Invention. My name is Robert Lamp and I'm
Joe Mccormickin Today, we're gonna be beginning and exploration of
the invention of air conditioning. This is going to be
a multi part series. And for the purpose of this conversation,
we're not going to be talking about all cooling, refrigeration,
(00:25):
all making stuff colder technology that has ever existed. We're
going to be focusing on the invention of systems primarily
for cooling and removing humidity from interior spaces, primarily, but
not exclusively, for the comfort of humans and other animals.
Right that. Now that being said, we are going to
mention some some some various cooling technologies and air circulation
(00:46):
technologies on the path to modern air conditioning exactly. So,
I will say that I can speak from pre recent
personal experience, actual actually multiple experiences, to say that if
you are lucky enough who have air conditioning in your home,
in your workplace, and the places that you dwell, especially
in the hottest months of the year, especially if you
(01:07):
live somewhere hot like in the American South or anywhere
near the equator, I guess, or Atlanta or Hotlanta, as
they know that they do not call it. If you
are one of these lucky people who has this technology,
you should not take this blessing for granted. You should
remember every sweltering day to be thankful for this luxury.
I once lived in an upper floor apartment in an
(01:29):
old house in North Carolina, as though there was an
apartment below me, and I went the better part of
a blistering summer there with no air conditioning. And you know,
I don't want to over dramatize my my own struggles,
but I just remember, like my brain didn't work. I
remember standing at the refrigerator with the freezer door open
(01:49):
and my head stuck in it, which don't do that, folks.
I mean, that's not energy efficient, but you know, it
just short circuited all my rationality to be in this
hundred degree apartment. I remember I would lie on top
of my bed and try to sleep at night, just
making like a human sweat angel, like a you know,
a human shaped sweat imprint on the top blanket. It
(02:10):
was disgusting and and more recently actually just last year,
our home air conditioning and it completely broke down. In
the middle of summer, and it was several weeks before
we get the problem fixed. And again, maybe I'm just
a whimp, but I found that in a house that's
like ninety degrees plus are close to a hundred degrees
with high humidity, my brain just broke. I remember sitting
(02:32):
at a desk trying to do work with like a
wet towel around my neck and a box fan propped
up pointing at my head, and it just it never
felt like enough. The hot, swampy summers down here can
be brutal, and it really makes you appreciate again how
lucky you are if you have access to this modern convenience,
especially in Hotlanta or swamp Planta. We can call it that,
(02:53):
I guess, but I got to give a shout out
to my A C guy, Mike, who Robert here referred
me to. Yes, my Mike is great. Effects fixed mine
up as well. And indeed, air conditioning is one of
those things when when it's working properly, you you hardly
notice it at all and you just take it for granted.
When something goes wrong, that's when you start sweating, and
(03:14):
in all possible ways. Uh, sweating at night getting the
proper terrifying night sweats on. And you know, one of
the things is, is I get older, I do find
that I enjoy the heat. Like I I love to
read and write on my front porch, and I'll generally
like push that as far as humanly possible in either direction.
(03:35):
Like when it's colder, I'll bundle up as much as possible,
but I can't quite bundle my fingers. And then at
that point I'm driven inside and I have to come
out when you know the warmer person portion of the day,
and then what is it gets hotter and hotter. Uh,
you know, I'll do whatever I need to do to
try and keep the mosquitoes away, you know, burning like um,
you know, ritual citronella candles, and wearing more clothing than
(03:57):
it's perhaps temperature appropriate, just to keep them from biting
that sort of feasting of my blood, that sort of thing.
But but but you know, I don't mind sweating out there.
I can also, you know, bring out a fan if
I need to to keep the air moving. And of course,
as is common with with a lot of you know,
front porch scenarios, if you have a porch swing or
(04:18):
a hammock on hand, like, that's ideal because you're able
to keep the air circulating by keeping yourself in more
or less continuous motion. Um. But then eventually you reach
the point or I reached the point where I I
have to come inside because it will just get too hot.
And I enjoy having the choice, the privilege of being
able to come inside and enjoy the you know, the
(04:40):
cooler air. And you know, it's not only a privilege
of our modern age, it is a privilege in our
modern age. Yeah, there are millions of people around the
world in hot climates these days without air conditioning, and
air conditioning does not come without costs, that's right. I
should also say that on my front porch, having uh,
you know, a readily refillable supply of ice water is
(05:02):
a must. And of course that's that the history of
refrigeration is is right up there with the history of
keeping spaces cool. Uh. So you know, both of these
are technologies that we take completely for granted. So many
of us that are listening to this podcast you have
not only um uh you know, cool air inside your home,
but you have a miraculous machine that can turn liquid
(05:23):
water into ice, perhaps automatically, and even if not automatically,
like still very passively, you're not having to actually crank
it out. All right. Well, before we start talking about
air conditioning systems or pre air conditioning systems for enclosed spaces,
we always like to ask the question what came before?
I guess the deepest you can go on what came
(05:43):
before for air conditioning technology is biological cooling systems and
thermoregulation in the body, right, and for us that means
sweat and and this is going to be key to
the methodology of all these various air conditioning and temperature
control UH technologies that we're going to discuss in these episodes. So,
your body produces sweat and UH with the in sweat
(06:05):
evaporates from the skin to cool the body. That's essential
is the evaporation, right. It's kind of how in fact
it works for anybody of water. Right. You can take
a just a bucket full of water, and the evaporation
off the surface of that water will cool the water
in the rest of the bucket because that evaporation is
an energy hungry phase transfer, and it as to suck
(06:27):
energy out of the heat from the rest of the water. Yeah, basically,
liquid water evaporates into vapor using the thermal energy in
the air, resulting in a lower air temperature. The water
in sweat absorbs your body's heat energy and then evaporates,
lowering your temperature in the process. That is evaporateate of cooling. Yeah,
evaporate of cooling is one of the really cool things
(06:49):
about chemistry when you really think about it. Here's the
questions kind of similar. Um, how come when you boil
a pot of water on the stove and it reaches
the boiling point, the entire pot of water doesn't transform
into steam all at once? Do you even think about that? Yeah?
I was wondering about this one time, one one contemplates
while watching the pot of water boil. Right, one of
(07:12):
the most entertaining of activities. But yeah, it can. It
can raise some interesting questions in your mind. And I
think the way this works is that as water boils,
some of that liquid water is turning into steam. That's
a phase transition. It's the same thing that's happening on
your skin. Liquid water in your skin is turning into water,
vapor into steam and coming off of your skin. But
(07:32):
as that happens in the pot, as that water is
turned into steam. The pot of water loses energy in
that process because it's a massively energy hungry process to
turn water into steam. And so as the water is
turning into steam, the water is constantly cooling back down
and you have to keep putting more energy into the
bottom of it to keep it boiling. And because it's
(07:53):
largely a good thing, because I'm thinking about scenarios in
which in which like large portions of water um are
turned to steam instantly, and you're generally talking about an
explosive situation. You're talking about an expansion of steam that
can you can have, you know, catastrophic effects. You wouldn't
want the pot of water you're boiling for spaghetti to
suddenly become steam all at once, No, I mean you
(08:15):
need massive energy inputs for that kind of thing to happen,
just because it takes so much energy to turn water
into steam. And again that's a good thing for your body.
Taking that energy from the body cools the body off. Now,
when we turn to technological solutions for cooling a space,
there were actually tons of brilliant inventions or little innovations
(08:36):
and tweaks in the design of homes and buildings, UH
for this purpose before the invention of modern like electrical
air conditioning using heat pumps or refrigeration or anything like that. Yes,
the accumulation of all these little tweaks, all these little
advantages that all add up to make hot temperature environments
more bearable. It reminds me of like, you know, the
(08:57):
the argument that you you you win a battle of
all the small, little advantages to your side, you know,
and it's very much that the case with you know,
waging war against a hot climate. Let's talk about some
of these little innovations throughout history. The first is I
would say the absolute most dirt simple probably doesn't even
need to be mentioned, but won't mention it anyway. How
(09:17):
about a roof that's having having a top level covering
provides shade and that blocks the radiation heating from the sun.
So that's one of the most important innovations in designing
a cooler space. Yeah, in the same way you would
take you might take comfort beneath the tree or you know,
by the side of a cliff, some naturally occurring shade. Uh,
we are able to construct our own shade as well.
(09:38):
But of course, by having a house that has a
roof on top if all else fails for keeping the
house cool at night, one option you would sometimes have
in the ancient world as you could go out and
you could sleep up on your roof. This seems to
have been common, for example, in ancient Egypt, where a
significant amount of living and sleeping happened on people's rooftops.
That's right. In in past episodes of No I honestly
(10:01):
can't remember it was this show or stuff to blow
your mind, we talked about some of the ancient cities.
I think this was in our toilets episodes. We're talking
about the archaeological remains of cities in which you know
there were entrances on all the roofs um. But also
we can look to ancient accounts, say Herodotus writing of
the hanging gardens of Babylon, or in Jewish lore, King
(10:24):
David glimpsing Bathsheba bathing uh while resting on the roof
of the palace. Yeah, I guess the idea is probably
that it was like nice and cool out in the
open air on the roof and where also you're going
to be. But there are tons of other little ways
that once you go beyond just having a structure with
a roof to block the sun. And you start building
houses with openings and windows and different hallways and rooms,
(10:45):
there is uh, there's all this investment in the architecture
of a house to help aid in cooling. And this
would include the positioning of windows or other openings, the
shape of rooms and floors that allow ventilation of the
inside and encourage cross breeze is to pass through. Also,
something that I feel like is is less uh is
thought about less in modern home design is the positioning
(11:07):
of windows away from direct sun or in the shade.
I think because houses are designed with the idea of
air conditioning in the mind often these days that there's
less planning put into Okay, where where are the windows,
What kind of light are they going to get? Is
there a tree to shade the window? And so forth. Yeah,
we'll definitely come back to this in the future. But
we we we see this, uh, this this trend where
(11:30):
all these tiny advantages were discussing in the With the
advent of modern air conditioning, so many of them were
just abandoned because they weren't seen as useful anymore as
necessary to keep a cool uh you know, habitat, and
part of the problem then, is when the air conditioning
goes away, or when the electricity goes away, whatever is
disrupting things, you have to fall back on a habitat
(11:54):
or building that is not built with any of these
advantages in place, or even if you're not talking about
using your air conditioning, if you're just considering energy efficiency.
I mean, I think that there are some houses that
are designed without proper thought about energy efficiency for heating
and cooling in the house, even if you have modern
heating and cooling devices. Yeah. I mean when you're when
(12:15):
you're a kid and you're around air can I remember
just loving it. I was like, I just love the
smell of the air conditioning and just wanted on all
the time. You know, when you're adult and you're actually
paying the bills, you don't necessarily want the air conditioning
all the time. It would be nice if it went
off a few times during the month of August. Uh So, yeah,
you know, it would be nice to have so many
(12:35):
of these other little, um, you know, design advantages in
place as well to just reduce you the necessity of
running the a C. Here's another design advantage that predates
modern air conditioning. How about construction that takes advantage of
the fact that warm air rises, also known as the
chimney effect. So one example of this might be high ceilings.
(12:57):
Another is top side ventilation including passive roof vents or
more recently, an attic fan, and so that this can
be paired with windows to create this ideal airflow situation
where cool air flows in through open windows on the
lower floors and then is drawn up through the house
in a sort of air column that goes up towards
the attic and towards the roof, creating pressure that pushes
(13:20):
the warm rising air out through vents in the upper
floors or in the ceiling of roof. Yeah, well, I
have one of these attic fans in my house, and
it's it's it's like being a spaceship, you know, because
you can just especially if you have only like one
window open, you can just create this terrific flow of
air through the house, which can make a huge difference
of you know, you get kind of like it's gotten
a little warm, it's got a little hot inside the house,
(13:41):
and you have a like a nice comfortable temperature drop
outside of the house. You can easily equalize things like
that a couple of other things would just be what
do you make the house out of, Is it insulated
in the proper way, something that's not going to heat
up and pass heat from the outside to the inside.
And then another thing would be the outside color ration
of the house that can affect how it absorbs heat.
(14:02):
Do you live in a like a black obelisk or
do you live in uh, you know, some sort of
a white reflective uh domicile, And it's gonna make a
huge difference. And back to your point about a heat
rising uh you know this also you see this in
designs of you know, older houses with high ceilings. Obviously
it's not the heat is going to rise out of
the area in which you were living. But also you
(14:23):
look at a lot of modern houses and the reliance
on a c and where do you see the master bedroom.
You see it on an upper floor, right like it
becomes more of a selling point of you're you know, saying, okay,
it actually has a master on the main floor. And
a lot of that has to do with, you know,
individuals get older. It's nicer to not have to go
up a flight of stairs in order to get to
your bedroom. But but also you have to to realize
(14:46):
it's going to take more to keep that cool up
there like it's it's it's ultimately from a temperature standpoint,
perhaps it's better to have the master bedroom on the
main floor. Yeah. Absolutely. The one thing I think we
shouldn't forget is how common I mean we mentioned people
sleep being on the roofs. You shouldn't forget that in
hot climates, it used to be extremely common for people
to sleep outside. Oh yes, I was reading about this,
(15:09):
and in times before air conditioning, and in places where
there's no air conditioning. Now it's just very common for
people to sleep on porches in front of their home,
or on the deck behind their home, or in or
just up on the roof for somewhere out in the yard.
I mean, this remains a way to stay cool at night.
So we've talked to you about a number of examples
of passive cooling design, uh, you know, far different from
(15:33):
the active cooling system that you may have in your
home or your apartment window. But we also have to
just consider that many of humanities, the oldest civilizations, they
resided in some pretty sweltering places. And while perhaps you know,
such people's were less coddled by temperature control technology. Uh,
you know, they still had to do what they could
(15:53):
to keep things chill. So I ran across a very
insightful article. This was This was an in g conservation
and management in two thousand and eight and it was
a paper by um Hatamapur and A. Betty and it
considers it concerns the town of the city of Bosher
in southern Iran. This is a region where today you
(16:14):
see more than of total annual power consumption going to
power a c window units. But people have been living
in this region for at least five thousand years. And
in this paper the authors point out the various strategies
that were utilized to keep things cool. Some of these
we've already discussed, but but just to you know, tie
(16:35):
them to a specific location in a very long habited
habitat region of the Earth. They pointed out that the
buildings were constructed closely together but with spaces for circulation
around each and they were built in the direction of
seasonal fresh and cold winds. The lanes were narrow for
the generation of circulation, and they employed ventilation shafts, balconies, terraces.
(16:56):
The separation of heat generating spaces such as kitchens. Uh,
that's another key one, you know, I think about because
I think a number of us have probably noted, especially
during the summer, just how hot it gets in the
kitchen when you're just doing something like cooking, you know,
frozen pizza. You could keep things a lot cooler if
you made sure that your your kitchen was somewhere else,
(17:17):
was located in an adjacent building. I mean, I think
it's one of the appeals of grilling in the summer,
like it's nice to be out in the in the
nice weather while you're cooking, but also the thing that
gets hot is not inside your house. Yeah, I think
it's a great point. Um Also balconies, coverings for direct sunshine,
windows and walls, trees planted for shading, colored glasses in
(17:41):
the windows, and wooden screens outside the windows, high roofed buildings,
light roof colors, and low conductivity materials like gypsum for
shell walls. So so yeah, I found that, you know,
again insightful considering that you know, this is a region
that uh, people have been living in for at least
five five thousand years, and throughout that five thousand history,
(18:02):
most of it has been without the aid of a
modern a C unit, but instead of having modern electrical
air conditioning, they had this sort of army of other
little ingenious design solutions to help keep things cool. Yeah,
every little advantage. And later in the episode we're going
to talk about one really ingenious system that you see
especially in ancient Persia. This this city was in ancient Persia.
(18:24):
But maybe we should take a break now and then
when we come back we can talk about ancient Egyptians
and ancient Romans. All right, we're back. So the ancient
Egyptians were known to have employed a simple but really
kind of ingenious system for for cooling their interior habitats,
(18:47):
and that was they utilized wet mats of reeds that
they hung in windows. Water evaporated from the wet mats,
reducing air temperature in the process, and then a breeze
is blowing through the window and uh and moving through
these mats, lowering the indoor temperature. This is the same
principle that we see later in stuff like the swamp cooler,
(19:08):
right that uses like evaporation in a window in order
to do this, And that there are places where this
is still a pretty common way of cooling your house.
Actually just like hanging a wet towel and a window,
maybe in conjunction with a fan. Yeah. I've also read
that it has been common if you're if you have
laundry that you're drying, you hang them in the window,
(19:28):
and then you're killing two birds with one stone. Yeah.
Of course the ancient Romans got in on the act
in large part thanks to you know, the aqueducts. Uh.
They had many advances in plumbing, which we've covered on
the show before and regards more to sewers, but it
also meant the Romans had the ability to channel water
through indoor pipes in certain homes, cooling them in the process. Yeah,
(19:49):
it seems like they had a few strategies that were
based on water and evaporation of water. Uh. This next thing,
it's hard to confirm that this story is true, but
it's reported it in ancient sources, including the Latin text
known as the Historia Augusta or the Augustine History, that
the third century Roman emperor Ella Gabalus had snow carried
(20:11):
down from the mountains to his palace so that it
could be piled up in a in a mountain of
snow in his orchard to help keep it cool in
the summer. Now, I do have to say that that
this sounds like just an ethically Roman emperor thing to do.
But but I do want to point out that in
the seventy grade Inventions of the Ancient World, Brian and
(20:31):
Fagin points out that in az Tech markets you would
have found mountain ice brought down from the mountains and
it would have just been available to purchase, at least
if you were Aztec nobility. Uh, you could purchase it.
But you know, that's got another like non Roman example
of of ice as a regional commodity. Oh yeah, and
(20:52):
this does appear to be in smaller quantities, something that
did definitely go on in the Roman world. Now, as
for having the snow brought down from the mountain to
make a mountain of snow in his garden, you know,
as with many allegations about the decadent behaviors of particular
Roman emperors, I think sometimes it's hard to know if
you're reading something that's based in fact, or if it's
just libel against an unpopular figure or a historical adversary
(21:15):
of the author. I think there are a lot of
Roman histories that are full of allegations like this that
may or may not be true, right, and it also
had it has an air of the unsensible to it,
you know, like they're going to be extremely diminishing returns
from trying to produce a pile of snow, uh you know,
in your palace or wherever. Whereas having a small amount
(21:36):
of ice, a small amount of snow, uh you know,
certainly what whatever would be able to survive the journey
could be utilized in an intelligent manner. Potentially. Well, it
does appear to be totally true that in smaller quantities,
ice and snow transported down from the mountains were stored
in special cold cellars and sold as a luxury item
or just used as a luxury item in ancient Rome,
(21:58):
though most of the other references I was reading two
imported snow seemed to be about people eating it, not
making a mountain out of it in their pleasure garden.
So some wealthy ancient Romans, including the Emperor Nero, are
said to have eaten snow, sometimes allegedly sweetened with honey
or with fruit juice or other flavors, of making snow cones. Yeah.
This this has turned up in preliminary research for a
(22:21):
potential episode on ice cream. Oh, we gotta do ice cream,
So yeah, we'll come back to that. But I've also
seen references to snow being a luxury ittem for Romans
just to be melted down and drunk like water because
they believed it was very pure and cold or used
to chill wine. So yeah, if you you know, you
were rich and you could shell out for some fresh
snow from somebody's seller that they had imported down from
(22:45):
the mountaintop, you know, go for it. Well, yeah, it
would have been exotic, it would have So much of
our appreciation of various beverages has to do with the
story of it, right, And it's like a it's like
a fine bottle of wine. It's the lore of the
wine to a large extent that you're drinking and tasting
and contemplating. And if you're adding that with the you know,
(23:05):
the properties of watching the snow melt in the in
the glass, certainly in this era or in a later era,
potentially having like a piece of an iceberg, you know,
in your beverage. You know that kind of thing. It
has bizzas. You can't blame them for being into the idea.
I think I was reading somewhere that the philosopher Seneca
wrote with disdain about youths when they're snow eating, as
(23:28):
if he was talking about always on their iPhones, always
eating snow. Either way, carrying snow down a mountain I think,
and dumping it in a pile in your house is
not a super efficient way to stay cool overall, considering
all the work needed to hauld the snow down. But
I was wondering, well, would making a big pile of
snow actually be effective at cooling your palace. I think
(23:48):
the answer is potentially yes. Having a large, massive snow
or ice in a room can actually cool the room
as the snow melts and then eventually evaporates those phase
transitions like we were talking about before, or will suck
energy out of the surrounding air, which will cool the
air in the process. I'm not sure this would do
much good just sitting there in an open air orchard.
(24:10):
But if you were to pair snow or ice with
moving air, especially so maybe you've have people constantly flapping
big fans at the pile of snow, especially in an
indoor space, I think you could actually get significant cooling effects.
Even if if you don't have air conditioning in your house,
you can probably somewhat cool room several degrees by like
setting up a fan and putting a bottle of frozen
(24:32):
water in front of it. This sounds kind of crude,
but it actually does work to to circulate colder air,
and in fact, there are even many large facilities these days,
such as large office buildings, that have in recent years
replace their traditional electric air conditioning systems with ice based
cooling systems. I mean on on. On the surface, it
(24:54):
can seem completely backwards, right, like you're stepping back into
a more primal, sort of pre a c means of
cooling your place. But this is actually, in some cases
a more energy efficient and more cost effective way to
cool a large building. So how on earth would this
work well? The ice based cooling system takes advantage of
a principle known as load shifting, because energy cost from
(25:17):
an electrical grid isn't just about the amount of energy
you use, it's about when you use it. So during
the daytime on a hot summer, there are these periods
of peak demand on power grids when too many people
are all trying to draw lots of electricity at the
same time to power their energy hungry building cooling needs,
and it's going to result in what like rolling brownouts,
(25:38):
right or yeah, I mean it's in any case, it's
like it's putting more demand on the system, and so
at these times of day there's more energy and efficiency
and higher costs instead. Now, many large buildings use this
ice cooling method, which switches it's the building's maximum energy
consumption for cooling purposes to night time off hours, and
(25:59):
the buildings what they do is they have giant water
tanks that can hold thousands of gallons of water, and
at night, when electricity demands are low, when power is
the cheapest, they use that power to freeze the water
into ice. Then in the daytime they use that ice
that they made in the night time to chill air
that is blown throughout the building's ventilation system. The ice
(26:21):
melts gradually throughout the day turns into water. Then the
melted water is frozen again the next night when power
is cheap again. That is impressive. Yeah, I would, I
would love to. I mean, of course, one of the
issues isn't you know we made very well then in
buildings they use this and just was not aware. Yeah,
we might not know, uh, And and it works because
what water is actually an extremely powerful thermal energy storage medium.
(26:44):
You can think of these giant tanks full of ice
as kind of like a thermal battery which can be
charged whenever energy and puts their cheapest and you charge
it by freezing it. But of course these ice based
methods need to be paired with like fans to circulate
the chilled air. So we should mention general fan based
cooling effects, which also go way back into history. Yeah.
(27:05):
I mean the simplest version of a fan, of course,
as if you have any kind of like suitable fan
shaped object that you can just flutter with your hand,
big leaf or something. Yeah. And and I think that
that's one of those things where it's at some point
to humans figure that out just basic tool use. Some
of the more one of the more elaborate, but still
simple and elegant in its simplicity. Uh. One of the
(27:28):
devices that certainly comes to mind is the punka fans
used in India uh from about five b C onward
it seems. And these are large sales that are hung
from the ceiling and they're flapped manually to circulate air. Um.
I imagine most of you have seen like some version
of this, if not like an image of one used
(27:50):
in India or in a depiction of say British occupied India,
then then you also see them in other historical settings
as well, you know, particularly hanging above like a din
or table is of a prime example of what you
might see one. Yeah, fans can be a fantastically useful
and very energy efficient way to make a room feel cooler.
(28:10):
I mean, there's a reason you see fans all throughout
the world and all throughout history. But the interesting thing
about fans is I sometimes even forget this myself. Fans
And let's well, so, if a fan is moving air
in or out of a room, it can change the
temperature in a room, right, if you're exchanging with an
outside system. If you have like a fan, uh, you know,
(28:31):
positioned in a window. Yeah, and the and the temperature
in the outside is different from the inside, that can
actually change the temperature in the room. But fans inside
a closed room do not change the temperature of the room.
They don't actually cool the room. In fact, and in
most cases they probably slightly increase the temperature in the
room because you're running an electrical device from the room,
(28:53):
and that's heating up somewhat, and so it's probably emitting
some heat, so it's moving the air around, but it's
not actually making the or any cooler. So why are fans,
even in a closed room, so good at cooling us
down if they don't actually lower the temperature in the room.
This is like a fun little if you want to
pause and try to figure this out yourself, if you
don't already know the answer. I don't know if it's
(29:15):
too didactic, but I had fun trying to figure this
last night while I was thinking about it. It's because
speeding up airflow increases the rate of evaporation from a
body of liquid like water, and essentially you're a water bag.
Your body is a bag of water, and your body,
as we were talking about earlier, cools by evaporation of sweat.
So in order for a fan to cool something, that
(29:37):
thing actually probably needs to be wet. And I did
an experiment like this in my house just last night,
using a desk fan and a high accuracy instant read
kitchen thermometer. So I set the desk fan going on
the kitchen counter, and I held the thermometer out in
front of the fan. And even though standing in front
of a fan makes us feel cooler, holding a thermometer
(29:58):
in front of a fan does not really change aange
the temperature that the thermometer registers. For me, the naked
thermometer probe just hovered around room temperature. Even though I
held it there for a long time. It didn't do anything.
But then I wrapped the thermometer probe in a wet
paper towel. Now this naturally dropped the temperature of the
thermometer already just because the water is cooler, right, and
so the water contact drops it down. Then it's stabilized.
(30:21):
And when you put the wet paper towel thermometer in
front of a fan, the temperature plummets. It drops down
as the circulation created by the fast moving air of
the fan speeds up the evaporation of water from that
wet paper towel, And the faster the water evaporates, the
colder the paper towel gets because it's stealing the energy
from the rest of that water. This rapid air flow
(30:43):
robbed the water of energy, made it cooler, and thus
you get a nice, icy cold paper towel. So when
you've got a fan running on you in a room.
Your body is that paper towel. You're that wet paper towel,
accelerating evaporation off the top of your skin. Now the
scenario you're again, you're using a desk fan, you using
a rotary fan. Uh So it's interesting to dive into
(31:04):
just you know, briefly the history of the rotary fan,
and it seems that the earliest example of this goes
all the way back to the Han dynasty in China.
Han dynasty engineer Ding Juan created a manually operated rotary
fan with seven wheels around one a d c uh
(31:25):
and then later on during the Tang dynasty of the
eighth century, hydraulic power was apparently added to this innovation
as a way of uh basically for use in blast
furnaces for industrial you know, um air movement circulation. So
flowing water powered the spinning of a fan to circulate air, yeah,
into a blast furnace. Now, but in Ding Juan's original idea,
(31:48):
it would have required, uh, you know, a little human power,
like somebody would have been turning a crank or or
something in order to manually operate all of these rotary fans. Uh.
So Juan's initial invention here was reported in the text
Mental Miscellaneous Records of the Western Capital and excavations from
a former Han tomb in seems to show the necessary
(32:12):
parts to carry this out. So the seven fans, so
there have been ten feet or three meters in diameter,
were connected so that one person could power them all. Uh.
And this is, of course, UH is another more elaborate
means of just circulating airflow, which can can make all
the difference in a stuffy room. Right. Uh. Now, it's
(32:33):
not evaporative cooling, though I've seen at least one wiki
lit listing that says Ding Juan had an evaporative cooling system. Uh.
Decided sources that I ran across on those wikis did
not support it. Uh, that they were just talking about
what I'm talking about, just air circulation. Uh. So there's
no evaporation beyond what's happening on your skin. Correct. And
(32:53):
I didn't see it mentioned in um Ian Inkster's The
History of Technology, which discusses this. But of course it's
entirely within the room of possibility that he can bind
a fan system with something like the Egyptian read Matt
scenario that we discussed earlier. Having some sort of you know,
wet fabric in front of it, but I could not
find direct reference to that myself. By the way, Ding
(33:17):
Juan also allegedly invented something like a zoo trope. According
to Lance Day and Ian McNeil in Biographical Dictionary of
the History of Technology, it was a quote zootrope lamp
which had a thin canopy bearing veins at the top
that were caused to rotate by an ascending current of
warm air from the lamp. The canopy bore images which
(33:40):
if the canopy were rotated fast enough, gave the impression
of movement. Wow, it's like a it's like a fan
for your eyes. Yeah. Uh, you know. It also shows
that like this is an individual who was clearly interested in, uh,
you know, the combination of of rotary machinery and the
movements of air. Uh. And also then just throughout Chinese,
(34:03):
ancient Chinese technology, you also see some other interesting advancements
in refrigeration, which maybe we'll come back to later on.
All right, we're gonna take a quick break, but when
we come back, we shall return to Persia. All right,
we're back. One genre of ancient cooling technology for buildings
(34:26):
is i think a really deeply ingenious solution, and we
find some great examples in ancient and medieval Persia, which
would be in modern day Iran. So this is going
to be the idea of wind catchers and a paired
technology known as connots. And we can start with a
simple version of the wind catcher that's just focused on
(34:46):
air flow. So I want you to picture a building
with towers reaching up above the roof on each side,
and each of these towers has four ports that can
be opened and closed, and each of these towers is
hollow and it connects down to the occupied space within
the building. So if the wind is blowing from the west,
(35:07):
you would open the west facing ports on the west
side of the building to accept the incoming air flow
into the towers, and then on the other side, you
would open only the east facing ports on the east
side of the building, so that would be the ports
facing away from the wind. Now, due to a couple
of quirks of fluid dynamics, if you have a shaft
(35:29):
like this that's only open on the side facing away
from the wind, air will naturally be pulled up from
inside the house through that shaft to flow out in
the same direction as the prevailing wind. I've seen this
attributed to both the Quanda effect and the Bernoulli effect.
I have to admit my fluid dynamics knowledge is not
(35:49):
sharp enough to evaluate whether these characterizations are correct, but
at least several have definitely attributed it to what's known
as the Kwanda effect, which just describes a property of
air flow and certain scenarios. But anyway, if you've got
towers on each side of a building, with towers on
one side accepting the prevailing wind and and routing it
down into the house, and then towers on the other
(36:11):
side with a negative pressure allowing wind to be sucked
up from the inside to blow out with the prevailing wind,
it creates a complete circuit of air flow where air
is sucked down into the house on one side and
sucked up out of the house on the other side.
And you can use this method to help drive hot
air out through the roof for the highest level of
(36:32):
the house, taking advantage of this chimney principle we discussed
earlier in the episode. Now, of course, at this stage
what I've described so far, this would still just be
circulation of hot air from outside. Right now, we know
that even if airflow doesn't actually cool a room, it
can help cool your body if just you you keep
the air moving because it replaces the air around your
skin and helps you evaporate faster. But you can also
(36:55):
greatly improve on the wind catcher design and generate a
true space cooling effect by pairing it with an underground
reservoir or subterranean water channel called a cannot. Oh wow,
So this it's it's almost like we're getting into the
like the creation of an artificial cave system kind of
to cool the air. So cannot is a chamber of
underground water resting or flowing deep in the earth, surrounded
(37:19):
by dense layers of rocks, so the water stays cool
even on the hottest days, and it can be used
for several things. I think from what I've seen, it
seems like it's most often used to sort of help
channel water down underground from from higher level water tables
up in higher elevations so that the water can be
brought down for irrigation in lower lying areas. But in
(37:42):
any case, it's underground water. It's a channel of underground water,
and the water stays very cool because it's deep underground,
so like even when the sun heats up the top
of the Earth's surface, it's not heating up that deep
bedrock below. Now picture this. You've got one shaft leading
down from the surface down into the cannot that looks
like it works like an intake shaft, and this can
(38:04):
be outside the house, drawing in dry air from the desert.
And then there's another shaft leading up from the same
cannot into the house, into the inside of the house
or whatever space you want to cool. And this is
paired with an outflow wind catcher facing away from the wind,
which naturally sucks air up from the inside of the house.
(38:25):
So the circuit created here pulls air from the outside
down through the first shaft through the cannot to flow
over and around the cold water down there in the
deep earth, and then up the second shaft into the house,
and the dry air passing through the cold humid environment
of the cannot becomes much cooler as it travels, and
(38:45):
the result is that you have cold air pulled up
into the house and flowing, which I think it's just brilliant. Yeah,
I mean, it's a it's it's one of these systems
that is um it's it. It's at once kind of
simple when you when you have it all explained to you,
but it is especially considering, you know, ancient buildings we
were talking about it, but pretty elaborate system here. And
(39:06):
you know, I've actually, I don't know if you ran
across any modern uses of this, but I read a
couple of references to UH designs for like large sports
facilities that utilize at least some version of this to
try and keep air circulating through um, you know, through
through the uh the sports arena. Oh okay, well, because
(39:27):
right if you've got like a sports arena, it sounds
crazy to try to like air condition that with like
with just electric air condition so just the sheer scale
if the building might require you know, a more you know,
less you know, electricity dependent method, and perhaps I don't know,
it seems like the kind of thing that that could
potentially be utilized in large industrial spaces as well, But
(39:49):
I didn't run across any examples of that. Well, I
don't know about the scalability of this kind of technology,
but maybe, yeah, I I just don't know, but I
do know they're they're ancient examples where things like this
were used pretty effectively to keep some sellers and basements
and and dwellings very very cool, and even to the
point where they could be used to store ice in
(40:11):
hot places like in Persia. Now we mentioned India earlier
on the subject of fans uh, but I want to
return to India once more, particularly to the use of
step wells and also step ponds. So as Morna Livingstone
and Milo Beach point out in the book Steps to Water,
(40:32):
the Ancient step Wells of India quote, the alternating absence
and abundance of water is crucial to Indian life, and
the step wells and stepped ponds generated by the use
of water are especially imaginative. So basically what they're saying
is that much of the subcontinent is subject to intense months,
soon seasons and intense dry spells, and during the dry
(40:52):
spells people need communal access to water UH. And during
the wet spells, the places they would go for unal access,
of course they're going to be likely to flood and
UH and greatly. And so this communal UH connection with
water is an important aspect of Indian life. A prime
example of this is it would be there the stepped
(41:14):
access that you see to the Ganges River in urban
areas U and think everyone's probably seen images of that,
you know, especially with religious rights and so forth taking
place close to the water. But a far less famous,
less visited and even less preserved example would be the
step ponds and the step wells. Uh. These are beautiful,
(41:34):
by the way, if you've never looked up images of them,
it is some of the most just sort of like
eye rending architecture I've ever seen, and it's actually not
all that complicated, is just like geometrically dazzling. Yeah. I
like to think of it this way. A mountain is
to a canyon as a ziggurat or a Mesoamerican pyramid
(41:56):
is to an Indian step. Well, it looks like there's
a hole in the ground and someone like took a
zigaratt out of it and left a ziggarat shape in
the earth descending into the earth inverted zigaratte. Yeah. So
like imagine these many lattices or steps going down, uh
to a ridiculous degree. Yeah. Yeah, they're essentially deep holes
(42:18):
in the earth, dug down to the water table and
then built out. So there's you know, generally a tear
there's terrorist access with stairs leading down to it um.
And one of the points that the author's made in
this book is that while generally you think of like
a journey into the deep earth, you know, like it
would be it would be claustrophobic, it would be frightening.
(42:40):
But that's not the sense you get when you look
at the photographs of stepwells, like it is. It is open,
it is inviting, it is It's not a sense of
the earth closing around you, but instead one of opening
up like a flower. They're yeah, they're beautiful, and why
do I get kind of an m C. S sure
sense from them? Yeah, there is kind that I think
(43:00):
part of it is that sort of inversion scenario you get.
It is like an inverted ziggarat when you look at it,
and yet you're you're you're sort of climbing up, but
you're climbing down. Um. So. The main distinction though, between
step ponds and step wells, according to Livingston and Beach,
is that step ponds were used for bathing and step
(43:21):
wells were use more for daily water use. Now, many
of these have fallen into disrepair or have been abandoned
in in recent years, in part because of falling water table.
You know, which renders them dry and useless, but also
due to the period of British colonial rule in which
the British condemned them as being you know, potential disease
(43:42):
of vectors and so forth. But there has been increased
interest in them in recent years to preserve their cultural importance,
but also, you know, to preserve them as potential water
sources and a changing climate. Now, obviously these things are
architecturally beautiful and you can see their importance as a
commune a water source, but how do they relate to
the idea of air conditioning or cooling of spaces. Well,
(44:05):
you know, some of them are more out in the open,
you know, get kind of a sense of almost like
a you know, it's like a you could easily mistake
them for some sort of ornate swimming pool sort of
you know, construction. But others are other step wells are
part of temple palace or other urban complexes. So they're
part of this other, this, this larger structure. And here
(44:27):
you know, they were, of course a means of access
in cool water, which in and of itself is a
cooling resource. Livingstone and Beach point out that splashing one's
face with cool water is a standard Indian means of
coping with the heat. A step well affords this cooling method.
It also affords one the ability to enjoy the shade
via the terraces. Or if you've got like hot dry air,
(44:49):
you could also have evaporative cooling there. Yeah. Yeah, Also
you can rest against the cool stone. That was That
was one example they brought up that I didn't think
of in the early portion of the podcast. Is it
It's You can also just like if you find some
cool rock to lay upon, that can be used as
a very primitive form of air conditioning. But they have
(45:09):
they have a wonderful quote in the book about uh
evaporative cooling via the step well quote. In dry weather,
the step wells pool provides some evaporative cooling, but in
high humidity, cooling happens only through contact with water. Unlike
a running fountain, still water and step wells evaporates little.
A moisture saturated layer forms over the water surface, and
(45:32):
if it is not ruffled by a breeze or broken
by splashing, it acts as a vapor barrier. Thus, in
hot humid weather, the body does not get cooled as
quickly in a step well as it does in air conditioning. Indeed,
step well air feels breathlessly still. Okay, so if it's
humid outside and the air isn't moving, the step well
isn't gonna have much of a cooling effect. But if
(45:54):
you had like hot, dry air and a breeze blowing
through moving the air along the surface of the step all,
if it was moved by humans somehow, then it sounds
like you're in business right. However, the humidity is gonna
also serve to conserve the water, so it has that
going forth at any rate. These are again we do
encourage you to do a Google image search on uh
(46:14):
Indian step wells and take a look at something. There's
also some wonderful like top ten step well images. Uh there.
It makes for some just wonderful architectural photography. We'd love
to also hear from anyone who has had the chance
to visit. These are some of the resources I was
I was looking at pointed out that you know these
are these have at least in recent years. I don't
(46:35):
know if it's changed, but in the past it's been
a situation where these places, despite just how beautiful they are,
they haven't been a sought out by tourists uh and
and and sightseers in India. But perhaps that is changing
again as as more conservation has been directed at them
and perhaps just more just sort of appreciation for what
(46:56):
they are. Yeah, all right, well, I think that probably
does it for today. But the next episode, in part
two of our exploration of air conditioning, we're gonna get
more into the modern air conditioner that's based on refrigeration chemistry. Right,
but we've hopefully we've we've laid the groundwork for those innovations,
Like like we've shown you what was possible in the
(47:18):
age before these new technological advancements, and it's pretty impressive,
you know. I think I think a lot of us
are going to be surprised because we have we are
so coddled by modern air conditioning. We think that the
different that there's basically a distinction between having a C
and just sweltering, and we don't realize that there are
all these uh these smaller things that can and have
(47:40):
been done to help ensure a less sweltering environment. Yeah.
So so many people now live in an a C
tamed world. If the a C is cut off, they
don't have all of the normal coping mechanisms that you
would have to to get around that heat. It's a
fundamental softening of our defenses against the evil sun. We
will return to air conditioning in the next episode of Invention.
(48:03):
In the meantime, check out past episodes at invention pod
dot com and indeed let us know you know what,
what is your relationship with air conditioning and particularly what
is your relationship with some of these these alternative methods
of dealing with the heat. Do you still employ some
of them today? Uh? Perhaps you have. You know, older
members of your family have told you about how they
(48:24):
used to do things before air conditioning. We would love
to hear about any of that. Huge thanks, as always
to our excellent audio producer Seth Nicholas Johnson. If you
would like to get in touch with us to send
feedback on this episode or any other, to suggest a
topic for the future, to join the Committee to Extinguish
the Sun, or just to say hello, you can email
us at contact at invention pod dot com. Invention is
(48:53):
production of iHeart Radio. For more podcasts from my heart
Radio because the iHeart Radio app, Apple Podcasts, or wherever
you listen to your favorite shows.
Welcome to Invention, a production of I Heart Radio. Hey,
welcome to Invention. My name is Robert Lamp and I'm
Joe Mccormickin Today, we're gonna be beginning and exploration of
the invention of air conditioning. This is going to be
a multi part series. And for the purpose of this conversation,
we're not going to be talking about all cooling, refrigeration,
(00:25):
all making stuff colder technology that has ever existed. We're
going to be focusing on the invention of systems primarily
for cooling and removing humidity from interior spaces, primarily, but
not exclusively, for the comfort of humans and other animals.
Right that. Now that being said, we are going to
mention some some some various cooling technologies and air circulation
(00:46):
technologies on the path to modern air conditioning exactly. So,
I will say that I can speak from pre recent
personal experience, actual actually multiple experiences, to say that if
you are lucky enough who have air conditioning in your home,
in your workplace, and the places that you dwell, especially
in the hottest months of the year, especially if you
(01:07):
live somewhere hot like in the American South or anywhere
near the equator, I guess, or Atlanta or Hotlanta, as
they know that they do not call it. If you
are one of these lucky people who has this technology,
you should not take this blessing for granted. You should
remember every sweltering day to be thankful for this luxury.
I once lived in an upper floor apartment in an
(01:29):
old house in North Carolina, as though there was an
apartment below me, and I went the better part of
a blistering summer there with no air conditioning. And you know,
I don't want to over dramatize my my own struggles,
but I just remember, like my brain didn't work. I
remember standing at the refrigerator with the freezer door open
(01:49):
and my head stuck in it, which don't do that, folks.
I mean, that's not energy efficient, but you know, it
just short circuited all my rationality to be in this
hundred degree apartment. I remember I would lie on top
of my bed and try to sleep at night, just
making like a human sweat angel, like a you know,
a human shaped sweat imprint on the top blanket. It
(02:10):
was disgusting and and more recently actually just last year,
our home air conditioning and it completely broke down. In
the middle of summer, and it was several weeks before
we get the problem fixed. And again, maybe I'm just
a whimp, but I found that in a house that's
like ninety degrees plus are close to a hundred degrees
with high humidity, my brain just broke. I remember sitting
(02:32):
at a desk trying to do work with like a
wet towel around my neck and a box fan propped
up pointing at my head, and it just it never
felt like enough. The hot, swampy summers down here can
be brutal, and it really makes you appreciate again how
lucky you are if you have access to this modern convenience,
especially in Hotlanta or swamp Planta. We can call it that,
(02:53):
I guess, but I got to give a shout out
to my A C guy, Mike, who Robert here referred
me to. Yes, my Mike is great. Effects fixed mine
up as well. And indeed, air conditioning is one of
those things when when it's working properly, you you hardly
notice it at all and you just take it for granted.
When something goes wrong, that's when you start sweating, and
(03:14):
in all possible ways. Uh, sweating at night getting the
proper terrifying night sweats on. And you know, one of
the things is, is I get older, I do find
that I enjoy the heat. Like I I love to
read and write on my front porch, and I'll generally
like push that as far as humanly possible in either direction.
(03:35):
Like when it's colder, I'll bundle up as much as possible,
but I can't quite bundle my fingers. And then at
that point I'm driven inside and I have to come
out when you know the warmer person portion of the day,
and then what is it gets hotter and hotter. Uh,
you know, I'll do whatever I need to do to
try and keep the mosquitoes away, you know, burning like um,
you know, ritual citronella candles, and wearing more clothing than
(03:57):
it's perhaps temperature appropriate, just to keep them from biting
that sort of feasting of my blood, that sort of thing.
But but but you know, I don't mind sweating out there.
I can also, you know, bring out a fan if
I need to to keep the air moving. And of course,
as is common with with a lot of you know,
front porch scenarios, if you have a porch swing or
(04:18):
a hammock on hand, like, that's ideal because you're able
to keep the air circulating by keeping yourself in more
or less continuous motion. Um. But then eventually you reach
the point or I reached the point where I I
have to come inside because it will just get too hot.
And I enjoy having the choice, the privilege of being
able to come inside and enjoy the you know, the
(04:40):
cooler air. And you know, it's not only a privilege
of our modern age, it is a privilege in our
modern age. Yeah, there are millions of people around the
world in hot climates these days without air conditioning, and
air conditioning does not come without costs, that's right. I
should also say that on my front porch, having uh,
you know, a readily refillable supply of ice water is
(05:02):
a must. And of course that's that the history of
refrigeration is is right up there with the history of
keeping spaces cool. Uh. So you know, both of these
are technologies that we take completely for granted. So many
of us that are listening to this podcast you have
not only um uh you know, cool air inside your home,
but you have a miraculous machine that can turn liquid
(05:23):
water into ice, perhaps automatically, and even if not automatically,
like still very passively, you're not having to actually crank
it out. All right. Well, before we start talking about
air conditioning systems or pre air conditioning systems for enclosed spaces,
we always like to ask the question what came before?
I guess the deepest you can go on what came
(05:43):
before for air conditioning technology is biological cooling systems and
thermoregulation in the body, right, and for us that means
sweat and and this is going to be key to
the methodology of all these various air conditioning and temperature
control UH technologies that we're going to discuss in these episodes. So,
your body produces sweat and UH with the in sweat
(06:05):
evaporates from the skin to cool the body. That's essential
is the evaporation, right. It's kind of how in fact
it works for anybody of water. Right. You can take
a just a bucket full of water, and the evaporation
off the surface of that water will cool the water
in the rest of the bucket because that evaporation is
an energy hungry phase transfer, and it as to suck
(06:27):
energy out of the heat from the rest of the water. Yeah, basically,
liquid water evaporates into vapor using the thermal energy in
the air, resulting in a lower air temperature. The water
in sweat absorbs your body's heat energy and then evaporates,
lowering your temperature in the process. That is evaporateate of cooling. Yeah,
evaporate of cooling is one of the really cool things
(06:49):
about chemistry when you really think about it. Here's the
questions kind of similar. Um, how come when you boil
a pot of water on the stove and it reaches
the boiling point, the entire pot of water doesn't transform
into steam all at once? Do you even think about that? Yeah?
I was wondering about this one time, one one contemplates
while watching the pot of water boil. Right, one of
(07:12):
the most entertaining of activities. But yeah, it can. It
can raise some interesting questions in your mind. And I
think the way this works is that as water boils,
some of that liquid water is turning into steam. That's
a phase transition. It's the same thing that's happening on
your skin. Liquid water in your skin is turning into water,
vapor into steam and coming off of your skin. But
(07:32):
as that happens in the pot, as that water is
turned into steam. The pot of water loses energy in
that process because it's a massively energy hungry process to
turn water into steam. And so as the water is
turning into steam, the water is constantly cooling back down
and you have to keep putting more energy into the
bottom of it to keep it boiling. And because it's
(07:53):
largely a good thing, because I'm thinking about scenarios in
which in which like large portions of water um are
turned to steam instantly, and you're generally talking about an
explosive situation. You're talking about an expansion of steam that
can you can have, you know, catastrophic effects. You wouldn't
want the pot of water you're boiling for spaghetti to
suddenly become steam all at once, No, I mean you
(08:15):
need massive energy inputs for that kind of thing to happen,
just because it takes so much energy to turn water
into steam. And again that's a good thing for your body.
Taking that energy from the body cools the body off. Now,
when we turn to technological solutions for cooling a space,
there were actually tons of brilliant inventions or little innovations
(08:36):
and tweaks in the design of homes and buildings, UH
for this purpose before the invention of modern like electrical
air conditioning using heat pumps or refrigeration or anything like that. Yes,
the accumulation of all these little tweaks, all these little
advantages that all add up to make hot temperature environments
more bearable. It reminds me of like, you know, the
(08:57):
the argument that you you you win a battle of
all the small, little advantages to your side, you know,
and it's very much that the case with you know,
waging war against a hot climate. Let's talk about some
of these little innovations throughout history. The first is I
would say the absolute most dirt simple probably doesn't even
need to be mentioned, but won't mention it anyway. How
(09:17):
about a roof that's having having a top level covering
provides shade and that blocks the radiation heating from the sun.
So that's one of the most important innovations in designing
a cooler space. Yeah, in the same way you would
take you might take comfort beneath the tree or you know,
by the side of a cliff, some naturally occurring shade. Uh,
we are able to construct our own shade as well.
(09:38):
But of course, by having a house that has a
roof on top if all else fails for keeping the
house cool at night, one option you would sometimes have
in the ancient world as you could go out and
you could sleep up on your roof. This seems to
have been common, for example, in ancient Egypt, where a
significant amount of living and sleeping happened on people's rooftops.
That's right. In in past episodes of No I honestly
(10:01):
can't remember it was this show or stuff to blow
your mind, we talked about some of the ancient cities.
I think this was in our toilets episodes. We're talking
about the archaeological remains of cities in which you know
there were entrances on all the roofs um. But also
we can look to ancient accounts, say Herodotus writing of
the hanging gardens of Babylon, or in Jewish lore, King
(10:24):
David glimpsing Bathsheba bathing uh while resting on the roof
of the palace. Yeah, I guess the idea is probably
that it was like nice and cool out in the
open air on the roof and where also you're going
to be. But there are tons of other little ways
that once you go beyond just having a structure with
a roof to block the sun. And you start building
houses with openings and windows and different hallways and rooms,
(10:45):
there is uh, there's all this investment in the architecture
of a house to help aid in cooling. And this
would include the positioning of windows or other openings, the
shape of rooms and floors that allow ventilation of the
inside and encourage cross breeze is to pass through. Also,
something that I feel like is is less uh is
thought about less in modern home design is the positioning
(11:07):
of windows away from direct sun or in the shade.
I think because houses are designed with the idea of
air conditioning in the mind often these days that there's
less planning put into Okay, where where are the windows,
What kind of light are they going to get? Is
there a tree to shade the window? And so forth. Yeah,
we'll definitely come back to this in the future. But
we we we see this, uh, this this trend where
(11:30):
all these tiny advantages were discussing in the With the
advent of modern air conditioning, so many of them were
just abandoned because they weren't seen as useful anymore as
necessary to keep a cool uh you know, habitat, and
part of the problem then, is when the air conditioning
goes away, or when the electricity goes away, whatever is
disrupting things, you have to fall back on a habitat
(11:54):
or building that is not built with any of these
advantages in place, or even if you're not talking about
using your air conditioning, if you're just considering energy efficiency.
I mean, I think that there are some houses that
are designed without proper thought about energy efficiency for heating
and cooling in the house, even if you have modern
heating and cooling devices. Yeah. I mean when you're when
(12:15):
you're a kid and you're around air can I remember
just loving it. I was like, I just love the
smell of the air conditioning and just wanted on all
the time. You know, when you're adult and you're actually
paying the bills, you don't necessarily want the air conditioning
all the time. It would be nice if it went
off a few times during the month of August. Uh So, yeah,
you know, it would be nice to have so many
(12:35):
of these other little, um, you know, design advantages in
place as well to just reduce you the necessity of
running the a C. Here's another design advantage that predates
modern air conditioning. How about construction that takes advantage of
the fact that warm air rises, also known as the
chimney effect. So one example of this might be high ceilings.
(12:57):
Another is top side ventilation including passive roof vents or
more recently, an attic fan, and so that this can
be paired with windows to create this ideal airflow situation
where cool air flows in through open windows on the
lower floors and then is drawn up through the house
in a sort of air column that goes up towards
the attic and towards the roof, creating pressure that pushes
(13:20):
the warm rising air out through vents in the upper
floors or in the ceiling of roof. Yeah, well, I
have one of these attic fans in my house, and
it's it's it's like being a spaceship, you know, because
you can just especially if you have only like one
window open, you can just create this terrific flow of
air through the house, which can make a huge difference
of you know, you get kind of like it's gotten
a little warm, it's got a little hot inside the house,
(13:41):
and you have a like a nice comfortable temperature drop
outside of the house. You can easily equalize things like
that a couple of other things would just be what
do you make the house out of, Is it insulated
in the proper way, something that's not going to heat
up and pass heat from the outside to the inside.
And then another thing would be the outside color ration
of the house that can affect how it absorbs heat.
(14:02):
Do you live in a like a black obelisk or
do you live in uh, you know, some sort of
a white reflective uh domicile, And it's gonna make a
huge difference. And back to your point about a heat
rising uh you know this also you see this in
designs of you know, older houses with high ceilings. Obviously
it's not the heat is going to rise out of
the area in which you were living. But also you
(14:23):
look at a lot of modern houses and the reliance
on a c and where do you see the master bedroom.
You see it on an upper floor, right like it
becomes more of a selling point of you're you know, saying, okay,
it actually has a master on the main floor. And
a lot of that has to do with, you know,
individuals get older. It's nicer to not have to go
up a flight of stairs in order to get to
your bedroom. But but also you have to to realize
(14:46):
it's going to take more to keep that cool up
there like it's it's it's ultimately from a temperature standpoint,
perhaps it's better to have the master bedroom on the
main floor. Yeah. Absolutely. The one thing I think we
shouldn't forget is how common I mean we mentioned people
sleep being on the roofs. You shouldn't forget that in
hot climates, it used to be extremely common for people
to sleep outside. Oh yes, I was reading about this,
(15:09):
and in times before air conditioning, and in places where
there's no air conditioning. Now it's just very common for
people to sleep on porches in front of their home,
or on the deck behind their home, or in or
just up on the roof for somewhere out in the yard.
I mean, this remains a way to stay cool at night.
So we've talked to you about a number of examples
of passive cooling design, uh, you know, far different from
(15:33):
the active cooling system that you may have in your
home or your apartment window. But we also have to
just consider that many of humanities, the oldest civilizations, they
resided in some pretty sweltering places. And while perhaps you know,
such people's were less coddled by temperature control technology. Uh,
you know, they still had to do what they could
(15:53):
to keep things chill. So I ran across a very
insightful article. This was This was an in g conservation
and management in two thousand and eight and it was
a paper by um Hatamapur and A. Betty and it
considers it concerns the town of the city of Bosher
in southern Iran. This is a region where today you
(16:14):
see more than of total annual power consumption going to
power a c window units. But people have been living
in this region for at least five thousand years. And
in this paper the authors point out the various strategies
that were utilized to keep things cool. Some of these
we've already discussed, but but just to you know, tie
(16:35):
them to a specific location in a very long habited
habitat region of the Earth. They pointed out that the
buildings were constructed closely together but with spaces for circulation
around each and they were built in the direction of
seasonal fresh and cold winds. The lanes were narrow for
the generation of circulation, and they employed ventilation shafts, balconies, terraces.
(16:56):
The separation of heat generating spaces such as kitchens. Uh,
that's another key one, you know, I think about because
I think a number of us have probably noted, especially
during the summer, just how hot it gets in the
kitchen when you're just doing something like cooking, you know,
frozen pizza. You could keep things a lot cooler if
you made sure that your your kitchen was somewhere else,
(17:17):
was located in an adjacent building. I mean, I think
it's one of the appeals of grilling in the summer,
like it's nice to be out in the in the
nice weather while you're cooking, but also the thing that
gets hot is not inside your house. Yeah, I think
it's a great point. Um Also balconies, coverings for direct sunshine,
windows and walls, trees planted for shading, colored glasses in
(17:41):
the windows, and wooden screens outside the windows, high roofed buildings,
light roof colors, and low conductivity materials like gypsum for
shell walls. So so yeah, I found that, you know,
again insightful considering that you know, this is a region
that uh, people have been living in for at least
five five thousand years, and throughout that five thousand history,
(18:02):
most of it has been without the aid of a
modern a C unit, but instead of having modern electrical
air conditioning, they had this sort of army of other
little ingenious design solutions to help keep things cool. Yeah,
every little advantage. And later in the episode we're going
to talk about one really ingenious system that you see
especially in ancient Persia. This this city was in ancient Persia.
(18:24):
But maybe we should take a break now and then
when we come back we can talk about ancient Egyptians
and ancient Romans. All right, we're back. So the ancient
Egyptians were known to have employed a simple but really
kind of ingenious system for for cooling their interior habitats,
(18:47):
and that was they utilized wet mats of reeds that
they hung in windows. Water evaporated from the wet mats,
reducing air temperature in the process, and then a breeze
is blowing through the window and uh and moving through
these mats, lowering the indoor temperature. This is the same
principle that we see later in stuff like the swamp cooler,
(19:08):
right that uses like evaporation in a window in order
to do this, And that there are places where this
is still a pretty common way of cooling your house.
Actually just like hanging a wet towel and a window,
maybe in conjunction with a fan. Yeah. I've also read
that it has been common if you're if you have
laundry that you're drying, you hang them in the window,
(19:28):
and then you're killing two birds with one stone. Yeah.
Of course the ancient Romans got in on the act
in large part thanks to you know, the aqueducts. Uh.
They had many advances in plumbing, which we've covered on
the show before and regards more to sewers, but it
also meant the Romans had the ability to channel water
through indoor pipes in certain homes, cooling them in the process. Yeah,
(19:49):
it seems like they had a few strategies that were
based on water and evaporation of water. Uh. This next thing,
it's hard to confirm that this story is true, but
it's reported it in ancient sources, including the Latin text
known as the Historia Augusta or the Augustine History, that
the third century Roman emperor Ella Gabalus had snow carried
(20:11):
down from the mountains to his palace so that it
could be piled up in a in a mountain of
snow in his orchard to help keep it cool in
the summer. Now, I do have to say that that
this sounds like just an ethically Roman emperor thing to do.
But but I do want to point out that in
the seventy grade Inventions of the Ancient World, Brian and
(20:31):
Fagin points out that in az Tech markets you would
have found mountain ice brought down from the mountains and
it would have just been available to purchase, at least
if you were Aztec nobility. Uh, you could purchase it.
But you know, that's got another like non Roman example
of of ice as a regional commodity. Oh yeah, and
(20:52):
this does appear to be in smaller quantities, something that
did definitely go on in the Roman world. Now, as
for having the snow brought down from the mountain to
make a mountain of snow in his garden, you know,
as with many allegations about the decadent behaviors of particular
Roman emperors, I think sometimes it's hard to know if
you're reading something that's based in fact, or if it's
just libel against an unpopular figure or a historical adversary
(21:15):
of the author. I think there are a lot of
Roman histories that are full of allegations like this that
may or may not be true, right, and it also
had it has an air of the unsensible to it,
you know, like they're going to be extremely diminishing returns
from trying to produce a pile of snow, uh you know,
in your palace or wherever. Whereas having a small amount
(21:36):
of ice, a small amount of snow, uh you know,
certainly what whatever would be able to survive the journey
could be utilized in an intelligent manner. Potentially. Well, it
does appear to be totally true that in smaller quantities,
ice and snow transported down from the mountains were stored
in special cold cellars and sold as a luxury item
or just used as a luxury item in ancient Rome,
(21:58):
though most of the other references I was reading two
imported snow seemed to be about people eating it, not
making a mountain out of it in their pleasure garden.
So some wealthy ancient Romans, including the Emperor Nero, are
said to have eaten snow, sometimes allegedly sweetened with honey
or with fruit juice or other flavors, of making snow cones. Yeah.
This this has turned up in preliminary research for a
(22:21):
potential episode on ice cream. Oh, we gotta do ice cream,
So yeah, we'll come back to that. But I've also
seen references to snow being a luxury ittem for Romans
just to be melted down and drunk like water because
they believed it was very pure and cold or used
to chill wine. So yeah, if you you know, you
were rich and you could shell out for some fresh
snow from somebody's seller that they had imported down from
(22:45):
the mountaintop, you know, go for it. Well, yeah, it
would have been exotic, it would have So much of
our appreciation of various beverages has to do with the
story of it, right, And it's like a it's like
a fine bottle of wine. It's the lore of the
wine to a large extent that you're drinking and tasting
and contemplating. And if you're adding that with the you know,
(23:05):
the properties of watching the snow melt in the in
the glass, certainly in this era or in a later era,
potentially having like a piece of an iceberg, you know,
in your beverage. You know that kind of thing. It
has bizzas. You can't blame them for being into the idea.
I think I was reading somewhere that the philosopher Seneca
wrote with disdain about youths when they're snow eating, as
(23:28):
if he was talking about always on their iPhones, always
eating snow. Either way, carrying snow down a mountain I think,
and dumping it in a pile in your house is
not a super efficient way to stay cool overall, considering
all the work needed to hauld the snow down. But
I was wondering, well, would making a big pile of
snow actually be effective at cooling your palace. I think
(23:48):
the answer is potentially yes. Having a large, massive snow
or ice in a room can actually cool the room
as the snow melts and then eventually evaporates those phase
transitions like we were talking about before, or will suck
energy out of the surrounding air, which will cool the
air in the process. I'm not sure this would do
much good just sitting there in an open air orchard.
(24:10):
But if you were to pair snow or ice with
moving air, especially so maybe you've have people constantly flapping
big fans at the pile of snow, especially in an
indoor space, I think you could actually get significant cooling effects.
Even if if you don't have air conditioning in your house,
you can probably somewhat cool room several degrees by like
setting up a fan and putting a bottle of frozen
(24:32):
water in front of it. This sounds kind of crude,
but it actually does work to to circulate colder air,
and in fact, there are even many large facilities these days,
such as large office buildings, that have in recent years
replace their traditional electric air conditioning systems with ice based
cooling systems. I mean on on. On the surface, it
(24:54):
can seem completely backwards, right, like you're stepping back into
a more primal, sort of pre a c means of
cooling your place. But this is actually, in some cases
a more energy efficient and more cost effective way to
cool a large building. So how on earth would this
work well? The ice based cooling system takes advantage of
a principle known as load shifting, because energy cost from
(25:17):
an electrical grid isn't just about the amount of energy
you use, it's about when you use it. So during
the daytime on a hot summer, there are these periods
of peak demand on power grids when too many people
are all trying to draw lots of electricity at the
same time to power their energy hungry building cooling needs,
and it's going to result in what like rolling brownouts,
(25:38):
right or yeah, I mean it's in any case, it's
like it's putting more demand on the system, and so
at these times of day there's more energy and efficiency
and higher costs instead. Now, many large buildings use this
ice cooling method, which switches it's the building's maximum energy
consumption for cooling purposes to night time off hours, and
(25:59):
the buildings what they do is they have giant water
tanks that can hold thousands of gallons of water, and
at night, when electricity demands are low, when power is
the cheapest, they use that power to freeze the water
into ice. Then in the daytime they use that ice
that they made in the night time to chill air
that is blown throughout the building's ventilation system. The ice
(26:21):
melts gradually throughout the day turns into water. Then the
melted water is frozen again the next night when power
is cheap again. That is impressive. Yeah, I would, I
would love to. I mean, of course, one of the
issues isn't you know we made very well then in
buildings they use this and just was not aware. Yeah,
we might not know, uh, And and it works because
what water is actually an extremely powerful thermal energy storage medium.
(26:44):
You can think of these giant tanks full of ice
as kind of like a thermal battery which can be
charged whenever energy and puts their cheapest and you charge
it by freezing it. But of course these ice based
methods need to be paired with like fans to circulate
the chilled air. So we should mention general fan based
cooling effects, which also go way back into history. Yeah.
(27:05):
I mean the simplest version of a fan, of course,
as if you have any kind of like suitable fan
shaped object that you can just flutter with your hand,
big leaf or something. Yeah. And and I think that
that's one of those things where it's at some point
to humans figure that out just basic tool use. Some
of the more one of the more elaborate, but still
simple and elegant in its simplicity. Uh. One of the
(27:28):
devices that certainly comes to mind is the punka fans
used in India uh from about five b C onward
it seems. And these are large sales that are hung
from the ceiling and they're flapped manually to circulate air. Um.
I imagine most of you have seen like some version
of this, if not like an image of one used
(27:50):
in India or in a depiction of say British occupied India,
then then you also see them in other historical settings
as well, you know, particularly hanging above like a din
or table is of a prime example of what you
might see one. Yeah, fans can be a fantastically useful
and very energy efficient way to make a room feel cooler.
(28:10):
I mean, there's a reason you see fans all throughout
the world and all throughout history. But the interesting thing
about fans is I sometimes even forget this myself. Fans
And let's well, so, if a fan is moving air
in or out of a room, it can change the
temperature in a room, right, if you're exchanging with an
outside system. If you have like a fan, uh, you know,
(28:31):
positioned in a window. Yeah, and the and the temperature
in the outside is different from the inside, that can
actually change the temperature in the room. But fans inside
a closed room do not change the temperature of the room.
They don't actually cool the room. In fact, and in
most cases they probably slightly increase the temperature in the
room because you're running an electrical device from the room,
(28:53):
and that's heating up somewhat, and so it's probably emitting
some heat, so it's moving the air around, but it's
not actually making the or any cooler. So why are fans,
even in a closed room, so good at cooling us
down if they don't actually lower the temperature in the room.
This is like a fun little if you want to
pause and try to figure this out yourself, if you
don't already know the answer. I don't know if it's
(29:15):
too didactic, but I had fun trying to figure this
last night while I was thinking about it. It's because
speeding up airflow increases the rate of evaporation from a
body of liquid like water, and essentially you're a water bag.
Your body is a bag of water, and your body,
as we were talking about earlier, cools by evaporation of sweat.
So in order for a fan to cool something, that
(29:37):
thing actually probably needs to be wet. And I did
an experiment like this in my house just last night,
using a desk fan and a high accuracy instant read
kitchen thermometer. So I set the desk fan going on
the kitchen counter, and I held the thermometer out in
front of the fan. And even though standing in front
of a fan makes us feel cooler, holding a thermometer
(29:58):
in front of a fan does not really change aange
the temperature that the thermometer registers. For me, the naked
thermometer probe just hovered around room temperature. Even though I
held it there for a long time. It didn't do anything.
But then I wrapped the thermometer probe in a wet
paper towel. Now this naturally dropped the temperature of the
thermometer already just because the water is cooler, right, and
so the water contact drops it down. Then it's stabilized.
(30:21):
And when you put the wet paper towel thermometer in
front of a fan, the temperature plummets. It drops down
as the circulation created by the fast moving air of
the fan speeds up the evaporation of water from that
wet paper towel, And the faster the water evaporates, the
colder the paper towel gets because it's stealing the energy
from the rest of that water. This rapid air flow
(30:43):
robbed the water of energy, made it cooler, and thus
you get a nice, icy cold paper towel. So when
you've got a fan running on you in a room.
Your body is that paper towel. You're that wet paper towel,
accelerating evaporation off the top of your skin. Now the
scenario you're again, you're using a desk fan, you using
a rotary fan. Uh So it's interesting to dive into
(31:04):
just you know, briefly the history of the rotary fan,
and it seems that the earliest example of this goes
all the way back to the Han dynasty in China.
Han dynasty engineer Ding Juan created a manually operated rotary
fan with seven wheels around one a d c uh
(31:25):
and then later on during the Tang dynasty of the
eighth century, hydraulic power was apparently added to this innovation
as a way of uh basically for use in blast
furnaces for industrial you know, um air movement circulation. So
flowing water powered the spinning of a fan to circulate air, yeah,
into a blast furnace. Now, but in Ding Juan's original idea,
(31:48):
it would have required, uh, you know, a little human power,
like somebody would have been turning a crank or or
something in order to manually operate all of these rotary fans. Uh.
So Juan's initial invention here was reported in the text
Mental Miscellaneous Records of the Western Capital and excavations from
a former Han tomb in seems to show the necessary
(32:12):
parts to carry this out. So the seven fans, so
there have been ten feet or three meters in diameter,
were connected so that one person could power them all. Uh.
And this is, of course, UH is another more elaborate
means of just circulating airflow, which can can make all
the difference in a stuffy room. Right. Uh. Now, it's
(32:33):
not evaporative cooling, though I've seen at least one wiki
lit listing that says Ding Juan had an evaporative cooling system. Uh.
Decided sources that I ran across on those wikis did
not support it. Uh, that they were just talking about
what I'm talking about, just air circulation. Uh. So there's
no evaporation beyond what's happening on your skin. Correct. And
(32:53):
I didn't see it mentioned in um Ian Inkster's The
History of Technology, which discusses this. But of course it's
entirely within the room of possibility that he can bind
a fan system with something like the Egyptian read Matt
scenario that we discussed earlier. Having some sort of you know,
wet fabric in front of it, but I could not
find direct reference to that myself. By the way, Ding
(33:17):
Juan also allegedly invented something like a zoo trope. According
to Lance Day and Ian McNeil in Biographical Dictionary of
the History of Technology, it was a quote zootrope lamp
which had a thin canopy bearing veins at the top
that were caused to rotate by an ascending current of
warm air from the lamp. The canopy bore images which
(33:40):
if the canopy were rotated fast enough, gave the impression
of movement. Wow, it's like a it's like a fan
for your eyes. Yeah. Uh, you know. It also shows
that like this is an individual who was clearly interested in, uh,
you know, the combination of of rotary machinery and the
movements of air. Uh. And also then just throughout Chinese,
(34:03):
ancient Chinese technology, you also see some other interesting advancements
in refrigeration, which maybe we'll come back to later on.
All right, we're gonna take a quick break, but when
we come back, we shall return to Persia. All right,
we're back. One genre of ancient cooling technology for buildings
(34:26):
is i think a really deeply ingenious solution, and we
find some great examples in ancient and medieval Persia, which
would be in modern day Iran. So this is going
to be the idea of wind catchers and a paired
technology known as connots. And we can start with a
simple version of the wind catcher that's just focused on
(34:46):
air flow. So I want you to picture a building
with towers reaching up above the roof on each side,
and each of these towers has four ports that can
be opened and closed, and each of these towers is
hollow and it connects down to the occupied space within
the building. So if the wind is blowing from the west,
(35:07):
you would open the west facing ports on the west
side of the building to accept the incoming air flow
into the towers, and then on the other side, you
would open only the east facing ports on the east
side of the building, so that would be the ports
facing away from the wind. Now, due to a couple
of quirks of fluid dynamics, if you have a shaft
(35:29):
like this that's only open on the side facing away
from the wind, air will naturally be pulled up from
inside the house through that shaft to flow out in
the same direction as the prevailing wind. I've seen this
attributed to both the Quanda effect and the Bernoulli effect.
I have to admit my fluid dynamics knowledge is not
(35:49):
sharp enough to evaluate whether these characterizations are correct, but
at least several have definitely attributed it to what's known
as the Kwanda effect, which just describes a property of
air flow and certain scenarios. But anyway, if you've got
towers on each side of a building, with towers on
one side accepting the prevailing wind and and routing it
down into the house, and then towers on the other
(36:11):
side with a negative pressure allowing wind to be sucked
up from the inside to blow out with the prevailing wind,
it creates a complete circuit of air flow where air
is sucked down into the house on one side and
sucked up out of the house on the other side.
And you can use this method to help drive hot
air out through the roof for the highest level of
(36:32):
the house, taking advantage of this chimney principle we discussed
earlier in the episode. Now, of course, at this stage
what I've described so far, this would still just be
circulation of hot air from outside. Right now, we know
that even if airflow doesn't actually cool a room, it
can help cool your body if just you you keep
the air moving because it replaces the air around your
skin and helps you evaporate faster. But you can also
(36:55):
greatly improve on the wind catcher design and generate a
true space cooling effect by pairing it with an underground
reservoir or subterranean water channel called a cannot. Oh wow,
So this it's it's almost like we're getting into the
like the creation of an artificial cave system kind of
to cool the air. So cannot is a chamber of
underground water resting or flowing deep in the earth, surrounded
(37:19):
by dense layers of rocks, so the water stays cool
even on the hottest days, and it can be used
for several things. I think from what I've seen, it
seems like it's most often used to sort of help
channel water down underground from from higher level water tables
up in higher elevations so that the water can be
brought down for irrigation in lower lying areas. But in
(37:42):
any case, it's underground water. It's a channel of underground water,
and the water stays very cool because it's deep underground,
so like even when the sun heats up the top
of the Earth's surface, it's not heating up that deep
bedrock below. Now picture this. You've got one shaft leading
down from the surface down into the cannot that looks
like it works like an intake shaft, and this can
(38:04):
be outside the house, drawing in dry air from the desert.
And then there's another shaft leading up from the same
cannot into the house, into the inside of the house
or whatever space you want to cool. And this is
paired with an outflow wind catcher facing away from the wind,
which naturally sucks air up from the inside of the house.
(38:25):
So the circuit created here pulls air from the outside
down through the first shaft through the cannot to flow
over and around the cold water down there in the
deep earth, and then up the second shaft into the house,
and the dry air passing through the cold humid environment
of the cannot becomes much cooler as it travels, and
(38:45):
the result is that you have cold air pulled up
into the house and flowing, which I think it's just brilliant. Yeah,
I mean, it's a it's it's one of these systems
that is um it's it. It's at once kind of
simple when you when you have it all explained to you,
but it is especially considering, you know, ancient buildings we
were talking about it, but pretty elaborate system here. And
(39:06):
you know, I've actually, I don't know if you ran
across any modern uses of this, but I read a
couple of references to UH designs for like large sports
facilities that utilize at least some version of this to
try and keep air circulating through um, you know, through
through the uh the sports arena. Oh okay, well, because
(39:27):
right if you've got like a sports arena, it sounds
crazy to try to like air condition that with like
with just electric air condition so just the sheer scale
if the building might require you know, a more you know,
less you know, electricity dependent method, and perhaps I don't know,
it seems like the kind of thing that that could
potentially be utilized in large industrial spaces as well, But
(39:49):
I didn't run across any examples of that. Well, I
don't know about the scalability of this kind of technology,
but maybe, yeah, I I just don't know, but I
do know they're they're ancient examples where things like this
were used pretty effectively to keep some sellers and basements
and and dwellings very very cool, and even to the
point where they could be used to store ice in
(40:11):
hot places like in Persia. Now we mentioned India earlier
on the subject of fans uh, but I want to
return to India once more, particularly to the use of
step wells and also step ponds. So as Morna Livingstone
and Milo Beach point out in the book Steps to Water,
(40:32):
the Ancient step Wells of India quote, the alternating absence
and abundance of water is crucial to Indian life, and
the step wells and stepped ponds generated by the use
of water are especially imaginative. So basically what they're saying
is that much of the subcontinent is subject to intense months,
soon seasons and intense dry spells, and during the dry
(40:52):
spells people need communal access to water UH. And during
the wet spells, the places they would go for unal access,
of course they're going to be likely to flood and
UH and greatly. And so this communal UH connection with
water is an important aspect of Indian life. A prime
example of this is it would be there the stepped
(41:14):
access that you see to the Ganges River in urban
areas U and think everyone's probably seen images of that,
you know, especially with religious rights and so forth taking
place close to the water. But a far less famous,
less visited and even less preserved example would be the
step ponds and the step wells. Uh. These are beautiful,
(41:34):
by the way, if you've never looked up images of them,
it is some of the most just sort of like
eye rending architecture I've ever seen, and it's actually not
all that complicated, is just like geometrically dazzling. Yeah. I
like to think of it this way. A mountain is
to a canyon as a ziggurat or a Mesoamerican pyramid
(41:56):
is to an Indian step. Well, it looks like there's
a hole in the ground and someone like took a
zigaratt out of it and left a ziggarat shape in
the earth descending into the earth inverted zigaratte. Yeah. So
like imagine these many lattices or steps going down, uh
to a ridiculous degree. Yeah. Yeah, they're essentially deep holes
(42:18):
in the earth, dug down to the water table and
then built out. So there's you know, generally a tear
there's terrorist access with stairs leading down to it um.
And one of the points that the author's made in
this book is that while generally you think of like
a journey into the deep earth, you know, like it
would be it would be claustrophobic, it would be frightening.
(42:40):
But that's not the sense you get when you look
at the photographs of stepwells, like it is. It is open,
it is inviting, it is It's not a sense of
the earth closing around you, but instead one of opening
up like a flower. They're yeah, they're beautiful, and why
do I get kind of an m C. S sure
sense from them? Yeah, there is kind that I think
(43:00):
part of it is that sort of inversion scenario you get.
It is like an inverted ziggarat when you look at it,
and yet you're you're you're sort of climbing up, but
you're climbing down. Um. So. The main distinction though, between
step ponds and step wells, according to Livingston and Beach,
is that step ponds were used for bathing and step
(43:21):
wells were use more for daily water use. Now, many
of these have fallen into disrepair or have been abandoned
in in recent years, in part because of falling water table.
You know, which renders them dry and useless, but also
due to the period of British colonial rule in which
the British condemned them as being you know, potential disease
(43:42):
of vectors and so forth. But there has been increased
interest in them in recent years to preserve their cultural importance,
but also, you know, to preserve them as potential water
sources and a changing climate. Now, obviously these things are
architecturally beautiful and you can see their importance as a
commune a water source, but how do they relate to
the idea of air conditioning or cooling of spaces. Well,
(44:05):
you know, some of them are more out in the open,
you know, get kind of a sense of almost like
a you know, it's like a you could easily mistake
them for some sort of ornate swimming pool sort of
you know, construction. But others are other step wells are
part of temple palace or other urban complexes. So they're
part of this other, this, this larger structure. And here
(44:27):
you know, they were, of course a means of access
in cool water, which in and of itself is a
cooling resource. Livingstone and Beach point out that splashing one's
face with cool water is a standard Indian means of
coping with the heat. A step well affords this cooling method.
It also affords one the ability to enjoy the shade
via the terraces. Or if you've got like hot dry air,
(44:49):
you could also have evaporative cooling there. Yeah. Yeah, Also
you can rest against the cool stone. That was That
was one example they brought up that I didn't think
of in the early portion of the podcast. Is it
It's You can also just like if you find some
cool rock to lay upon, that can be used as
a very primitive form of air conditioning. But they have
(45:09):
they have a wonderful quote in the book about uh
evaporative cooling via the step well quote. In dry weather,
the step wells pool provides some evaporative cooling, but in
high humidity, cooling happens only through contact with water. Unlike
a running fountain, still water and step wells evaporates little.
A moisture saturated layer forms over the water surface, and
(45:32):
if it is not ruffled by a breeze or broken
by splashing, it acts as a vapor barrier. Thus, in
hot humid weather, the body does not get cooled as
quickly in a step well as it does in air conditioning. Indeed,
step well air feels breathlessly still. Okay, so if it's
humid outside and the air isn't moving, the step well
isn't gonna have much of a cooling effect. But if
(45:54):
you had like hot, dry air and a breeze blowing
through moving the air along the surface of the step all,
if it was moved by humans somehow, then it sounds
like you're in business right. However, the humidity is gonna
also serve to conserve the water, so it has that
going forth at any rate. These are again we do
encourage you to do a Google image search on uh
(46:14):
Indian step wells and take a look at something. There's
also some wonderful like top ten step well images. Uh there.
It makes for some just wonderful architectural photography. We'd love
to also hear from anyone who has had the chance
to visit. These are some of the resources I was
I was looking at pointed out that you know these
are these have at least in recent years. I don't
(46:35):
know if it's changed, but in the past it's been
a situation where these places, despite just how beautiful they are,
they haven't been a sought out by tourists uh and
and and sightseers in India. But perhaps that is changing
again as as more conservation has been directed at them
and perhaps just more just sort of appreciation for what
(46:56):
they are. Yeah, all right, well, I think that probably
does it for today. But the next episode, in part
two of our exploration of air conditioning, we're gonna get
more into the modern air conditioner that's based on refrigeration chemistry. Right,
but we've hopefully we've we've laid the groundwork for those innovations,
Like like we've shown you what was possible in the
(47:18):
age before these new technological advancements, and it's pretty impressive,
you know. I think I think a lot of us
are going to be surprised because we have we are
so coddled by modern air conditioning. We think that the
different that there's basically a distinction between having a C
and just sweltering, and we don't realize that there are
all these uh these smaller things that can and have
(47:40):
been done to help ensure a less sweltering environment. Yeah.
So so many people now live in an a C
tamed world. If the a C is cut off, they
don't have all of the normal coping mechanisms that you
would have to to get around that heat. It's a
fundamental softening of our defenses against the evil sun. We
will return to air conditioning in the next episode of Invention.
(48:03):
In the meantime, check out past episodes at invention pod
dot com and indeed let us know you know what,
what is your relationship with air conditioning and particularly what
is your relationship with some of these these alternative methods
of dealing with the heat. Do you still employ some
of them today? Uh? Perhaps you have. You know, older
members of your family have told you about how they
(48:24):
used to do things before air conditioning. We would love
to hear about any of that. Huge thanks, as always
to our excellent audio producer Seth Nicholas Johnson. If you
would like to get in touch with us to send
feedback on this episode or any other, to suggest a
topic for the future, to join the Committee to Extinguish
the Sun, or just to say hello, you can email
us at contact at invention pod dot com. Invention is
(48:53):
production of iHeart Radio. For more podcasts from my heart
Radio because the iHeart Radio app, Apple Podcasts, or wherever
you listen to your favorite shows.
Invention News
Hosts And Creators
Robert Lamb
Joe McCormick
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