
The Revenge of the Circulating Fan - lispython
http://www.lowtechmagazine.com/2014/09/circulating-fans-air-conditioning.html
======
kijin
Apart from a few isolated statements that suggest using fans together with ACs
(which, of course, is a totally reasonable thing to do), the overall tone of
the article is very much "AC = evil, fan = cool."

Unfortunately, fan-only cooling only works in a narrow range of climates.

> _For instance, instead of cooling down a space to 24°C (75°F), the aircon
> can cool it to 29°C (84°F), which is a comfortable temperature if combined
> with fans._

Whether or not 29°C can be considered a "comfortable temperature", even with
fans, depends a lot on other factors, the most important of which is humidity.
29°C at 30% humidity is very different from 29°C at 90% humidity. The former
is common in Europe and the American West. The latter is much more common in
the Southeast, as well as the majority of newly industrialized countries such
as China and India.

Try installing a radiant cooling system in one of those hot & humid places.
See all that condensation on the walls? That's a recipe for explosive mold
growth. All the fans in the world will not make that pesky H2O go away, since
the air is already oversaturated with it. People can tolerate a lot of heat
with nothing but a paper fan, but there's no alternative to a good ol'
electron-guzzling compressor when it comes to humidity control.

You might feel totally comfortable with a fan in your cool and dry Northern
California summers, but be very careful before you try to generalize your
energy-saving hack to different climates. There's a reason why millions of
people won't give up their AC's for fans, and it's not because they don't know
how to stay cool.

~~~
linuskendall
I've lived in India for years, generally my experience has been that fans work
much better in humid air than dry air. So 29 degrees with 90% humidity and fan
would be much more comfortable than 29 degrees with 30% humidity and fan.

In Delhi (45 degrees in summer) we would manage with desert coolers + fan,
which specifically work by increasing the humidity of the air and then using a
fan.

I believe though that, AC vs. coolers vs. fans vs. any combination of them is
really not at all as important as the way cities and the buildings within them
are built. In Delhi it is estimated that 3-5 degrees local heating is caused
by bad urban design. As an anecdote, I've been in mud-huts where despite 45
degree temperatures outside, insides felt like they were AC. Sure, mud-huts do
have problems with mould and require a lot of maintenance, but it's
illustrative that we've dug ourselves into a hole where AC is required because
we build buildings of inappropriate materials.

~~~
lutusp
> In Delhi (45 degrees in summer) ...

That's 113 degrees Fahrenheit for American readers. The rest of the world has
wisely adopted more rational measurement units. Even Canada, a stone's throw
away from the U.S., uses the Metric system.

~~~
mnw21cam
Both temperature scales are (thankfully) rational. Some physicists have been
dabbling in complex temperatures, but thankfully most of us don't need to know
anything about them.

Sorry, mathematician joke.

~~~
Kurtz79
Celsius used two very reproducible tresholds (freezing and boiling points of
water), associated them to two very easy to remember values (0 and 100), and
defined his scale according to them.

The way Farenheit got to his scale seems really less practical to me, from
Wikipedia :

"Fahrenheit proposed his temperature scale in 1724, basing it on three
reference points of temperature.[9] In his initial scale (which is not the
final Fahrenheit scale), the zero point is determined by placing the
thermometer in brine: he used a mixture of ice, water, and ammonium chloride,
a salt, at a 1÷1÷1 ratio. This is a frigorific mixture which stabilizes its
temperature automatically: that stable temperature was defined as 0 °F (−17.78
°C). The second point, at 32 degrees, was a mixture of ice and water without
the ammonium chloride at a 1÷1 ratio. The third point, 96 degrees, was
approximately the human body temperature, then called "blood-heat".[12]"

~~~
philh
> two very reproducible tresholds (freezing and boiling points of water)

Reproducible if you happen to be near sea level.

~~~
mcguire
And have the appropriate "water".

------
jrkatz
I live on the first floor of a house in Boston, and this summer made it
through without AC. By keeping heavy curtains drawn and closing both layers of
the double windows during the day, then opening windows at night and using
fans to draw cooler air through the apartment, I was able to keep the
apartment relatively cool throughout the summer.

Sure, there were nights my apartment still hit 87F indoors by the time I was
going to bed -- a week of nights that don't dip below 80 will do that -- but
it doesn't take that long to get used to it and the breeze from open windows
and running fans made it much more tolerable.

There are a lot of places in the US that benefit tremendously from AC -- I
grew up in the Mojave desert and there is little arguing with AC at 110F --
nonetheless the the machines are overused. If more people decided to tolerate
80F as room temperature, even without active measures to _replace_ AC in their
homes, we'd see a precipitous decline in energy usage. Add to that careful
control of airflow and insulation and many regions simply don't need AC.

Meanwhile, I am at my office, and the AC is run so high in the summer that
many people wear jackets indoors year round here. Lovely.

~~~
300bps
_the machines are overused. If more people decided to tolerate 80F as room
temperature...we 'd see a precipitous decline in energy usage_

When I first moved into my current house I was setting the air conditioning at
78 degrees. Then I had my central AC unit serviced and the tech showed me
little dots of mold throughout the inside of the unit in the basement. He told
me not to set the thermostat above 75 degrees in the summer time because it
doesn't get enough humidity out of the air. He also said to make sure I kept a
dehumidifier running in the basement.

Now I keep the thermostat on 75 and keep the basement at 50% relative humidity
using a dehumidifier in the summer. I also ended up installing a UV light
inside the basement unit myself to kill microorganisms.

So it's easy to say to just tolerate higher temperature but the unfortunate
thing is that high humidity levels inside a home can lead to serious issues.

------
jrapdx3
No question ceiling (and other) fans are useful for cooling, also for heating
by distributing warm air that otherwise pools overhead, especially in high-
ceiling rooms.

A cool water radiant system certainly seems it would save electric power. But
I wonder if such use of water is potentially a problem in regions where water
is a precious commodity.

Growing up in the desert of Arizona in the era before air conditioning became
widespread, there were interesting approaches to dealing with summer heat.
Relevant here, the "swamp cooler" was a fixture in most homes.

Sort of a combination of moving air and water methods, the cooler worked by
running a squirrel cage fan in a slatted metal box and water dripped through
material mounted on the interior box surface. Air flowed through the openings
in the box, evaporating water and cooling the stream of air which was piped
into the house though metal ducting.

This worked great when the air is dry. The later summer monsoon season was its
ruin: high humidity did not favor evaporation, or much cooling at all. It was
enough to make people think air conditioning would be a really good thing.

------
carlob
I think another solution that is often overlooked in the US is the passive
flow caused by open windows. I've been to so many buildings in the US where
it's impossible to have windows wide open and in some cases open at all.

I tend to think this is a bit like suburbia: a design choice made when energy
was much cheaper.

~~~
pimlottc
I've heard some fascinating stuff about passive airflow architecture. The
floor plans of old buildings were often laid out in very specific and
sophisticated arrangements designed to take advantage of local prevailing
winds and weather patterns so that opening certain pairs of windows at certain
times of day would effectively ventilate the entire structure. It's
interesting to also think of the secondary effects we've lost by effectively
sealing out the outside world and living in a closed box.

~~~
girzel
I would love to read a book on this: How far can you get relying purely on
design and structure, not technology. "Passive" solutions, as you say. A
fascinating topic.

~~~
jacquesm
100% passive is possible today.

[http://en.wikipedia.org/wiki/Solar_Umbrella_house](http://en.wikipedia.org/wiki/Solar_Umbrella_house)

------
mturmon
The five ceiling fans in my Southern California house are on virtually
nonstop, night and day, from July through September. I haven't done analysis,
but anecdotally they make rooms feel a lot cooler. If you get quality fans,
they are inaudible (at low speed) and seem to be trouble-free (i.e., no
problems after ~10 years of this level of activity).

~~~
jacquesm
Brushless AC motors (short circuit cage type) are extremely reliable, there
are only two things that can happen: eventually the bearings will run out or
the coils will short due to the mechanical friction resulting from the
changing flux which tries to push the wire around. The stators are usually
cast into a resin to counteract this as much as possible but in spite of that
some freedom of movement usually remains.

------
ferongr
I don't know, I can't say I agree with the article. I grew up (and still live)
in a small apartment in Greece. My family had fans (because air-conditioning
was expensive back in the day) all around the house. We "managed", but it was
definitely not comfortable when ambient temperature increased above 32C. After
installing air-conditioning (3 12000 BTU ductless mini-splits) everything
changed. Summers were finally comfortable afterwards and today I would never
think of decommissioning the A/C units, regardless of electricity costs.

~~~
papercrane
Article says the limit of this is 30C. I don't think the argument here is that
fans can replace all uses of AC, but rather can supplement them.

------
kingmanaz
The Bonelli house in Kingman, Arizona was built before central air
conditioning became common in homes. Temperatures in Kingman regularly reach >
110F (43C) in the summer, yet the Bonelli house was comfortable without air
conditioning or fans. To cool the house, a trap door in the center of the
first floor was opened, drafting cool air from the deep, unfinished basement,
through the intervening floors, and out a roof cupola. The system was passive
and still functions today.

[http://kingmanhistoricdistrict.com/homes/bonelli-
house/index...](http://kingmanhistoricdistrict.com/homes/bonelli-
house/index.htm)

Other locals would hang burlap or bedsheets over open windows, periodically
dampening the material with a hose. The hot breezes would blow through the wet
material, evaporating the moisture, and cooling the air. Many older homes
still have the blanket hooks above windows, though residents have long since
switched to air conditioners or swamp coolers for cooling.

------
cornewut
The article mentions that fans don't work when air temperature is higher than
that of the skin(35C).

This actually is not correct as increased air flow facilitates evaporation
(making sweating more effective).

~~~
kijin
Only if humidity is low enough.

Otherwise, moisture from the air will condense on your skin (making sweating
completely ineffective).

~~~
rurounijones
Helloooo Japanese summers.

------
callesgg

        "AC accounts for approximately 20% of year-round electricity consumption
        by American households, and 15% of total electricity use. [1] The widespread
        use of AC explains in large part why Americans use so much more electricity
        than Europeans: AC electricity use by an American household equals 60% of
        all electricity used by the average European household. [2]"
    

That math with that statment does not realy work.

~~~
nyc640
I think it means..

    
    
      American Household : [XXXXXX------------------------]
    
      European Household : [----------]
    

Where the X's are electricity usage by American households on air conditioning
(20% of total electricity use), which is equal to 60% of all electricity used
by a European household.

~~~
DamnYuppie
Europe is also much cooler then most of the USA in the summer. You all are
welcome to come and hangout in the south any summer you want, then you will
have a better understanding of the AC usage here. If I lived in Europe I
probably wouldn't need AC either.

~~~
gambiting
And you are welcome to try and stay in any of the southern countries of EU in
summer and survive without AC - Portugal, Italy, Spain, Greece are all
unbearable without AC.

~~~
DamnYuppie
I did say _most_ of the USA. I also am quite confident that the average
temperature in the south is much higher then even those countries.

A quick search shows that in Texas the average is 36 degrees while Greece is
28 degrees and 28 degrees in Barcelona. Also that doesn't even include our
lovely humidity!

------
kazinator
_> [Fans] can only provide cooling at air temperatures below the mean skin
temperature, which is about 35°C (95°F). Fans cannot cool people above that
treshold, because moving air cannot reduce the skin temperature below the
ambient temperature – no matter how high the air speed._

The statement applies to passive heat sinks. If a device's heat sink has a
surface temperature of 35°C, then blowing 40°C air across it faster will not
only help, but it will be counterproductive: the warmer air heats the heat-
sink, and moving air does it faster.

In 40°C relatively dry air, your skin is 35°C only because of active heat
removal: evaporation. This changes the picture. Moving air can speed this up
even though it is warmer. If the air doesn't move, then evaporation wraps you
in a blanket of humid air. Ventilation displaces the humid air, replacing it
with dry air that can take up moisture.

------
pnathan
I've lived with box fans for _years_. This is our second summer in the Pacific
Northwest, and our current apartment has _no_ air movement. I.e., you can have
box fans in the windows all night, and the kitchen is this mass of warm air
when you get up. The apartment heats up very quickly and loses heat slowly for
some reason. The apartment quickly reaches 78-80 degrees and is really
unpleasant. So this summer indicated an AC purchase for the bedroom was a good
idea. It's been extremely nice to sleep in a cool & dry room.

I'd be quite happy to have a residence that had decent air movement design,
along with ceiling fans, but I don't think I'm giving up the bedroom AC.

------
ScottBurson
If anyone is looking for a product recommendation, permit me to suggest the
Fanimation Landan [0]. My wife and I have one in the living room and love it.
6 speeds, remote control, LED lights built in (dimmable using the remote),
efficient DC motor.

[0]
[http://www.fanimation.com/products/landan/](http://www.fanimation.com/products/landan/)

------
a2tech
As someone that lives in a house built in 1860 (so windows open to allow
passive airflow) that has been retrofitted with ceiling fans and AC I can tell
you that if you're in a region with any sort of humidity that AC is
unbeatable. The ceiling fan is great if its slightly warm, not humid, and you
have the windows open.

------
eclipxe
The first fan pic in the article - the Big Ass Fan Haiku - awesome fan with
lots of tech

------
mrfusion
Has anyone installed a whole house fan? I've heard they can rapidly cool your
house to the outside temp at night?

I can't decide if it would hurt resale value too much to have a giant fan vent
in the middle of the ceiling though.

~~~
kd0amg
My apartment has one, but it's too loud to run it overnight. The vent itself
doesn't seem like a big deal though. It falls shut when the fan isn't in use.

~~~
mrfusion
Can it cool down your place really fast? For example in my house, when it's 80
degrees inside and 65 outside, I can open all the windows, and it gets down to
75 overnight :-(

~~~
kd0amg
I don't know. We don't run it overnight. I just use a pair of box fans (≈
intake + exhaust) to push cool night air through my room.

------
qwerta
Other option is to go underground. On continental climate it also saves winter
heating costs

~~~
girzel
Why isn't this considered as a solution more often? Is it just because
construction costs go up, or for reasons of culture and habit? It seems like
this is absolutely the best approach for stabilizing temperatures in both hot
and cold climates. Might not work well in a place with a lot of ground water,
I guess, but in general it seems like a win. Reduces building profiles, as
well.

~~~
rprospero
While I've read enough Asimov to believe that the future is underground, I'll
also be the first to admit that the lack of windows is a major problem with
the system. You both lose natural light and the cooling air currents provided
by the wind.

~~~
girzel
Well I didn't mean _all the way_ underground -- I think you'd get substantial
benefits from going three-quarters down on the ground floor. If there's only
one floor, skylights do the trick. For multiple stories, high windows, and
then fans circulating air between floors. Hmm, I guess this is getting a
little expensive after all...

