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."<p>Unfortunately, fan-only cooling only works in a narrow range of climates.<p>> <i>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.</i><p>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.<p>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.<p>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.
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.<p>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.<p>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 <i>replace</i> 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.<p>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.
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.<p>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.<p>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.<p>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.<p>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.
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.<p>I tend to think this is a bit like suburbia: a design choice made when energy was much cheaper.
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).
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.
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.<p><a href="http://kingmanhistoricdistrict.com/homes/bonelli-house/index.htm" rel="nofollow">http://kingmanhistoricdistrict.com/homes/bonelli-house/index...</a><p>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.
The article mentions that fans don't work when air temperature is higher than that of the skin(35C).<p>This actually is not correct as increased air flow facilitates evaporation (making sweating more effective).
<p><pre><code> "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]"
</code></pre>
That math with that statment does not realy work.
<i>> [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.</i><p>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.<p>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.
I've lived with box fans for <i>years</i>. This is our second summer in the Pacific Northwest, and our current apartment has <i>no</i> 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.<p>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.
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.<p>[0] <a href="http://www.fanimation.com/products/landan/" rel="nofollow">http://www.fanimation.com/products/landan/</a>
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.
Has anyone installed a whole house fan? I've heard they can rapidly cool your house to the outside temp at night?<p>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.