Jason -- air conditioning (refrigerating air) and evaporative cooling work completely differently. Air conditioning requires that moisture be removed from the intrerior air (and the air entering the house) and that is why you must keep windows and doors closed tightly. It's not to keep hot air out nearly so much as to keep interior air dry.
Whereas evaporative cooling works in dry climates by adding moisture to dry air and allowing it to evaporate. This requires a constant supply of dry air and relatively constant flow of air exchange. And, to work well, requires serious air movement -- a blower -- pushing the moist air into and through the interior dry air. You really don't want your exhaust to be on the ceiling. That's because you want to both exhaust damp air and draw in fresh dry air. The damp air settles as it cools the dry air. So a few filtered vents on north, east and west facing walls, at shoulder height or lower, should allow for plenty of air circulation and flow. (My best guess.) I wouldn't put one on the southface because that will get sun -- and heat -- all day long. And, as was suggested by others, filter and or screen the vents to keep out playa dust (and insects). You WANT some hot, fresh, dry air entering the room at all times that the evaporative cooler is operating. No need at all for an exhaust FAN or blower. The swamp cooler's fan or blower will create enough positive air pressure to push interior air out of the vents. On Wed, Sep 4, 2013 at 2:03 PM, Vladimir Khodel <[email protected]> wrote: > The fans that you have in swamp coolers should create enough air pressure > to keep outside breezes out, so just taping a furnace filter over an > opening that matches total area of your intakes should do the trick. It > will also no allow any dust to get in through any remaining gaps, except > for a real dust storm situation (we did not have those at all this BM :)). > > Cheers, > > Vladimir > > > On Wed, Sep 4, 2013 at 12:52 PM, Jason Adams > <[email protected]>wrote: > >> Everyone, >> >> Thanks for your responses - top notch scientists in here haha. >> >> Ken, you are right that my test was at Burning Man. So the air was not >> moist, and it seems that your correct in that my problem was inadequate new >> flow of dry air. The only air coming into my yurt, was from my swamp >> coolers or whenever I opened my door. Almost no air was escaping, because >> i went as far as to tape seal the bottom of the yurt to my tarp. >> >> It seems that the ideal situation would be a small fan blowing out >> towards the top of the yurt, and a vent allowing breeze in (with filter on >> it) for allowing fresh dry air in. Sound about right? At some point does >> the volume of air going out and new dry air coming in, negate the effects >> of the evaporative cooling? For example if I'm air conditioning my house, >> but have all my windows and doors open, the hot air from outside almost >> negates the air conditioning -- is it a similar effect with swamp cooling? >> >> >> >> >> On Wed, Sep 4, 2013 at 6:19 AM, ken winston caine < >> [email protected]> wrote: >> >>> I should add to my earlier observations and advice: >>> >>> You not only want to let moist air buildup escape, but you also need to >>> let fresh, dry air in. Continuously. >>> >>> In a house with evaporative cooling, you typically leave windows cracked >>> open a couple inches. That serves several purposes that help swamp cooling >>> work well: >>> >>> -1- Creates cross-ventillation to keep air moving / flowing throughout >>> the living quarters to be cooled. >>> >>> -2- Draws in fresh dry air to mix with and evaporate the inside moisture >>> and thus cool the inside air. >>> >>> -3- Allows moist air to escape preventing excess buildup of humidity. >>> >>> You do not want the system sealed and airtight. You want a small amount >>> of fresh air coming in and old air moving out throughout. >>> >>> I should also note that I pulled the "30 percent relative humidity or >>> less" number off the top of my head and am remembering that swamp cooling >>> does work in conditions where relative humidity is higher than that. It >>> just doesn't work as well. There are diminishing returns with each few >>> percentage points increase in relative humidity. I recall it worked a >>> little bit -- but not well -- the July lived in El Paso during monsoons >>> when relative humidity was hovering in the 60 percent range. >>> >>> The more humid the air, the less cool and comfortable it feels. >>> >>> Best, >>> ken >>> >>> P.S. Am also realizing that your test was probably at the Burn, under >>> desert conditions. Am pretty sure, from what you described, that lack of >>> adequate ventilation was the reason you didn't experience significant >>> cooling. >>> >>> >>> On Wed, Sep 4, 2013 at 2:39 AM, Lucas González < >>> [email protected]> wrote: >>> >>>> So I could (some other day) set up a spreadsheet with a few cells. The >>>> critical factor is local humidity, which can be measured. All other factors >>>> considered, there'll be a humidity threshold beyond which evaporative >>>> cooling won't work. >>>> >>>> Helpful, thanks! >>>> >>>> (Note to self: link to said spreadsheet (when done) from cooling >>>> wikipage (if that page exists). As usual, unless someone beats me to it. >>>> O:-)) >>>> >>>> Lucas >>>> El 04/09/2013 09:56, "Henner Zeller" <[email protected]> escribió: >>>> >>>> On 4 September 2013 00:51, Henner Zeller <[email protected]> wrote: >>>>> > On 3 September 2013 23:54, Lucas González < >>>>> [email protected]> wrote: >>>>> >> Interested. Would evaporative cooling work _at all_ in humid >>>>> climates? >>>>> > >>>>> > If you are close to 100% humidity: no. In particular since you want >>>>> to >>>>> > cool down the air, you need to look at the amount of humidity in the >>>>> > _target_ temperature range; if you already have a pretty humid >>>>> > climate, then this might already be oversaturated at the target >>>>> > temperature, so nothing can be evaporated more. Swamp coolers are >>>>> only >>>>> > useful in dry climates. >>>>> > >>>>> > It is relatively simple: you really just need to calculate the >>>>> partial >>>>> > gas pressure of water vapor in the given target temperature (colder >>>>> > air can hold less water), and how much more could 'fit in' given the >>>>> > dryness of the climate (how much water vapor is already there per m^3 >>>>> > and how much more you can add). This looks like a useful resource: >>>>> > >>>>> http://www.engineeringtoolbox.com/water-vapor-saturation-pressure-air-d_689.html >>>>> > With that, you can calculate the amount of water you can evaporate >>>>> > into a given volume. >>>>> > Given the required target temperature and knowing how much heat >>>>> energy >>>>> > is supplied every second (estimate energy intake by the yurt area in >>>>> > sun in Joule (<< 1000 J/(m^2 * s) (1000W energy of sun per m^2, but >>>>> > most of it is reflected with aluminum covered sheets, hence the 'much >>>>> > less than' sign) + number of people * 100 J/s (typical heat 'exhaust' >>>>> > of a human is 100W) >>>>> >>>>> + temperature gradient outside/inside and energy flow due to that >>>>> depending on the insulation >>>>> of your insulation material. >>>>> >>>>> > and the amount of energy taken by the water->steam >>>>> > transition (2260 J/g water evaporation heat) - you can calculate the >>>>> > grams water you need to evaporate per time unit (to fit the energy >>>>> > bill) and flow rate (to keep the air dry enough to be able to take on >>>>> > this mass of water per time-unit). >>>>> > >>>>> > -h >>>>> > >>>>> >> Perhaps with some modifications? I think not but haven't tried. >>>>> >> Sleepbreeze.com.uk does seem to work, but that's one body, not one >>>>> room. >>>>> >> >>>>> >> Thanks, >>>>> >> >>>>> >> Lucas >>>>> >> >>>>> >> El 04/09/2013 08:32, "ken winston caine" < >>>>> [email protected]> >>>>> >> escribió: >>>>> >> >>>>> >>> David is right. You definitely need to have an exhaust vent. Swamp >>>>> cooling >>>>> >>> cools by moisture evaporating in dry air -- not by creating >>>>> increasingly >>>>> >>> swampy air. You must draw fresh dry air in, and let the moist air >>>>> out. >>>>> >>> >>>>> >>> Since the moist, cooler air falls to the floor, it is best not to >>>>> depend >>>>> >>> upon a roof exhaust vent. A mid-height window, or open door will >>>>> do the >>>>> >>> trick. >>>>> >>> >>>>> >>> RE: your test. You didn't tell us WHERE, what region, you were >>>>> conducting >>>>> >>> the test in. Were you in a region with 30% or less relative >>>>> humidity? If so, >>>>> >>> your test would be a good indicator of the effectiveness of the >>>>> evaporative >>>>> >>> cooling, once you have the intake and exhaust set up correctly. If >>>>> you were >>>>> >>> in a higher humidity zone, there is no point in running the test. >>>>> It simply >>>>> >>> won't give you any indication of how the evaporative cooling will >>>>> work in >>>>> >>> low-humidity, desert conditions. >>>>> >>> >>>>> >>> Hope that helps. >>>>> >>> >>>>> >>> ken winston caine >>>>> >>> >>>>> >>> >>>>> >>> On Tue, Sep 3, 2013 at 11:41 PM, David Kelso < >>>>> [email protected]> >>>>> >>> wrote: >>>>> >>>> >>>>> >>>> A swamp cooler needs to be constantly moving fresh air in, humid >>>>> air >>>>> >>>> out in order to keep cool. So you should aim to have a directional >>>>> >>>> airflow path. It can go up to the roof, or out to the door. You >>>>> need >>>>> >>>> to make sure the outlets are big enough that the fan isn't >>>>> fighting >>>>> >>>> any extra pressure inside the yurt. An outlet fan would help with >>>>> that >>>>> >>>> but isn't strictly necessary >>>>> >>>> >>>>> >>>> The major factor in swamp cooler effectiveness is fan speed. >>>>> Which fan >>>>> >>>> were you using? >>>>> >>>> >>>>> >>>> For anecdotal evidence, last year I was in a 6ft stretch and was >>>>> >>>> getting at least 30 degree F cooling throughout the whole yurt. >>>>> >>>> >>>>> >>>> On Tue, Sep 3, 2013 at 10:19 PM, Jason Adams >>>>> >>>> <[email protected]> wrote: >>>>> >>>> > So I setup an H12, with two swamp coolers, with insulated ducts >>>>> into >>>>> >>>> > opposite ends of my Yurt. Just cut a hole for the ducts. >>>>> >>>> > >>>>> >>>> > Its going to be hard to describe, but I still felt like the >>>>> swamp >>>>> >>>> > coolers or >>>>> >>>> > the yurt wasn't really cooling much. I felt like being out in >>>>> the sun, >>>>> >>>> > but >>>>> >>>> > in the breeze was way more cooling that in a h12 with two swamp >>>>> coolers >>>>> >>>> > running. The airflow really close to the duct holes was nice, >>>>> but once >>>>> >>>> > you >>>>> >>>> > got more than a foot away from duct, you didn't really feel it. >>>>> >>>> > >>>>> >>>> > It also felt hot inside, maybe thats just the moisture or >>>>> sticky icky >>>>> >>>> > feeling you get from releasing that much moisture in the air. >>>>> >>>> > >>>>> >>>> > It's definitely nice not having the intense light on you, the >>>>> yurt >>>>> >>>> > certainly >>>>> >>>> > kept alot of that sun off the ground , probably getting a >>>>> cooling >>>>> >>>> > ground >>>>> >>>> > effect, but I feel like I was missing some comfort. >>>>> >>>> > >>>>> >>>> > I feel like my options are to basically vent the yurt, or do a >>>>> fan >>>>> >>>> > exiting >>>>> >>>> > air at the top of the yurt. Which would ideally get more >>>>> airflow in the >>>>> >>>> > yurt >>>>> >>>> > -- however I feel like that would lose some of the effect of >>>>> the swamp >>>>> >>>> > cooling (after all I'm sealing the bottom to keep the cool air >>>>> in >>>>> >>>> > right?). >>>>> >>>> > >>>>> >>>> > Maybe what I really needed was some type of airflow in the >>>>> yurt, either >>>>> >>>> > up >>>>> >>>> > the power of the swamp cooling fans -- or hang a big fan from >>>>> the top >>>>> >>>> > of the >>>>> >>>> > yurt. >>>>> >>>> > >>>>> >>>> > Just trying to figure out how to make this thing more >>>>> comfortable, >>>>> >>>> > because I >>>>> >>>> > honestly felt cooler under a shade structure, with some pillows >>>>> and the >>>>> >>>> > breeze coming through. >>>>> >>>> > >>>>> >>>> > Thoughts? >>>>> >>>> > >>>>> >>>> > -- >>>>> >>>> > You received this message because you are subscribed to the >>>>> Google >>>>> >>>> > Groups >>>>> >>>> > "hexayurt" group. >>>>> >>>> > To unsubscribe from this group and stop receiving emails from >>>>> it, send >>>>> >>>> > an >>>>> >>>> > email to [email protected]. >>>>> >>>> > To post to this group, send email to [email protected]. >>>>> >>>> > Visit this group at http://groups.google.com/group/hexayurt. >>>>> >>>> > For more options, visit >>>>> https://groups.google.com/groups/opt_out. >>>>> >>>> >>>>> >>>> -- >>>>> >>>> You received this message because you are subscribed to the >>>>> Google Groups >>>>> >>>> "hexayurt" group. >>>>> >>>> To unsubscribe from this group and stop receiving emails from it, >>>>> send an >>>>> >>>> email to [email protected]. >>>>> >>>> To post to this group, send email to [email protected]. >>>>> >>>> Visit this group at http://groups.google.com/group/hexayurt. >>>>> >>>> For more options, visit https://groups.google.com/groups/opt_out. >>>>> >>> >>>>> >>> >>>>> >>> -- >>>>> >>> You received this message because you are subscribed to the Google >>>>> Groups >>>>> >>> "hexayurt" group. >>>>> >>> To unsubscribe from this group and stop receiving emails from it, >>>>> send an >>>>> >>> email to [email protected]. >>>>> >>> To post to this group, send email to [email protected]. >>>>> >>> Visit this group at http://groups.google.com/group/hexayurt. >>>>> >>> For more options, visit https://groups.google.com/groups/opt_out. >>>>> >> >>>>> >> -- >>>>> >> You received this message because you are subscribed to the Google >>>>> Groups >>>>> >> "hexayurt" group. >>>>> >> To unsubscribe from this group and stop receiving emails from it, >>>>> send an >>>>> >> email to [email protected]. >>>>> >> To post to this group, send email to [email protected]. >>>>> >> Visit this group at http://groups.google.com/group/hexayurt. >>>>> >> For more options, visit https://groups.google.com/groups/opt_out. >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "hexayurt" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to [email protected]. >>>>> To post to this group, send email to [email protected]. >>>>> Visit this group at http://groups.google.com/group/hexayurt. >>>>> For more options, visit https://groups.google.com/groups/opt_out. >>>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "hexayurt" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to [email protected]. >>>> To post to this group, send email to [email protected]. >>>> Visit this group at http://groups.google.com/group/hexayurt. >>>> For more options, visit https://groups.google.com/groups/opt_out. >>>> >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "hexayurt" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To post to this group, send email to [email protected]. >>> Visit this group at http://groups.google.com/group/hexayurt. >>> For more options, visit https://groups.google.com/groups/opt_out. >>> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "hexayurt" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To post to this group, send email to [email protected]. >> Visit this group at http://groups.google.com/group/hexayurt. >> For more options, visit https://groups.google.com/groups/opt_out. >> > > -- > You received this message because you are subscribed to the Google Groups > "hexayurt" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/hexayurt. > For more options, visit https://groups.google.com/groups/opt_out. > -- You received this message because you are subscribed to the Google Groups "hexayurt" group. 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