Greetings, On Sat, 2010-07-31 at 12:47 -0700, kenwinston caine wrote: > As "Critical Path" reference noted, another reason this cools air is > the "Bernouli" effect of speeding the air -- as a fan does, and as > Percival alluded to in his mention of ancient stone window cover > designs (which I'd like to know more about!) here, in this thread: > http://groups.google.com/group/hexayurt/browse_frm/thread/3108984409d21ac5?hl=en# > > Percival, if you see this, can you tell me what those stone window > covers were called so I can research them a bit?
I can't recall what they were called off the top of my head (mostly because it was in arabic, but from what I recall, they were from 10th and 11th century buildings and mosques, but the museum I got my research from was the one, unfortunately sacked in the recent ... unpleasantness in the area, and while their collection is intact, I don't think I could get back in, right now, to do further research. Americans are not popular out that way right now for some reason ... But, from memory, there were foot-thick stone walls, with carved wooden and (for the more opulent) stone screens, similar to the ones pictured in http://home.jtan.com/~cellio/house/sources/mosque-screen.jpg Basically what I remember is that the air, moving across the screens would be pulled through narrower and narrower spaces, therefore having to move faster, and shed energy, so becomes cooler. I don't remember if the Hamilton-Jacobi equation lead me there, or my research into Bernoulli did, but since both were well after the carving of the screens, I had to do sideways research from their descriptions. But I can definitively state that, in my yurt (ger, actually) this summer, opening the ceiling hole, and pulling up the side-walls gave a very nice convection breeze. I was enjoying it too much to measure it's directionality, I'll do so the next opportunity I get. Percival > > > > > > On Jul 31, 1:02 pm, "ken winston caine" > <k...@mindbodyspiritjournal.com> wrote: > > Has anyone experimented with Buckminster Fuller's repeatedly demonstrated > > passive "chilling effect?" (Sometimes also written about as the "cooling > > effect.") > > > > He accomplished this with a chimney in the center of the roof (with a vent > > flap which could be opened and closed), and with a series of wall vents just > > inches to a foot above the floor all around the building -- those vents, > > too, could be opened and closed. > > > > As the sun rises, all the vents are opened. Heat reflecting off the ground > > and off the building create an updraft all around the building. This updraft > > draws air OUT of the vents just above floor level. (It appears to me that > > these vents often were about 1 foot off the floor -- and that in total, they > > exceeded the volume, by at least 8::1 or greater of the volume of the > > chimney vent.) > > > > As air is sucked out of the bottom vents by the updraft around the building, > > air is drawn in through the chimney. > > > > Fuller said the chimney downdraft effect extends hundreds of feet upward > > into the air and draws down a much cooler air than is found closer to the > > ground. > > > > He demonstrated this effect in equatorial desert regions with domes equipped > > as described above. But, the dome shape was not a significant factor in the > > "chilling effect," he said. > > > > This "chilling effect" was also implemented in Fuller's "Dymaxian Home," > > which somewhat resembled a hexayurt. (Do believe that it may work best in > > quasi-round buildings -- which the hexahurt is.) While Fuller promoted the > > cooling effect in hot climates, he also promoted the same process as a > > "self-cleaning" effect. > > > > Because this effect creates a cool downdraft and floor-level exhaust, it > > tended to draw out most of the ambient dust from the house, reducing the > > need for frequent cleaning/dusting. > > > > In Fuller's demonstrations -- in both humid Kansas summers and in equatorial > > deserts -- indoor temperature was lowered by about 15% after opening the > > events and setting up the "chilling effect." > > > > People reporting on the experiments frequently noted with amazement the > > sensation of cool air falling on them when they walked into one of the > > demonstration buildings. > > > > Fuller wrote, in what may be his last book, "Critical Path," on page 212 > > that the " pressure differential between the small air entry and large > > exhaust openings produces the Bernoulli chilling effect, which in hot > > weather will swiftly cool the ... interior." > > > > On that page he also provides a drawing of how it works with a geodesic > > dome. > > > > Here's a Google Books link to that > > page:http://books.google.com/books?id=2rPqFvn3nocC&pg=PA211&lpg=PA211&dq=b... > > > > You can read more about the effect in these two books also: > > > > Air Cooling Tendency > > Buckminster Fuller's Universe pp 208-09 > > And Chilling Effect > > BuckyWorks pp 114, 116 > > > > This is all counter-intuitive, I know. We all "know" that heat rises and > > that you need to vent it via an updraft at the highest point in your > > building. But not if you want to enjoy Buckminster Fuller's "chilling > > effect." > > > > In that case, you want to out-vent via convection at a low point all around > > the exterior of the building, and actually draw in a downdraft cool column > > of air from much higher in the atmosphere through a chimney at the peak of > > the roof. > > > > Fuller explained somewhere -- and I can't find my old notes at the moment > > -- > > that a column of hot air rising from around a circular building actually > > creates a downward vacuum in its center that pulls cool air down through its > > middle. > > > > I asked a couple years back if anyone would demonstrate / experiment with > > this at Burning Man and report here their experience, but found no takers > > then. > > > > How about this year? > > > > I would think that for the Playa, you would want to cover the vents with a > > filter material, such as the cheap blue synthetic stuff used for swamp > > cooler filters now that they rarely use straw any more (because of its > > tendency to grow mold). That way, during dust storms, it would be unlikely > > that you would experience much dust intrusion. Or, you might set up another > > simplie way to block the vents during periods of extreme blowing dust. > > > > In my original experimental designing with this, I found located some dollar > > store air-filled plastic balls (bouncy balls) that would perfectly fit > > inside 3-inch pvc pipe. So I created a design using pvc pipe for the floor > > vents and the balls to seal them closed. I also drew into the design pieces > > of fiberglass insect screen crudely tied around the outside openings of the > > pipes. (The pipes fit through the wall panels and extend a couple inches > > beyond the wall on both inside and outside -- though could be cut to mount > > flush for a neater install.) > > > > And for the roof vent, you can use a capped stovepipe and a damper flap > > section. The damper flap can be used to close (and open) the roof vent. Or > > just use another piece of pvc pipe and plastic ball and buy a $2 sewer-vent > > cover at an > > RV supply joint for a rain cap. > > > > Or, you could go even lower tech and just cut vent holes and save the > > cut-out material and stuff it back in and tape it in place to close the > > vents. > > > > I remain astounded with how this "chilling effect" works and, even more, > > that about 70 years after Fuller first began demonstrating effective, > > passive air conditioning drawing cool air from hundreds of feet above ground > > that it is NOT being designed into buildings in warm and hot areas > > worldwide. > > > > This MAY be because it works best in quasi-circular buildings (if that is > > true), and conventional design does not use round buildings. > > > > Do believe that it was engineered into the early sports domes. > > > > And I know that there is an emphasis since the late '70s on airtight, > > sealed, stale-indoor-air-filled, atmosphere-controlled buildings (which this > > is the opposite of) for energy efficiency. > > > > Anybody up to testing / demonstrating this at Burning Man this year? > > > > If you do, would you report on it here? Maybe shoot a video with a > > thermometer demonstrating temperature with vents closed, after an hour with > > vents open, and of the outside air temp? Then, for all time, everyone could > > *see* the results in action. > > > > Best, > > ken winston caine > > > > > > > > ----- Original Message ----- > > From: William Ozier > > To: hexayurt@googlegroups.com > > Sent: Friday, July 30, 2010 3:53 PM > > Subject: Re: [hexayurt] Insulation Thickness > > > > I am going to try and create a solar chimney on mine to help keep it cool. > > You put a black tube coming out the top. The sun heats the tube which heats > > the air and causes an updraft, which vents out the hot air and pulls in cool > > air...of course finding cool air to bring in on the playa maybe difficult, > > so there are a few more details to be worked out. > > > > On Fri, Jul 30, 2010 at 2:45 PM, Spiral Syzygy <spiralena...@gmail.com> > > wrote: > -- You received this message because you are subscribed to the Google Groups "hexayurt" group. To post to this group, send email to hexay...@googlegroups.com. To unsubscribe from this group, send email to hexayurt+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/hexayurt?hl=en.
