Reflective dome covering methods and materials

[Akela]

Hi everybody,

I've been intermittently lurking for since my virgin burn in 2012, and until now always found all the info I needed without having to start my own topic. So hi. I'm looking to build a 17' diameter 2v geodesic dome out of 3/4" EMT. I've been doing an unhealthy amount of research on coverings, and had an idea that I hadn't seen explored. If an active thread already exists on this topic, please direct me to it and I'll delete this one.

I'd like to have a highly dust-proof, sealed dome, with the minimum amount of waste and work assembling a cover (none of these precisely measured and cut out five-polygon conglomerations for perfect fits, please) with a vent or screen at the top and 5 gallon evap cooler inside. I'm attracted to the idea of a reflective surface more than a white one--I don't mind it being dark and gloomy inside, and would prioritize cooling effect over light transferal. Heavy duty silver tarp seems like it would just trap heat without reflecting sufficiently on the outside, though I know that a lot of people swear by it. I covered a 15' monkey hut with it in 2012 and it was suitable for that purpose, but I don't think it's what I'm looking for in a dome.

I'd rather go for a real, reflective radiant barrier. What I've seen up to this point in that department has been reflectix cut into triangular pieces and attached with melty tape (I'm forgetting the name, but the heat-sealed stuff). That seems effective, but like a lot of work. What about long, 4' high rolls of reflectix or other radiant insulation, wrapped horizontally around the perimeter of the dome in a few levels, with the long horizontal and short vertical seams taped, and a door cut in with velcro or other attachments? That seems like a really obvious method, but I've never seen anyone talk about it so I wonder if I'm overlooking some flaw(s).

Also, what kind of barrier would be ideal for keeping the dome as cool as possible? I'm not worried about retaining heat at night, I've got footie pajamas and a good woman to keep me warm. Here are several examples of products I'm looking at, arranged by price:

1. http://www.homedepot.com/p/Reflectix-4- ... 203927012# -- cheapest, lightest material by far, and that's for 125 ft compared to 100 ft for most others. Woven polyester. Claims to be heavy duty, but its .006" thickness makes me wonder if it would instantly shred in the wind.

2. http://www.insulation4less.com/Insulati ... sq-ft.aspx -- white on one side, reflective on the other, .15" thick. Large air bubbles in the middle. Also 125 ft long. Advertises a tear strength of 4.9 lb, which seems insanely low to me (like mylar film or something), but none of the Home Despot links specify and I don't really have anything to compare to. Same company sells a similar product for $5 more with two reflective sides.

3. http://www.homedepot.com/p/Reach-Barrie ... 204476669# -- white on one side, reflective on the other, .02" thick, small air bubbles in the middle.

4. http://www.homedepot.com/p/Reflectix-48 ... 202851861# -- white on one side, reflective on the other, considerably thicker (.3") but unclear if that depth is sealed air or corrugation or something else. Home Depot also sells a similar product for $10 less with two reflective sides.

Thoughts, advice, verbal abuse? Are all of these materials doomed to become little silver shreds floating downwind? Would a reflective surface on the inside retain a lot more heat than a reflective outside/white inside, or does that only matter with a light/heat source like the sun directed at it? So many questions...

Thanks all.

[MrBeardy]

Dome covers are a pain in the butt. that said I still bring mine out each year, each time with a modified cover. One year part of a huge old tent and a sail that I somewhat fit over it(way too hot during the day). A half covered dome with hammocks and chill space and then a suspended sealed area for sleeping made from said sail of previous year(best design but I went solo, so i didn't need to accomodate many people). And last year with the loved/hated parachute which I vented during the day when we were refueling at camp. In all honesty as much as I love the dome, a good cover is hard to come by and a hexayurt will probably be a better solution to achive your somewhat dust proof area. The reflective stuff you use is somewhat durable as I used some in my car and it stayed in tact, but the wind it gonna be a pain and you would be better off layering some covers over the dome and then adding a shade cloth or camo netting above it to take of some of the direct light. Best of luck and report back with your experiements, but I think a hexayurt or a vented dome would be your best bet.

[LowePro]

You are searching for a Holy Grail. There's a reason you haven't found the dome cover described yet....it doesn't exist (Or it needs to be invented!) If you make some progress, please let us know what you discover.

I certainly no expert, but I have done 2 burns, 2 different dome-types, 3 different types of coverings, and an unhealthy amount of research as well, but IMO you have to find a balance between dust, shade, ventilation, heat, and stability. The more dustproof, the less ventilation, and more likely to catch a big wind gust. More opaque is more shade, but also more heat trapped. The Parachute managed to do perform poorly on all criteria.

Trying to "seal" a dome so that it keeps out dust and keeps cool air from the swamp cooler is a lost cause unless you go with the fitted, labor-intensive covering. Also I think a single 5-gal swamp cooler is vastly undersized for a 17' dome, see the related threads on that topic.

My best quicky recommendation would be to use a roll of fabric as you suggest, but be aware it will not fit properly (Flat surface wrapped around tilted triangles = excess material) so be ready to secure the excess fabric at the joints. Tape will not hold it in the wind. Zip ties and grommets might. Then put a second layer of camo netting over the fabric. The first layer of camo net will shade the fabric and deflect some of the wind energy. We found the double-layer to be the best at cooling and minimizing dust.

[some seeing eye]

I saw one in the Alternative Energy Zone of something like your #2 sort of fish scale fitted and with a swamp cooler. Ask on their message board.

[Akela]

Thanks for the prompt responses, folks. I started on the AEZ website, couldn't find what SSE was talking about, but did find my way eventually to something very interesting. Check it out:

http://www.flickr.com/photos/orbitald/s ... 668137566/

That's pretty much exactly what I've been looking for, and judging by the photo descriptions, it was highly successful as a cool and relatively dust-free covering for at least two kinds of structures (1v starplate domes and bjurts, both of which seem very simple to cover from a geometric standpoint). It looks like the material used was something similar or identical to link #3 in my original post. Looking at how simple and clean those structures look, I'm considering buying the necessary connector kit for one or the other instead of building a 2v dome from scratch. I'm definitely drawn to the floor space:height ratio of a 2v, but I have to admit that those designs look reasonably sturdy, and that's without even guy-lining them down.

I've found a couple options that I think will work for me, PM me for details if you're interested.

[BAK3R]

I had a swamp cooled dome in the AEZ last year. I use white billboard vinyl cut into triangles and then glued with hh66 vinyl glue . I had a 25 gallon swamp cooler and it works good but am going with 2 - 25 gallon swampies this year.

[Canoe]

Good luck with the radiant barrier cover.
Do report back how it goes.

As to dust and heat.
A larger DIY swamp cooler, with the low current Endless Breeze 12 VDC fan, will not only provide cool moist air for inside, but it is also dust-free air. That incoming air pushes out any hot dusty air already inside, and it slightly pressurizes the shelter, making it somewhat difficult for hot dusty air to blow in.

I'm sure you already know that you need an exhaust vent to allow the hot air inside the shelter to be pushed out by the incoming cool air (without such a vent, the cool air resists being blown in, and that airflow is required for swamp cooler's evaporative cooling to take place). If the intake for the exhaust vent is located high up in the shelter, then you'll be exhausting the hottest air (hot air rises). There's a diagram showing the idea at the link.
viewtopic.php?f=280&t=33842&p=974558#p974558
You can exhaust that vent through the side down low, away from the high velocity winds that could rip the top of your structure open.

The exhaust vent can be closeable or one-way, to prevent hot air & dust entry when the swamp-cooler is not running (or driven in by wind). Some use a manual door that they put over or close when the swamp-cooler isn't running, and particularly when they're away from their shelter so a dust storm can't blow hot dusty air inside. A one-way vent is more convenient as it's one less thing to do and you don't have to think about it. Some use or make a light weight flap (clothes-drier vent type flap); others like using a furnace filter on the exhaust; others use an upside down “U” tube or a downward aimed 90 degree tube to discourage air blowing in, which also conveniently ignores rain.

Figjam can advise you if you need one swamp-cooler (I'm assuming a Box Cooler size), or should be using two.
His latest recap of the DIY Swamp Coolers is here viewtopic.php?f=280&t=33842&start=2430#p990806