After 2 wonderful weeks in McDowell Mountain Park we stocked our liquor cabinet, loaded up the fridge and got ready to roam far-far-away back into the boonies where many would say we ruffians belong. Thanks to the folks on the forums at rv.net we managed to scope out yet another sweeeeeet spot on free BLM land just west of Yuma, AZ. We’ve got a view of the mountains, unlimited desert landscape and not a single neighbour in sight. I have to admit I’m starting to love winter desert boondocking.
But our first order of business (after tilting the solar panels & having an appropriate sundowner cocktail) was to think about insulation. Those of you following the blog may remember our freezing boondocking experience just over a month ago in the Sierra Nevada Mountains. One of the things we bemoaned during that trip was our complete and total lack of proper insulation for the rig.
It’s not quite as cold down here in Yuma, but night-time temps have been dropping to right about freezing. Our rig, although equipped with dual-pane windows, is not really a 4-season performer and we get quite of bit of chilly air coming in especially through those pesky windows. So, with plenty of time on our hands and no-one to laugh at what we’re doing this was the perfect spot to geek out a solution.
Mathematically it all starts with R-values. Now thermodynamically heat is always on the move and can enter (and escape) a space via 3 basic methods; convection, conduction and radiation. RVs conveniently provide all 3 escape methods (e.g. conduction through walls, convection through the air, radiation through windows etc.) and it can get a little complicated thinking about all of them at once.
Thankfully there’s an approximate short-cut and that’s to look at thermal resistance. Thermal resistance is basically a measure of how well a given object resists heat flow and it’s summed up in a handy formula and a single number by R-value. In layman’s terms the higher an object’s R-value the more it insulates against heat-loss. R-values are standard listing on most insulation materials that you buy so you can kinda tell up-front how well it’s going to work (it gets more complicated when you layer different materials together incl. air-gaps, but the basic idea is there).
Having been educated as a Materials Scientist this kind of stuff get me pretty excited especially when you start looking at the weird and wonderful materials that haven’t yet made it into standard life. For example, Aerogels are super-light, super low-density structures that provide the highest R-values (>10) of any single material in existence. Check out this epically cool 1-min Aerogel vs Flamethrower battle here:
I have dreams of wrapping the entire RV in silica aerogel and lighting it up like a neon-blue alien spaceship, but unfortunately the stuff is pretty brittle and only really made in small quantities. However new flexible “blanket-like” composites are being made which will one day provide super-light insulation for everything from shoes to buildings. Once those price comes down we’re there, baby!
The next best solution, for the average RVer, are regular insulators such as Reflectix, foam, bubble-wrap or Polartec. Our biggest heat-loss problem in the rig is currently our windows so we went with double-bubble 5/16” thick Reflectix from Home Depot (R-value 1-4 depending on whether you install with an air-gap). It not only helps with conductive heat-loss, but is also shiny (reflective) and so acts as a radiant barrier too.
We bought the 4-foot wide, 25-feet long version (BP48025) for ~$45, enough to make covers for all our windows (Note/ 4-foot is as wide as they make it in one piece -> the websites selling 6-foot or 8-foot versions are simply using two strips taped together so don’t get suckered into buying them).
For the front it was a simple case of cutting to shape using the Magna Shade windshield shade that we bought earlier this summer as a base pattern. Since our front window is actually ~5-foot tall we had to join two pieces using aluminum tape…easy, peasy. For the other openings I cut pieces to approx. size and then squeezed them into the windows, marked the outline with a pen and cut to a perfect fit.
And our first night with the insulation? MUCH, MUCH warmer. Rather than an almost-constant cycling of the furnace, we only had a few cycles during the night despite very similar temps. Pretty cool or rather pretty hot, either way you look at it. And all for only $45 too….
Other sealing/insulating ideas:
1/ Windows – Look at Shrink Insulator Film or try cheap and easy Bubble Wrap.
2/ Vents – Buy those nifty vent-pillows for ~$10. We use them all the time and they’re super-easy to inset & take out (e.g. when you need to cook).
3/ Openings - Any openings from the outside into the rig (e.g. gas lines) can be sealed with self-expanding foam or rubber.
Got any good tips of your own?