Crazy? Superinsulated 'sleeping box' separate in bus

[nearhomeless]

I have this idea i've been mulling over in my head since i'm stuck in minnesota and trying to find a way to live on the cheap and there seem to be limits to how much you can insulate the exterior of a bus to stay warm, or the impossibility of staying cool in summer with anything short of a 7kw genset and triple 13.5kbtu coolers.

What about walling off the very rear of it and putting in extra thick (even superinsulated level like 12 inches of fiberglass batt on the sides for R38, same on the floor, and 18 inches on the 'roof') insulation for a "room within a room" that has a separate door sealed from the rest of the bus. (or possibly including the shower/toilet) The idea is just that sub-room would have it's own heat and cooling ability, and is made as small as possible, mostly for being comfortable at night (no freezing to death, and no sweltering in the summer) or perhaps sitting room only to sit at a desk and work on paperwork or the laptop even if the rest of the bus isn't going to be too happy and you wont like coming out in the morning much or doing your cooking in subfreezing or sweltering heat.

I mean I know I could insulate the entire bus to this level (and lose 2 feet of width making it really tiny inside, plus losing two feet of headroom in whats rarely much over 6 feet... you see my problem) but I thought if it was just the sleeping area it might be more feasible. Small 5000btu 400watt window AC unit could probably even run off batteries/inverter briefly for such a small area (think maybe 8x6 by 4 feet high so technically 2/3 the volume of even a 48sq ft room and 1/3 to 1/4 the capacity of the AC unit) and stay cool with the superinsulation for awhile. Propane is expensive but use for such a small superinsulated area should be very low. Pipes or water tanks in the rest of the bus might have to be freeze proof for winter but that might be riggable too.

Now maybe on the most miserable of days i'll just spend all day reclining in bed reading books or watching TV or something without even venturing into the rest of the bus but that's better than having inescapable misery (or freezing to death in winter) and when the area cooled/heated becomes small enough, and insulated enough without windows, it seems alot more feasible to keep it liveable with deep cycle batteries and minimal energy use. For cheapness and health over fiberglass I might even go with the 2 string strawbales INDOORS as my insulation source as an experiment to see how liveable it is.

Or is this loony??

[Papabear]

There are a lot of crazier ideas. I would think you still need a small window or something for a freah air intake. A carbon monoxide detector might not be a bad idea. In the winter, if your room is totally sealed, you might suffocate yourself from you own out take. Especially if your using some type of propane heat. A thermal pane window with escape hatch capability would not be a bad idea. You could still put some kind of insulation square over it and it's there if you ever need it.

[Papabear]

P.S. We are all a little looney or we would not be members of this forum

[TygerCub]

I think superinsulating a small space for rest is a great idea. As others said above, make sure you have a source of fresh air. But there's nothing wrong with making one space a little less costly to survive during severe weather.

My only suggestion... If you're going to be superinsulating, go ahead and use foam. This has the triple advantage of providing more R value per inch of thickness than fiberglass batting, will not steal as much interior space, and will seal the space against air leaks. You could frame the room with hollow walls using 1"x2" as thermal breaks against the metal braces, add a nice plywood sheet for the interior walls, then spray in the slow-rise forumula to make a foam-core wall. OR you could spray in an inch of insulation, leave a small air gap, then back the interior wall with reflective insulation to retain heat in the summer and cool in the winter.

If that much spray-in foam is too expensive, use your refrigerator as an example and just frame-out your bunk with 2" of foam board, face the space with some of those mylar Survival Blankets (which supposidly retain up to 80% of your body heat), and put a drop-down door over the entrance. When it's REALLY cold outside, this will give you a small space that your body heat can keep comfortable. As long as the "drop door" just lays against the frame (doesn't seal at all), you should (and I say "should" because I'm no expert) still get enough fresh air. In the summer, just put in an evaporative cooler and leave the door open (latched to the ceiling).

BTW... the "cheapliving.com" address I gave you earlier was missing an "RV" in the middle. Sorry for the typo. Took me forever to refind the site. Try this link for some more great ideas: http://www.cheaprvliving.com

[lapeer20m]

i think your idea is great!

making a solid 1 foot thick foam igloo inside a bus should be incredibly energy efficient.

the concerns about ventilation, co2 detector and emergency egress sound pretty valid too

having a small propane furnace that draws in fresh air seems like a good method for heating. A/C units also have the ability to bring in fresh air. You could also include some 1 way vents that allow air to escape when new air is introduced from the furnace/air conditioner.

I like it!

[paul iossi]

great idea,
start looking at resturants that are going out of business, the 4'' modular panels used in the construction of walk-in coolers and freezers would be ideal, just make sure to allow for proper ventilation.

another thought that just came to me is i was writing this would be an insulated freezer box off of a refrigerated truck or semi-trailer, remove part of the bus ody and install an insulated section, maybe from the door to the bumper and then do your conversion.

[nearhomeless]

Wow lots of responses, here goes...


I know air quality is a problem, if you research superinsulated houses you'll find standard faire is to have a small forced air fan of 50-100cfm I think and a heat exchanger so that you dont lose all the energy out the fan hole. I plan to do the same.

I've even considered using a thermal mass - basically build a water tank around myself inside the insulation, and use a water heater or something to heat the water up so once I turn off the fuel the mass holds the heat all night. Heck a smaller waterbed would amount to the same effect and might have some freeze proofing but they usually need electric heating. Thermal mass holds the "coolth" of the night too possibly eliminating the need for AC.

I planned two exits from it even if the second is just being next to the emergency escape door out the back or top with an unnailed section I can kick off in an emergency. The area i'm planning would be pretty small maybe 8x8ft by 5ft high.

To vanguy67 - how much fuel and propane or electricity is typically used to heat or cool a bus in harsh weather? With people talking of 40,000btu of constant air conditioning (almost as much as my house probably) just to drop 25 degrees on a hot summer day I figure raising it 110 degrees on a -40 day would be obscene. Even if the use is half that of a house, the fact the propane costs 3x as much as natural gas or to try and run solar AC kind of kills the plan to have lower bills.

Mylar survival blankets retain body heat by reflecting it back as we lose alot of body heat through that, they wont work as door insulation.

Foam is what i'm planning to use if I can afford the couple hundred dollars worth of foam or find some used source.

I dont know how well a reefer (freezer box) would work, i'm not sure but they probably have 2 inches foam max to minimally impede transport space and just use a powerful diesel air conditioner since transit times usually aren't excessively long.

I know i'd be happier having a way to heat and cool the entire bus but the fuel cost will be too high. :( My alternatives are "be miserable" or be content with living out of most of the bus most of the year and having a retreat for the intolerably hot and cold days which always come.


I'm hoping that a small space could actually make solar AC feasible. (a 5000btu AC unit should cool a 320 cubic foot 8x8x5ft volume from 108 down to 68 with 230btu or in 3 minutes using 400 watts sustained, if I keep the duty cycle down 100-200w solar panels should make even the worst summer tolerable) Likewise being 1/8th the volume of an already hard to insulate bus (no way to put in thermal breaks really) plus no windows and controlled air infiltration means comfortably warm in the worst weather on at least 1/8th probably 1/16th the energy, and as long as my plumbing is either freezeproof or also insulated it should be surviveable. The worst part would be boredom or claustrophobia since going out into the rest of the bus much to cook would either suck or require heavy clothing. Better that than dying from not being able to afford the propane it's using. :( Call it my hibernation cave. Spend months reading books or typing on the laptop in the worst case scenario.

I'd still consider strawbales on end alongside foam. Far cheaper, less insulation per inch, but actually does "breathe" i'm told but since it's insulated the heat isn't lost. Whether it's enough to not need the vent i'm not sure. Alternately i'd consider loose straw (with borax as fire retardant) if I needed thinner walls. Strawbales would give me R50+ even on end.

If possible i'd design the shower/toilet as part of the superinsulated structure for obvious reasons.

[Sojakai]

Dont forget that any lights or appliances/electronics that are in your box are going to be adding to your heat. I live in Northern California (Fairfield-ish), and even in the dead of winter, only use my full size computer (2'2" tall, amd+3200, 4hd(these make lots of heat)) for heat in my room (10'H x 10'L x 8'w)... well, I use a thin fleece blanket draped over my legs, too.

I have to ask though, is 68 degrees the hottest that you are willing to put up with? Couldnt you shave a bit more energy out of the equation by only cooling to 86 or so? Its still comfortable without having to run the AC for the extra 20 degrees. Or, instead of using the AC, you could also use several frozen water/soda bottles, a small tub or plate for condensation, and a small fan for cooling. Circulates the air and cools at the same time. Or a 5gal bucket, some copper tubing, submergable water pump, and that fan.

Just a couple ideas. Going to hide in my hole again...

[TygerCub]

One of the things we've neglected to ask is this: What's the relative humidity in your area?

Having moisture in the air is a big factor when deciding the best way to heat and cool your space. Here in Virginia, evaporative coolers (aka swamp coolers) won't work in the summer because it's so stinkin' humid that all us natives wish we had gills in the summer time. The (relatively) dry 86 degrees that's comfortable in California is down right miserable in Virginia when the relative humidity is up. On low humidity days, that same temp is just fine.

So... is it humid in your neck of the woods? If so, then using a dehumidifyer will make your living space easier to live in regardless of the season.

Other, inexpensive measures to make the space livable in extremes:
WINTER
1) Wind is your enemy as it will rob your vehicle of heat faster than anything else. Block off the entire bottom of the bus with a wind break. This can be as simple as plastic stretched over wooden framework, or as complex as the straw bale approach.
2) The sun is your friend. When you park, be sure to orient the windshield and the wall with the most windows towards the south & east to collect as much solar energy as possible. You can gain extra heat by creating a "green house effect" by arching thin PVC pipes or 1x2 poles (or even saplings if you have a supply handy) over the bus then draping the entire thing with heavy-duty garden plastic (available from any greenhouse supply company). If completely wrapped (front and rear as well as sides) this will do double duty by creating a thermal shell and by blocking the wind. The only break in the envelope should be your door, which can be blocked off with a piece of fitted foam board wedged in place whenever you're inside. Because the PVC can rest on top of your bus, you don't have to worry about the greenhouse collapsing under a snow load like normal green houses do.
3) Foam board and reflective insulation is your friend. It's relatively inexpensive, can be cut to perfectly fit windows and doors, and can be easily removed and stored when no longer needed.

SUMMER
1) Shade is your friend. Make your own shade by building a roof-rack on the bus (or just laying a couple of 2x4's lenghwise over the top). As long as there is 2" or more between the metal roof and the deck material, you have enough of a radiant break to shade the roof of your vehicle. Extend a tarp from the deck out to shade the southern walls of your bus. Many places like Harbor Freight, Northern Tool, Home Depot, Lowes, etc sell a variety of tarps that will work, from the cheap, thin blue things that last a couple of months, to the thicker, silver-coated tarps meant to last several years.
2) Control your air moisture . If you live in a dry climate, add water to the air by either carrying a spray bottle to mist your personal space when hot, or create a swamp cooler. If you live in humid climates, invest in an energy efficient dehumidifyer and dedicate resources to run it (be it a plug run to a residential electrical plug, or a solar recharged battery set up specificly for this one item).

ANYTIME
1) Timing is everything. Whether it's in the winter when you have to block windows before the sun goes down to store heat, or it's in the summer and windows must be opened at night to let the relatively cooler air in to conserve energy, you're going to have to constantly monitor the conditions and adjust quickly to save stored air conditioning (that includes heat as well as cooling).
2) Remain flexible. You may have to start out using simple, scavenged items for the first couple of seasons to get by until you can afford to get more efficient systems in place. If you see something that might work, try it until you can find something different, or something to suppliment it to make it work better.

Hope you can find something useful here. I think you're on the right track by thinking "efficiency". But if you combine several inexpensive ideas you'll do much better than trying to find just one "holy grail" solution.

[paul iossi]

assumptions can get us all into trouble,
my limited experience with commercial walk-in freezers and truck freezer boxes is that they are usually a minimum of 4 inches thick, and filled with the tan colored high R value spray foam.
which brings up the insulating values of the different types of foam and the air infiltration of sheets vs spray foam, insulation is good but controling air movement is just as important.

[the_experience03]

Originally Posted by TygerCub

One of the things we've neglected to ask is this: What's the relative humidity in your area?

Minnesota is the Land of 10,000 Lakes so there is plenty of humidity for a few months each year. Actually, humidity in the winter can be more brutal than during the summer.

Speaking of Minnesota...STUCK in Minnesota? Pfft...this is God's Country ok...the Twin Cities Metro isn't so much

[lapeer20m]

Originally Posted by the_experience03

Minnesota is the Land of 10,000 Lakes

according to wikipedia, Michigan has 64,980 inland lakes......just thought i'd point that out...

[paul iossi]

an extra inch of poly insulation under your matress will do wonders to keep the cold from creeping thru you from the bottom, add a stack of good blankets and a knit hat to keep your ears warm, and you should be able to stay warm enuf to sleep at 0 F.
we used to winter tent camp with the boy scouts, we would break open straw bales and fluff them up under the ground cloth, pitch the tent, and oll out the sleeping bags, add an extre blanket inside the bag and sleep good all nite, only down side was who gets up first to get the fire going.

[the_experience03]

Originally Posted by lapeer20m

according to wikipedia, Michigan has 64,980 inland lakes......just thought i'd point that out...

Lake is all in how you define it. I *think* Minnesota has more lakes over 10 acres in size, but I'm not positive. You guys get all those nice winds off the lakes too. We're stuck with the clippers coming down from Manitoba.