Cooling the Bus

Now that the weather has finally started turning a little cooler (not fast enough! Texas just can’t seem to let go of summer), I thought I’d talk a little bit about our trials and tribulations regarding keeping the bus not…ass hot. It’s not quite as a rage inducing problem as it was a month ago.

While we were building the bus we were taking temperature control into account but it became very apparent once we were living in it that this was another thing where our planning wasn’t nearly enough for reality.

We tore out all of the old insulation- there was water damage from the hatch leak, mold, 2 separate colonies of giant ants that taken up residence in the insulation…oh, and a mouse- and replaced it with rigid sheets of polystyrene insulation. Because of the size of the ribs running across the roof the sheets on the ceiling are not very thick, we have only an inch of insulation up top. We chose this route because it was fast, easy, pretty cheap, and I hate fiberglass. It gives me hibbie jibbies. We also painted the roof white to help reflect the sun and at least offset a little bit of heat.

Well, let me tell you, that was not nearly enough. What we should have done was to eat the cost and do the spray insulation. Then we wouldn’t have any gaps and the spray insulates way better.

We are currently in a spot in the full sun. There wasn’t anything available in the shade at our campground. It gets boiling lava hot inside the bus on a clear summer day.

We bought a little portable air conditioner to help out. Now, I wasn’t expecting to be able to get the bus down to 65 in the middle of the summer but I was expecting to be able to keep it at least 10 degrees cooler inside than the temperature outside. We had read about other conversions and that seemed like the general consensus on what most other conversion were able to do. NOPE. With the AC running full blast, set super cold, and with the extra assistance of a fan to help move the cold air away from the AC we were able to keep the bus a whopping 1-2 degrees cooler inside, if we were lucky. I think the highest temperature I recorded in the bus was 98 and that was right where the AC was. It was stifling. I don’t know if that’s just because we got a bad air conditioner or if its poor performance is indicative of portable AC units as a whole. Frankly, I bought it because we needed one immediately and it was what was available at 11:00pm on a week night. Maybe other portable AC units don’t suck as much but I do not, under any circumstances, recommend that air conditioner. It cannot keep up with the heat coming into the bus.

So, we started poking around and realized that a huge amount of heat was coming in through the windows. The glass was radiating heat. We found a window treatment that is supposed to reduce solar heat coming in through your windows by 75%. It’s very easy to apply. I did a whole video on it and then realized afterwards that I had set the camera in front of the TV (it’s hard to get good angles of stuff in the bus) while I had Scooby-Doo on as background noise and that was all you could hear. Nice. Anyway, it’s basically a tinted film that you stick on your windows using a little bit of soapy water and good ol’ static cling. I don’t think it did anything to help mitigate the heat. There is the barest hint of a difference in temperature if you touch the glass but nothing close to what I imagine 75% should be. One good thing is that it makes the windows more private and harder to see into from the outside so at least we’ve got that going for us.

Next, we got super thick blackout curtains for all of the windows. We needed new curtains anyway since our original ones were mostly destroyed. I had taken our curtains from our old apartment and trimmed them down to be the right size for the bus windows. I hate sewing so rather than properly hem them (which I should have, there is a trend here of trying to shortcut things and having it backfire) I cut everything with pinking shears which helps prevent fabric from unraveling. Usually you use pinking shears to cut off the excess fabric after it’s been properly hemmed. Wellll, we forgot to secure the curtains when we started our drive out of Florida and next thing we know the curtains are flapping in the wind as we drove down the highway. It looked like the bus had little white wings. They couldn’t withstand that and it shredded the edges. Like irreparably shredded them. So we got black out curtains since those do have the added bonus of blocking the heat. And they do. There is a noticeable difference with them but not enough to offset the overall heat in the bus.

At this point we are probably about $350-$400 in the hole (including the AC unit) trying to keep the bus livable. And none of it has seemed to make any difference. It was still sweltering. We were afraid to leave Finn by himself during the hottest parts of the day lest he overheat and die. We left several times to just drive around town (the 3 of us) and drink milkshakes while basking in the AC of the Honda.

The only thing that we’ve found that really seems to make a noticeable difference is being in the shade. Good shade is worth more than anything. Park in the shade, open the windows, turn on the fan, and it’s ok.

I think that having the windows closed and the AC running makes the heat worse. Psychologically. The heat bothers me more with the AC running because it shouldn’t be so bad. It should be cool, we have an air conditioner for goodness’ sake! But with the windows down and a fan it is less bothersome because well, yeah, it’ll be warm because it’s the summer and that’s what the summer does. We get a great cross breeze with all the windows open and we can open the hatches to help release some of the hottest air. And it helps air out the smell of dog which gets really strong, really fast in such a small place. Finn gets regular baths but he can be quite the stinky dog.

I always thought that summer was my favorite season. Yeah no, only if I can escape from it as needed. Let’s just say that now I really understand why crime goes up in the summer.

So do I think any of what we did was worth the expense? No. No, I do not. The curtains look way better so that’s a win but I think that particular AC unit and the window films were a waste of money.

We will eventually upgrade to a mini-split AC unit now that we’ve actually researched what would work best on a bus (they are expensive!) and we plan on adding exterior window shades/a canopy but at least we’ve got until next summer to sort that out.

Now we just have to worry about not freezing to death this winter. Which hopefully will be easier than preventing heatstroke. Fingers crossed.


  1. OMG Katy! You had your own little piece of hell on earth this summer! Here’s hoping for a shady spot next summer, cool breezes and a good air conditioner! I’m enjoying your writing.

    • Thank you! It was almost amazing how uncomfortably hot it got in there. On the plus side, we barely have to heat the bus and it’s getting fairly cold at night now.

  2. This idea may not work for you, hell, it may not work for me. Lol!
    I am planning to buy and start the gutting and conversion process on a bus before summer ends. I have been researching the subject for close to a decade. (Thank you and so many others who have innovated and shared your experience over the last few years! )
    My thought to cool was to install Maxxaire vent fans directly into both of the emergency hatch covers. With some of the side windows open and the vent fans blowing out of the bus, i am hoping to get enough breese going to really make the difference.I think that mounting a roofrack on top of the bus and attaching solar panels to them would help to shade the roof, as well.
    I want to be totally self contained (I will have the ability to hook up to electricity, i just do not plan to actually be near hookups all of the time.) So, battery pack and solar panels will not push an A/C unit.i would have to start the generator…I don’t wanna…lol
    You guys think that this may work?

    • Alex, all of what you described should work to some extent and may in fact be all that you need. If you’re in the southern US, it may not be enough but at northern latitudes you will definitely see that effort pay off. A big part of the problem comes from the sun and how much of the bus is directly being hit by it. by building a rack and mounting solar panels you will effectively provide yourself with your own portable shade which is always helpful. We are actually working toward something similar. Right now as I type this, I’m sitting in the bus with no AC, and even though the sun set a few hours ago, and after leaving the bus under the best tree shade cover I could ask for, the bus is still a bit sweltering hot and uncomfortable. But we are in florida in early summer and sometimes its just hot, no matter what you do. Good luck with your build, and drive north in the summer !!!

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