While parked for a weekend we had the generator set on auto start for battery monitor and air conditioner. This is what got me to thinking about insulation. The generator started a few times during the night for the AC, but once the sun started rising it was on full time trying to keep us cool enough to sleep comfortably. That day it got to 95° Fahrenheit, sun was pounding on the sides of the truck and in the windows. We do have curtains and they were pulled all around, blocking most of the sun/heat. The AC was working overtime trying to keep up. We also have a refrigerator that creates its own heat, flowing directly into the sleeper.
One time when we were home I had the fridge out of its cabinet for cleaning and realized the cabinet was only insulated on the outer sleeper wall behind the fridge. Knowing that weight is a great concern when doing anything to a truck, I got to wondering if more insulation could be added without much weight. I saw a trip to the lumberyard in my immediate future.
Homes, for the most part, have lots of space for thick fluffy insulation. Trucks do not. What I did find was an insulation that looks similar to bubble wrap but is silver in color. It came in a roll, weighing in at 6lbs, four feet wide and twenty-five feet long and its only 3/8" thick. That was way more than I needed but I can get creative. After doing some measurements, I figured out I could add multiple layers to get more R-value, it's only R- 3.8 in a single layer.
The ceiling of the cabinet had lots of room so it got three layers. The walls only got two layers. I have never timed or measured how often or how long the compressor cycles on the fridge, but I can say I believe it doesn't run as often or as long. We have also lowered the temp control from 4.5 to 4 and my water is just as cold. Bonus is I don't hear it running while in bed, as it is right there by my head. This was a simple install using a good spray adhesive. I measured the cabinet and cut the insulation to fit. I sprayed both pieces, allowed the glue to dry some and stuck it in.
I learned during this project that anything shiny could be used for insulation, even aluminum foil. You may have noticed aluminum foil is shiny on one side, matte on the other. The idea, as I understand it, when using it in cooking, put the shiny side to the food. That will reflect the heat back into the food but the matte side will allow heat to go through, cooking the food more evenly. The key is making sure the shiny side is to the direction you want the heat to go back to, reflected towards, or away from whatever you want to keep from heat.
The roll of insulation I got is called Reflectix, shiny on both sides. I thought this would be good for my project because it will keep summer heat out and heat in during winter, win win. There was a lot of Reflectix left after the fridge cabinet. What can I do with the rest? Thinking back to that summer day at 95°, I could make my own sunshades. That is just what I did. Did I mention you can cut Reflectix with scissors or a knife? I made a cardboard template for the side windows and just cut them out. We roll the window down some hold the shade into the glass groove then roll the window back up. The shade will stay in place even opening and closing the doors.
You will have enough to make a custom fit shade for your windshield too. We store all of our shades flat under the mattress. They are easy to get to and easy to put away for storage. It is truly amazing how much they help keeping the truck cool by reflecting the heat back to the great outdoors.
OEM's do a great job insulating with the space they have to work with while working to keep costs down. Technology in this field is advancing slowly, for home and automotive. I believe what is available now that is very expensive will be more affordable in the near future, I hope anyway. There are paints that have an R-value, last time I checked they were near $200.00 a gallon and the R-value was not that good. There are people thinking about this kind of stuff all the time. Someday it will be affordable and readily available and do a better job than what we have now.
Till next time keep cool (or warm).