R-value vs thermal capacity

[Juan Chacho]

I hear that vans with lots of insulation material might do well in cold weather but take hours to cool off at night in hot climates. Has anyone here experienced that, and with what insulation?

If so, I want to strike a balance between r-value and thermal capacity.

I found this article with an interesting chart: Thermal Conductivity and Specific Heat Capacity of Insulation materials at Different Mean Temperatures

 

[bullfrog !]

A lot depends on your build and the materials you use but again you are starting out with a metal box with glass windows and doors. If a high top most likely fiberglass also. You are trying to isolate the interior from the exterior while still having enough space to sleep, change clothes and maintain physical hygiene in comfortably. Any time you connect anything to the metal exterior it will conduct temperature so it becomes a concern, using aluminum strips with metal screws to hold panels for example. Opening a door, window or vent quickly equalizes the inside temperature to the outside temperature. One reason a curtain or wall is sometimes used between the driver’s front area and the back sleeping area is to reduce the effects of getting in an out of the vehicle and the large amount of glass in that area. Main reason we follow the seasons is we mainly live outside as there isn’t really enough space in a van to “live” inside for most of us and insulation or maintaining temperature in the van takes up a lot of space we need to do the other things well enough. Just my opinion stated here. I built a foam box with insulated air spaces with a entry chamber and just enough venting for two people to sleep in 7’ x 7’ x 6’ and it was still a pain to heat and cool. Main problem was keeping enough air flow to avoid condensation build up and stay alive! Lol!!! In a van insulation on the roof in the summer and on the floor in winter is important but head room for me was more important. 1/4” Luan or plywood panels with thin carpet that was easily removed and replaced worked best along with a very minimalist build worked best for me.

 

[Juan Chacho]

@bullfrog ! , have you run into the problem where, after a hot day, the insulation stays hot and makes the rig hot for hours into the night?

 

[bullfrog !]

@bullfrog ! , have you run into the problem where, after a hot day, the insulation stays hot and makes the rig hot for hours into the night?

My box is extremely less dense being foam filled interior doors covered in Poor man’s Fiberglass and has no metal fasteners and very little materials to conduct heat. If you like to experiment tape up a cheap foam cooler in a 70 degree room, take it outside and let it sit in the sun on a warm day. Poke a food thermometer into the interior and check it every hour. My box stays cool inside most of the morning as long as it stays pretty well shut up even in direct sunlight. By afternoon in 100 plus degree weather it is above 80 degrees inside. About an hour before sunset it is equal to the outside temperature. As soon as the sunsets I open vents and doors. If using my 5,000 btu AC it cools it off in less than an hour to 70 degrees. Humidity/ventilation play a role in this as well and condensation needs to be considered. By opening up things I sleep better and by midnight it is 70 degrees on the hottest days. Originally I figured no matter how well I built it it wouldn’t be air tight. I was wrong and nearly did myself in! Should have known when I couldn’t close the door when slamming it! lol!!! I installed a 14” x 14” vent and two 6” diameter floor vents which I can regulate. Even if you insulate to an extreme you will still need to heat and cool it as you will need to ventilate it to prevent condensation therefore especially if starting with a metal box it wasn’t really to me practical which is why I went to building my box. You will quickly come to the point of diminishing returns in a van in my opinion. I viewed my van as a metal tent and used a good sleeping bag with a little ventilation and carpeted panels I could easily replace to keep down condensation and followed the seasons. No sense trying to beat Mother Nature! If you do a diesel heater or propane generator and AC can easily be made high capacity enough even without insulation to do the job cheaper and better in my opinion. Full hookups if you can and it still won’t be as easy and nice as inside an apartment.

 

[INTJohn]

I hear that vans with lots of insulation material might do well in cold weather but take hours to cool off at night in hot climates. Has anyone here experienced that, and with what insulation?

If so, I want to strike a balance between r-value and thermal capacity.

I found this article with an interesting chart: Thermal Conductivity and Specific Heat Capacity of Insulation materials at Different Mean Temperatures

View attachment 37169

What climates are you going to be in?
Dude; you’re not designing an indoor amphitheater arena for 10000 people located in a 4 season city.

I think you are waaay overthinking this. I used 3M thinsulate designed & sold for vans. It’s on the expensive side as far as van insulation goes but worth it so I went with it. It’s on the sides; doors & roof.

Over the roof I put a DuraTherm ceiling liner and The floor has a Bedrug floor insulation liner covered with 3/4” plywood.

bch bum jonny

 

[Juan Chacho]

@INTJohn Hey, overthinking is a hobby of mine! There's so much conflicting information.

My climate will probably be all over the place until I get familiar with areas. Then I'll chase comfort, but with a few days a year cold (sometimes very) traveling to family for the holidays. If thinsulate and a heater is enough, that's great!