Storing herbs, spices, coffee and tea in my Florida van? Temperature inside insulated bag inside insulated freezer

Question

I live in South Florida where the summer sun has no mercy. I drive a new van and I've taken steps to keep the inside cooler during the day. I live in the van for weeks at a time and need to store things in the van. I rarely hang out inside the van from 11am to 3pm unless it's parked in the shade or unless the AC is turned on. At night I have a very large and powerful vent fan and have no issues sleeping in the van even in July and August. However, my goal and concern here is with keeping some items in the van when parked in the sun. I can't afford to run my freezer every day. Items include dry good and things like Herbal supplements, Teas, instant coffee and Olive oil. These are not things that are generally very sensitive to some warmth and humidity ... but I want to see what I can do to offer them a safe storage in my van. Here's what I've done so far:

1. Install a large aluminum and glass solar panel on my roof, this the space directly above the place i store these things and blocks the sun.
2. Open large vent opening under the solar panel where heat escapes.
3. Install reflective mirror vinyl where the solar panel does not cover.
4. Install reflective insulation a 1/2 inch below the roof metal
5. Install a sealed plywood ceiling
6. Placing said items in an insulated bag
7. Placing the insulated bag in a highly insulated and sealed Freezer (that is usually off)

These updates make a huge difference, but still the inside of a metal van who's exterior can get so hot you can fry an egg so it's not like the cabinets inside my insulated, air conditioned Cinder Block and Wood house were it's always below 80F.

So I am wondering...

I need to test and confirm this with a thermostat, but any idea how hot it might get inside that insulated bag/freezer in a van set up as described parked in the Florida sun? Does it sound like these items are going to go bad or worse be dangerous for consumption if stored as describe ... I mean, tea and herbs are dry leaves and roots ... what if the temp inside the bag is 90 F degrees? Is it even possible it could be 90F inside that bag?

Answer 1

Insulation does not keep things cool or hot, it just slows heat transfer. In the end, the temperature in the cooler will stay at roughly the average car temperature. If you want to keep it cool, freeze two bottles of water (squeezing out a little bit so it doesn't expand enough to break the bottle). Each day, exchange the melted water bottle with the frozen one. The temperature will still swing a lot (after the bottle melts), but it will stay much cooler than the ambient car temperature.