best way to warm a minivan ?

[davester]

Filliam H. Muffman wrote:
"Reflective bubble wrap is only good for reflecting radiant heat. It's works only at high temperatures."

So why are there so many places that sell reflective emergency/survival blankets?
http://www.amazon.com/PrimaCare-Medical-...B000FNQ7A4

Good question. The answer is that the blankets only work when they're within about an inch of your body where they can: 1) reflect back the small amount of radiant heat coming off of your body, and; 2) since they are impermeable they stop any advective loss of the warm air immediately adjacent to your body. Putting foil on the windows of a cold van is not going to do diddly because the radiant heat from your body attenuates quickly with distance away from you.

As an aside, although reflective bubble wrap has some uses, it is waaaay oversold based on specious claims and lack of understanding of the thermodynamics (and I'll be the first to tell you that thermodynamics was one of the most difficult classes I ever took, so understanding it is not an easy thing).