Small camping trailer venting in cold weather

[skyl4rk]

I have a small cargo trailer converted to a camper. It is a 4'x8' trailer and it has 1" foam insulation.

Cargo Trailer Camper - Imgur

I slept in it this weekend with 32F outside and here is the dilemma:

If the windows are closed up, it will start to warm up a bit and get comfortable, but eventually you need fresh breathing air, so you need to open the windows. Then it gets cold again. It is not bad as long as you stay under a sleeping bag and cover your head. But as soon as you get out of bed, the cold hits you.

I am trying to figure out a way to get fresh air to my sleeping area, but to temper it a bit so it is not so cold. Opening a window is hard to control how much cold air is coming in, and the cold air just flows around, rather than being moved to your head, where you want fresh breathing air.

My thought is to put a pipe through the floor, with a pc fan underneath the trailer. The pipe would extend up to near the pillow on my cot so I would always have a good supply of fresh air. Hopefully the pipe would warm up the air a bit.

I was trying to think of ways to improve this to keep as much heat in the trailer as possible. for example, use steel stovepipe to increase the surface area to transfer heat, but keep the supply and outlet diameters smaller to limit the amount of airflow. I am thinking (guessing) that a one inch to two inch diameter vent would provide enough fresh air using a pc fan as a blower.

Maybe even make up a small heat exchanger from coroplast as in the other heat exchanger thread. I am not sure it is worth it for my trailer project but it is interesting to think about using body heat as the main source of heat.

I am wondering if it is possible to heat a small insulated box using just body heat. How many R's of insulation would it take to heat a 4'x4'x8' box? If the box were made of iso foam panels, how many inches would it take to stay warm? The ventilation question complicates things but if there were a good heat exchanger, you might be able to build a tiny-tiny house/box requiring no external heat.

That would be the ultimate shelter, requiring no heat other than body heat.