Coffin bed

The idea is to minimize energy use.  We want to have the least amount  of cubic feet  required for climate control.  That strategy minimizes energy use.   As an example,  a bed of 24 cubic feet should suffice.
Using this wall unit as an example, which will cool 100 square feet using 5k btu, then 12 square ft would need only about 600 btu.

Then 6 hours of cooling at that rate uses 1 kWh.

Update:

No.  This is bound to be less than 1 kWh.  The area covered is too small.

The idea is related to the Iron Man suit from some of the Brainstorming for mining an asteroid series.

Update ( couple days later )

Here's an application of this idea to the storage shed post in the off-the-grid series.

Update ( 8/20/14 or about a week later )

Here's some denim insulation for the area that will be directly below the loft.  Fairly cheap and easy to install.

Storage loft may be big enough for a twin size mattress

It may require some additional modifications to make it insulated enough, but that's no biggie.