Temporary cheap heating

Hi there, I find myself living in one of those portable (via crane) office cabins over the winter. Its a temporary thing, and will be used again as an office next year.

My budget is tight, and as it'll be used as an office again next year I am wondering if there are any simple and cheap ways to get a little more heat inside it.

Its 18m2, very well insulated (50mm xps) - so it doesn't get too cold most of the time and thus I don't need much heat to take the edge off.

- A portable gas cabinet heater has appeal in price/temporary nature, but is off the cards for 1) safety 2) the amount of moisture gas creates (i also have a gas oven which is essentially the same thing with the same risks).
- diesel heaters are just about cheap enough, but I am not very keen to make permanent holes for the venting..
- my solar set up is pretty small. 12v, 560w panels, 270ah battery, so I don't thiiiiink an electric heater works.
- i am very short on time currently trying to get the farm set for spring so I can hopefully live somewhere more appropriate next winter!!

I figure permies might have some ideas to bump the temperature up a degree or two. I have wondered if i can use the oven to heat something with dense mass each night...

Build a fire outside, heat some rocks, put them in a basket or bag and bring them inside? We've done this with a caravan and it's surprisingly effective as long as the space is small and well insulated.

Phil Stevens wrote:Build a fire outside, heat some rocks, put them in a basket or bag and bring them inside? We've done this with a caravan and it's surprisingly effective as long as the space is small and well insulated.

Mmm, that's what I was thinking with the "dense thing (brick/rock)" in oven idea. Thanks :)

Heat Storage.
Come home Heat up 1000lbs of water in 30minutes venting thru a window/etc and then let it slowly cool over night.
Just a regular gas hot water tank to heat and hold 40gal (US$500) and then 1000ft of pex piping (30gal) to circulate some of that heat ever so often.  

You could also try sleeping in a sleeping bag inside a tent inside the "tiny house".

This won't help you create heat, but it will help you store it.  Windows are the biggest culprits when it comes to losing heat, especially in a well insulated structure.  These cheap, simple curtains increase the insulation value of your windows tremendously.  Instructables - kume curtains

Can you open the window partially and close it back off again with a piece of wood with vent holes in it?  Then vent something out the window?

Alternately, there are set-ups where people heat a hot tub with a separate fire system.  So maybe put a 55 gallon drum of water in the house, pipe two water lines from it out to a fire with a coil of pipe in the fire.  Little pump to push the water out of the tank, through the fire and back to the tank.  I'd think that could heat up the barrel nice and toasty and keep you warm through the night.