Covering the windows with clear plastic is good. If one of the windows gets sunshine, you can get some solar heat gain during the day, then, at night, you need some old covers to cover the opening. While the plastic helps with cold air infiltration, it still only has an R-value of about 1. the old covers or blankets will help curb heatloss at night.
Find some dark green or bown beer bottles (40's would do) , fill them with water, and they too can collect solar heat, when the sun sets, move them to the center of the room. If you got industrious, you could find one of those 50 gallon plastic barrels, fill it, wrap it in an industrial garbage bag so it's a dark color. Again, you'll get some nice solar heat gain. You could even use the warmed water for bathing and dishes.
Standard residential electric usage has been studied.
6% of total load is for lighting. So, if you normally run a $100 elec bill, and you turn of ever stinkin light , for 30 days, you save a grand total of $6. whoopie. The cost of re-bulbing with lower wattage may even be a wash. It would literally take years to recoupe the cost of those fancy energy efficient bulbs.
OK, Coldwood can make an ethical decision on this one, but, how is this for out of the box thinking?
Each Apt. evidently has it's own elec. meter, therefor it's own wiring. While the neighbors are at work, find some of their electric wire on a common wall. Splice ito it. Use it very sparingly! (you'll have to re-spackle the drywall so the landlord doesn't catch you on a surprise inspection).
Their electric bill might spike by $10 or $15 bucks, but, if you are careful, and use it judiciously, you'll probably get away with it.
Less sneaky would be an extension cord, as long as you knew their patterns for being away, you could "sneak" some power, a little here and a little there.
I liked the false ceiling idea from Longbow, how about just use the clear plastic again, one or two layers, taped, bring ceiling hight down to 7 feet from the 8 feet standard. You have now reduced the heated space by about 12.5% , and are keeping the heat lower, closer to you.
Sealing off unused space is another good one. Keep space on the South side, seal up the North side (and hope the pipes don't freeze in January).
Visit friends, a lot. Their place is warm.
There is no reason a healthy individual couldn't find some kind of work?
Shovel snow for the neighbors or landlord? Make some scratch here and there, day laborer, tax free stuff.
Oh ,crap, pile snow up to window sill for more insulation value, don't comrpess it, leave it as fluffy as possible.
Being sandwiched in between those other units would be life saver.
Food: Rice is cheap. Get a PT job at a restaurant, you can typically eat for free while working. Take a ziplok bag to work and bring leftovers home.
Dumpster dive. Lots of cool stuff to be had, sell it on Ebay.
