Keep a Room Warm for 14 $ Cent a Day
Here a guy who claims you can keep your little study warm during the winter with a computer installation, one human exothermic chemical process… plus 2 * 4 = 8 waxine lights.
P.S. We did not test this idea. Our hobby horse remains thermo-wired cloths as the cheapest way to stay warm during the winter. And the safest. Other simple means to stay warm: 5 minutes/hour of intensive physical exercise on a home trainer or rowing machine.