Do you want to save on heating costs but not freeze? Then give it a try with a home-made oven. You will need three terracotta pots of different sizes, a candle in a jar, two bricks and a long screw. First you have to put the three pots into each other. Now screw them together with the screw and a nut and possibly with washers so that the holes in the floor are tight. This construct stores a lot of heat. Now put the whole thing on the bricks and light the candle. Put it underneath and the oven is ready - without an open fire.