Parent is right, with some assumptions to be made explicit. Considering the reactions this deserves more explanations ;) Let's say that the heat energy of the

Parent is right, with some assumptions to be made explicit. Considering the reactions this deserves more explanations ;) Let's say that the heat energy of the warm thing is "E" and the outside and fridge are at same temp for simplicity. Let's also assume that the house is not heated using a heat pump. Consider the two cases: 1) The warm thing is put into a fridge. It's a heat pump, with coefficient of performance C. To cool the thing the fridge will consume E/C, and E will be released as heat inside your room. So you paid E/C of electricity to get E Joules of warming in your home; 2) The warm thing is put outside. The energy E is wasted outside, and then the piece put into the fridge with no extra cooling there. No energy spent by the fridge, but no warming of the house either. To do a fair comparison with the same final state, we need to add E joules of energy to heat the house, which will require E Joule of electricity or primary energy (because no heat pump to heat the house). So to reach the same point, in case (1) we spent E/C of heating energy, and E in the second case. It is indeed more efficient to put the warm thing directly into the fridge, as this will contribute to heating the house with the efficiency of a heat pump. And if you heat your house with a heat pump of same efficient C, you don't care either way: it's equivalent.