[AmosLightnin]

When cooking, the rate of heat needed to maintain the same temperature is exactly the rate at which the food is cooling. So heating up a pot and insulating it is roughly equivalent to heating up a pot and continually heating it to maintain the same temperature. If we changed the culture of cooking to recognize this, we could save a lot of energy.

[falcolas]

The pot in this "cooker" is dropping in temperature. Slowly but surely, since no insulation method is perfect against heat transfer.

[AmosLightnin]

True. But if the rate of heat loss is low enough, then it doesn't much matter.