What is the difference in the cost to fire a kiln in a warm room compared to firing in a cold room?

Room temperature has almost no effect on the electrical cost of firing a kiln. However, if your kiln is under a carport that has open sides, protect the kiln from the wind. Air blowing against the case can raise the electrical cost slightly. If you use a fan to lower the temperature of the switch box, position the fan so that the air blows into the switch box louvers but not onto the firing chamber case.