Hi Al, Mostly correct I think except for one key item: On Tue, Apr 29, 2008 at 11:07 PM, Al Shinn wrote: > so, 50kWsec/60= 833 KWmin = 13.8 KWhr at $.10/KWHr = $1.38 / cooldown > Can this be so? I'm never gonna open that sucker again as long as I > live!! At least not till I need the next cold beer. 50kWsec = 0.833 KWminutes=0.0138 KWhrs=0.1 cents per cooldown Also, as you say, I doubt that all of the air fully exchanges in a typical door opening. The thermal mass of all the other stuff in there will do two things: 1) make it so that there is less air 2) make the compressor have to turn on and off less. Other than that, it will not change the average amount of energy needed per cooldown, as whatever cooling effect you get from the cold food has to be recuperated by the compressor. Sean -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist