I think you are missing my point...efficiency can be measured in many ways. While watt per watt, an air conditioner might be more efficient, my point is that the Iceprobe works very well for situations where an air conditioner would be overkill due to its size and power. Even the smallest air conditioners use around 500 watts of power. Meanwhile, my iceprobe uses less than 50 watts of power. So, using 1/10 the power of an air conditioner, I can chill my insulated reservoir roughly 15-20 degrees. To chill my reservoir any more would be pointless. So, in other words, your cooling idea uses 10 times as much power as mine does. And while that extra power might be useful when cooling many many gallons of water, it would be a tremendous waste to use that to cool a smaller reservoir. So regardless of the science involved, the sheer size and scale of an air conditioner will always make it less efficient when cooling small amounts of water, just by virtue of the fact that you can achieve similar results with a much less powerful product. It's like I said in the last post, you are basically suggesting that we should use a semi-truck to move only 1 box of stuff. I'm not arguing with the science, I'm simply stating that your application of it misses the point. You have yet to explain why it is more efficient to use a 500 watt (minimum) device to cool something that could be adequately cooled by something consuming 1/10th the power. An air conditioner=overkill. Overkill=waste. Waste=less efficient.