Fairchij: The above statement assumes a 100% efficient cooling system which we know isn't possible. Therefore, the savings might be even larger. That is to say it would probably take more than one watt of energy to take away the heat of one watt.

Yes, that's right. A factor of 1 is a very rough estimate. This author says it takes ca. 1.3 W of cooling power to take 1 W of IT equipment power away, at least in small data centers. Larger data centers require even more factors to be taken into account than small ones.