The article is very good, but there is a couple of serious omissions in order for someone to technically evaluate it. Figure 3, illustrates the point. The red

The article is very good, but there is a couple of serious omissions in order for someone to technically evaluate it. Figure 3, illustrates the point. The red items are overhead and the green ones the IT components. The major energy consumption comes from the HVAC equipment. HVAC equipment - like everything else - is governed by the Laws of Thermodynamics. Energy conversion efficiency should be measured against the theoretical maximum efficiency. Any heat engine depends only on the temperatures it operates between. This efficiency is usually derived using an ideal imaginary heat engine such as the Carnot heat engine. It would be very interesting for graphs of these temperatures and theoretical vs actual efficiencies to have been provided. Anyway, Google is to be congratulated both for their interest in minimizing energy consumption as well as making these partial stats public.