All good stuff
For commercial customers your prices are determined by four things:
How much you use
When you use it
The maximum you use in any half hour
The grid connection capacity
So a 35% power saving won't alter maximum demand or grid connection capacity needs as these are set by the data centre running at full chat. As the power savings will be maximised at lower utilisations (so off peak) the unit cost savings will be lower than Google's average unit rate as well.
At a guess this is a 5-7% cost saving on the total power bill rather than the claimed 20%. Still worth working for, but nothing to get in a lather about.