Google is once again beating the drum for cloud computing, using the angle that it's cheaper and greener. It's a message we've championed here at Input/Output UK as well. But we should beware of being dazzled by big numbers...
Google is quite right when it says that cloud computing can be energy efficient. It's also right to conclude that moving to the cloud from traditional in-house data centres will save you money and help the environment. But that's true if you're moving to any energy efficient data center.
Google's latest headline cost-savings figure makes interesting reading:
The U.S. General Services Administration (GSA)...recently switched approximately 17,000 employees to Google Apps...reduc[ing] server energy consumption by nearly 90% and carbon emissions by 85%. That means the GSA will save an estimated $285,000 annually on energy costs.
My morose, GCSE-grade-C-maths summer-job temp tells me that's ten quid per employee per year. Doesn't sound so impressive when you put it like that, does it?
Of course, when swapping out hardware, or moving to a whole new data centre, you should also calculate the embodied energy used in that new infrastructure. The energy used to run a data centre is only part of the story; it’s also important to consider the energy that was already used to manufacture it. Greenpeace has some great data on how green major manufacturers' products are.
And that's even without thinking about how the power grid needs to get considerably greener. If the GSA is using 90% less energy and emitting 85% less CO2e, it sounds like Google's data centres are running off slightly dirtier power than the GSA's were.
So if there's life left in your current gear, don't be too keen to dump it without first doing your sums.
Richi Jennings 
, editor of Input Output UK, is also an independent analyst, specializing in blogging, email, spam, security, and other technology topics. His writing has won ASBPE and Neal awards. You can encircle him at +richi, follow him as @richi on Twitter, pretend to be his friend at Facebook.com/richij or just use boring old email: io@richij.com.
