There are many articles about green IT initiatives and many articles about software as a service (SaaS). But there aren’t many at all about whether SaaS is inherently greener than on-premise software deployment. And after looking the subject over I can see why.
It is a very complicated question, more so than it seems at first glance. But Chris Thorman of SoftwareAdvice.com has made a start by crunching the numbers and comparing simply the power usage of an on-premise server plus user computers against the power usage of a server at a data center with those same computers linked over the internet. It is a very clearly written piece that not only explains what SaaS is but also how the two set-ups work.
Approached in this manner, he found a 93% decrease in power consumption for the individual user in his scenario. And that is very impressive. But, as Dan Woods points out in a Forbes.com article, the decrease in energy consumption only occurs on one side. Unlike other green initiatives where the energy decrease is entirely due to the total saving of the energy in question, using SaaS for the energy decrease doesn’t really save all of the energy; it is just shifted to the data center and away from the user’s environment.
Now that doesn’t mean that SaaS doesn’t save energy; it just means it doesn’t save as much energy as it appears. But if we are to get a bigger picture of the energy savings we would have to study the energy used by a data center not only to deliver software to one set of users but to deliver software to all the users who rely on that center for their applications.
How much energy is used by a datacenter serving a large number of users who each have a different application running on that server? And how much more energy is used for data storage? Add to that the energy needed to maintain the data center environment and the physical structure where it lives and the savings may be less than hoped.
I do think Chris has made an excellent start. But there are so many variables to be discovered and checked, it will be devilishly difficult to fully answer the question of net energy savings through the use of software as a service.