Sep
10
WRITTEN BY:
Greg Goode
Thursday, 10 September 2009
You’ve probably heard the term ‘follow the sun’. Effectively, it is saying that as one set of staff are finishing for the day as the sun goes down in their part of the world, another set of staff, in a totally different location and time zone, are commencing their day. It’s used as a way to describe how, for example, call centres, help desks and financial dealing rooms can provide continuous service across a 24-hour day without having to maintain a shift roster of many people in one location. That all seems to make sense.
So, I was bemused by a comment in an article in Data Center Knowledge about a significant data centre user, Google: Google’s Chiller-less Data Center, July 15th, 2009, by Rich Miller.
The article’s author proposed a concept to reduce energy costs which he named ‘follow the moon’. ‘Huh?’, I hear you say. What’s the planet Earth’s natural satellite, the moon, got to do with energy?
Well, if you were employing free-air cooling in your data centres, you would get the largest benefit when Sol drops below the horizon and the atmosphere cools down. By having data centres located across the world, you could continually push your computing to those data centres that were at a location where it’s night time. In this way, free-air cooling is providing maximum energy savings and, of course, electrical tariff rates are lower to provide energy to the cooling plant and your computing equipment. Not bad lateral thinking and, I have to say, a pretty neat idea! The moon comes into it because, to most people, the moon is associated with the night.
But hey, I am a pedantic amateur astronomer, and guess what? The moon can be up in the sky when Sol’s up. Just because the moon seems to have a high level of visibility at night doesn’t imply that’s the only time it’s overhead—it can be quite visible on a clear day. So, it isn’t technically true to imply that to follow the moon you are following the night.
Let’s not start using this term as it is bad science and has no relevance to day or night. Day and night is caused by the Earth’s rotation on its axis over 24 hours with the Sun tracing an apparent path over the surface of the Earth—known as the ecliptic—causing approximately half of the Earth to be in shadow, or night.
So, what would be a better way to define night or, in this case, when the Earth’s atmosphere is cooler and when energy costs are lower?
Well, there seems to be no astronomical body in the sky that creates the same phase of reference to night and day. At any moment in time, day or night, stars and planets are overhead. Comets aren’t of any use; they come and go for eons. So I think we’re back with the Sun as the frame of reference. Just by tightening up the terminology we could solve the problem of having a term that is the opposite to following the sun.
Let’s be a little more prescriptive. We can use the term ‘follow the rising sun’ for businesses which use a geographically-diverse workforce to support continuous operation. And we can use ‘follow the setting sun’ for businesses that use virtual technology to move computing power to data centres operating at night-time in order to save on energy use and costs. Simple, Watson!
The data centre industry has to-date been pursuing some pretty smart science and engineering. Let’s not sully the waters with terms that show a lack of understanding in other sciences.