The Kill A Watt device Karl mentioned in his blog post, “Are You a Power User?” has given me a good experiment.  I wanted to see how much power our 3 main printers drew while they were in their low-power sleep mode and how much the electric costs would be over a year.

Since these devices stay on continually, over the course of the day they spend the majority of time in a low-power sleep state.

How much time is this?  There are about 15 hours a day on weekdays and 24 hours a day on weekends where there is nobody in the office and therefore nobody needing the printers.  For the work week, that’s 75 hours where nobody’s around and the device is on and asleep.  For the weekend, it’s 48 hours.  With 52 weeks in a year that comes to 6396 hours that the 3 printers are on and in sleep mode.  Now the juicy question:  What does this actually mean in dollars and cents?

With a few phone calls to find out what commercial category we are in, I could find out the rate PG&E is charging for power.  It turns out it’s in a range from $.10/kwh to $.15/kwh for Tier 1.  For simplicity’s sake, I used a rate of $.13 kwh and assumed that all usage would fall in the Tier 1 category.  Using the Kill A Watt, in their sleep mode the three devices together drew .22 kwh of power and end up costing about $.03/hour.  Not a huge amount…  However, when we look at it over time it starts to seem a bit larger.  It ends up being $3.68 every week to keep them asleep.  For the year, it’s $191.

Here’s a little perspective.  With James’s help, we calculated the energy cost of running our network’s firewall over the course of the year.  It turned out to be around $1135.  Our servers are going to be even more.  However, the real difference between those and our three office printers is that the firewall and servers have to stay on continuously for us do our business.  The printers only need to be on when the office is open and they’re needed.  The simple solution is to turn them off when the day is over.  Rather than assigning someone that task, we’ve purchased a simple $25 programmable timer to do it automatically.

This is one of the first steps taken to save energy and lower costs and we’ll be doing more in the future.  Let me know if you have any ideas or suggestions.  Stay tuned!  More energy and cost savings are on the way!