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How much does it cost to run a PC?

Last updated on the 12th December 2011 by Simon Culligan.

Energy suppliers always seem to be in the news these days, if they are not trying to justify some cryptic new tariff then they are explaining why prices are rising again.  Over the summer most energy suppliers announced increases in energy tariffs of 12-18% for gas and electricity, so it is no surprise that everyone is looking for innovative ways to save money on their energy bills.

At home I'm always the one telling my kids to turn off lights and computers when they are not using them, so for a joke they got me a wireless electricity monitor.  As soon as I had configured it and switched it on it was simple to see the amount of electricity being consumed was £0.04 per hour.  I handed the monitor over to my six year old with the instructions to go round and turn everything off that was using electricity and see if he could get the value down to zero. When he had finished, I went round and switched a few things back on like the fridge, alarm clock, but everything else that was sat in standby mode, DVD, TV, printer etc.. was switched off, which takes usage down to £0.02 per hour.

 

So "How much does it cost to run a PC?"

 Using my home PC and energy tariff as an example, with the help of the wireless electricity monitor it was simple to find out.

PC POWERED ON	PC POWERED OFF

 

The PC and flat screen monitor powered on and being used costs 1.67 pence per hour, now if I was to leave this powered on 24/7 with no power saving functions enabled that would equate to a staggering cost of £146 a year. On the other hand if I was to enable a power management scheme that switched the monitor and the PC into standby mode after a period of inactivity then this bill could be significantly reduced.

So it is quite simple to measure the power consumption of my PC at home, but how could I do this for a thousand PC's as the cost of running them with no effective power management scheme could be as much as £146,000 a year.

 

Measuring power consumption for thousands of PC's

Measuring the power consumption for thousands of PC's individually using the method described above would be expensive and time consuming, but the above method has shown us that in known power states the cost of running a computer can be determined. So if I could accurately track the power states of a desktop / laptop then using some simple assumptions for hardware power consumption and costs per kWh I could determine the approximate cost of running thousands of PC's.

 

How can I track the power states for thousands of PC's?

Tivoli Endpoint Manager for Power Management determines approximate power consumption and costs by measuring the amount of time a computer spends in ACTIVE, STANDBY, IDLE and OFF power states.

 

How to reduce power consumption?

The most effective way to reduce computer power consumption is to deploy power profiles that place a computer and monitor into a standby state after a period of inactivity. The following process highlights how Tivoli Endpoint Manager for Power Management can be used to reduce desktop / laptop power consumption.

 

The above process can be broken down into six steps, with the most difficult being deploying Tivoli Endpoint Manager, and that is simpler than you would imagine.

Step 1 - Deploy Tivoli Endpoint Manager server and agents

The solution requires a single Windows Server with an MSSQL database with agents deployed on all clients you wish to manage.   The agents can be deployed using AD as they are about 6 MBytes and can be deployed silently without rebooting a system. For more more information on deploying Tivoli Endpoint Manager contact This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Step 2 - Subscribe agents to power management

With the agents deployed the next step is subscribe the agents to the Power Management License.

 

Step 3 - Configure cost and hardware assumptions

Next you need to configure your cost and hardware assumptions, a simple wizard takes you through the process.

You can calculate your own hardware assumptions or accept the defaults.

Step 4 - Activate power tracking

Activating power tracking is simply a case of selecting the required analyses and activating for your computers that are subscribed to Power Management.

Step 5 - Report on power usage

Now that we are tracking power states we can report on approximate power consumption and potential savings.  The power management module contains many powerful reporting tools. The following dashboard shows the overall view of power usage in your environment, and displays  the potential savings that could be made from deploying more aggressive power management schemes.

Step 6 - Deploy new power profiles

Now that we understand the amount of power the desktop estate is consuming we are ready to create some new power profiles and offer them to the end users. There are simple wizards to help you create these offerings, not all end user requirements will be the same, so you will need to create several power management schemes and also an option to opt out.

 

Getting end users involved is important and there is an end user console that allows users to see their own power consumption, and deploy more aggressive power management schemes.

Now that power consumption is being tracked in the environment the reporting tools will allow you to view how the power settings and consumption change over time.

Conclusion

When a computer is powered on but is idle it is using more power than it needs to, the cost of running a PC with little or no power management scheme could be up to £146 a year.