This question was just posed to me by an administrator at an art museum. She is about to present a greening of the facility to a staff of 300 and she was wondering about the issue of shutting off computers off-hours vs letting them sleep. The IT folks were somewhat neutral but had a notion that extra boot-ups could shorten the life of the hardware and add to the impact. I suggested putting a watt meter on a typical computer and getting a read on running, sleep, sleep with monitor power off and phantom load, and calculate the energy savings. Any notions out there for best practice? She is presenting next tuesday.
Thanks in advance for your input.
David Kadlec
[email protected]
Eco Footprint of Computers
Sign in or Sign up to comment
Energy-wise, and wear-and-tear-wise, it's better to turn computers off at night, weekends, or whenver not in use. I think it was the energy group at Lawrence Berkeley Lab that did this study but don't have the reference - you could poke around their website to see if it's there. Note that for many computers, even when they're turned "off" they still draw some power. Many folks put them on power strips and then turn off the power strip to avoid that "vampire" power use. An experiment as you described is always a good idea. Remind them to check around the facility for all the other types of equipment that may not get fully turned off (TVs, printers, peripherals, etc.)
Anne Gracestone, Inc.
Boulder, CO USA
303.494.4934 vox
303.494.4880 fax
Please find response below. More information to come.
Cheers
-Peter
Peter,
Regarding lifetimes of equip, my understanding was that this was no longer an issue. May even be a case for turning off as some hard drives and cpu's get very hot, which can shorten lifetimes if the case is inadequately cooled. Add to this the burden of additional air con costs in warm climates compensating for the heat that PC's are generating, and the immediate savings in greenhouse gases (PCs in an office are generally used less than 1/3rd of hours in a week) and the argument for turning off becomes clearer. I think I may have some info at home on energy usage - I did some fairly detailed tests some time back. From memory, our PCs PIV 2.6 GHz ran at about 65 watts with windows fired up but no-one logged in. Went up to around 80-90 watts under load (running tasks, not including screens. I have some data on screens also, with figures (from memory) around 90 watts for a 19inch crt screen displaying predominantly white, less for 17 inch and around 25 to 30 watts for an active 17inch LCD screen (doesn't vary much with colour). Will chase up my doc for you from home with the detailed figures based on the "Centometer"(?) power meter.
Cheers
Dave
http://www.energystar.gov/index.cfm?c=power_mgt.pr_power_management
...
Hi David,
These days most PC manufacturers recommend that their computers be switched off outside office hours or if the user is going to be away from their desk for more than a couple of hours. As well as saving energy, this reduces wear and tear on the hard drive and cooling fan bearings. The energy savings resulting from switching a PC off varies widely depending on the type and age of the unit. We have found with our PCs that energy use ranges from about 30W to 110W with flat screen laptops having the lowest energy consumption. When the PCs were switched on but were in "sleep" mode, energy use fell by about 10W - 50W depending on the make and type of unit (i.e.. monitors can add up to another 50W). When switched off but plugged into a power supply that was switched on the standby energy use ranged from 1W to 5W. Your suggestion to use a watt meter on a typical computer to get a reading on running, sleep, sleep with monitor power off and phantom load, and then calculating the energy savings is the way to go. This is the way we determined the savings for our PCs.
Regards
John
John Osborne
Renewables, Sustainability Victoria
T: 03 8626 8783 | F: 03 9663 1007
Level 28, Urban Workshop,
50 Lonsdale Street, Melbourne 3000
www.sustainability.vic.gov.au