Computers and Energy Efficiency

Tufts guidelines on how to lower electricity consumption of computers.

UIT energy use computer guidelines (PDF)

Download our computer brochure with lots of information about computers, energy consumption, and climate change. As a PDF file or as a Word document. Detailed comments on the figures and facts (PDF) used in the brochure.

FAQ about Power Management.

Power Management
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Tufts University owns about 4,300 personal computers; in addition there are about 3500 student owned computers. Much of the increase in electricity consumption at Tufts over the last few years can be attributed to the large increase in technology usage (see inventory).

EatonMac.jpgA survey done by Tufts undergraduates during the fall semester 1999 revealed that almost 80% of students leave their computer on sometimes or nearly always.

A majority of Tufts staff used to shut their computers down at night. Yet, with heightened security risks, some IT departments at Tufts now require computers to be on 24/7 for security updates to be installed as soon as needed. This is currently true for Arts & Sciences, whereas the Boston and Grafton Campus, as well as Central Services, still recommend shutting computers down over night and on weekends. Arts & Sciences recommends that staff and faculty shut off their screens at night and on weekends. Unfortunately, this makes it impossible to recommend uniform guidelines. OOS is collaborating with IT services and is hoping that new software will become available that will make it again possible to shut computers off when they are not used.

CRT monitors are being more and more frequently replaced with LCD monitors. These use only about a third the energy of a CRT (ca. 25W instead of 75W)

The university could save much money and energy and reduce CO2 emissions if staff, students, and faculty could be educated to shut down their computers when they are not using them. (A few computers, called “servers,” that store network information must be on all the time.)

Data Centers and Data Closets also are major power consumers because most of them are air conditioned. See more about Data Centers and Closets.

A Few Simple Calculations:The average desktop computer uses about 120 Watts (the monitor uses 75 Watts, and the CPU uses 45 Watts.) Laptops use considerably less, around 30 Watts total.

4,300 Tufts-owned computers X 0.12 kW X 250 workdays X 8 hours = The university uses 1,032,000 kWh per year to run all of Tufts computers just during business hours.

This amounts to: 1,032,000 kWh X 11 cents =
$113,500 per year in electricity costs.

Greenhouse gas emissions for this electricity amount to: 1,032,000 kWh X 1.45 lbs of CO2 per kWh / 2,000 =
748 tons of CO2 per year.

100,000 – 500,000 trees are needed to offset these yearly emissions of CO2! (A tree absorbs between 3-15 lbs of CO2 per year.) More on Sequestration.

If 500 of these computers (which is only one in nine) are left on all the time this adds:

500 computers X 120 Watts X 365 days X 16 additional hours = 350,400 kWh
$38,544 in electricity costs
254 tons of CO2

It would take 34,000 – 169,000 trees to offset the same amount of CO2!

Click here for detailed comments on the figures and facts (PDF) used in the brochure.

TCI works with Tufts Information Technology Services (ITS) on technical and behavioral changes to lower energy consumption of computers at Tufts:

1. Technical:

EatonPC2.jpgPower management of the monitor: Most computers have energy saving features (power management) that can be activated.

The power management feature powers down the screen after it is not used for 15 minutes (the time can be set). Instead of the “screen saver,” the monitor just goes dark. Tufts ITS is routinely enabling this feature on the computers where that is possible.

Power management features have sometimes interfered with some software and caused problems. According to Bruce Nordman, researcher at the Lawrence Berkeley National Research Laboratory, and other sources if only the monitor power-down feature is enabled, there is no interaction with other software. FAQ about Power Management.

TCI is also researching software technology that would enable computer lab staff to shut off computers centrally from a server.

2. Behavioral

Shutting the screen down: Very often there are times during the day, when we don’t use the computer for a while (e.g., during lunch hour or during meetings). It makes sense to shut the screen off during these times.

Shutting the computer off: Most computers (except servers) can be shut down at night, on weekends, and during the day if they are not used for several hours.

There are still prevailing myths about computers that might prevent people from being willing to change these behaviors. Switching computers on and off used to be a problem in the very early days of computers, but this is no longer the case. On the contrary, some literature suggests that leaving the computer on will actually shorten the computer’s lifetime.

The following statement is taken from: User Guide to Power Management for PCs and Monitors, Lawrence Berkeley National Laboratory, 1997

“The belief that frequent shutdowns [of PCs] are harmful persists from the days when hard disks did not automatically park their heads when shut off; frequent on-off cycling could damage such hard disks. Conventional wisdom, however, has not kept pace with the rapid technological change in the computer industry. Modern hard disks are not significantly affected by frequent shut-downsShutting down computers at night and on weekends saves significant energy without affecting the performance. Power-managed equipment also may actually last longer than conventional products. Because most such equipment will spend a large portion of time in a low-power sleep mode, mechanical wear on disk drives and heat stress on other components can be reduced.”

Office of Sustainability Computer Brochure
Computersticker.jpgTCI developed a computer brochure that has been distributed to all Tufts faculty, staff, and students. The brochure gives energy use information and explains how they can reduce the energy consumption of their computers.The brochure includes this sticker that people can put on their monitors next to the on/off button as a reminder to save energy. (Download our computer brochure as a PDF file or as a Word document. Detailed comments on the figures and facts (PDF) used in the brochure.)

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