POWER USED BY COMPUTERS

By: Wyatt Berlinic and Lyndon Chan

Outline

• Possible interpretations– Global– Home– University– Engineering

• Our interpretation– Focus on computers in the engineering building– Extrapolate this data to the rest of the campus.

• Chose this interpretation because we could make the measurements and do actual calculations.

What we did

• We purchased a blue planet EM100 energy meter from Canadian Tire

• We then sampled different computers around the Engineering Building for power consumption

Assumptions

• Computers with the same CPU and GPU consumed the same amount of power

• The computers are not used 70% of the time• Power consumption would not increase by

much when in use• The cost of electricity is 10.61 cents/kWh

Power Measurements (Computers)

Lab # of computers Idle Power/Computer (W) Total Lab Power (W) Alpha 32 51 1 632

Beta 8 51 408Gamma 16 51 816Delta 30 51 1 530Epsilon 45 51 2 295Zeta 12 51 612Tau 14 51 714EE labs 12 79 948Total 181 --- 8 955

Xi lab could not be measured, as it is running on the servers

Power Measurements (Monitors)

• Each monitor uses about 35W of power when the computer is in use and when a screen saver is on.

• The monitors use almost no power when asleep. We measured 0W.

• We have counted 231 monitors in the Engineering labs, giving us a total of ~8 kW

Power Measurements (Totals)

Lab # of desktops Idle Power /desktop (W) Total Lab Power (W)Alpha 32 121 3 872Beta 8 86 688Gamma 16 121 1 936Delta 30 86 2 580Epsilon 45 86 3 870Zeta 12 86 1 032Tau 14 121 1 694EE labs 12 114 1 368Total 181 --- 17 040

Energy Use and Cost

Time span Total Energy (kWh) Total Cost ($)

1 day (24h) 409 43

1 month (30d) 12 269 1 302

1 year (365d) 149 270 15 838

Time span Wasted Energy (kWh) Total Cost ($)

1 day (24h) 286 30

1 month (30d) 8 588 911

1 year (365d) 104 489 11 086

Comparison of Results

• A typical household uses an average power of 1kW 1

• The computers here use as much power as nine households, and 17 households with monitors

• The total energy wasted in a year is equal to 119 100W light bulbs running all year round

Estimation of University Computers

• Estimated total number of computers on campus from Student Computing website

• Since the computers generally have one monitor, we estimate each computer to use 80W

• 68 labs X 20 computers per lab = 1360 total computers

• Total power 109 kW• Yearly energy 953 088 kWh• Yearly cost $101 123

Power Saving Recommendations

• Put computers to sleep 30 minutes after logging off

• Power usage in sleep mode is about 5W including monitors 2

• In engineering, 96 561 kWh could be saved each year saving $10 245

Conclusions

• A large portion of the university’s power is wasted by leaving computers on all the time

• This wasted power can be mostly saved by sleeping computers when idle

• Remote desktop is important, so software could be added to wake sleeping computers

References

[1] K. J. Cassidy (2005). What’s a Watt [Online]. Available: www.solartanic.com/index_022.htm

[2] M. Bluejay (2011). How much electricity do computers use? [Online]. Available: michaelbluejay.com/electricity/computers.html