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Tufts Saves Energy: Guidelines for Computer Power Management at Tufts
Power Management Recommendations
Newer computer equipment and power consuming devices and peripherals run much more efficiently than they did in the past and the types of devices and they way we use them varies greatly. That said the recommendations below depend on your device and the way you use it.
| Recommended Action* | Impact | When to follow |
|---|---|---|
| Shut off your machine/device | Greatest Energy Saving |
|
| Put machine to sleep | Minimal use of energy |
|
NOTE: It is most important to ensure that you receive and keep your devices up-to-date to receive critical security patches and updates while saving as much energy as possible.
*Action may vary depending on the type of device.
Introduction
Running a typical laptop at full brightness for an hour uses about 50 watts of energy. It's about the same as a table lamp turned on for an hour, and costs less than 1¢. That doesn't sound like much, right?
But consider all the classrooms, labs, shops, and offices on the Tufts campuses, and all the electricity used in all the pieces of equipment which have been left on overnight, even when no one is using them.
If we do a ballpark estimate of the number of computers, monitors, printers, routers, lights, etc, powered up all night — and multiply that by the number of people at Tufts, and by 365 nights in a year, the wattage adds up astronomically. The tables below show estimates of how much energy we consume if we leave equipment on at night, and the cost in dollars. We're talking at least $300,000 worth of electricity per year! And that's a conservative estimate.
In just one year, by setting our equipment to sleep/standby/hibernate, rather than keeping it awake all night, the university can save at least 1,947,000 kW of electricity, keeping 1,380 metric tons of carbon out of the atmosphere. That's equivalent to the carbon sequestered by growing 22,818 tree seedlings for 10 years!
Definitions
- Awake: device is on whether in use or not
- Sleep, Standby: device is not being used and is in an energy-saving mode
- Hibernate: computer workspace is saved and device is shut down
- Off: device is completely shut down
Every Watt Helps
So how can we go about it? Well, since every watt helps, the key ways to save electricity and money are to get into some good habits.
For any given piece of of equipment you can:
- Put it in sleep/standby mode when not in use
- Adjust settings so it goes into sleep/standby automatically
- Shut it all the way down when possible
- Turn off power strips that gear is plugged into
TIP: for any piece of equipment, do a search on "how do I set __________ sleep settings", using the name of the equipment to fill in the blank, and you will find useful guides and instructions.
Did you know that you can put your computer to sleep at night (instead of hibernating) and save energy while having Google Chrome (your browser) and Outlook start up with any tabs or email messages you had open when you shut down the night before.
At first you might have to remind yourself to take these small steps, but over time it'll become second nature!
Every Watt Helps Stickers
As a visual reminder you can request Every Watt Helps stickers to place on your laptop and other devices to help remind you. Click on the orange box or the link below to request some and share with your friends.
Energy Savings
TABLE 1: Estimated nighttime energy savings comparison by Tufts devices awake vs asleep vs shut down*
| Device | Awake (in use or with screen-saver |
Asleep/Standby (plugged in but not in use, in sleep/standby mode) |
Completely Off (shut down, unplugged, or power strip turned off, or in hibernate mode |
|---|---|---|---|
| Laptop | 240-600W | 12-72W | 0W |
| Desktop computer | 780-3000W | 12-72W | 0W |
| LCD monitor | 240-480W | 24W | 0W |
| Tablet, charging | 180-360W | 12W | 0W |
| Smartphone, charging | 30-60W | ~0W | 0W |
| Network router | 24-240W | 24W (always on) | 0W |
| Inkjet printer |
360-600 W (when printing) |
36-60W | 0W |
| Large Laserjet printer |
6,000W-12,000W (when printing) |
960W | 0W |
| Plasma screen | 1800W - 3600W | 12W | 0W |
| 100W lightbulb | 1200W | 0W | 0W |
*Cells show approximate electricity use by a piece of equipment PER NIGHT (12 hours), in watts.
Units:
- Watt - unit of power usage over time
- Kilowatt - a thousand watts
- Watt-hour (Wh) - number of watts used in one hour
- Kilowatt-hour (kWh) - number of kilowatts used in one hour
Cost Savings
TABLE 2: Estimated Cost Saving per Device per Year at Tufts**
| Device | Awake for 12 hours (in use or with screen-saver) |
Asleep/Standby for 12 hours (plugged in, not in use) |
Energy Savings Per Device Per Night, i.e Awake vs Asleep/Standby | Total Number of Devices on all Tufts Campuses | x 365 days in a year = savings in kW per year | Cost Savings per Night (12 hours) for Device Category | Savings Per Year for Device Category |
|---|---|---|---|---|---|---|---|
| Laptop | 240-600W | 12-72W |
228-528W (median 378W) |
11,281 (2/3 of all people) | 1,556,440 | $687 | $250,898 |
| Desktop computer | 780-3000W | 12-72W |
768-2928W (median 1848W) |
300 (low estimate) | 202,356 | $89 | $32,620 |
| LCD monitor/TV | 240-480W | 24W |
216-456W (median 336W) |
90 (TTS) + 50 (low additional estimate) | 17,170 | $7.58 | $2,768 |
| Network router | 24-240W | 24W (always on) |
0-216W (median 108W) |
300 (low estimate) | 11,826 | $5.22 | $1,906 |
| Inkjet printer |
360-600W (when printing) |
36-60W |
36-60W (powered down) (median 48W) |
300 (low estimate) | 5,256 | $2.32 | $847 |
| Large Laserjet printer |
6,000W-12,000W (when printing) |
960W |
960W (powered down) |
300 (low estimate) | 105,120 | $46 | $16,945 |
| Plasma screen | 1800W-3600W | 12W |
1788-3588W (median 2688W) |
50 (low estimate) | 49,056 | $22 | $7,908 |
| 100W lightbulb | 1200W | 0W | 1200W | ||||
| Total Estimated Savings Per Year: | 1,947,224kW | $313,892 |
**Cost savings per device, PER NIGHT (12 hours) x number of devices x 365 = cost savings per device type per year at Tufts, when device is Asleep/Standby vs Awake
These estimates are based on the following Tufts population counts from Fall 2019:
Total students: 11,878 + Total faculty: 1,546 + Total staff: 3,498 = total people: 16,922
Average cost of electricity for Tufts (based on TAB building rate in 2020) was $0.1612/kWh
References
- How Much Energy Do My Appliances Use? SmarterBusiness.co.uk
- Saving Electricity: How much electricity do computers use? MichaelBlueJay.com
- What's the difference between Sleep, Standby, and Hibernate? MichaelBlueJay.com
- How Much Electricity Does A Computer Use? PaylessPower.com
- Average Energy Prices In Boston-Cambridge-Newton – December 2018 US Bureau of Labor Statistics
- How Much Electricity Do Your Gadgets Really Use? Forbes
- Just How Much Power Do Your Electronics Use When They Are ‘Off’? New York Times
- How Much Electricity Does Your PC Consume? PC Magazine
- Should You Shut Down, Sleep, or Hibernate your Laptop? How-to-Geek
- Should You Keep Your Printer On or Off? Cartridge World
- Your Printer's Standby Mode Could Save You Money Consumer Reports
- Electricity Usage of a Printer Energy Use Calculator Energy Use Calculator
- Electricity usage of an LCD/LED Display or TV Screen Energy Use Calculator
- Tufts At-a-Glance Tufts University
