In the business world, the use of desktop computers, printers and other devices, is the fastest growing area of electrical use. See how much your home computer—and equipment in your place of business—might be costing to operate.
Note: You can see from the table that “sleep” mode is very important to saving energy. The 80 percent sleep mode estimate is actually low for most office equipment. Fax machines and copiers typically operate less than 5 percent of the time, and even if the computer screen is active 90 percent of the 40 hour work week, PCs are still “sleeping” 80 percent of the time overall, when compared to 24/7 hours of operation.
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Typical Operating Power(Watts)
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Typical "Sleep" Power (Watts)
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Annual Energy Cost* – 20% operating time for PCs, 5% for other office equipment
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Annual Energy Cost if Operating 100% of the Time at Full Capacity**
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| Computer |
150
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10
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$33
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$131
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| Monitor (15”) |
75
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4
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$17
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$66
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| Laser Printer |
350
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20
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$32
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$307
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| Fax Machine |
300
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10
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$21
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$263
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| Copier (small) |
300
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20
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$30
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$263
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| Copier (large) |
1,400
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40
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$84
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$1,226
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*Assumes $0.10/kWh, 8 hour operating day, 5 days/week, 2080 hrs/yr, 80% overall sleep mode for computers and monitors, 95% for printers, faxes, and copiers.
**Assumes $0.10/kWh, 24 hour operating day, 7 days/week, 8760 hrs/yr, no sleep mode. This is an unrealistic number because no office equipment operates 100% of the time, and nearly all office equipment has a sleep mode. It is presented for comparison only.
Sources: Manufacturer's specifications, Energy Star (DOE), and Office Equipment Energy Savings Calculator (LBL)
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The following table shows a selection of common printers and the Energy Star recommended energy use for each type.
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Energy Star Recommended “Sleep” Mode
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Printer Speed
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Laser B/W and Ink Jet
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Laser Color
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| Less than 10 pages/min. |
10 watts or less
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35 watts or less
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| 11-20 pages/min. |
20 watts or less
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45 watts or less
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| 21-30 pages/min. |
30 watts or less
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70 watts or less
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| Source: Federal Energy Management Program |
In addition to FEMP recommendations on energy efficient printers, there are also recommendations for computers, monitors, fax machines, copiers, and vending machines.
Computers and Laptops
A typical desktop computer will consume somewhere in the range of 150 watts in active use, plus another 75 to 150 watts for a CRT monitor, depending on its size and vintage.
In “sleep” mode, the PC will consume 10-25 watts and the monitor will consume 3-5 watts for the more efficient models. As expected, different designs are more energy efficient, with a 17" LCD monitor typically rated at 40 watts compared to a 17" CRT at 120 watts for operating mode energy use.
Accessories such as speakers can add another 30 to 40 watts. Laptop computers use less energy than desktops because they are smaller and have LCD displays. They can generally be found in the 15-45 watts range, but can be as high as 60-70 watts.
Copiers
Copiers are the most energy-intensive type of office equipment because they need to keep warm so that the toner can fuse to the paper. Copiers have a “low power” mode after they have not been in use for 15 minutes, and an “off” mode consuming 5 to 20 watts of energy typically after 2 hours of inactivity. These low and off power modes can enable energy savings of 40 to 50%, compared to standard models.
Printers and Scanners
Printers and scanners are large energy consumers in the office landscape. As an example, the HP Color LaserJet 2550L printer power consumption is listed at 17 watts (standby), 368 watts (printing), and less than 1 watt (off), while the larger business size HP LaserJet 9040 Printer consumes 36 watts (powersave), 205 watts (standby), 1000 watts (printing), and 0.3 watts (off).
By comparison, the HP LaserJet 3200 printer/fax/copier/scanner is more energy efficient and received the Energy Star listing with power consumption of 7 watts (standby), 174 watts (printing), and less than 1 watt (off). The user will find quite a range of energy consumption for all manufacturers, depending on size, print quality, speed, color capability, etc.
The sleep or standby mode is essential to reduce energy use, sometimes by over 60%. In the sleep mode, printers and scanners typically consume 5 to 10 watts for standard size models, but can consume as much as 25 to 30 watts for wider width color printers.
Fax Machines
The typical office fax machine that is left on continuously, day and night, is estimated by the DOE to be in “active”sending or receiving mode 270 hours per year (3% of the time). Once again, the sleep mode becomes a critical issue. By powering down, fax machines can reduce energy costs by almost 40%. The more efficient fax machines consume 3 to 20 watts in sleep mode, with the greater energy users occupied by the color fax machines at higher transmission speeds (33,600 bps compared to 14,400 bps or 9,600 bps).
Source: Questline June 2006 Newsletter