Equipment

The dropdown lists for 'PC' and 'Monitor' allow you to choose one of 4 presets for the equipment. The values of on-, sleep- and off-mode as well as the purchase prices ('Buy' or Lease) will automatically adjust. You can change these values (click in the box and type), based on the specific values of the equipment you use or intend to buy.
The same goes for the dropdown lists of the 'Use' column, that give presets for the typical daily usage.

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Presets: PC

Specifications below are typical for June 2010.
Note: 'Value' can be translated with 'low-cost' etc.

• Small server : Typical low-end 'small office/home server' (Xeon / 2,8 GHz / 4 GB RAM).
• Value PC : Value desktop (e.g. Core2 Duo (2,8 GHz) or Athlon II X2 / 2 GB RAM / 500 GB). Price estimate = Systems price (incl. 17" LCD) minus € 100.
• Multimedia PC : Multimedia desktop, e.g. Phenom II or Core i7 / 2,7 GHz / 4 GB RAM / 500 GB and more powerful graphics.
• Workstation : Professional custom-made desktop PC for CAD / Computer Graphics / Science Research. E.g. Xeon / 2,7 GHz / 8 GB RAM / 500 GB / 64 bit OS.
• Netbook: Atom or Via Nano, 10” LCD-TFT screen.
• Ultraportable notebook: Optimised for battery life and portability (extra light and flat). Typically Core2 Duo ULV, 13-15" LCD-TFT screen. Best energy features, but not inexpensive.
• Value notebook: Core2 Duo or Turion 64 X2, 15-17” LCD-TFT screen (15"=approximately comparable to 16" CRT).
• Large notebook: As above but with large 17-20” LCD-screen and best mobile graphics. Excellent desktop replacement. Energy consumption is high for a notebook, but still at least 50% of a comparable desktop PC system.

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Presets: Monitor

Specifications below are typical for June 2010.
Note: 'Value' can be translated with 'low-cost' etc.

• System 17" LCD: System monitor (buy with PC).
• Value 17" LCD: Average range monitor. Sold as separate monitor.
• System 19" LCD: System monitor (buy with PC).
• Value 22" LCD: Average range monitor. Sold as separate monitor.
• Value 24" LCD: Average range monitor. Sold as separate monitor.
• Top 24" LCD: Excellent 24"-LCD, sold as separate monitor.
• Top 30" LCD: Excellent 30"-LCD, sold as separate monitor.

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Presets: Use

• Light office: Estimated average EU use 2003 (mainly web, e-mail). Derived from 'on-mode' 1.6 h/day in 2000 and 2.3h/day in 2010.
• Average office: Based on use for e-mail and occasional search/document/presentation: 3 hours per day active 'on' use, 1 hour 'on' preparing for sleep. On 'sleep' in other office hours (e.g. managers, sales representatives). Switched 'off' (using the PC power button, not disconnected from mains) at night. Power Users (video-editing, CAD) will probably better fit in the 'average office' profile.
• Busy office: Profile for desk-workers with overtime. Possibly applicable also to Home office workers.
• Never off: Average office profile, factory setting power management (hibernating off), but PC is never turned 'off' at night (=goes into sleep).
• Always on: Typical for e.g. servers. Requires active disabling of power management. Although power management could be implemented, in practice most servers in networks are 'on' all the time (power management disabled).

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On-mode

PC power values are an estimated average for 'Windows or Mac desktop' (= 'on', but processor is hardly working) and 'full load', also weighted for the type of use (e.g. workstation and multimedia PC closer to the full load). Power management features for on-mode (ACPI, Speedstep/PowerNow/etc.) are assumed to be implemented.
Monitor power 'on' values are at default (high) brightness with a primarily light screen.
Hint: Tuning down brightness to a middle level might save you some 15 -20%. At the low brightness level -e.g. featured on many laptop when on batteries-you could save some 40%.

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Sleep

If you haven't changed the factory power settings, most desktop PCs go into sleep if you don't touch them for 20-30 minutes. To fill in the number of hours in sleep just estimate the total time (longer than 20 minutes) you went for meetings, breaks, etc. and subtract 20 minutes for each time event. Also if you don't switch your PC off at night it counts as 'sleep'.

To wake your PC from sleep, you need to press the power button or specific keys. It is not to be confused with screensaver-mode (which hardly saves energy), where it is enough that you move the mouse to get a picture on the screen.
Also, don't confuse it with the hibernate mode, if you have enabled this very energy saving setting (see Power Management to know how), that saves your data on the hard disk and shuts down. To resume work after hibernating the system reboots to bring you back to where you were.

For technical background on sleep see Technical Library | Power Management.

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Off-mode

Practically all modern PCs and quite a few monitors (esp. LCDs) use power when switched 'off'.

The only way to avoid that is to unplug them or use the switch on a switchable socket (extension). If you do that, fill in zero ('0') W in the 'off-mode' boxes for PC and monitor.

0 W "off" mode: unplug or use the switch on your socket panel

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Power Management PC & Monitor

You can choose 3 options for Power Management in the E-Calculator:

• Disabled: Default for the 'Always on' user.
• Normal setting: Default value, represents 'Home/Office' 'power scheme, usually goes into full sleep-mode after 30 minutes. This should be the standard factory setting, but please check! See Power Management.
• Energy saving setting: Represents 'Laptop' or 'Notebook' power scheme but can also be applied to desktop PCs, usually goes into full sleep-mode after 15 minutes; see Power Management on how to implement.
  The effect in the E-Calculator is that this scheme subtracts 25% from your 'on' hours and adds them to your 'sleep' hours before calculating your annual electricity consumption and costs.
  

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BUY

Prices (incl. VAT) are estimates, based on 'street'-price offers in June 2010.

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LEASE

Various vendors offer lease contracts for PC systems. Please refer to your lease contract.

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Product Life

Default value is 6 years (2003 EU average) for bought equipment. For lease contracts fill in the period indicated in your lease contract.

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UPS

An Uninterruptible Power Supply (UPS) is an intelligent battery pack to protect your computer (and data) from power surges and black outs. Capacity is dimensioned to allow for a controlled shutdown of the PC. Even a small UPS uses between 8 and 25 W -depending on the model/specs— continuously (8760 hrs/year). If you tick the UPS-checkbox, the calculator assumes a modest UPS for a single PC/small server and adds 87 kWh to your energy consumption and 120 € to your Total Cost-of-Ownership.

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Months Room Air-conditioning

When air-conditioning cools your room/office, the heat load of the PC and monitor contributes to the electricity consumption of the air-conditioning installation.
Specify how many months per year the air-conditioning is used for artificial cooling (not heating).

The air-conditioning is assumed to function with an efficiency of 300% (COP is 3.0). Formula: Extra electric energy for air-conditioning= (energy use of equipment/3) * (Months/12).

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Electricity Rate

Default value is an average EU figure of approx. € 0.15/kWh as indicated by MEEUP Report (2005). Please apply your local electricity tariff.

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Total costs

This is defined as electricity costs + purchase/lease costs + air conditioning costs over product life. If UPS-checkbox is ticked, its price and energy costs are included.

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Total electricity consumption

This figure is for the PC equipment and -if indicated by you— UPS and air conditioning.

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Add printer / Add modem

If you tick the 'Add Printer' or 'Add Modem' checkboxes, the outcomes of the separate mini-Energy Calculators will be added to your total cost-of-ownership and annual energy consumption (in kWh/year). Just uncheck them and then click the 'Calculate!' button to see what each of these items adds.

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Calculator History

The last 5 scores of the Energy Calculator are kept in a separate table, where column '1' represents the actual score, '2' the previous score, etc.
If you click the header ('1', '2', '3', etc.) of a column, the calculator will show the input values that resulted in those results.

Keeping the score helps you to see if (and how) you are improving. A new score is added (and the oldest score is dropped) each time you click the 'Calculate!' button.

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Mini-Energy Calculator for Printers

This calculator lists several inexpensive printers and MFDs (Multi-Functional Devices, combining at least the printer/copier/scanner functions; if a facsimile function is also included it is indicated as 'MFD + fax'). They represent a typical consumer's choice, with speeds in the range of 6-10 pages per minute (ppm) for colour prints and up to 20 ppm for 'normal quality' black-and-white prints. Resolution is in the range of 600x600 or 1200x1200 dpi. Their robustness (indicated by what is known as 'Monthly Duty Cycle') is in the lower ranges (3000 - 10000 pages).

The mini-calculator shows typical presets for purchase price (incl. VAT), paper (plain paper set at around 1.6 to 2 Eurocents/page) and ink/toner costs, electricity rate, a given annual production of 850 pages in black&white and 150 colour pages. The product-life and electricity rate is assumed to be equal to that of the PC system. Only the sleep-mode energy use is given, because at the typically low residential use the extra energy use during printing is negligible.

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Mini-Energy Calculator for Modems

This simple calculator just distinguishes the three modem types that make a difference in terms of energy consumption:

• An internal modem (usually 56 k modem, but could be of any type) using only a few Watts and switching off or in sleep when the PC does.
• A USB external modem (usually xDSL, but could be of any type) powered only through the USB 2 port of your PC/laptop, by definition using no more than 2.5 W and switching off or in sleep when the PC/laptop does.
• Other external modems (usually xDSL, but could be any type) powered by an external power supply. Energy use of this modem could be some 7 W and it never switches off (8760 h/yr 'on'). This is the only type of modem that will make a noticeable difference for your energy bill.