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 typical daily usage.
Specifications below are typical for January 2012.
- Home server : Typical low-end home server (Atom / 1,6 GHz / 2 GB RAM / 1000 GB).
- Value PC : Value desktop (e.g. Core i3 or Athlon II X2 / 2 GB RAM / 500 GB). Price estimate = Systems price (incl. 18" LCD) minus € 50.
- 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 / 16 GB RAM / 1 TB / 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 Core i5 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: Core i7, as above but with large 17-18” 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.
Specifications below are typical for January 2012.
- System 18" LCD: System monitor (buy with PC).
- Value 18" LCD: Average range monitor. Sold as separate monitor.
- System 1229" 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 27 " LCD: Excellent 30"-LCD, sold as separate monitor.
- Home: 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.
- Power Users Home (gamers, video-editing) / 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 by disconnecting from mains) at night.
- Home office / 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).
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 laptops when battery-powered you could save some 40%.
If you haven't changed the factory power settings, most desktop PCs go into sleep mode 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. This is not to be confused with the screensaver-mode, where it is sufficient to move the mouse or touch the keyboard to get a picture on the screen (and which hardly saves any energy). Also, don't confuse it with the hibernate mode, which saves your data on the hard disk and shuts down, if you have enabled this highly energy saving setting (see Power Management to know how). To resume work after hibernating requires a system reboot to bring you back to where you were.
For technical background on sleep see Technical Library (Power Management).
Practically all modern PCs and quite a few monitors (esp. LCDs) use power when switched 'off'.
The only way to avoid this is to unplug them or use the switch on a switchable power strip. If you do that, fill in zero ('0') W in the 'off-mode' boxes for PC and monitor.
0 W "off" mode:
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.
Prices (incl. VAT) are estimates, based on 'street'-price offers in June 2010.
Various vendors offer lease contracts for PC systems. Please refer to your lease contract.
Default value is 6 years (2003 EU average) for bought equipment. For lease contracts fill in the period indicated in your lease contract.
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.
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).
Default value is an average EU figure of approximately € 0.15/kWh as indicated by MEEUP Report (2005). Please apply your local electricity tariff.
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.
This figure is for the PC equipment and -if indicated by you UPS and air conditioning.
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.
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 produced 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.
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.
This simple calculator distinguishes the three modem types that make a difference in terms of energy consumption:
- An internal modem (usually 56 k modem, but it 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 it 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 it 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 to your energy bill.