Active Mode Discussion

Chris Calwell

Ecos Consulting

Summary of NRDC/Ecos Research Process

• Reviewed independent monitor research from DisplaySearch, IDC, Europeans, and others

• Met with monitor manufacturers at COMDEX, CES, DisplaySearch, and one-on-one

• Analyzed self-reported data from manufacturers in STAR database

• Independently measured monitor power use• Compared data with LBNL, ADL studies• Made recommendations to EPA. EPA weighed

them with others and created draft specification.

What Does The Term “Energy Efficient Monitor” Mean?

• Efficiency = Useful Output or Service Provided / Total Energy Input

• Useful output or service could be diagonal inches of screen size, square inches of screen size, or total pixels displayed

• Monitor not displaying information (providing useful output) in sleep or standby modes, so minimize power use at those times to achieve high overall efficiency

• Can account for all energy use in all three modes separately or with a duty cycle

• ENERGY STAR seeks to recognize top 25% efficiency

Estimated Annual Energy Use for CRTs and LCDs

The Advantages of Pixels/Watt

• Pixels/watt approach has a number of key advantages:• More technology neutral – avoids difference between

viewable screen size and total• Screen area (square inches) unknown to consumers• Credits CRTs for their present resolution advantage, yet

allows for very high resolution options like IBM’s new 9.1 million pixel LCD

• Emphasizes display quality over physical size• Avoids difficulty of trying to estimate a representative “duty

cycle” for all monitors• Simple, like lumens/watt (lighting) or CFM/watt (fans).

Can also be characterized as watts/megapixel

Effect of Resolution and Monitor Type on Active Power Consumption for Monitors 17” and Less

Effect of Resolution and Monitor Type on Active Power Consumption for Monitors Greater than 17”

Effect of Resolution and Monitor Type on Active Power Consumption

Applying Active Power Spec to Standard Resolutions

Resolution Category Total Pixels Maximum Power Use

640 x 480 VGA 307,200 37 watts

800 x 600 SVGA 480,000 40 watts

1024 x 768 XGA 786,432 46 watts

1280 x 1024 SXGA 1,310,720 57 watts

1600 x 1200 UXGA 1,920,000 69 watts

1800 x 1440 2,592,000 82 watts

2048 x 1536 3,145,728 93 watts

Need for Consistent Measurement

• STAR database contains self-reported data from manufacturers

• Not all monitors measured under identical conditions in active or “on” mode

• Depending on user settings and image displayed, CRT power variations can be +/- 30%. LCD variations can be +/- 50%.

• ENERGY STAR has helped develop common test methods to the ventilation and lighting industries – may be able to bring standardization to monitor measurements as well.

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Resolution Refresh Rate Brightness Contrast # of Colors Image Displayed Extremes

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Effects of User Settings on Power for a 21” CRT Monitor

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Resolution Refresh Rate Brightness Contrast # of Colors Image Displayed Extremes

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Effects of User Settings on Power for a 17” LCD Monitor

Comparing the Proposed Specification to Compaq’s Self-Reported Data

Key Market Research Findings

• Laptops were first major market for LCD technology; Desktops now shifting decisively from CRTs to LCDs

• LCDs provide size, weight, comfort, clarity, and energy advantages to users. Even better technologies (OLEDs, others) coming soon

• LCDs are often more profitable for manufacturers to sell (CRTs have become a commodity)

• Presently hard to market LCDs on an energy efficiency basis – virtually all monitors have ENERGY STAR® label and no standardized power use information is shown on packaging

• Need for a new specification and test method to fairly compare monitors on total energy use in active, sleep and off modes.

Entry Level (<$1,000) Computer Systems Now Commonly Offer LCD Screens