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ENERGY STAR Computer Monitor Test Methodology

ENERGY STAR Computer Monitor Test Methodology

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ENERGY STAR Computer Monitor Test Methodology

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  1. ENERGY STAR Computer Monitor Test Methodology Craig Hershberg US EPA

  2. Objectives of Today’s Presentation • Provide an overview of the final test methodology • Share key points of discussion during the test methodology development phase, and their resolutions • Present and gather industry input on two remaining issues regarding multiple measurements

  3. Test Methodology Goals • Develop sound procedure for testing computer monitors in On Mode; incorporate existing methodologies for Sleep and Off • Design a methodology that is comprehensive and produces repeatable test results • Decrease burden on manufacturers by referencing, where applicable, existing and widely used industry standards for testing • VESA • IEC

  4. Development Phase • Extensive input from stakeholders • Manufacturers, trade associations, European and Japanese stakeholders, TCO Development • Various drafts broadly distributed for comment during 9-month development phase • Final test methodology emailed to stakeholders in February 2003 – minor changes made since then • “Development Summary” captures key additions and changes that led to final methodology • Emailed to stakeholders and available on Web site • Basis for today’s presentation

  5. Non-Energy Factors

  6. Removed References to Three Non-Energy Factors • Three non-energy factors from Draft 1 have been removed from Draft 2 • Defective pixels (no effect on power consumption) • Contrast ratio (VESA Flat Panel Display Measurements (FPDM) Standard 2.0 does not define parameters for measuring contrast ratio) • Warranty (market-specific so hard to implement and police for global products like computer monitors)

  7. Retained Two Non-Energy Factors • Two non-energy factors originally included in Draft 1 of the specification have been moved to the test methodology • Refresh rate • Luminance (brightness) • Ensure all computer monitors are being tested under similar conditions

  8. Refresh Rate • Different refresh rates given for LCDs and CRTs, to accommodate differences in technologies • LCDs: Measured at 60 Hz, unless a different refresh rate is specifically recommended by the manufacturer • CRTs: Measured at 75 Hz (long-time norm in North America) • Discussion over use of 75 Hz or 85 Hz, which is consistent with TCO ’99 and general practice in Europe • 75 Hz chosen because most appropriate for power measurement purposes, whereas 85 Hz better for ergonomic purposes (reduces flicker, but increases power consumption)

  9. Luminance (Brightness) • Levels chosen that support the implementation of a performance-based specification • Allow for comparisons of power use between computer monitors when providing the same visual experience for the user • CRTs: Measured at minimum of 100 candelas per square meter (cd/m2) • LCDs: Measured at minimum of 175 cd/m2 • Higher than CRTs because 100 candelas per square meter is much easier for LCDs to attain than for CRTs • All luminance test patterns borrowed from VESA FPDM Standard 2.0

  10. 125 vs. 175 cd/m2 for LCDs • 125 cd/m2: Not selected because it would unfairly advantage models that only have brightness control, or operate in digital mode • Adjusting brightness to get 125 cd/m2 may lower power consumption by reducing power to backlights, allowing these models to qualify more easily • Maximum brightness: Not chosen because it may punish better performing models with a high brightness range, to allow for some degradation over time

  11. Dark Room Conditions and Color Controls and Peripherals

  12. Dark Room Conditions • Suggested by several members of industry for light measurements • References current industry norms through VESA FPDM Standard 2.0

  13. Color Controls and Peripherals • All color controls and peripherals should be placed at factory default settings • No external devices should be connected to any USB hubs/ports • Any built-in peripherals should be set to off, or placed in their minimum power configuration (as adjustable by the user) • Circuit removal or similar actions not under user control may not be undertaken (e.g., removal of built-in speakers)

  14. DVI Inputs and Digital Monitors

  15. Addressing DVI Inputs and Digital Monitors • Added a clarifying statement re: stable power measurements in Off Mode • Test methodology for all three operating modes states that power measurements should be taken once the power readings are stable • Power readings never quite stabilize due to DVI input check cycle • For models with DVI inputs, manufacturers should ignore the DVI input check cycle when measuring power consumption in Off • Included information on how to test digital only interface monitors • Monitors with both analog and digital interfaces should be tested in analog interface • See footnote 1

  16. Multiple Measurements

  17. Data Variability Analysis • First round of testing: Requested testing of 5 units at each of 3 different voltage/frequency combinations • 100 Volts/50 Hz, 115 Volts/60 Hz, 230 Volts/50 Hz • Data analysis: Considered the variability of manufacturers’ test data provided at each of the voltage/frequency combinations • Findings: 1) Much greater variation by sample than by voltage; 2) In On Mode, power use was often higher at 115 than 230; and 3) More data points submitted by manufacturers at 115 than other voltages

  18. Active Power Variability Among Different Samples • Up to 30% variability by sample for some models

  19. Active Power Variability Among Different Voltages • Less than 4% variability by voltage for majority of models

  20. Reduced Number of Measurements per Model • Second round of testing: Requested that interested manufacturers only test 3 units at 115 Volts/60 Hz • Overall testing reduced from 15 data points per model to 3 data points per model

  21. Questions for Industry • Does industry agree that testing at only one voltage/frequency combination is sufficient? • And if so, does it make sense to test at 115 Volts/60 Hz, as proposed in Draft 2? • Another option is to test at the voltage/frequency combination of the country where the monitor will be sold • Which option would industry prefer, and why? • Are there any manufacturer concerns with requiring three test units per model? • Do manufacturers have any other alternatives that they would like EPA to consider?