ENERGY STAR Spec for Displays Reaches Next Phase

Thu, 04/30/2015 - 10:42 -- MrGreen

When I last discussed the ENERGY STAR Display program spec, the U.S. Environmental Protection Agency (EPA) had just published Draft 1 of its proposed version 7 spec (see blog: EPA Seeks Feedback on Draft 1 of ENERGY STAR Spec for Displays). The need for the revision (formerly limited to computer monitors) was due to the rapidly changing technology and application for displays.

In response to Draft 1 stakeholder feedback, the EPA recently published Draft 2. Below is a summary of some notable changes, as well as information on an upcoming webinar and how to submit Draft 2 feedback.

Adoption of Total Energy Consumption (TEC) Approach

The EPA is moving from the current "modal" test approach (i.e., on mode, sleep mode, off mode) to a Total Electricity Consumption (TEC) approach for evaluating display efficiency. The maximum allowable TEC of a monitor is determined by the following formula:

(ETEC_MAX + EEP + EABC + EN + EOS ) × effAC_DC

Where:
ETEC is the calculated TEC (kWh), ETEC_MAX is the maximum TEC requirement (kWh), EEP is the enhanced performance display allowance (kWh), EN is the full network connectivity allowance (kWh), EOS is the occupancy sensor allowance (kWh), effAC_DC_SLEEP is the power conversion adjustment (1 for AC-powered displays and 0.85 for DC-powered displays)

ETEC_MAX is calculated using the formula below:

ETEC_MAX = 6.13 x r + 91 x tanh(0.0016 x [A - 59] + 0.085) + 9

Where:
r = Screen resolution in megapixels, A = Viewable screen area in in2

Enhanced Performance Displays

Based on the number of models that cover the sRGB gamut*, the EPA proposes to revise its allowance for enhanced performance displays (EPDs) based on this criteria, with a 25 percent allowance for models meeting current EPD criteria with a color gamut that is 99 percent or greater of sRGB and a 65 percent allowance for models meeting the current EPD criteria with a color gamut that is 96 percent or greater of Adobe RGB.

*A color standard developed for displays in the 1990s.

Signage Displays

The definition for signage displays, different from monitors in that it is intended to be seen by multiple viewers in a public environment, was modified. A signage display must meet any two of the following conditions:

  • Screen size > 30 inches (diagonal)
  • Maximum Reported Luminance > 400 candelas per square meter
  • Pixel density ≤ 5000 pixels per square inch

On Mode Requirements for Signage Displays

The Maximum On Mode Power (PON_MAX) in watts is calculated by the formula below:

PON_MAX = (7.5 x 10-5 x ℓ x A) = 82 x tanh(0.001 x (A - 200.0) + 0.01) + 6.0

Where:
A = screen area in square inches, ℓ = maximum measured luminance of the display in candelas per square meter

To read the complete spec, visit the ENERGY STAR website. Stakeholders are requested to provide comments on Draft 2 by May 22, 2015. Comments can be emailed to displays@energystar.gov.

On May 7, 2015, from 11:00 AM – 2:00 PM (U.S. Eastern Time), the EPA will host a stakeholder webinar on Draft 2. If you wish to attend this webinar, please register prior to the webinar by using the ENERGY STAR registration form.