Last March, the U.S. Environmental Protection Agency (EPA) started the revision process for its ENERGY STAR spec for displays (see: EPA Starts Revising ENERGY STAR Display Program Specs). The action was in response to the increased efficiency of computer monitors and signage displays.* The EPA announced that it would also begin to address DC-powered displays.
Draft 1 of the revision (version 7) was recently published and includes the following proposed changes.
The EPA proposes expanding the scope of the program to allow products with a viewable diagonal screen size greater than 61 inches. This is to include the growing number of larger signage displays.
Automatic Brightness Control (ABC)
To determine if ABC is enabled by default and can therefore qualify for an allowance, the EPA proposes calculating power consumption at 12 lux in lieu of the current 10 lux.
On Mode Requirements
The EPA is proposing power consumption limits reflecting the performance of the top 20 percent of monitors available in the market today.
For all displays, the measured On Mode power (PON) shall be less than or equal to the calculation of the maximum On Mode power (PON_MAX) with the applicable allowances and adjustments per Equation 1.
Equation 1: On Mode Power Requirement for All Monitors and Signage Displays
PON ≤ (PON_MAX + PEP + PABC) x effAC_DC_ON
The maximum On Mode power (PON_MAX) is calculated using the equations in Table 1 below.
Table 1: Calculation of maximum On Mode Power (PON MAX) in Watts
PON Max (watts)Where:
A = screen area in in2, r = Total screen resolution in megapixels, and I = Total luminanace of display in megacandelas calculated as As-shipped Luminance multiplied by Area.
|Monitors||(2.0 x r) + 17.1 tanh (0.0040 x (A - 63.0) + 0.22) + 0.3|
|Displays||(75.0 x l) + 82.1 tanh (0.0010 x (A - 200.0) + 0.1) + 6.0|
Sleep Mode Power Requirements
Sleep Mode power is limited to 0.5 watts plus adders for additional functionality (i.e., touch technology, network capability, and occupancy sensing).
Off Mode Power Requirements
The EPA is proposing to maintain version 6’s maximum Off Mode power consumption at 0.5 watts.
The EPA proposes providing a 2.0 watts per megapixel allowance instead of the current allowance of 6.0 watts per megapixel.
The EPA has modified the “included products” language to mention dc-powered products. These products are expected to become more prevalent on the market with the recent updates to USB and Power-over-Ethernet.
Test method changes include: a test procedure for products powered by standard DC and also introduces testing products with full network connectivity.
The EPA is also proposing moving from the current “modal” approach (i.e., on mode, sleep mode, off mode) to a Typical Electricity Consumption (TEC) approach for evaluating display efficiency. Its purpose is to address new features and functionality such as touch, occupancy sensing, and network connectivity.
Version 7 is expected to be finalized mid next year and become effective in the second quarter of 2016.The EPA is requesting stakeholder feedback; comments should be submitted to firstname.lastname@example.org no later than January 16, 2015. To read the proposed revisions, visit the ENERGY STAR website.
* Monitors are defined as having greater than 5,000 pixels per inch and typically desk-based for single person viewing. Signage displays have ≤ 5,000 pixels per inch and are non-desked based to be viewed by multiple people.