42.2: Invited Paper: Ambient Light Levels During Television Viewing

Abstract

The results of the CLTC study show the television light sensor measured illuminance levels from less than 1 lux to more than 300 lux (lx). The vast majority of viewing (79.5%) occurred at illuminance levels below 50 lx, while very little viewing (3.6%) occurred at illuminance levels greater than 300 lx. The results of this study indicate that 0 lx illuminance is unnecessary and that other illuminance levels (10, 50, and 100 lx) should be considered for power measurements, to better reflect actual illuminance levels during TV viewing in residential applications. Author KeywordsAutomatic-Brightness-Control (ABC); Ambient Light; EnergyStar; Residential; Energy Savings; Test Procedures; Television Background and ObjectiveTelevision energy consumption has been a growing portion of residential energy use. Globally, televisions account for approximately 168 terawatt hours (TWh) of electricity consumption (Park, Phadke, Shah, & Letschert, 2011). A 2011 study showed that the adoption of more efficient televisions could potentially result in 37.6 TWh of cumulative electricity savings by the year 2020. This includes 7.3 TWh of cumulative potential savings in the United States (Park, Phadke, Shah, & Letschert, 2011).The Environmental Protection Agency (EPA) has managed an Energy Star endorsementlabeling program for televisions since 1998. In 2010 the U.S. Department Of Energy (DOE) appliance standards program initiated efforts to develop a range of policies aimed at reducing television energy consumption.Energy efficiency standards require test procedures that describe how to measure energy consumption. It is important that measurements be done under typical operating conditions that are repeatable, reproducible and accurate. To support the development of federal efficiency standards for televisions, the Collaborative Labeling and Appliance Standards Program (CLASP) launched a study in 2010 to assess the energy performance of televisions and the Energy Star test procedure for energy consumption measurements (Jones 2011). This study addressed several issues related to television energy performance, including the Energy Star procedures for measuring energy use for televisions that use automatic brightness control (ABC) based on ambient light levels. The ABC feature adjusts the brightness of the television screen based on ambient light levels, aiming at reducing brightness at low ambient levels to reduce television energy consumption. Energy Star test procedure required energy measurements at ambient levels of 0 and 300 lx illuminance on the television screen.The 2011 study included television energy consumption measurements of 39 televisions, following Energy Star test procedure at 10, 50, 100, 150, 200, 250, and 300 lx to determine energy consumption changes with the ABC feature enabled. The results showed that only 10 of the 39 televisions reduced power consumption as the ambient light level was lowered.The study found that the Energy Star Version 5 testing procedure, which calculates energy consumption as an average of cons...