In the 15 years our researchers have been studying televisions, we’ve encountered a number of surprises along the way. There are remarkably large differences in the energy use of different TV models of similar size, when all of them are measured the same way. But the energy use of a given TV model can vary quite widely too, depending on how we measure it. The details about how the testing is conducted matter.
After our 2015 research for NRDC found significant power increases associated with 4K resolution and HDR content, NRDC asked us in 2016 to take a closer look at the underlying test procedure itself. They wanted to better understand differences in TV energy use when being tested by the government vs. being watched normally in the home.
What we found, in brief, is that many televisions enable a range of energy saving features like automatic brightness control (ABC) and motion detection dimming (MDD) when first taken out of the box and plugged in for use. This allows them to obtain very low energy consumption values when tested by the government with its standardized test clip, so they can report low annual energy bills on their Energy Guide labels and qualify for the voluntary ENERGY STAR label.
But once users make even small changes to picture settings or modes, those energy saving features often shut off. And when the content being played on screen is more typical of what people often watch than the government test clip, energy use goes up even further – sometimes dramatically. NRDC’s report highlights these problems and identifies differences in the way various manufacturers’ televisions behave. The report concludes by calling for major changes in the way governments test and label televisions for efficiency.
Overall, we have found that much of a television’s energy use is proportional to how much light it produces. That’s why the brightest models will often use more energy than typical TVs. Models displaying high dynamic range (HDR) content or operating in really bright picture settings like Vivid or Dynamic will experience dramatic increases in energy use relative to the values produced by government testing in default conditions. Energy-saving features like automatic brightness control (ABC) and motion detection dimming (MDD) achieve their savings by temporarily dimming the screen even further from default conditions when room lighting conditions are dark or scenes are changing rapidly on screen.
By the same token, some television models still use a significant amount of energy when their screens are displaying a completely black image, while others can scale their power consumption downward dramatically in that situation. This offers another opportunity for energy savings, by recognizing and rewarding the TVs that do the best job of reducing their power consumption proportionally as the light being delivered by the screen is reduced.
ENERGY STAR is now revising its television labeling specification to address the persistence of energy saving features and some of the concerns raised recently about the representativeness of test results. For more information, see ENERGY STAR’s webinar and data set.
An NRDC info-graphic, summarizing key findings from the NRDC report: