Samsung, LG, and Vizio are misleading customers about their TV energy usage, according to a new report from an environmental group. The three companies designed their screens to take advantage of the methods used in government testing, the Natural Resources Defense Council claims, enabling them to perform better in energy efficiency tests than regular models would in the home.

LG and Samsung TVs dim their backlights during tests

The report says that the companies were able to obtain higher scores in official government tests because the US Department of Energy has used the same 10-minute clip to measure TV sets for energy efficiency for the past eight years: a reel of rapid cuts that features video from 260 different scenes. TVs sold by Samsung and LG were found to dim their backlights during such fast-paced footage, a process that saves energy, but — according to the NRDC — presents an unrealistic reflection of the standard TV-watching experience people have at home.

The NRDC's study found that scenes in football games and shows like Breaking Bad lasted longer than the sections of the government's 10-minute test clip, keeping the TV's backlight on, and driving up energy use accordingly. After testing on TVs from this year and last year, with screens bigger than 55 inches, the group estimated that the increased energy consumption could produce more than 5 million metric tons of carbon dioxide over the next 10 years, and cost $1.2 billion in the same period, with the average household spending an extra $20 annually on electricity over the 10-year lifespan of an HDTV.

NEW: TVs may be consuming $1.2 Billion more energy than expected https://t.co/sBr7AlwN1e via @nrdc pic.twitter.com/kqeAxBt7ay — NRDC Energy Team (@NRDCEnergy) September 21, 2016

The tactics reportedly used by the three companies are similar to those employed by Volkswagen, which infamously cheated on emissions tests by providing modified cars for government testing. Samsung has also been accused of cheating efficiency tests in the past, with a European body pointing to the same backlight-dimming technology as a way to score higher ratings. But Samsung, LG, and Vizio didn't actually break any US laws, the NRDC report notes. Instead, Noah Horowitz, the director of the NRDC's center for energy efficiency, said that the apparent gaming of the system "smacks of bad faith," and called on the US Department of Energy to change its tests to more accurately reflect TV-watching habits.

The Department of Energy has used the same testing clip for eight years

Samsung has issued a statement saying it "firmly rejects" the NRDC's accusations, specifying that the Motion Lighting and Auto Brightness Control features — the same ones that reduce backlight brightness — are enabled by default in its TVs. The company says that its Energy Star rating was based on its default TV settings, and while it does have viewing options that disable the features, the majority of users maintain the same default settings on their TV during its lifespan. LG, too, disputed the NRDC's claims, a spokesperson telling Phys.org that the company was "confident that our products are being tested properly and are delivering energy efficiency in real world use."