A while back some or other agency of the Australian government was talking about banning TVs that were threatening to destroy the planet. Something about using too much power, and therefore causing too much carbon dioxide to be generated. As I understand it, the government has backed off a bit and is now talking about a star rating for energy usage.
But back then there was talk of plasma TVs being banned because they used too much power and so on. A draft international standard for conducting the measurements was promulgated, and the necessary pass mark to achieve at least one star was, using this measurement protocol, using less than 480 watts of power per square metre of screen.
So how do you measure this consistently? A ten minute set of short video clips were created which, apparently, represents the average brightness levels of typical TV broadcasting. You measure the amount of energy used to display this clip, divide by time, and thereby derive the average power used. From there it’s easy to work out whether a TV passes or fails.
Except for one thing. What settings should you use? Fiddling with the user picture settings can change the amount of power used very significantly. Two TVs I’ve reviewed, when switched to ‘Movie Mode’ actually use less than half the amount of power they do when switched to ‘Vivid Mode’. Both plasma TVs and LCD TVs with a ‘dynamic’ backlight vary the amount of power used according to the overall produced brightness of the picture.
The standards body settled on an ‘out of the box’ setting. It reasoned that most people take a TV out of its box, install it and watch it without ever playing with its settings. Sadly, they are probably right.
When I started measuring TVs for this a year ago, few passed. The last few I have measured have, however, passed.
What has changed? Most major brand TVs now, when switched on for the first time, start up with a question: are you installing in a shop or the home? If you choose the latter, as you should, then the TV starts up with the picture defaulting to its ‘Standard’ rather than ‘Dynamic’ settings, and therefore uses a lot less power. The ‘Dynamic’ setting used to be the default.
Incidentally, some TVs complicate matters by providing a setting which varies their overall brightness according to the ambient light within the viewing environment. The standard, contrary to the previously mentioned ‘leave the defaults unaltered’, requires that this be switched off.
Why? Because it would be too hard to measure otherwise. You’d have to come up with some estimate of the average room luminosity in the evening and in the day time, and the proportion of time spent by the general public viewing at those respective times. And then conduct your measurements with the luminosity set to two or more levels (at a controlled point on the front of the TV) and …
Oh, it’s all too hard! We throw up our hands in frustration! So in order to support the regulatory standards sought by various governments (I assume Australia isn’t alone on this one), we have a standard that, in the case of some TVs, requires them to be measured in an unrepresentative state.