Eco TVs – how green is your TV?

Come 1 October 2009, two things are going to happen to our televisions. First, the new ones in shops will sport shiny yellow labels (which “shall not be smaller than 70mm wide and 105mm long”, says the government). Second, some models of TV may disappear completely.

This is due to the introduction of new Minimum Energy Performance Standards (MEPS) for televisions, and a related labelling scheme.

Under the ‘MEPS’ scheme, TVs that fail to achieve a certain energy efficiency will not be available for sale. This was a point of some controversy a couple of years ago since it looked like most plasma TVs would have been consigned to oblivion, at least in this country. However time has moved on and clever engineers have applied themselves to the problem.

As part of this article we reviewed 5 current model TVs, looking specifically at how they manged to be both energy efficient while at the same time producing a high quality, high definition picture. You can find the 5 reviews gathered together in the article 5 eco TVs tried and tested

Meeting the MEPS standard means earning at least one star on the energy rating label. Calculating that is a complicated process, and it is not something that we are yet confident of doing with complete authority. But we can venture some opinions based on the five TV models we’ve examined in the following pages, plus some others we’ve checked in the past.

In short, things have changed for the better. Whether you’re concerned with saving energy dollars, or reducing carbon emissions, the new breed of Australian TVs do both in comparison to earlier models.

To take just one example, the plasma TV we look at in the following pages scores a fairly impressive three stars under the new scheme. Yet a plasma of the same size from the same maker two years ago would have scored a negative star under this scheme!

Efficient technology, efficient settings

Plasmas have become better with new technology that isn’t easily explained. But, basically, at the ‘cell’ level they manage to produce more light for less power. That could be used to make brighter TV pictures, but in today’s greener times, plasma TV companies have opted for the same brightness, and greatly reduced power consumption.

For LCD TVs, the main area of energy efficient development has been with the backlight. Remember, the LCD panel doesn’t produce any light itself. It acts as a kind of coloured slideshow over the front of a white ‘backlight’. It is the backlight that consumes the bulk of the power of an LCD TV. Older LCD TVs always had the backlight running full blast whenever the TV was switched on.

As it happens, improving backlight performance on LCD TVs also improves picture performance, because the weakest area of LCD performance has long been their inadequately dark blacks. Indeed, ‘dynamic’ backlights were first developed to improve this aspect of performance.

Basically, these are backlights that can be turned down. When darker, black levels are deeper, of course. And power consumption is also reduced.
Some TVs will automatically adjust the backlight level to match the overall brightness of the picture, thereby accidentally yielding some energy saving. As some of the TVs we look at in this article demonstrate, the ability to set the backlight level low has been used to give them better energy ratings on their labels (see the box for how this is measured). One TV defaults to a ‘Standard’ picture mode with the backlight set to a lower level than is usual even for the ‘Cinema’ mode, which is designed for use in a dark room.

However, the perception of picture brightness is generally a highly subjective thing, and in normal ranges, is based on relative brightness. If you start with a bright TV picture and turn it down, it will look dull for a while. But if it switches on a bit darker, it will usually look fine.

Different technologies have also been employed for backlights, with latest being the LED. These offer more efficiency than the cold cathode fluorescent lamps (CCFLs) traditionally used. Another more efficient technology used by at least one company is HCFL, or hot cathode fluorescent lamps.