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LCD TV Power Consumption

written by: Debasis Das•edited by: Rhonda Callow•updated: 3/26/2010

When choosing the right HDTV, one of the things that needs to be looked at is power consumption. That is what translates to day-to-day dollar cost. It can be a constant drain too! Here is a guide to what to expect in terms of LCD TV power consumption.

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    Introduction to LCD TV Power Consumption

    There are several factors that affect the power consumption of an HDTV. The underlying HDTV technology is of course the key. For example, LCD TV power consumption is lower than a plasma TV. Besides the type of HDTV affecting power consumption, there are still other factors that need to be taken into consideration. LCD TVs typically consume the least amount of power on average when compared to all HDTV technologies. Read on to find what else contributes to additional LCD TV power consumption.

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    Factors that Affect the Power Consumption of an LCD TV

    LCD TV technology consists of a liquid crystal that is polarized by an electric current. Depending on the electric current the crystal either blocks or passes light from a light source (backlight) that is placed behind the liquid crystal layer. (See “How does LCD TV work?" for more details.) The core of the power consumption therefore comes from a) power required to polarize the liquid crystal, and b) the back-light consumption. The size of the screen then determines the main component of power consumption. In simple terms, the larger the size the more power the LCD TV will use. Remember though, the power consumption does not increase linearly with the diagonal screen size. For example, a TV that is twice the size (in diagonal inch terms) will have more than 3 times the power consumption. This is because what matters is the number of square inches that the screen is. Typically, therefore, the power consumption is quoted in terms of per-square-inch. (See the next section for a web-based guide to power consumption.)

    The power consumption of an LCD TV naturally depends on the brightness of the picture that is currently on screen. In order to reduce power consumption (and also to increase longevity) a calibration procedure can be carried out. The calibration procedure basically attempts to limit the maximum brightness or luminance of the picture, thereby setting a limit on the peak power consumption of the set. The calibration process is a one-time fix on the peak power consumption of your unit, but the day-to-day power consumption can also be reduced if the brightness of the screen is lowered. If you watch the TV in a bright room, you will definitely have to have the high brightness settings. On the other hand simply drawing the curtains/blinds, or dimming the lighting can help reduce the brightness of the LCD TV screen. Some TVs have light sensors to automatically adjust the picture depending on light conditions. An ISF calibration can also enable you to have presets that adjust the brightness according to the light conditions.

    Overall power consumption really boils down to the LCD TV's usage. One important factor often overlooked is that it is more sensible to talk of TV-related power consumption than the TV power consumption alone. Things such as the set-top-box (or DVR), a gaming device, a DVD player, and even the external speaker system that may be attached to the TV all consume power. These need to be taken into account when you look at power consumption in the long run.

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    A Guide to Power Consumption of HDTVs

    There is a great guide to the power consumption of a whole lot of HDTVs that are available on the market today. It is available at The Chart: HDTV power Consumption Compared . Make sure you take a look at that for a quick reference for your LCD TV's power consumption. The guide quotes power consumption per square inch and an estimated cost per year based on daily usage of 5.2 hours. There are other such guides available on the web. Plus, a manufacturers specification will state the factory-rated power consumption of a given unit.

    The chart clearly shows that calibration can reduce power consumption significantly. However, this needs to be balanced against the cost of the calibration itself. If you look at the Toshiba 46SV670U for example, you’ll see that power consumption decreases almost 20% via calibration, but that translates to only about a $7 savings per year. Consider how many years it would take to pay the price of the calibration according to that estimate. You may of course want to do it simply because reducing power consumption is doing the right thing for a greener world!