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In the early days of computing, users stared at drab monochrome screens displaying green or white text. In just a few decades, monitors have evolved to match the ever more powerful video capabilities of computers, displaying digital photos, movies, and complex life-like video games. Today’s monitors come in sizes 20 inches and over and can resolve millions of colors in high resolution. Because monitors have become as ubiquitous as the personal computer, and are now found in almost every business and a majority of homes, they represent a huge opportunity for businesses and consumers to not only save money on their electricity bills through improved operational efficiency, but also reduce electricity consumption and therefore carbon dioxide production.

What do we mean when we say "monitor"?
A CRT and LCD TV

Technically speaking, a monitor is an appliance that can display a video signal from a connected device. This might sound very much like a television, and in fact the only feature separating monitors from TVs is that TVs contain internal tuners that can receive broadcast signals, whereas monitors do not. In the not-too-distant future, TVs and monitors are expected to converge into one single product category that might be described as “displays.” At the moment, EfficientProducts.org limits the discussion of monitors strictly to the variety used to display images generated by a computer.

There are two primary types of computer monitors: cathode ray tubes (CRTs) and liquid crystal displays (LCDs). A CRT monitor works by directing electrons, which are generating in the back of the monitor toward a phosphor-coated screen. When the electrons collide with the screen, it glows. An LCD monitor utilizes a grid of tiny, electronically-controlled shutters to regulate the passage of fluorescent light through to the screen.

How many monitors are in use and how much energy do they use?
As computers become an integral part of the home and office, monitor sales have seen steady growth. For the past five years (1999 to 2004) unit sales of computer monitors in the U.S. are estimated to have increased by 60% from 4.2 million to 6.8 million[1]. As sales increase, so do the number of monitors in use. There are an estimated 150 million monitors operated in the U.S. today, split roughly half and half between homes and offices[2].

Monitors have made dramatic efficiency improvements over models just a few years prior. A typical CRT monitor in an office setting will consume roughly 270 kilowatt hours (kWh) of electricity per year and cost about $20 per year to operate. A commercially operated LCD monitor uses about 140 kWh of electricity per year and costs under $12 per year to operate. These numbers are comparable to the amount of electricity used by some computers themselves, so choosing an efficient model is important and can save money on electric bills. Larger businesses in particular stand to save hundreds, potentially thousands of dollars per year in electric costs by upgrading to more efficient models.

How can I find today's most efficient monitors?
The U.S. Environmental Protection Agency’s (EPA) ENERGY STAR voluntary labeling program certifies monitors for energy efficiency in active, sleep, and standby modes and awards the most efficient models the ENERGY STAR label. For an overview of ENERGY STAR’s monitor efficiency specification and a list of qualifying models, please visit the ENERGY STAR monitors web page.

The monitor industry has so readily accepted energy efficiency market transformation efforts such as ENERGY STAR’s labeling specification that a great deal of today’s LCD monitors exceed even the most efficient monitor labeling requirements. In 2005, Ecos Consulting developed a more stringent monitor procurement specification that allows individuals and corporations to identify the absolute most efficient computer monitors on the market today. Check back with EfficientProducts.org soon for an update on this important research.

What is the definition of efficiency for monitors?
The energy efficiency community began to actively promote efficiency in monitors in 1992 through the ENERGY STAR® program, based on a monitor’s ability to enter a sleep mode when not receiving a signal from a computer or when not in use for a period of time that is defined by the user. Formerly, the ENERGY STAR labeling program defined an efficient monitor based on the amount of power that it consumed during this sleep mode. A model that consumed less than a certain level of power was awarded the ENERGY STAR label.

Today, the definition of monitor efficiency has expanded to include active mode, or the period of time when the monitor is displaying images to the user. Since larger monitors consume more power, the metric for efficiency takes monitor size into account so that it does not unfairly penalize larger products that can display more information. As a result, active mode monitor efficiency is defined as the amount of watts per million pixels (or megapixels) required to illuminate the screen under tightly controlled brightness and contrast conditions.

Is there a way to test efficiency?
The ENERGY STAR program has refined and adopted a standard test protocol to measure monitor efficiency in the active mode of operation. The method provides specific test conditions for measuring the active mode power consumption of a monitor as well as the power consumed in sleep mode (when the monitor has automatically powered itself down) and standby mode (when the user has switched the monitor off manually but some additional power consumption still occurs). Click here to view the ENERGY STAR monitor test procedure.

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Consumer Electronics Association Market Research. US Consumer Electronics Sales and Forecasts 1999-2004. July 2003.
Based on Ecos Consulting estimates of the number of desktop computers in operation, the vast majority of which require an attached monitor.

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