Monitoring LCDs Savings Is Elusive

By John Taschek  |  Posted 2002-08-26

Monitoring LCDs Savings Is Elusive

If one thing is clear, judging from the responses to eWeek Labs recent Tech Analysis comparing LCD and CRT monitor technologies, its that LCDs are a hot item. Er, we mean a cool item, since the vast majority of respondents raved about how LCDs reduce energy costs further than we stated. (See a sampling of the responses we received.)

Its clear that LCDs use less energy, but as eWeek Labs pointed out in a July 29 story, the energy cost savings is marginal at best when averaged across the country.

Last year, for example, the average cost of electricity was less than 10 cents per kilowatt-hour across the nation. Even in the state where its most expensive—Hawaii—electricity still costs only 13.9 cents per kwh.

Because there are few up-to-date studies of the impact of LCDs vs. CRTs on heating and air conditioning, we used an arbitrarily high cost in our calculations—20 cents per kwh, a cost that should stay in line for a five-year depreciation of any display/monitor technology.

Geographic sensitivities are one reason that cost-savings calculations for LCDs remain somewhat elusive. In a climate that has just as many cold months as hot months, for example, there may be little if any cost savings. The reason: CRTs might reduce heating costs in the winter to the same degree (so to speak) that LCDs lower cooling costs in the summer.

"In terms of HVAC costs, work we did about seven years ago showed that on average the heating penalties and the cooling benefits of greater efficiency more or less canceled out when you consider the country as a whole," said Jonathan Koomey, staff scientist at Lawrence Berkeley National Laboratory, in Berkeley, Calif.

"From the perspective of a building operator in the South, however, the cooling benefits might be 20 percent to 30 percent additional to the direct energy savings of the equipment," Koomey said.

This national leveling out has led many scientists to minimize energy consumption calculations that are directly related to LCDs and CRTs. For example, "energy operating costs are a minor factor in the economics of office equipment—[although] the small numbers can add up," said Jeffrey Harris, a scientist at Berkeley Labs Washington office. "[Air conditioning] savings are an added factor but not a strong driver, and a lot depends on the building specifics. Commercial building energy as a whole is still dominated by heating energy, not cooling, but the latter is more costly per Btu."

A Bright Idea

A Bright Idea

This is not to say that LCD investments cant pay for themselves—they can, especially in newer offices, because of their relative brightness.

Most energy-use calculations are based on more or less traditional office configurations, which include offices and cubicles brightly illuminated with headache-inducing fluorescent lighting. The brightness of LCDs allows office designs based on more efficient lighting systems. We expect that many of the LCDs in use today sit in executives offices, which appear not to be shrinking in size.

Meanwhile, the workers are being cramped into redesigned, "upgraded" cubicles that are better for the bottom line. Its in these offices that LCDs will have the biggest impact on cost and space savings. Not only will LCDs make some employees feel better (because theyre getting a new gadget), but LCDs also free up space. The same is true of smaller, more efficient computer systems.

Reduced lighting costs can also be factored into any LCD cost-saving analysis (see www. for a report on lighting and associated costs). In addition, if the LCDs are used in a computing room, companies planning for new or replacement air conditioners can get smaller, more efficient units.

The savings associated with smaller air conditioners may even pay for LCD upgrades in the computing room. When monitors are grouped in a computing room environment, LCDs can reduce energy costs considerably.

Vestal Tutterow, principal research associate at Berkeley Lab, in Washington, said, "In a computer-intensive office or call center, or similar, [heat output] can become significant." The use of LCDs also represents a "step in the right direction for any company trying to develop or boost a green image," Tutterow said.

In general, most cost-savings calculations are based on monitors that are on as opposed to a mix of "on" and "standby" modes. However, LCDs take less power to start from standby mode (even though they consume about 1 watt per hour more than CRTs in standby mode).

"LCD screens recover faster than CRT, so it encourages users to configure the power savings management schemes [for shorter periods of time]. Thus, it cuts down on active power time," said Alan Meier, at Berkeley Lab, in Berkeley. "These savings can be substantial."

The result is that dozens of factors affect LCDs and energy consumption, even though energy use is the major driving factor behind corporate sales, according to industry experts.

Officials at Sony Corp., manufacturer of some of the best LCDs weve seen, said reduced energy costs are the top selling points of LCD monitors. Sony Senior Marketing Manager Jim Neal said the factors driving LCD purchases are "60 percent energy, 20 percent AC and 20 percent cubicle location." Therefore, Sony—like every major monitor vendor—has armed its sales force with a total-cost-of-ownership calculator that shows how much money LCDs can save over CRTs, said Neal, in San Diego.

Nevertheless, LCD purchase decisions should not be based on energy savings alone. Instead, LCDs should be incorporated into the designs of office buildings and build-outs because of their reduced energy consumption and the related benefits they provide of reduced office space and smaller, more efficient HVAC systems.

eWeek Labs Director John Taschek is at

  • Readers Weigh in on Monitor Costs
  • Power Sapped? Think Again

  • Rocket Fuel