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."