For example, if your CRT is eating up 150 watts per hour of energy, and you use the monitor 8 hours a day, 200 days a year, it uses 240 kilowatt hours (kWh) per year. At 7 cents per kWh, your CRT costs $16.80 a year to run.
On the other hand, LCDs typically use only about 50 watts per hour while on. And following the same equation, we find that an LCD costs $5.60 per year to operate, a savings of $11.20.
To find out how much energy your specific monitor uses, look for a label on the back of the monitor, usually near the inputs. If the watts per hour isn't listed there, check the documentation that came with your display. The U.S. Department of Energy's Web site
also provides a list of typical wattages for various appliances.