Following the puzzling discovery that a new TFT monitor was using more energy than the CRT that it replaced, I did some more measurements. Here are the results:
| ADI VD-695 15" CRT | Acer AL1716 17" TFT | ADI MicroScan M700 17" CRT | LG Flatron 17" TFT | |
|---|---|---|---|---|
| Video cable unplugged | 62 W | 1 W | 45 W | 23 W |
| Black | 62 W | 30 W | 53 W | 23 W |
| Normal display | 83 W | 29 W | 57-67 W | 22 W |
| Power save | 5 W | 1 W | 44 W | 1 W |
| Power factor | 0.49 | 0.47 | 0.51 | 0.51 |
Most of our computers are set to switch to the "Power save" mode (no signal to the monitor) after 20 minutes. Just using the screen saver is not good enough, as this leaves the monitor fully operational but displaying a black picture.
Looking back in this blog, my earlier statement that the LG Flatron was using an average of 61 W must have been wrong! Judging by the table above, 6.1 W would have been more likely. Perhaps I misread the display of the plug-in energy monitor. If I find out what went wrong, I will let you know.
By the way, the latest meter readings for the whole building are now in the usual place:
http://blogs.picotech.com/index.php/2008/04/07/latest-energy-usage-chart
This week's meter reading is a bit higher than last week's (see Energy Usage Chart). This is probably because the cooling system is now working harder in the warmer weather.
Today's meter readings are now on the "Latest energy usage chart" page. The current clamp readings from EnviroMon seem to be converging with the meter readings, which is reassuring.