some personal power consumption facts
After a month away from home I received a $40 bill (190 KWh). After blaming a leaking air conditioner, the fridge, the utility company (UTE), and may others, I took some time to discover the facts.
During my month away everything was off except for the fridge and my home office servers:
- a mac mini
- a Linux backup server, with 4 hard drives and Pentium dual E2160 1.8G
- 2 UPS.
- a wap.
After measuring with a clamp meter I’ve found that this setup draws 0.7A.
The fridge runs about half the time (summer), and when running draws 0.9A.
So, adding this up we find out that the dreaded meter is right.
(31 days, 24 hours, 220V, 0.7A all the time, 0.9A half the time, W to KW conversion, in lisp).
(/ (* 31 24 220 (+ 0.7 (* 0.9 0.5))) 1000)
188.2 KWh
If we add the tax (22%) and the fixed monthly fee, we get the $40 bill.
Some other measurements:
- Two 19” LCDs on: 0.2A
- Mini idling: ~0.1A
- Mini at full CPU: 0.3A.
- Linux server idling (4 hard drivers, raid): 0.4A
- Linux server copying files: 0.6A.
- Linux server at full CPU: 2.0A !
- Two laser printers idling: 0.2A
- One of them printing, varies, but while the page is rolling it’s around 1.5A.
Nothing new here, but some lessons re-learned: Turn off your printers, set monitors to power off as soon as possible and use warm compact fluorescent for your desk.
(Mains 220V. Prices in dollars. KWh prices: $0.1/KWh up to 100KWh. $0.14 above 100KWh.)
