Measuring the energy consumption of everything you own

Voltcraft Energy Check 3000

Inspired by this post from Lars Wirzenius, I recently bought an electricity meter (or energy meter) and measured the energy consumption of everything I could find in my flat.

I did not yet perform any long-term tests, i.e. measuring the average consumption over multiple days or so, only some quick ad-hoc checks. I just recorded the number of watts the respective device used when powered on.

Here are the results:

Kitchen stuff:

  • Microwave. Off: 0 W. On: 1150 W.
    Depends on the configured "mode" of the microwave, I used the highest/hottest mode here.
  • Coffee machine. Off: 0 W. On: 884 W.
  • Mini-oven. Off: 0 W. On: 800 W.
    Depends on the configured "mode" of the mini-oven, I used the highest/hottest mode here.
  • Kettle. Off: 0 W. On: 2035 W.
    Quite a shock. I bet there are more energy-efficient ones out there, but still...
  • Toaster. Off: 0 W. On: 168 W.
  • Fridge. Off: 0 W. On: 110 W.
    This needs testing over a longer period of time. Fridges are not powered all the time.

Computer stuff:

  • Printer (Epson Stylus DX4200). Off: 0 W. Idle: 2.6 W. Printing: 10 W.
  • Laptop (Toshiba Satellite A80-117). Off: 0 W. On: 40 W. Heavy CPU load: 50 W. In powersave mode: 32 W.
  • PC (ASUS P4B266, 2 GHz). Off: 2.7 W. On: 60 W. Heavy CPU load: 92 W.
  • Computer monitor (CRT). Off: 1.7 W. On: 77 W. Pretty dark screen contents: 60 W. Text console: 50 W.
  • NSLU2. Off: 0 W. On: 3.5 W. Heavy CPU load: 3.9 W.
    This is one of the greatest pieces of hardware I ever bought, and these numbers are one reason for that!
  • External USB hard drive. Off: 0 W. On: 9.6 W. Heavy I/O load: 10.8 W.
  • DSL splitter + router. Off: 0 W. On: 1.2 W.
  • Radio. Off: 0.6 W. On: 2.1 W.
  • Shredder. Off: 0 W. On: 40-60 W.
  • External loudspeakers ("bass booster"). Off: 1.5 W. On: 3.5 W.
  • Portable mini CD player. Off: 0.4 W. On: 1.6 W.

By removing all devices which draw more than 0 watts in stand-by mode, I was able to reduce the overall (useless) energy consumption (and costs!) quite a bit.

I also replaced a bunch of 40 W and 60 W lightbulbs with energy saving lightbulbs which are equally bright, but only consume 8 W or 12 W respectively. On the long run you can save quite some amount of energy (and money) with them. They do cost a little bit more than normal lightbulbs, but save lots of electricity costs and they also last a lot longer (8000-15000 hours vs. 1000 hours according to Wikipedia).


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Could you tell me how to operate the energy check 3000? Either its dead or I don't understand how to operate it anymore (the device was bought quite some time ago, manual lost...)

Lex Nicolai


Hi, the manual can be found on the web, e.g. here (PDF).

HTH, Uwe.

I haven't got the courage to

I haven't got the courage to do what you did, my all appliances are old and they have a high energy consumption. It took me a while to figure out that I need new appliances parts to get rid of this energy problem, so I am setting a plan to buy them.

Ohms Law

Never ever even try to measure the energy consumption of anything that uses a switching power supply (especially computers..). The meter will display funny things but they are far off from the real power consumption.
check this for some more information:

Those meters are only made for devices that do not introduce a phase shift e.g. light bulbs,kettles.. Anything with an advanced power transformation (read: complex) would produce bogus output.

Voltcraft 3000

You are absolutely right that many (cheap) meters don't include the phase-shift, but the meter shown above does a true Watt measurement. The "Voltcraft Energy Monitor 3000" can show both VA and Watt, as well as the current cos-phi. the "Voltcraft Energy Check 3000" does not display the cos-phi, but uses the same measurement electronics, and does include phase shift in its Watt measurement.

The site you quoted also

The site you quoted also says that:

"Um den Strom bei nichtlinearen Verbrauchern ‘gerade zu biegen’, setzt man eine elektronische Schaltung vor Gleichrichternetzteile, die Power Factor Compensation (PFC). Eine solche Schaltung verteilt die Stromaufnahme wieder über die ganze Spannungshalbwelle und hebt den PF so auf Werte um 0,95, also fast das Optimum. PFC wird für nichtlineare Verbraucher vom 1.1.2001 an in der EU zur Pflicht."

That means that anything sold in the EU after 2000 doesn't have this problem anymore.


Waouh! The power consumption of the NSLU2 is really, really interesting. I know this device for a while now, and was not really sure about this utility for me... but now, I think I'll buy one just to reduce my energy consumption...

The only problem is: on which 'support' can I run Debian, as you asked on your previous post. Did you find the solution?



For the moment I'm sticking with a USB thumb drive (which has 5 years warranty, so I hope it'll last a while)...


nslu2 consumption

ad the NSLU2 consumption: is is great, but the device itself is probably not much useful.. you need a different computer to connect to it, to be able to work with it.. Just try to measure power consumption of some PDA ;-) . But I'd definitely buy one (nslu2), if I find some below 50€.


Not necessarily, or at least not always. Sure you need another computer to connect to it, but only for administration and installing. After that it can run all kinds or servers (webserver, print server, webcam image capturing, IRC logger, etc.) without any user intervention...

Below 50,- is not realistic at the moment, but ca. 70,- is possible to find... The Planet.

Thanks, Uwe, I didn't know anything about this type of device... I think that it is important to know how you are using the energy, and so, be "able to reduce the overall (useless) energy consumption (and costs!) quite a bit". It is important for us and FOR THE PLANET.

Kind regards.

Cost of meter

Uwe, how much did the meter cost?


This one cost me 25 Euros, but there are some (with less features) which are about 10 Euros...


You've only measured the electricity usage of the kettle. To get the efficiency you need to know how much of that is used in heating the water and how much is lost to the surroundings.

Kettle: 2035 W

That's quite normal, isn't it? They pretty much have a rendement of almost 100%, because they're supposed to generate heat.

I guess that about 2030 W of the total goes into the water, so if you take a lighter one, the only difference you'll notice is that boiling the water takes longer, thereby using the same amount of energy: You still need to heat up the same amount of water the same amount of degrees.

Kettles are not wasting energy

Kettle. Off: 0 W. On: 2035 W.
Quite a shock. I bet there are more energy-efficient ones out there, but still...

Eh, no. Kettles are extremely efficient (if you look only at electricity and not gas) for heating water[1]. What you just learned is that it takes a lot of energy to heat water. So unless you want to wait longer for your water (without saving energy!), a kettle should have as much power as possible.



Nice, thanks all for the clarifications!

Stand-by power consumption

Hi Uwe?
My name is Shani- I'm a university student from Australia...
I was just wondering if you know of a way to determine the stand-by power consumption without using an 'electro-metre' (the little thing you used to measure the power used at different stages of use of the appliances in your flat). Im sure these are available here in Aust., but am avoiding that path. Something in the form of equations with known variable such as wattage, hours of use, or max current draw, etc.
Thanks. Kind Regards, Shani

Take the lower values with a

Take the lower values with a grain of salt. All power meters I have seen have a resolution (of the internal AD converters) that is aimed at measuring normal currents. The device has to determine the phase difference between voltage and current ( though, which gets more complicated to do exactly for lower currents.


Yes, sure, you shouldn't fully trust the (exact) values. But I think they're good enough to get a general idea of where you consume the most energy, and where you can easily save some (stand-by energy consumption, for example).

Ad kettle

A kettle might actually be more efficient when it takes more power, because it means shorter time to boil the water, so less heat is lost.

Kettle efficiency

The above is absolutely correct. A UK consumer magazine did a survey about the real energy cost of all the gadgets in the kitchen. The nost expensive was actually the ice-cream maker: energy cost to make was high, energy usage to whip up ice cream was high but thenkfully real usage on a regular basis was virtually nil. A plastic kettle with auto-switch off on boil is actually the cheapest - used most often, energy cost to make virtually nil. The trick is to remember that coffee is better made with cooler water and not to let it boil - also to remember that it is marginally more energy efficient to boil only the amount of water you need at a time. If you only need two cups, only heat two cups worth rather than 1.1 litres. It may seem sensible that you can always reheat warm water quickly, but its quicker and better to only use the kettle for 1 minute on two cups rather than 4 minutes on litres which you then leave to stand. Plastic kettles don't radiate heat well, so are more energy efficient than equivalent metal kettles.