How to measure your electrical energy consumption

Do you know how big your CO2 footprint is for the electrical energy you consume?

I did not know either, so I found this how to calculate. Result: close to half a kilogram (401gr) per kWh, using the 2020’s German mix.

Is this much? Let’s go along my own consumption: My house consumes 10kWh per day, almost constant, with 4 people living in it. Each kWh creates an anual CO2 footprint of 0.0365 tons: 0.401kg/kWh/ 1000(kg into tons) * 365 / 4 (people) = 0.0365. So, my personal CO2 footprint for electricity is about 0.365 tons p.a. Curious to hear how big your footprint is.

Read your electricity consumption – but how?

The all-inclusive solution is a Shelly 3EM. Fits into your fuse cabinet, reads power for all 3 phases, forwards by Wifi / MQTT. Interesting solution also if your energy meter is outside the Wifi range. Versions for 1 phase exists as well.

Other solutions – various types of energy meters

Spinning disc – ferraris

ferraris meter – and reader, found here

many of you might have a simple „spinning silver – red disc“ inside your meter, called ferraris counter. The example was found in Pinterest, see here

Ready to use readers exist as well, for example at, either the complete solution for in this example for FHEM, or the reader unit only, which forwards pulses to an 8266

Electrical meters with LED pulse output

example of a digital electricity meter

if your electrical meter is a bit younger, it might look like this. There should be a LED, blinking 1000 times per kilowatt-hour.

Many solutions exist to count the pulses, such as this one. Same principle: connect to an 8266 board and forward to your home automation system using MQTT

It goes without saying that all devices connected to your electricity meter are now included into your CO2 footprint: Air condition, electrical heating, charging your e-car. Cool, or?

Side effects: What else can you do once you have your power consumption online?

identify your minimum power consumption: Which power in Watts is your house never under? Sounds like a very low thing, but keep in mind that each single Watt consumes 8.8kW hours a year. More on my success journey later here

Learn how your power consumption looks like over the day. It is easy to optimize once you know it – and once you compare yourself with your friends.

Community: How can you help?

Tell us about your electrical meter and the solution that works for you

Tell us about your learnings and life hacks how you lowered your energy consumption