Qball's Weblog

YouLess: Get grips on your energy usage.

Tags YouLess 

What is YouLess

Image from youless.nl

Image from youless.nl


YouLess is a cheap and small energy meter you attach to your the energy-meter you get from your electricity company. It is a small device that you can attach (using Ethernet cable) to your network. For more information see the website.

The device has a few downsides;  a) it has limited storage space, b) it has little visualization, c) you cannot do any analysis.

a,b,c can be solved by automatically uploading the data to bidgely, but personally this is something I do not want.

So, as usual, I wrote I small tool that can get you some more insight in the energy usage.




EnergyPoint: A small tool to get insight


Getting the data

Because of the limited storage, it can only store 1 minute resolution data for the last hour, we need to store the data in a local db.

To get the data from the YouLess i use a cronjob that downloads data the past 30minutes every half hour. You can get the data in json format.
I use:

wget "" -O `date +%Y-%m-%d-%H%M-1.json`
wget "" -O `date +%Y-%m-%d-%H%M-2.json`

This downloads data from the past hour every 20 minutes,  this makes sure I do not loose data points if the cronjob is late or missed.

EnergyPoint imports this data into a custom sqlite database and will make sure no duplicate data is stored.

Importing data is as simple as:

ep import data/*.json


Analyzing the data

The following analyze are possible (I am looking to build more, ideas are welcome):

You can limit the the range these work on by specifying a range on the command-line:


So if you want to see the energy consumed on average per weekday over the past 2 weeks you can do: (numbers are dummy numbers)

$ ep statistics weekdays range  4/16/2012 4/30/2012
Range:            16/04/2012 - 00:00 --> 30/04/2012 - 00:00
Average power:      470.30 W
Energy consumed:    158.02 kWh
========== Week days ==========
Day:    Average:    Total:
 1      857.49 W     10.58 kWh
 2      766.46 W      8.40 kWh
 3      665.26 W     10.97 kWh
 4      779.53 W     11.71 kWh
 5      898.13 W     11.56 kWh
 6     1037.53 W     14.90 kWh
 7      870.62 W     10.89 kWh
Total:               79.10 kWh

Visualizing the data

Beside printing data out, it can also plot graphs:

And extra options for each command:


So if you want a plot over the past day:

./ep  plot points range 4/27/2012 4/28/2012 average svg plot1.svg

Plot of 1 day.



There is still many things left todo in the tool, like cleanups, fix tooltips, etc. Help is (again) welcome.

It was written mostly on the train traveling from/to work. So do not be scared.

The code is written in: Vala, GTK 3, cairo, json-glib.



You can get it from github: here