Observing our current lifestyle - and thinking about ideas and solutions for a more sustainable one.
Here is a report about a first attempt at observing.
(In case you were wondering, "abefahre" is swiss german for "reducing" or "shutting down" :)
Homemade 2025 is the 2025 edition of the summer camp of the Swiss Mechatronic Art Society (SGMK), which this year took place at Wartburg in Mannenbach-Salenstein (Switzerland) by Lake Constance.
To measure electrical power consumption (maybe even production?) of all projects at Homemade 2025 and visualise it in real time. We can learn many things from this, e.g. how much power do appliances consume, Smart Home concepts, networking with WiFi and with Zigbee, data visualisation, virtualization and much more.
Ultimately, the goal is to raise awareness about how much electrical power we consume every day - and by understanding this, help reduce unnecessary consumption.
Contact Oli W (oliver dot walkhoff at mechatronicart dot ch)
The sensors are "smart switches" which will be integrated at every as many as possible power outlets throughout the venue. We will use Home Assistant to gather and visualise sensor data in a dashboard. Home Assistant runs as a Docker container inside an Ubuntu Server, inside a used mini PC.
Smart switches come in two flavours: with either WiFi or Zigbee connectivity. WiFi is trivial: the device simply connects to the local IP network. Zigbee requires a "coordinator", as a gateway to the IP network. In the case of Zigbee, each smart switch is also a "router" that extends the (mesh) network from one device to the next as far as we need to reach. The switches provide readings for voltage, current and power. (Besides, they can also be turned on or off from Home Assistant.)
What's challenging is that we will be working not only in and around the main house, but also the forest house ("Waldhaus") which is located about 100 metres down a steep slope, and with no connection to the router in the main house. Internet connectivity in the forest house will be provided from various hotspots with different SSIDs - which all makes creating the desired topology very difficult...
There must be one coordinator in a Zigbee network. We tested two different models:
Brand: Sonoff
Model: ZB Dongle E
Chipset: Silicon Labs EFR32MG21
Type: Zigbee 3.0 to USB
Source: Bastelgarage.ch, 07.07.2025, 1 x CHF 25.90
Brand SMLIGHT
Model: SLZB-06M
Chipset: Silicon Labs EFR32MG21
Type: Zigbee 3.0 to Ethernet, USB, and WiFi
Source: Aliexpress, 17.07.2025, 1 x CHF 32.40Both models are good, we picked the SLZB-06M because it can be placed anywhere on the IP network, whereas the ZB Dongle E can only be connected to the machine that's running Home Assistant.
These are the sensor devices that provide energy measurements.
Brand: ebelles
Manufacturer:
Model:
Rated current: 10 A
Power monitoring: Yes
Connector: Screw terminals
Source: Aliexpress, 05.07.2025, 9 x EUR 5.69 / 17.07.2025, 6 x EUR 5.69
Name in HA: Smart switch 001
Brand: Moes
Manufacturer:
Model: ZM-104-M-16AM
Rated max. current: 16 A
Power monitoring: Yes
Connector: Screw terminals
Source: Aliexpress, 01.07.2025, 2 x EUR 10.29
Name in HA: Smart switch 002These use split core toroidal current transformers as sensors, so no need to interrupt the power line. (Not implemented during Homemade 2025.)
(Didn't find any Zigbee smart plug with Swiss connector, only European Schuko, US, Brazil and others.)
Most of the available WiFi smart switches and smart plugs are based on the ESP SoC by Espressif Systems. They can be flashed with the open source Tasmota firmware for full control.
Brand: IoTorero
Manufacturer: Athom, www.athom.tech
Model: RS01
Rated current: 10 A
Power monitoring: Yes
Connector: Screw terminals
Source: Aliexpress, 29.06.2025, 1 x EUR 14.49
Brand: IoTorero
Manufacturer: Athom, www.athom.tech
Model: PG05
Rated current: 16 A
Power monitoring: Yes
Connector: CH Type J / Type 13
Source: Aliexpress, 29.06.2025, 2 x EUR 13.29The first measurement was on Wed 2025-08-06 14:00.
The last measurement was on Sat 2025-08-09 18:00.
The time axis of the following graphs ranges from Wed 2025-08-06 00:00 to Sun 2025-08-10 00:00.
The numbers:
2025-08-06
Total consumed: 4.6 kWh
Switch 002: 2.81 kWh
Switch 001: 1.24 kWh
Switch 003: 0.55 kWh
2025-08-07
Total consumed: 3.89 kWh
Switch 002: 1.87 kWh
Switch 001: 0.22 kWh
Switch 003: 1.13 kWh
Switch 004: 0.35 kWh
Switch 006: 0.21 kWh
Switch 007: 0.11 kWh
2025-08-08
Total consumed: 5.19 kWh
Switch 002: 1.45 kWh
Switch 005: 1.40 kWh
Switch 001: 0.12 kWh
Switch 003: 1.25 kWh
Switch 004: 0.19 kWh
Switch 006: 0.78 kWh
2025-08-09
Total consumed: 5.31 kWh
Switch 002: 0.78 kWh
Switch 005: 3.11 kWh
Switch 001: 0.15 kWh
Switch 003: 1.19 kWh
Switch 006: 0.08 kWh
Total: 18.99 kWhHow does this compare to the overall consumption during the whole camp? The official electricity meter "Waldhaus" read 31269 kWh on August 3 (the first day of the camp) and 31489 kWh on August 10 (the last day). So the overall consumption at the forest house was 220 kWh in 7 days. Our readings (from 4 days) represent roughly 10 percent of that.
The sensors were placed at power outlets in the forest house, with extension cords connected to them. Some were feeding only one consumer (labeled "Refrigerator") or a few (labeled "3D Printers"), while some other extension cords, for example those running outside (labeled "Outdoor A", "Outdoor B", "Jonas") or to the synthesizer table upstairs ("Sound A") were feeding multiple projects simultaneously.
Unfortunately there wasn't enough time during Homemade 2025 to set everything up as planned. Mainly, the situation at Wartburg with two separate houses, no network connection between the two, and only a GSM based router at the forest house was quite challenging.
Nevertheless, some measurements could be made and it was interesting and fun to experiment with Home Assistant and the sensors. Stay tuned for updates :)
By the way, here is some statistics about Internet usage on the GSM WiFi router:
03.08.2025 18:20 2.84GB used of 12 GB (O2 account topped up)
04.08.2025 15:04 6.2 GB used of 12 GB
05.08.2025 01:14 10.56 GB used of 12 GB (12 GB volume used up)
06.08.2025 14:49 3.62 GB used of 25 GB (account topped up)
08.08.2025 01:34 25 GB used of 25 GB (25 GB volume used up, 37 GB total)
08.08.2025 account topped up with 50 GB
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Page last modified on 2025-12-08 15:15.