TL;DR: it was fun to build great graphs. But the battery did not last long, air quality is difficult to track.

Above, the box with plywood. Because I do not have a 3d printer, and I like wood.

Ingredients

For the sensor box

• ESP 8826, WEMOS D1
• LCD 20x16
• Humidity sensor DHT11
• Air quality sensor MQ9
• Red and Green LEDs, corresponding resistors

For the outside sensor

• Old pickes glass jar, and glue or silicon to seal it.
• ESP 8826, WEMOS D1
• 11B12 Temperature sensor
• Batteries AA, rechargeable (because environment)

the server side

• Nginx, with full encryption and authentication for the
• InfluxDB, for storing the datapoints
• Grafana

the result

Nice graphs were plotted, at year end was not too cold in Berlin:

Lessons learned

1. If you cannot know why is not working, its hardware. This is from the PoV of a Software Developer tottally newbie in electronics.

2. Battery life is hard. Stuff we take for granted like doing TLS encryption, in embedded development becomes a critical point for power consumption.

3. Air quality measurement with MQ sensor was disappointing. Maybe have to spend a bit more, or just learn how to calibrate it.