September 2025: Neon Nights, CO2 Sensors, and Cosy Autumn Evenings

There’s something about September that always feels like a fresh start. Maybe it’s the back-to-school energy that never quite leaves you, or perhaps it’s just the relief of escaping the unpredictable British summer. Either way, this month brought a nice mix of social outings, geeky projects, and those first proper cosy evenings of autumn.

Getting Out and About

Mid-September saw us venturing into town for a well-deserved night out. We ended up at a place called Thirst Trap, which lived up to its name with some excellent cocktails and an aesthetic that’s basically designed for Instagram. The exposed brick and neon lighting combo never gets old.

It’s easy to fall into the routine of work, home, repeat – especially when you’ve got projects calling your name from the workbench. But nights like this are a good reminder that sometimes you just need to put the soldering iron down and go be social.

Tinkering Time

Speaking of the workbench, September was a productive month for home automation projects. I finally got around to setting up some proper environmental monitoring with an SCD41 CO2 sensor. These tiny sensors are brilliant – they measure CO2 levels, temperature, and humidity all in one compact package.

The plan is to integrate this into Home Assistant so we can monitor indoor air quality throughout the house. It’s surprising how quickly CO2 levels can rise in a closed room, and there’s good evidence that keeping levels in check helps with focus and sleep quality. More on that project once it’s fully integrated.

Embracing the Cosy Season

As the evenings drew in, the blankets came out. There’s nothing quite like settling in on the sofa with a cup of tea and a very demanding dog who’s convinced she’s a lap dog despite all evidence to the contrary.

The matching star blankets weren’t planned, but we’re leaning into it. Autumn is officially here, and we’re ready.

Tech Corner: Getting Started with CO2 Monitoring

Since I mentioned the SCD41 sensor, here are some tips if you’re thinking about adding environmental monitoring to your smart home:

Why Monitor CO2?

Indoor CO2 levels are a surprisingly good indicator of air quality. Outdoor air sits around 400-420 ppm, but poorly ventilated rooms can quickly climb to 1000+ ppm. Studies suggest that levels above 1000 ppm can affect cognitive function, and anything over 2000 ppm might cause drowsiness.

Sensor Options

• SCD41 – What I’m using. True CO2 measurement (not calculated from VOCs), plus temp and humidity. Around £30-40.
• SCD30 – Larger but slightly more accurate. Good for stationary setups.
• MH-Z19 – Budget option around £15-20. Decent accuracy but needs calibration.

Quick ESP32 Tip

If you’re connecting an SCD41 to an ESP32 for Home Assistant integration via ESPHome, here’s the basic config:

i2c:
  sda: GPIO21
  scl: GPIO22

sensor:
  - platform: scd4x
    co2:
      name: "Living Room CO2"
    temperature:
      name: "Living Room Temperature"
    humidity:
      name: "Living Room Humidity"
    update_interval: 60s

The sensor needs about 30 seconds to warm up on first power, and it’s worth running the automatic self-calibration for a week or so to get accurate readings.

Looking Ahead

October is shaping up to be busy – there’s talk of Halloween decorations (any excuse for more RGB lighting), and I’ve got a few more sensors to deploy around the house. The goal is to have a proper environmental dashboard by the end of autumn.

Until next time!