diff --git a/nodes/d1-mini-scd40-27afc1/.gitignore b/nodes/d1-mini-scd40-27afc1/.gitignore
new file mode 100644
index 0000000..d8b4157
--- /dev/null
+++ b/nodes/d1-mini-scd40-27afc1/.gitignore
@@ -0,0 +1,5 @@
+# Gitignore settings for ESPHome
+# This is an example and may include too much for your use-case.
+# You can modify this file to suit your needs.
+/.esphome/
+/secrets.yaml
diff --git a/nodes/d1-mini-scd40-27afc1/firmware.yaml b/nodes/d1-mini-scd40-27afc1/firmware.yaml
new file mode 100644
index 0000000..35a6471
--- /dev/null
+++ b/nodes/d1-mini-scd40-27afc1/firmware.yaml
@@ -0,0 +1,247 @@
+---
+
+substitutions:
+  macsuffix: "27afc1"
+
+wifi:
+  power_save_mode: LIGHT
+
+improv_serial:
+
+globals:
+  # Configure CO2 indicator thresholds
+  - id: threshold1
+    type: float
+    initial_value: '750'
+  - id: threshold2
+    type: float
+    initial_value: '1200'
+  - id: threshold3
+    type: float
+    initial_value: '1500'
+  - id: threshold4
+    type: float
+    initial_value: '1750'
+  - id: threshold5
+    type: float
+    initial_value: '2000'
+
+  # Configure the brightness values for the LED indicator
+  - id: dim
+    type: float
+    initial_value: '0.5'
+  - id: bright
+    type: float
+    initial_value: '1.0'
+
+esphome:
+  name: "d1-mini-scd40-${macsuffix}"
+  project:
+    name: "cccda.d1-mini-scd40"
+    version: "2023052001"
+  comment: "https://git.darmstadt.ccc.de/cda/co2-sensor-workshop/"
+  on_boot:
+    then:
+      - light.turn_on:
+          id: indicator
+          red: 0
+          green: 0.2
+          blue: 1.0
+          effect: "None"
+          brightness: 30%
+
+esp8266:
+  board: d1_mini
+
+captive_portal:
+
+logger:
+  level: DEBUG
+  logs:
+    light: INFO
+    sensor: INFO
+
+web_server:
+  port: 80
+
+api:
+  reboot_timeout: 0s
+
+# Enable either SNTP or Home Assistant as a time source
+time:
+  # https://esphome.io/components/time/sntp.html
+  - platform: sntp
+    id: time_source
+    timezone: "Europe/Berlin"
+    # Disable LED indicator during nighttime
+    # https://esphome.io/components/time/index.html#on-time-trigger
+    on_time:
+      - hours: 8
+        minutes: 0
+        seconds: 0
+        then:
+          - light.turn_on:
+              # cold white
+              id: indicator
+              red: 0.9
+              green: 0.9
+              blue: 0.9
+              effect: "None"
+              brightness: !lambda |-
+                return id(dim);
+          - logger.log: "Leaving night mode via on_time, enabling LED indicator."
+      - hours: 22
+        minutes: 0
+        seconds: 0
+        then:
+          - light.turn_off: indicator
+          - logger.log: "Entering night mode via on_time, disabling LED indicator."
+    on_time_sync:
+      then:
+        - if:
+            condition:
+              lambda: |
+                return
+                  (id(time_source).now().hour < 8 ||
+                   id(time_source).now().hour >= 22);
+            then:
+              - light.turn_off: indicator
+              - logger.log: "Entering night mode via on_time_sync, disabling LED indicator."
+
+i2c:
+  scl: GPIO5
+  sda: GPIO4
+  scan: false
+
+sensor:
+  - platform: scd4x
+    id: scd40
+    # low power mode
+    measurement_mode: low_power_periodic
+    update_interval: 30s
+    # Apply a temperature correction offset, that gets substracted
+    # from the measured temperature, defaults to 4.0
+    #temperature_offset: 1.5
+    co2:
+      name: "${macsuffix} CO2"
+      on_value:
+        then:
+        - if:
+            condition:
+              and:
+                - lambda: return (x < id(threshold1));
+                - light.is_on: indicator
+            then:
+              - light.turn_on:
+                  # cold white
+                  id: indicator
+                  red: 0.9
+                  green: 0.9
+                  blue: 0.9
+                  effect: "None"
+                  brightness: !lambda |-
+                    return id(dim);
+        - if:
+            condition:
+              and:
+                - lambda: return (x > id(threshold1) and x < id(threshold2));
+                - light.is_on: indicator
+            then:
+              - light.turn_on:
+                  # neutral white
+                  id: indicator
+                  red: 1.0
+                  green: 0.84
+                  blue: 0.54
+                  effect: "None"
+                  brightness: !lambda |-
+                    return id(bright);
+        - if:
+            condition:
+              and:
+                - lambda: return (x > id(threshold2) and x < id(threshold3));
+                - light.is_on: indicator
+            then:
+              - light.turn_on:
+                  # warmwhite
+                  id: indicator
+                  red: 1.0
+                  green: 0.75
+                  blue: 0.0
+                  effect: "None"
+                  brightness: !lambda |-
+                    return id(bright);
+        - if:
+            condition:
+              and:
+                - lambda: return (x > id(threshold3) and x < id(threshold4));
+                - light.is_on: indicator
+            then:
+              - light.turn_on:
+                  # orange
+                  id: indicator
+                  red: 1.0
+                  green: 0.5
+                  blue: 0.0
+                  effect: "None"
+                  brightness: !lambda |-
+                    return id(bright);
+        - if:
+            condition:
+              and:
+                - lambda: return (x > id(threshold4) and x < id(threshold5));
+                - light.is_on: indicator
+            then:
+              - light.turn_on:
+                  # red
+                  id: indicator
+                  red: 1.0
+                  green: 0.0
+                  blue: 0.0
+                  effect: "None"
+                  brightness: !lambda |-
+                    return id(bright);
+        - if:
+            condition:
+                - lambda: return (x > id(threshold5));
+                - light.is_on: indicator
+            then:
+              - light.turn_on:
+                  # red pulse
+                  id: indicator
+                  red: 1.0
+                  green: 0.0
+                  blue: 0.0
+                  effect: "Fast Pulse"
+                  brightness: !lambda |-
+                    return id(bright);
+    humidity:
+      name: "${macsuffix} Humidity"
+    temperature:
+      name: "${macsuffix} Temperature"
+
+button:
+  - platform: template
+    name: "${macsuffix} Force CO2 Sensor Calibration"
+    icon: "mdi:restart"
+    on_press:
+      then:
+        - scd4x.perform_forced_calibration:
+            # Average outdoor value for March 2023
+            # https://www.co2.earth/daily-co2
+            value: 421
+            id: scd40
+
+light:
+  - platform: neopixelbus
+    id: indicator
+    name: "${macsuffix} CO2 Level Indicator"
+    type: GRB
+    variant: WS2812
+    pin: GPIO0
+    num_leds: 3
+    effects:
+      - pulse:
+          name: "Fast Pulse"
+          transition_length: 0.5s
+          update_interval: 0.5s