The E1 Pro Multi Sense can be expanded with an optional air quality add-on. Unlike the S1 Pro, which already includes a BME688 air quality sensor on the PCB, the E1 Pro allows you to choose the sensor that best fits your application.
Only one air quality add-on can be installed on the E1 Pro. Users can choose between the BME688 multi-parameter air quality sensor or the SCD40 true CO₂ sensor.
On the S1 Pro, the BME688 is included by default, with the option to add the SCD40 for precise CO₂ measurement.
What both add-ons do
• Integrate locally with Home Assistant via ESPHome
• Enable smart ventilation and comfort automations
• Measure temperature and humidity
• Provide indoor air quality awareness for data-driven decisions
• Keep all data inside your home network
Key differences
BME688 – multi-parameter air quality sensing
• Measures IAQ and eVOC
• Estimates CO₂ levels based on VOC activity (eCO₂)
• Measures temperature, humidity, and pressure
• Detects pollutant trends using gas resistance sensing
• Provides broad environmental insight beyond CO₂ alone
• Cost-effective option with richer automation signals
SCD40 – precision CO₂ sensing
• Measures true CO₂ using NDIR technology
• Measurement range up to 40,000 ppm
• High accuracy and long-term stability
• Integrated temperature and humidity measurement
• Ideal for ventilation control and occupancy-based automation
• Focused on precision rather than broad air quality metrics
Important difference between S1 Pro and E1 Pro
The S1 Pro already includes the BME688 air quality sensor, providing built-in IAQ, VOC, and estimated CO₂ monitoring, and can optionally be expanded with the SCD40 for true CO₂ measurement.
The E1 Pro focuses on flexibility and requires selecting a single air quality add-on, allowing users to choose between broader environmental insight (BME688) or precise CO₂ sensing (SCD40).
Which one to choose
Choose the BME688 if you want a broader overview of indoor air quality, including VOC awareness, comfort monitoring, and trend-based CO₂ insight with additional environmental data.
Choose the SCD40 if you need accurate CO₂ measurement for smart ventilation, occupancy estimation, or environments where precise CO₂ data is important.
Both add-ons enhance the Multi Sense ecosystem with advanced environmental sensing while maintaining full local processing and privacy.