Sensy-One E1 Pro BME688 Add-on – IAQ, VOC & eCO₂ Sensor

🌬️ One sensor, 7 measurements.

Air quality is more than just CO₂. The Sensy-One E1 Pro BME688 Add-on provides a complete picture of your indoor air: from volatile organic compounds (VOCs) and estimated CO₂ levels to air pressure, temperature, and humidity—all processed via the BME688 chip's AI-powered gas detection. This optional expansion for the E1 Pro Multi Sense sensor is ideal if you want a broad and intelligent overview of your living environment.

The BME688 estimates CO₂ levels based on VOC activity (eCO₂). This isn't a direct measurement like the SCD40 CO₂ add-on , but it offers valuable insights into trends and ventilation effectiveness – perfect for comfort automation and air quality monitoring. All data is processed entirely locally via ESPHome and Home Assistant, without the cloud and without data leaks.

⚠️ Please note: Only one air quality sensor can be installed on the E1 Pro . Choose between the BME688 (wide-range air quality) or the SCD40 CO₂ add-on (accurate CO₂ measurement). Read the differences below to make the best choice.

✅ What does the BME688 Add-on Measure?

• IAQ (Indoor Air Quality) – Combined air quality score based on all measured parameters
• eVOC (Estimated Volatile Organic Compounds) – Detects paints, cleaning products, cooking fumes and other contaminants
• eCO₂ (estimated CO₂) – CO₂ estimation based on VOC activity; useful for trends and ventilation insights
• Temperature – Accurate internal temperature for automation
• Humidity – Relative humidity for comfort and mold prevention
• Air Pressure – Barometric Pressure for Weather Patterns and Environmental Monitoring
• Gas Resistance – Detects changes in air quality for early warning

🆚 BME688 vs. SCD40 – Which One Will You Choose?

Choose the BME688 if you want a comprehensive overview of the air quality in your home, including VOC monitoring, comfort monitoring, and estimated CO₂ trends.

Choose the SCD40 if you need accurate CO₂ measurement for ventilation control, occupancy detection, or environments where precise CO₂ data is important.

🏠 Practical Example: Smart Ventilation & Air Quality Automation

1. The BME688 detects an increase in VOC levels and gas resistance during cooking.
2. The IAQ score falls below the set threshold value.
3. Home Assistant automatically activates the extractor hood at a higher setting.
4. Once the IAQ score recovers, the hood switches back to standby.
5. The Home Assistant dashboard provides real-time VOC trends, eCO₂ estimates, and IAQ scores for each room.

⚙️ Technical Specifications

⚠️ Points of attention

• Only one air quality sensor per E1 Pro – Choose between the BME688 or the SCD40 CO₂ add-on ; installing both at the same time is not possible
• eCO₂ is an estimate – No direct CO₂ measurement; for precise CO₂ values ​​the SCD40 is the right choice
• This is an accessory – the E1 Pro Multi Sense sensor is sold separately and not included.

❓ Frequently Asked Questions (FAQ)

What is the difference between eCO₂ and real CO₂ measurement?

The BME688 estimates CO₂ levels based on measured VOC activity and gas resistance (eCO₂). This provides valuable trend information about ventilation and air quality, but is not a direct measurement. For accurate CO₂ measurements, the SCD40 CO₂ add-on is the better choice.

Can I install both the BME688 and the SCD40?

No. The E1 Pro can only accommodate one air quality sensor. Want both? Then check out the S1 Pro – it has the BME688 built in as standard and the option to add the SCD40.

Does the BME688 work completely locally?

Yes. All data is processed locally via ESPHome and Home Assistant. No data is sent to the cloud.

Which entities are created in Home Assistant?

ESPHome creates entities for IAQ score, eVOC, eCO₂, temperature, humidity, air pressure, and gas resistance. All these values ​​can be used directly in automations and dashboards.

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