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Indoor Air Quality Management: Monitor PM2.5, CO2 and TVOC at Home with IoT and Smart Auto-Ventilation

Indoor Air Quality Management: ติดตาม PM2.5, CO2 และ TVOC ในบ้านด้วย IoT ระบายอากาศอัตโนมัติ

May 12, 2026 · 1 min read
Indoor Air Quality Management: Monitor PM2.5, CO2 and TVOC at Home with IoT and Smart Auto-Ventilation

Bangkok regularly exceeds WHO AQI standards, particularly in the cool season (November–February) when PM2.5 can reach 80–150 µg/m³ (WHO 24h standard: 15 µg/m³). Energy-efficient sealed buildings accumulate CO2 and TVOC rapidly. Indoor Air Quality management has become a foundational element of healthy SmartInterior design.

Recommended IAQ Sensors

PM2.5/PM10: Sensirion SPS30 (laser particle counter, ±10% accuracy, 8-year operational life) or IKEA VINDRIKTNING with ESP8266 Tasmota firmware (THB 400–800).

CO2: Sensirion SCD40 (photoacoustic sensing, ±50 ppm, NDIR technology) — recommended for every bedroom and home office. WHO guideline target: below 1,000 ppm. Levels above 2,000 ppm significantly impair concentration and decision-making.

TVOC/Formaldehyde: Sensirion SGP41 (VOC + NOx Index), Cubic CM1106 (formaldehyde HCHO sensor, target ≤0.1 mg/m³ per WHO). New MDF and plywood furniture emits elevated formaldehyde during the first 6 months.

Smart Ventilation Automation

When IAQ sensors detect threshold exceedances, Home Assistant controls ventilation: CO2 above 1,000 ppm → activate HRV/ERV for 10–15 minutes. Indoor PM2.5 above 25 µg/m³ → run air purifier at high speed. TVOC Index above 150 (Sensirion scale) → increase outdoor air supply via DOAS.

If outdoor PM2.5 (from AirVisual or IQAir API) is higher than indoors → close HRV to prevent importing polluted air, maintaining indoor positive pressure with HEPA air purifier instead.

Air Purifier Integration

Air purifiers with Home Assistant integration: Xiaomi Air Purifier (Zhimi, Miio protocol), Philips Air Purifier (AC Series, HomeKit), Blueair (Wi-Fi + IFTTT webhook), Coway (HA community integration). Automation: activate automatically when indoor PM2.5 exceeds 15 µg/m³ or outdoor AQI exceeds 100, with speed adjusted automatically to real-time PM2.5 readings.

Outdoor AQI API Integration

Home Assistant REST integration pulls Bangkok AQI in real time from AirVisual API or the GISTDA Air4Thai API (free for non-commercial use). A dashboard side-by-side comparison of indoor versus outdoor PM2.5 informs the decision: open windows or run air purifier.

Preventable Health Impacts

Maintaining CO2 below 1,000 ppm: Lawrence Berkeley National Laboratory found a 66% reduction in decision-making errors. CO2 above 2,500 ppm for 2.5 hours significantly impairs cognitive function. Controlling PM2.5 below 15 µg/m³ reduces long-term cardiovascular and respiratory disease risk — particularly critical for elderly residents and children.

Questions & answers

Is modifying IKEA VINDRIKTNING for Home Assistant difficult?
Not at all. Use an ESP8266 D1 Mini (~THB 120) with Tasmota firmware, connecting 3 wires to the VINDRIKTNING UART port. The modification takes 30–60 minutes, requires no soldering (JST connectors work), and full video tutorials are available on YouTube. Total cost: THB 500–900.
How high does CO2 typically get in air-conditioned Thai homes overnight?
In a sealed bedroom with air conditioning and no fresh air supply overnight, CO2 commonly reaches 2,000–4,000 ppm by morning. Outdoor baseline is approximately 420 ppm. Achieving the target of below 1,000 ppm requires an HRV or briefly opening windows before sleep and on waking. An SCD40 sensor makes this problem immediately visible.
Is HEPA or UV-C air purification better for Bangkok conditions?
HEPA filtration removes PM2.5 most effectively (>99.97% for 0.3µm particles). UV-C kills bacteria and viruses but does not filter PM2.5. The best choice is an air purifier combining HEPA plus activated carbon filter (removes TVOC and odours) with UV-C as an optional feature. Xiaomi Mi Air Purifier 4 Pro and Coway AP-1512HH both offer this combination.

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