Multifunctional indoor air quality transmitters for building automation systems

Siro is an indoor air quality transmitter with a modern design. The transmitter is available with several optional air quality sensors. The modular device can be equipped with CO2 concentration and VOC (Volatile Organic Compounds) measurements or alternatively PM (Particulate Matter) measurement, and in addition, temperature and humidity measurements. It offers easy installation and adjustment, several different model options and various output signals that are configurable separately for each measurement parameter.


The Siro series devices are available with a user interface that includes an LCD display and buttons making the configuration of the device quick and easy. An external configuration tool is available for devices without the user interface. Siro utilizes the industry standard NDIR measurement principle with self-calibrating ABC logicTM for CO2 measurement.


Siro series devices include:

  • Several options for indoor air quality measurements (CO2, VOC,
    PM, rH, T).
  • Field configurable outputs for selected measurements.
  • Proportional output options including voltage (0–10 V, 0–5 V,
    2–10 V) and optional current (4–20 mA).
  • Offset feature enabling field calibration for each measurement
    parameter (CO2, VOC, PM, rH, T).
  • Optional LCD-display and buttons.

Technical details

CO₂: ±43 ppm + 3 % of reading (typical),
additional ±60 ppm for first weeks
Relative humidity: ±2.4 % rH (typical at 20 °C, 30 % rH)
Temperature: ±0.5 °C (typical at 20 °C)
VOC*: ±15 % of reading (typical)
*VOC sensor is tuned for typical IAQ Mix of 22 VOCs as defined by Mølhave et al. (1997)
0…100 μg/m3:
PM2.5: ±15 μg/m3 (at 25 °C ±5 °C)
PM1/PM10*: ±15 μg/m3 (at 25 °C ±5 °C)
100…1000 μg/m3:
PM2.5: ±15 % (at 25 °C ±5 °C)
PM1/PM10*: ±15 % (at 25 °C ±5 °C)
*PM1 and PM10 values are calculated from PM2.5 measurement reading with the default particle distribution.
Measuring elements: CO2: Non-dispersive infrared (NDIR)
VOC: Complementary Metal Oxide
Semiconductor (CMOS)
PM: Laser-based light scattering particle sensing
Temperature: Integrated to CMOS
Relative humidity: Thermoset polymer capacitive sensing element
Measuring units: CO2: ppm
Relative humidity: % rH
Temperature: °C
VOC CO2eq: ppm
TVOC: ppm, μg/m3
PM1/2.5/10: μg/m3
Calibration (CO2): Automatic self-calibration, ABC LogicTM
Supply voltage: 24 VDC/VAC ±10 %
Output signal 1–4: 0...10 V (optional 2...10 V / 0...5 V, display or configuration tool required)
Optional 4...20 mA
Linear to selected measurement (CO2, VOC, PM, rH or Temp)
Operating temperature: 0...50 °C
Protection standard: IP20




Product series

Indoor air quality transmitter

CO2 sensor

With CO2 sensor (option not available with PM sensor)
Without CO2 sensor

VOC sensor

With VOC sensor (option not available with PM sensor)
Without VOC sensor

PM sensor

With PM sensor (option not available with CO2 and VOC sensors)
Without PM sensor

Relative humidity sensor

With relative humidity sensor
Without relative humidity sensor (option not available with VOC sensor)

Temperature sensor

With temperature sensor
Without temperature sensor (option not available with VOC or rH sensor)


Voltage output
Voltage and current output


With display
Without display

Other Indoor air quality: