In a side-by-side comparison of low-cost NDIR sensors to measure outdoor carbon dioxide levels, the SenseAir K30 Sensor was selected as the most accurate over the Vaisala CMM222C, ELT Company S100, Korean Digital Company (KCD) AN100 and GE Sensing T6615 CO2 Sensors.
The detailed comparison was published in the article "Comparison of the Characteristics of Small Commercial NDIR CO2 Sensor Models and Development of a Portable CO2 Measurement Device" in the MDPI Open Access Journals Platform.
The authors wrote the article as the result of a study to determine if low cost NDIR CO2 sensors could be easily calibrated and were accurate enough to use in a low-cost portable device designed to record carbon dioxide levels from many locations in a large urban environment over time.
To conduct their experiment, the team purchased three copies of five different commercially available NDIR sensors and tested them in a classroom. In addition, they tested each sensor against four samples of standard gas with different CO2 concentrations.
According to their results, "The outputs of K30 and AN100 models showed linear relationships with temperature and length of use. Calibration coefficients for sensor models were determined using the data from three individual sensors of the same model to minimize the relative RMS error. When the correction was applied to the sensors, the accuracy of measurements improved significantly in the case of the K30 and AN100 units. In particular, in the case of K30 the relative RMS error decreased from 24% to 4%. Hence, we have chosen K30 for developing a portable CO2 measurement device."