Three inexpensive CO2 sensors compared
Sniffing the Air
© Lead Image © vladnikon, 123RF.com
Monitor your indoor air quality with an inexpensive CO2 sensor. We look at three candidates to help you find the best solution.
In the winter, you spend a lot of time indoors, making it important to keep an eye on CO2 concentrations. In contrast to sensors for measuring temperature and humidity, CO2 sensors are quite expensive, with prices consistently in the double-digit range. This quickly adds up if you want to monitor more than one room. To make CO2 monitoring more budget friendly, this article focuses on three inexpensive solutions: the Winsen MH-Z19C [1], the ScioSense ENS160 [2], and the Sensirion SCD40 [3].
The latter sensor from brand manufacturers such as Adafruit, Pimoroni, or SparkFun are really expensive, costing between $40 and $80. AliExpress gives you cheaper options with prices below $15, but those come with the added thrill of not knowing whether parts will even work.
Infrared Measurement
The Winsen MH-Z19C (Figure 1) consists of a small box measuring approximately 13.3mm x 26mm x 4.4mm. It measures the CO2 value using the non-dispersive infrared method (NDIR). Two versions of the sensor are available: one with a normal pinout and one with a cable connection and a pin spacing of 1.25mm. If you don't relish the prospect of crimping connections, you will want to opt for the pinout version. Besides the MH-Z19C, there are other older models on the market, such as the MH-Z19B, MH-Z14, or MH-Z18, which have similar but not identical functions and specifications.
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