Like measurement range, measurement accuracy is one of the most important indicators of a sensor. Every percentage point improvement represents a significant leap forward, even a change in class, for the sensor. This is because the manufacturing costs and selling prices vary greatly depending on the required accuracy. For example, an inexpensive imported humidity sensor costs only a few dollars, while a full-range humidity sensor for calibration costs several hundred dollars-a difference of nearly a hundredfold. Therefore, users must choose according to their specific needs and avoid blindly pursuing "high-end, precise, and cutting-edge" sensors.
Manufacturers often provide the accuracy of their humidity sensors in segments. For example, ±2%RH for the medium and low humidity range (0-80%RH), and ±4%RH for the high humidity range (80-100%RH). Moreover, this accuracy is based on a specific temperature (e.g., 25℃). If the humidity sensor is used at different temperatures, the reading must also account for the effect of temperature drift. As is well known, relative humidity is a function of temperature, and temperature significantly affects the relative humidity in a given space. Every 0.1℃ change in temperature will result in a 0.5%RH change in humidity (error). If a constant temperature is difficult to achieve in the application environment, demanding excessively high humidity measurement accuracy is inappropriate. Since humidity fluctuates with temperature changes, discussing high humidity measurement accuracy becomes meaningless. Therefore, temperature control is paramount for humidity control, which is why integrated temperature and humidity sensors are widely used rather than simply humidity sensors.
In most cases, if precise temperature control is unavailable, or the measured space is not sealed, an accuracy of ±5%RH is sufficient. For applications requiring precise control of a constant temperature and humidity in a localized space, or where continuous monitoring of humidity changes is necessary, ±3%RH should be selected.
