What is a Humidity Sensor? How They Work, Types, and Applications

Posted on Friday Mar 29, 2024 at 11:00AM  


If you've ever noticed that the air feels heavier after a rainstorm, you've observed a change in humidity. While they're a natural occurrence, fluctuating humidity levels can make indoor spaces uncomfortable and cause equipment and machinery to malfunction. Humidity sensors help you avoid those issues while also maximizing energy efficiency and improving air quality.

What is a Humidity Sensor?

A humidity sensor is a device that detects and measures the amount of humidity, or water, in the surrounding air. They're available in many sizes and forms, ranging from handheld sensors to small components built into air quality systems. The readings from these sensors allow you to make adjustments if the air becomes too dry or humid.

How Do Humidity Sensors Work?

Humidity sensors have a sensing element to measure moisture levels, and some also feature a thermistor to measure temperature. They convert this data into an electrical signal and report the humidity level on a built-in display or a connected device with special software.

Depending on their design, humidity sensors measure relative humidity (RH) or absolute humidity (AH). RH compares the current humidity at a certain temperature to the highest possible humidity at that same temperature. A lower RH percentage means that the room is dry.

Unlike RH, AH doesn't require a temperature measurement. It's the amount of water vapor present in a unit volume of air and is expressed as grams per cubic meter rather than a percentage.

Types of Humidity Sensors

When purchasing a humidity sensor, you can choose from one of three varieties:

  • Capacitive: This linear sensor measures relative humidity from 0% to 100% humidity. It features a metal strip between two electrodes.
  • Resistive: A resistive humidity sensor has ionized salts between two electrodes. The resistance of the electrodes changes when the humidity level goes up or down.
  • Thermal: Thermal humidity sensors use two separate sensors, one in a layer of dry nitrogen and the other freely measuring ambient air. The difference between the two measurements is the humidity level.

Keep in mind that capacitive and resistive sensors measure RH, while thermal sensors detect AH.

Where Should a Humidity Sensor Be Placed?

Humidity sensors are useful in many places both inside and outside a home, business, or other facility. When installing a wall-mount sensor, choose a spot on an interior wall that's at least 4 feet from the floor and has unrestricted air circulation.

Another important place to use a humidity sensor is the center of a duct. To get an accurate measurement, keep it away from fans, corners, coils, and dampers.

Many people also use humidity sensors on exterior walls. Find a place that's protected from rainfall and that's not too close to condensing units or building vents, which can skew the humidity readings.

Benefits of Humidity Sensors

Humidity sensors offer many advantages, including:

  • Increasing energy efficiency: Humidity sensors provide real-time information about the level of moisture in the air so you can optimize the temperature, airflow, and ventilation and reduce your energy consumption.
  • Achieving precise climate control: When you know current moisture levels, you can make adjustments to environmental conditions and improve occupant satisfaction.
  • Preventing mold and mildew: A humidity sensor detects excess moisture, which promotes potentially harmful mold and mildew growth.
  • Maintaining industrial environments: Because humidity levels can affect machinery performance and product quality, industries like pharmaceuticals use sensors to ensure it stays within an acceptable range.

These benefits of humidity sensors ultimately help you cut costs, streamline your operations, and establish a comfortable work or living environment.

What Is a Humidity Sensor Used For?

Humidity sensors are essential in heating, ventilation, and air conditioning (HVAC) systems because they monitor humidity levels in buildings. You can use this information to adjust HVAC settings and improve indoor air quality and energy efficiency.

Meteorologists also use humidity sensor readings to make accurate weather forecasts and conduct climate studies. The data helps them predict precipitation patterns and weather phenomena.

In agriculture, humidity sensors are critical to crop management and greenhouse control. Agriculturists take moisture measurements from the air and soil and use them to plan and adjust irrigation, watering, and temperature settings and strategies.

Monitor Humidity Levels With Veris

Humidity sensors offer valuable insights into moisture levels and contribute to improved indoor air quality. Veris is proud to offer a line of quality humidity sensors for multiple applications. Contact our team to learn more about which of our products is the best fit for your needs.

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