09,18,2026 11 views
The optimal humidity level in indoor air has a significant impact on human comfort. The key to successful humidification control begins with reliable humidity measurement.
Human comfort, productivity, health, and happiness are positive outcomes of a healthy indoor environment, where indoor air is fresh, free from odors, dust, and other pollutants. Human comfort depends on the complex interaction of multiple variables, with humidity being just one of them. However, optimizing temperature and relative humidity can meet the comfort requirements of more residents, rather than just adjusting temperature.
Low relative humidity in indoor air can cause discomfort to the human body. Headache, eye inflammation, sore throat, and dry skin are all symptoms of a dry indoor environment. Dry air reduces the natural defense against airborne infections, making people vulnerable to attacks from viruses and other microorganisms.
In addition to issues related to low humidity, excessive humidity can also cause problems. These issues are related to the growth and spread of unhealthy biological pollutants, as well as the destructive effects of moisture on building materials.
Usually, humans are less sensitive to humidity than to temperature. People usually do not associate discomfort and potential health problems with changes in relative humidity. This is where good technology can support human senses. Reliable humidity measurement is the key to successfully controlling humidity.
● Guidelines for placing humidity transmitters
The sensor position should be carefully selected to represent the conditions in the controlled space.
● Avoid approaching the exhaust outlet of the air supply duct, near external doors and windows, and inside walls exposed to solar radiation.
Place the sensor away from heat and moisture sources.
Ensure that a gentle airflow is allowed around the humidity sensor. Avoid places where air circulation is obstructed, such as indoor textiles or furniture.
If humidity is centrally controlled at the air handler level, it is recommended to add additional space sensors in critical locations or problematic areas (such as shower rooms).
During pipeline installation, place sensors in a location that is easy to maintain and calibrate. Ensure that the pipeline joints are tightly sealed to prevent air leakage.
For the installation of air supply ducts, please choose a sturdy humidity transmitter that can withstand humidity fluctuations, condensation, and external air pollutants. Avoid positions near cooling and heating coils.
When installing outdoors, please use a radiation protection cover to protect the sensor from the effects of precipitation and solar radiation.
Suggestions for indoor air humidity
The recommendations for indoor air relative humidity vary by country/region. ASHRAE Standard 55 stipulates that in order to reduce the possibility of discomfort caused by low humidity, the dew point temperature should not be lower than 2.8 ° C (37 ° F). This is equivalent to a relative humidity of 30% at 21 ° C. The upper limit of dew point is set at 16.7 ° C (47 ° F), which is equivalent to 76% relative humidity at 21 ° C.
The UK Health and Safety Executive recommends that the relative humidity in the workplace environment be between 40% and 70%. At higher temperatures, the relative humidity should be at the lower limit of this range. Similarly, the US Occupational Safety and Health Administration (OSHA) recommends controlling indoor air humidity within the range of 20-60%.
Humidity issues are usually related to high humidity, especially in colder climates. For example, the Finnish National Building Code stipulates that the humidity in indoor air should not be high enough to cause sustained damage, and condensation water should not be allowed to concentrate on the structure or its surface. This regulation further stipulates that high humidity is not allowed in ventilation systems, as it may cause moisture damage, microbial growth, or any other health hazards.
Capacitive humidity measurement - from Vaisala's innovation to industry standards
Vaisala launched the Vaisala HUMICAP in 1973 ® Thin film capacitive humidity sensor. Since then, Vaisala has become a market leader in the field of relative humidity measurement, and thin-film capacitive humidity sensors have evolved from a company's innovation to a global industry standard.
Nowadays, capacitive thin film polymer humidity sensors have been widely used in industrial and commercial applications. The sensor consists of a substrate on which a polymer film is deposited between two conductive electrodes. Thin film polymers absorb and release water vapor as the relative humidity of the surrounding air increases or decreases. The dielectric properties of polymer films depend on the amount of water absorbed. The change in relative humidity of the surrounding environment will alter the capacitance of the sensor. The electronic components of the instrument measure capacitance and convert it into humidity readings.
Vaisala HUMICAP ® — The humidity is well controlled
Vaisala HUMICAP ® Sensors are renowned for their accuracy, excellent long-term stability, and negligible hysteresis. All instruments have been calibrated and adjusted by the manufacturer before shipment. Vaisala HUMICAP ® Include a commitment to customer quality and reliability. In typical HVAC applications, this means long-lasting measurement performance, providing convenience for on-site instrument maintenance.
In humidity control applications, humidity sensors are typically located in air supply ducts, and even in outdoor environments where condensation may occur. Vaisala HUMICAP ® Sensors can recover from condensation without changing measurement stability, making them an ideal choice for these applications.
Vaisala HUMICAP ® The series of relative humidity and temperature instruments is complete and suitable for various applications, including Zuike's conditions. For the calibration and spot check measurement of fixed instruments, Vaisala offers a variety of portable and handheld instruments.
