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Outdoor humidity and temperature measurement is essential for a lot of activities – it is important in energy management, agriculture, and indoor climate control.

Outdoor Humidity Sensor
Just one outdoor humidity sensor is often enough to optimise the energy efficiency of cooling equipment. However, if this sensor is not accurate, both energy efficiency and human comfort may be compromised.

Use a Professional Solar Radiation Shield

Accurate readings can only be obtained when using a professional radiation shield to protect the sensor. 

When measuring outdoor humidity, the measurement instrument is exposed to sunlight and rain. Without a proper solar radiation shield, temperature and humidity readings get distorted by the heat of the sun, and sensors can be damaged from water ingress. Erroneous measurements are useless to the control system and reduce energy savings. The radiation shield protects the temperature and humidity sensor from rain and solar radiation, whether it’s direct or scattered.

The Elements of a Good Radiation Shield

The standard design for radiation shields is based on the “Stevenson Screen”, however often this is streamlined into a smaller, rounded design with louvres, which takes up less space and reduces the cost.

Radiation Shield Materials should be:

  • Non water-absorbing
  • Dirt and corrosion resistant
  • Low thermal conductivity
  • UV proof

Functional Design:

  • White external surface that efficiently reflects solar radiation
  • Black inside to absorb accumulated heat and scattered solar radiation
  • Efficient air flow to the sensor due to its uniquely profiled and naturally ventilated multiple disc structure.
  • No moving parts – requires no maintenance

Eight Things to Remember When Choosing an Outdoor Humidity Instrument

1. Ensure that the instrument works even in your most extreme conditions. For most places on Earth the operating temperature range should be from -40 to 60°C (-40 to 140°F) and the instrument should measure the full 0 to 100% RH range.

2. Never purchase a humidity sensor for outdoor measurements without a proper radiation shield.

3. The radiation shield should be designed for use with your specific humidity sensor to ensure easy mounting and optimal performance.

4. The radiation shield can be made of either metal or plastic, but it should have low thermal conductivity, high reflectivity, good corrosion resistance, UV durability, and resistance to dirt accumulation.

5. The enclosure should protect both the electronics and the humidity sensor from rain water, dust, and dirt, as well as from animals.

6. Consider installation accessories and ease of installation for your selected installation site: pole, horizontal beam, flat surface, or wall.

7. Ensure the sensor can recover rapidly from condensation for undisturbed operation outdoors.

8. Make sure that the humidity sensor can be easily calibrated according to your needs – either on-site without detaching the instrument, or off-site at a calibration facility.

Setting up a weather station? Talk to the experts at ESIS to make sure you use the right equipment for the job. Contact us today to find out more.

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