Effects of Temperature and Humidity- Why do we need to monitor?

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Temperature and Humidity displayed in Fluke 971
Temperature and Humidity displayed in Fluke 971

Temperature and humidity are the most monitored environmental factors based on the facilities that I have visited. Have you ever experienced being exposed to a high temperature and humidity environment? I believe all experienced it but not just aware regarding the effects of temperature and humidity in our daily
activities or some of our activities.

In this topic, you will learn the importance of monitoring these  environmental conditions specifically temperature and humidity, the negative effects of having them very high or very low as applicable to some process or activities.

I will also introduce the instruments used to measure both temperature and humidity and also how it is related and being used in calibration process.

In our Daily Activities……..

I live and grow in a high area ( mountains) where the environment is cool, fresh and clean. You will not perspire unless you make a physical effort like exercise. During summer, the temperature is a little bit hot but  it is still fresh because when you perspire, the air is cool that your skin dries up so fast.

But when I travel to the lowlands, where temperature is high ( in the range of 28 to 34 deg C), it seems that you cannot feel the air that you are breathing in and you perspire a lot. The most uncomfortable feeling is that when you perspire, it stays in your skin longer that makes it very sticky.

These feelings (discomfort and irritated) we encountered are the effects of temperature and humidity in our body.In our home, wooden furnitures that gets very dry tends to crack or expand. Because of this, we should be familiar about the importance of temperature and humidity monitoring in order to prevent and control these things that happens in our daily processes.

Idealy, Relative Humidity (RH) should be within the range of 30% to 50% and temperature is within 20 to 25 deg Celsius . Above this will cause fungus or molds to grow and below this will cause dryness and discomfort.


Some common examples on why we need to monitor and control temperature and humidity  are:

  1. fruits-and-vegetables
    Fruits and Vegetables in temprature controlled room

    To prevent the formation of molds and fungus that can cause diseases,

  2. To keep a certain product fresh in a room like where fruits and vegetables are stored, or a sealed box like a cigar in a humidor,
  3. To monitor the environment for fermentation like in beer or wine making or for incubation of eggs,
  4. To ensure maintenance of good quality in some special personal collections like  paintings,  guitar or clothing,
  5. To give a healthy environment like maintaining a good air quality  to avoid dryness on skin and eyes that causes discomfort and breathing related illness like asthma.

Temperature and Humidity in Calibration Laboratory

As required in the ISO 17025 standard under clause 5.3, accommodation and environmental conditions should be monitored and controlled . Two of this environmental conditions are the temperature and humidity.

It is not just controlled but it should be documented, means that there is a continuous monitoring and recording at a specified interval. Furthermore, monitoring and control is not just during the calibration process  but also during storage and handling of equipment.

This is how important it is to consider these two parameters because failing to follow and consider them can cause a lot of problems where discontinue of calibration work is imposed if this requirement of humidity and temperature is not met.

And technically speaking, this is not just applicable to instruments in a  laboratory but also in equipment or machines used in manufacturing that is why it is also controlled inside the facilities of every manufacturing company.

Does Temperature affect  Humidity?

Temperature can affect the humidity, they are inversely proportional, meaning , as temperature increases, humidity decreases and vise versa.  So in order to control humidity, we need also to control temperature.

What are the Effects of Temperature and Humidity in our instruments?

There are guides and recommended practice for the use of  temperature and humidity in a laboratory. You may find it through NIST handbook, ISO guides, or NCSL in their websites.  Requirements for dimensional lab for temperature and relative humidity (RH) is 20 +/-1 with an RH of 30% to 40%  Electrical or electronics is within 23 +/-3 Deg C  temperature and a humidity of 35% to 55%.

Please take note that provided requirements is not fixated on every lab, it is still based on the equipment specifications so the best thing to do is to check first all instruments specs before performing the calibration. It is a best practise to record all the necessary environmental requirements specifically temperature and humidity of a specific instruments for calibration for easy reference.

 Below are some reasons why we monitor and control Temperature and Humidity Inside a calibration laboratory:

  1. In pressure calibration , density changes with temperature.
  2. Dimensional calibration where the use of gauge blocks and other dimensional instruments are affected by thermal change usually  a temperature higher than 20 Deg C. If you are calibrating or measuring a highly accurate instruments, this will be a problem.
  3. With  a humidity >60% , metals like gauge blocks will rust quickly.
  4. In electrical area, when metals rust or corrosion occurs, this will create a leakage paths for voltage and current which causes a malfunction or inaccurate reading.
  5. If below 20% ,where air is very dry,  it will be prone to  static electricity which can damage electronic equipment.
  6. Most of the manufactured instruments has a requirement on its environmental condition in order to function on its full accuracy. You may check it  on its specifications.

Because of these reasons or effect of uncontrolled parameters, temperature and humidity are included as one important factors in the area of quality control. This is also to ensure that any detected errors in the readings of calibrated instruments is not the cause of temperature and humidity variations.


Instrument used to measure and monitor Temperature and humidity ( a thermo-hygrometer)

In monitoring a temperature and humidity, we can use a separate thermometer and a humidity meter or hygrometer. But why waste our resources if we can have both in one instrument. This is now the thermo-hygrometer, a hygrometer thermometer meter in one.  Todays advancement,  a chart recorder is also included depending on the manufacturer. The advantage of monitoring and recording are already in place.

How to calibrate a thermo-hygrometer?

For the procedure in calibrating a thermo-hygrometer and other details, please visit  my other post in this link.

Below is a review of some commonly used thermo-hygrometer these days.

1.SensorPush Temperature and Humidity Smart Sensor review

Monitoring of  temperature and humidity these days are now very easy to do. Since the advancement of technology, most of the products specifically electronic products are becoming smaller and better. If you are looking for a smaller, compact and easy to use thermo -hygrometer, SensorPush temperature and Humidity sensor is one of them.  Its small size can be placed inside a refrigerator, a humidor, or any confined space where monitoring is necessary. Best thing is it is a wireless device where the display and control used is your mobile device.

Who its for

  • This is for you if you monitor temperature and humidity inside a laboratory
  • This is for you if you are making a wine or a beer
  • This is for you if you need to keep your cigar fresh in a humidor
  • This is for you if want to monitor the temperature of your refrigerator or freezer
  • This is for you if you want to preserve your artwork or other personal belongings  ( maybe in the attic).
  • This is for you if you are monitoring a healthy environment for you or your animals.

And For obvious reasons,   this is for all those people who monitor temperature and humidity for them to know whether the process, project, condition or activity they do has an acceptable environment for them to maintain health, quality, security, accuracy , preservation and a lot more reasons.


Dimensions 40mm x 40mm x 16.5mm / 1.57″ x 1.57″ x 0.65″
weight 40g / 1.4oz
temperature Range -40°C to 60°C
Temperature Accuracy ±0.3°C / ±0.5°F typical
Humidity Range 0 to 100% 
Humidity Accuracy ±3% typical


The battery

Uses CR2477 battery, typical battery life is 1-2 years; more in warm conditions and less in extreme cold.

How data is sync

Data is sync through  Bluetooth

Pros ( features)

  • Easy to navigate
  • Can be installled on Iphone and android phone.
  • Data can be extracted and transfer to excel file
  • Bluetooth capable where wireless communication and control is possible through the use of your Iphone or android phone
  • Easy to calibrate, just compare to a reference standard then can be adjusted based on the reference.
  • Can store up to 20 days of data.
  • When you are in range, it automatically updates and stores data on your phone
  • Can withstand the low temperature inside a refrigerator.
  • A highly accurate device ( +/-0.5 Deg C and  +/- 3 %RH)
  • It is compacted, you can carry it anytime and anywhere needed.
  • long battery life


  • Some Bluetooth  version is not compatible, use the latest version of Bluetooth to ensure connection.
  • Distance is limited on the range of Bluetooth capability.

For Sensorpush Calibration Procedure, we can use the related procedure in this link


Basing it on the features of this product, this is a must have device when monitoring a certain temperature or humidity, since it is wireless, you can control and extract data in your own comfort. The compact and small size can fit even in a small box like a humidor.  The accuracy of both temperature and humidity is high enough if your process is not that very strict in tolerance.

SensorPush Wireless Thermometer / Hygrometer for iPhone / Android – Humidity & Temperature Smart Sensor with Alerts has a good customer support so any problems encountered during its usage can be relayed to them for help and support.

2. Extech Humidity-Temperature Chart Recorder Review

Extech RH520A Humidity and Temperature Chart Recorder with RS-232 Computer Interface

Temperature and humidity ( relative humidity) monitoring involves data recording and review. It is where we  based our analysis  about their effect whether it is acceptable  or not. Since there is analysis and review involve, we need to have a clear picture of what is to be analyzed. This is where this instrument are a big help, it does not only display the reading but it also records and display data in a chart from a previous hours or days. Monitoring will be easy because you can directly observe  the  highest or lowest reading based on its chart.

In the lab that I worked for,Extech RH520A Humidity and Temperature Chart Recorder ( Model RH520) is the thermo-hygrometer that we are using. Its capability meets our expectations where it is a perfect tool for the job (as per my experience).


What I Like in this product (Pros/Features)

  • Its probe (where sensors are located) can be  mounted to different position depending on your needs. It has a stretchable cable ( 1 meter) to be positioned easily. You can place the probe inside a confined space if you need to with out including the whole unit like inside a refrigerator.
  • The unit can be used with a battery ( AA) or power supply and therefore can be portable where it can be carried to a different remote locations. It also designed to be mounted on a wall or just placed it on a table top.
  • It has a memory where data is stored and can be extracted on a defined schedule.
  • Programming or setting up  is easy to follow basing it to its user manual, user friendly.
  • Temperature and humidity are digitally displayed plus a chart to view the past and current state. Also to view and analyze if temperature difference or fluctuations has happened. Display are large enough for you to see it easily in a distance.
  • Data can be extracted to excel format in a computer ( Laptop) to further review and analyze ( need to install  the software provided).
  • It can also display date and time where monitoring can be analyzed together with temperature and humidity.
  • With a low battery indicator
  • Alarm can be set  for proper timing and notifications when needed.


What I Dislike in this product (Cons)

  • I am not sure if this is including all the models but sometimes when I connect it to my laptop, it has a difficulty in communicating. It will search first for the exact port before communication  or connection takes place.
  • The storage memory is not that very big where data should be downloaded on a defined schedule ( say 1 month, but I guess this is already good enough if download schedule is shorter ), then reset it again to clear and have a new fresh start to save and record a new data. This  is applicable if you need the past  data for storage and future review.
  • Needs to reset time and date if the power is accidentally turned off (battery can be a back- up power if installed) or battery is changed ( not a big deal).

Who its for

This is primarily useful almost in every  temperature and humidity monitoring specially in a room environment monitoring. If you want to make your monitoring more detailed with some automated features, this one is for you.



Dimensions 5.0×7.7×0.9″ (127x196x23mm)
weight 357g / 12.6oz
temperature Range -28°C to 60°C(-20 to 140°F )
Temperature Accuracy ±1°C / ±1.8°F
Humidity Range 10 to 95% 
Humidity Accuracy ±3.0% typical
Internal Memory Storage 49 152 complete reading sets
Sample Interval selectable recording rate: 0.1 to 199.9 minutes
Graph scaling User selectable in 10 , 5 and 10% increment



Uses an AC adaptor (4.5 VDC, 300 mA) and a 3 ‘AA’ batteries. Typical battery life is 4 weeks.

How data is sync

Data is sync  in a PC through  RS-232 serial port.

For Extech RH520A Calibration Procedure, please visit this link


Based on the features and performance that I have observed during my usage, this is an excellent product and I highly recommend it specially for your room or laboratory usage.


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2 Responses

  1. Sariah
    | Reply

    In preparation for this upcoming winter season, we plan to have transmission calibration for our HVAC systems and chambers. This article provides us with the importance of monitoring temperature and humidity so as to have a healthy environment. Such informative article!

    • edsponce
      | Reply

      Hi Sariah,
      Thank you for taking time reading my article. I appreciate your positive comments, glad you liked it.

      Best Regards,

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