If you live in a warmer region of the world or if you have experienced hot, sweltering summers, you’re probably familiar with muggy days when your skin feels sticky or heated and the air is so thick that it makes it difficult to breathe.
Have you ever wondered why this happens? The main culprit is humidity. Humidity is the dampness of air in our environment.
Despite its unpleasantness, it does have some benefits. If you’ve ever wanted to alter the dry air in your home or office into more damp air, you can humidify the air around you with the help of humidification – let’s see how!
What is Humidity?
The presence of water vapor in the air around us is called humidity. Water vapor is the gaseous state of water, which is formed due to high temperatures that prevent water molecules from condensation.
Have you ever wondered why hotter places are more humid compared to colder regions? The answer is temperature. Hotter areas tend to be more humid because the heat causes the water in the air to evaporate faster, creating more water vapor in the environment.
When humidity levels are high, it can feel hard to breathe and the air around you may feel heavy. Alternatively, when humidity levels are low, the air around you is typically drier and your skin may feel dry or itchy.
Humidity may sound like an unfavorable phenomenon that can create an uncomfortable living environment. So, do we need it? Well, to put it simply, humidity is due to water evaporation, and if water did not evaporate there would be no clouds, and no clouds mean no rain.
You can calculate humidity in two ways: absolute humidity and relative humidity.
Absolute humidity is the simplest way to measure humidity. It is the total mass of water vapor in a given volume of air, regardless of the air temperature. Scientifically, this is the most accurate way of measuring humidity levels.
The dew point is the temperature of the air that causes water to condense and evaporate at the same rate.
If the air temperature falls below the dew point, condensation happens. If air temperature gets above the dew point, evaporation takes place.
The dew point is used to measure relative humidity.
The measure of water vapor saturation compared to the maximum saturation is called relative humidity.
Relative humidity compares the air temperature with the dew point, and how close the air temperature is to the dew point. If the air temperature reaches the dew point, the relative humidity is at 100%. The closer to the 100% dew point, the more humid it feels.
Life Without Humidity
You may be wondering, can we survive in zero percent humidity? First, let us look at what 0% humidity means – air completely devoid of water vapor – the thought of this scenario sounds intriguing, but in reality, it’s not possible.
You cannot see humidity, but it is always around us. There is no place on earth with zero percent humidity.
The key factors of Antarctica’s weather show the lowest relative humidity at the south pole can be as low as 0.03%. The moisture is frozen out of the air as frost due to extremely cold weather.
The lowest humidity ever recorded in an urban area was a relative humidity of 0.36% recorded in Safi-Abad Dezful, Iran, on the afternoon of June 20, 2017.
You might still be wondering what would happen in 0% humidity. Since it’s not naturally possible, suppose we somehow managed to get 0% humidity in a closed room and placed a person inside it. In this situation, the air does not have water vapor so the dry air will try to extract water from your body through sweating. This would lead to excessive sweating and you’ll be dehydrated in a few hours.
If you’re breathing in these conditions, the air will extract moisture from your windpipe with every breath, leading to a strong urge to drink water. The dryness in the space can also cause your nose to bleed.
To avoid all these unfavorable circumstances, humidification can help to increase the moisture level of the air around us for a more comfortable environment.
What is Humidification?
Have you ever experienced static shocks when you touch a home appliance or a vehicle and wondered why that happens? Let’s see!
On very dry days, your skin may feel dry or itchy and you’re forced to keep a lip balm in your pocket because your lips get chapped without it. Your eyes may start itching, your nose or throat gets scratchy, and even paper, books, or magazines might feel brittle.
This all happens because of a lack of humidity in the air. Humidity may create uncomfortable circumstances for warmer regions but, at the same time, humidity is quite important to those living in the colder areas.
A lack of humidity is not ideal in a similar way that excess humidity is not ideal. Balanced humidity is necessary to create the most comfortable environment.
With the advancement of technology, there is a solution for dry environments, which allows us to make our surroundings a little damper.
The artificial regulation of air humidity levels is called humidification. The addition of water or moisture to the air can be done with the help of humidifiers.
Psychrometry is an important part of the study of humidity. It is a study of properties that include mixtures of air and water vapors.
There are two key aspects of psychrometry: dry-bulb temperature (DBT) and wet-bulb temperature (WBT).
Let’s say that the temperature today is 10 degrees Celsius (50 degrees Fahrenheit). You may think that sounds a bit chilly, and consider a jersey or jacket before you go outside.
If, however, someone tells you that the wet-bulb temperature is 10 degrees Celsius, there’s not much you can do with that information.
By itself, it could mean that the day is going to be chilly and you need a jersey, but it could also mean that today is going to be a scorcher, and you’re going to need sunscreen and plenty of water.
The word “bulb” in both wet-bulb and dry-bulb temperatures refers to the bulb on a mercury thermometer. The bulb acts as a reservoir storing the mercury, which expands and contracts as it heats up or cools down to indicate temperature.
Dry-bulb Temperature (DBT)
Dry-bulb temperature is a temperature of the air that is measured using a normal thermometer exposed freely to the air, shielding it from moisture and radiation.
The DBT should not be changed during humidification. It can be used to determine the quantity and the type of humidification required.
Wet-bulb Temperature (WBT)
Wet-bulb temperature is measured by wrapping the thermometer bulb in a water-soaked cloth (also known as a wick) and passing a large amount of air through that or spinning it around a lot so that you get a different temperature.
Wet-bulb temperatures are usually lower than dry-bulb temperatures. You’ve probably experienced this concept whenever you’ve taken a shower. Before you step into a shower, you’re likely not feeling particularly cold, but once you’ve taken your shower and stepped out, you suddenly feel cooler.
The reason you feel cold following a shower is that the water that’s on your skin is an energy thief. It requires energy for water to evaporate and go into the air and that energy is known as vaporization.
Water is an energy thief that takes energy to evaporate from your skin and it leaves your skin feeling cold. It’s the same phenomenon that takes place when measuring wet bulb temperature.
Types of Humidifications
There are two types of humidification: the cooling humidification process and the heated humidification process.
The cooling and humidification process is one of the most adapted processes used in air conditioning for cooling.
In this process, moisture is added to the air which then passes over a stream or spray of water with a lower temperature than the dry-bulb temperature of the surrounding air.
The particles of water present in the stream are evaporated by giving up the heat to the stream. The evaporated water is then absorbed by the surrounding air, which makes a damper environment, increasing the humidity.
During this process, the absorbed moisture is cooler than the dry-bulb temperature of the air so it reduces the overall temperature of the air.
The most widely used and prominent application of cooling and humidification is the desert cooler, also known as an evaporative cooler. It serves as both a cooling and a humidification system.
A desert cooler is a simple machine with a very basic operation. It is a box of different sizes with a small tank-like base for storing water. The electric components of this cooler include a water pump and a fan. With the help of a water pump, the water is circulated and sprayed on the walls of the cooler, the fan then blows out the cool air dampening and cooling the surroundings simultaneously.
It is a very budget-friendly cooling device, with a low operational cost compared to air conditioners. Keep in mind that it is useful in hot and dry climate areas only, not in hot and humid ones, as it increases the humidity in the air.
The cooling and humidification process is also implemented on a larger scale in industries like textile, where maintaining a certain temperature and humidity level is required for smooth operations. In these cases, a large blower is used to circulate the air passing through sprays of water.
During the cooling and humidification process, an increase in wet-bulb and dew point temperatures, along with the amount of moisture in the air, results in increased humidity, and the dry-bulb temperature of the air is decreased.
In the heating and humidification process, the dry-bulb temperature of the air also increases along with the increase in its wet-bulb and dew point temperatures. The idea of this process is to create a warmer environment with an increase in air moisture.
This process works the same as the cooling and humidification process but the only difference is that in the heating and humification process, the stream or spray of water from which the air has to pass is kept at temperatures higher than the dry-bulb temperature of the surrounding air.
The moisture particles are then evaporated into the air. Since the temperature of moisture is greater than the dry-bulb temperature of the air, it contributes to the increase in the overall temperature of the air.
A homemade alternative of heating and humidification has been practiced since early ages where a pot full of water was kept on a burning stove that created steam, releasing the water vapors into the air which helped in heating and dampening the air.
Importance of Humidification
Dry air craves water vapor, so it will seek and extract moisture from any source it can, including humans. It can also draw moisture from the hygroscopic materials within its reach.
Hygroscopic materials include items like wood, paper, food, or leather, which can absorb water vapor from the air if exposed to it.
This is nature’s way of humidification, and it sounds pretty simple and harmless, right? Well, it’s not entirely harmless. It can be a dangerous kind of humidification costing human comfort, material deterioration, and production issues.
In dry atmospheric conditions, static electricity can accumulate which will create problematic situations for production machinery and office electronics. That might not be a big issue for things like paper or plastic, but it can be extremely dangerous in an explosive atmosphere.
In today’s world, there are plenty of electronics around us, and each one needs a certain level of humidity to operate smoothly. The most important part of electronics these days is the integrated circuit (IC), which is prone to meltdown due to voltage spikes.
A major reason for voltage spikes is an electrostatic discharge which is most likely to occur due to a lack of humidity in the air.
All these situations demonstrate the importance of air that has balanced humidity, which can be obtained through different humidification processes, depending on the situation.
We have discussed how boiling water on a stove can contribute to the heated humidification process, and below we have even more DIY humidification ideas too.
Water in Front of a Fan
The concept is similar to the desert or evaporative cooler. Placing a bowl of water in front of a fan can produce a cool breeze that adds moisture to the air around it.
Bowl of Water
The simplest way of adding minimal humidification to your room is to put a bowl of water in your room. Although it may evaporate at a very slow rate, it can still contribute to humidification.
This idea may be a good idea in situations where you are planning to leave your house for long durations, in which case it would help to protect your pets or electronics.
If you want a larger-scale alternative to water bowl humidification, you could fill your bath with water and stop it from draining, leaving the water to evaporate slowly on its own.
Another possibility would be to leave the bathroom door open while you shower so that the moisture from the shower can humidify the air around your house.
The concept of a fish tank for humidification is the same as leaving a bowl of water out somewhere in your home. The standing water from your fish tank or aquarium can be a great contributor to humidity in your house.
Drying Your Clothes
Back in the days when dryers were not as popular as they are now, people used to dry their clothes by hanging them on clotheslines in their backyards or terraces.
Nowadays, you can easily obtain a foldable drying stand to dry off your clothes by simply hanging them on a stand somewhere inside your house. The wet clothes can naturally increase the humidity inside the house.
Flowers in a Vase
If you like keeping flowers inside your home, the water in that flower vase serves the same purpose as keeping a bowl of water inside the home.
House plants can be good and easy contributors to indoor humidity because they release water into the air through their foliage during plant transpiration.
All plants have different levels of humidification, but NASA recommends the spider plant as one of the best air purifying plants for the home. They are easy to grow and can be a good contributor to humidity inside a house with minimal effort on your part.
English Ivy is also a good contributor to air moisture, and it is also very good at reducing carbon monoxide in the air.
Other good house plants for adding humidification are rubber plants and dwarf date palms.
The Opposite of Humidification – Dehumidification
Now that you’re well versed in the importance of humidity, how about the situations when there is excessive humidity? Is that more comfortable for humans? Not really. Often in situations where there is too much humidity, we try to lower the humidity levels.
In extremely humid conditions, the environment can be so uncomfortable that it makes it difficult to breathe and everything feels sticky.
But is there any way to get rid of humidity in such situations? Yes! Technology has advanced a lot over years and there are now processes and machines to help remove moisture from the air and lower humidity levels, just like there are ways to add it when needed.
To reduce moisture in the air, we use the opposite of humidification, which is dehumidification.
Types of Dehumidification
Dehumidification has the same working processes as humidification: cooling dehumidification process and heated dehumidification process.
This is the most widely used dehumidification process and it is usually available in domestic scale air conditioning solutions like split or window air conditioners.
The basic principle of this process is that air blows through a cooling coil which is set at the desired temperature, typically lower than the dry-bulb temperature of the surrounding air.
The cooling process continues until it reaches the dew point temperature. At this point, the water vapor in the air is condensed and forms dew particles that reduce humidity levels.
During the cooling and dehumidification process, the dry-bulb, wet-bulb, and dew point temperatures are all reduced creating a cooler environment due to the reduction of moisture in the air.
If you want to reduce the moisture from the air while also heating a space, you can try a heated dehumidification process.
In this process, the air is passed over hygroscopic chemicals like alumina and molecular sieves, and heat is added while moisture is removed. More specifically, these hygroscopic elements are enclosed in a large vessel, and then highly pressured air is passed through these vessels. When the air comes into contact with these chemicals, the heat is emitted and the moisture from the air is absorbed.
The heating and dehumidification process focuses on the reduction of dew point temperatures. In chemical plants, for example, there are several automatic valves operated by compressed air at high pressure. If the dew point temperature of the air is high, it creates an opportunity for the formation of dew inside the valves that can lead to corrosion and faults in their operations. The air needs to have low dew point temperatures to provide smooth operations.
During this process, the dry-bulb temperature of the air is increased which warms up the surrounding air while decreasing dew point and wet-bulb temperatures are observed.
Since science has advanced over the years, research has shown how important humidity can be to humans, and new ways to regulate humidity were discovered, including humidifiers.
A humidifier is a device that releases moisture into the air to increase humidity in our environment.
These are some of the different types of humidifiers currently available:
- Central humidifiers
- Impeller humidifiers
- Steam vaporizers
- Ultrasonic humidifiers
Types of Humidifiers
The type of humidifier you choose depends on your preference, usage, and budget.
Humidifiers come in different sizes. Some can be large enough to add moisture to the entire house, and they usually have wheels to enhance their portability.
Other humidifiers are smaller in size making them easier to move from room to room. These smaller units can be kept by your desk or on the side table by your bed. The smaller humidifiers are typically battery-operated, ensuring portability and even allowing you to take them along while traveling if needed.
You might be aware of the central air conditioning systems, and how they are integrated and fixed into the house, sending cool air through air ducts all over the house.
Most central humidifiers have the same working principle. They are integrated directly into your home’s heating or air conditioning units. It is the best choice if you want to add moisture to the entire house. These are the most expensive humidifiers.
Central humidifiers are usually integrated into HVAC (Heating, Ventilation, and Air Conditioning) systems. HVAC is a large-scale system that is used in enclosed spaces ranging from submarines to family homes.
HVAC systems have large air ducts spreading throughout your house covering every corner. They are connected to the main terminal, which is an outdoor unit that blows the air through the ducts.
In your HVAC system, there is a thermostat to control the temperature of the air flowing through it. If your HVAC system is more advanced and has humidity control, it will also feature a humidistat.
The humidistat controls the moisture level of air in your home, maintaining the correct humidity levels effectively.
There are three main types of central air humidifiers:
- Steam: This type of central humidifier operates electrically, boiling water and creating steam. The steam is then transferred through the air ducts and spread throughout the home, increasing the humidity. Steam humidifiers are the most efficient, and expensive, type of central air humidifiers.
- Drum-type: The drum-type humidifier has a rotating sponge-like surface that absorbs water from the tray at the bottom. The absorbed water evaporates during the rotation releasing water vapors in the air and increasing humidity.
- Flow-through: This is the most commonly used central air humidifier in which water flows through an aluminum panel and then the air crosses perpendicularly through the same panel evaporating the water into the surrounding air and increasing the moisture.
Evaporators are humidifiers that turn water into a gaseous state releasing moisture. A fan blows air through moistened filters expelling humidity into the air.
These are more affordable than the central humidifiers as they are smaller in scale and designed to support one room at a time. Wheels attached to the bottom allow for easy transport from room to room.
These humidifiers, however, do not have a humidistat to control the humidity levels.
The basic operation of the impeller humidifier includes the rotation of disks at very high speeds which fling water at a diffuser. The diffuser splits the water into droplets that are then released into the air.
These humidifiers are noisier than the others with more risks of spreading bacteria into the air if unclean water is used. Impeller humidifiers are smaller in size and are only effective for single rooms. It’s important to note that overusing an impeller humidifier can trigger breathing issues for asthmatic or allergic individuals.
Steam vaporizers are the small-scale, portable, and most widely used humidifiers that are powered by electricity. These are readily available at pharmacies and other retail locations.
Having a very basic working principle, they operate on steam. The water in the chamber is heated with the help of electricity. After reaching a certain temperature, the water is then formed into steam. The steam is then released, which dampens the surrounding air.
The most advanced option is the ultrasonic humidifier. These humidifiers use ultrasonic waves that vibrate against the water with high frequency resulting in water droplets which are then released into the room as a fine mist.
This is the safest kind of humidifier, as it does not involve any boiling water to create steam like other humidifiers – the high-frequency waves are enough to break down the water into small droplets.
Ultrasonic humidifiers do not include any mechanical whirring parts so that makes the operation of humidification very quiet in this case. These humidifiers are also energy-saving since they require very little electricity.
In conclusion, humidity is a vital part of our everyday life, despite how uncomfortable it may feel at times. Both a lack of humidity and an excess of humidity can create unbearable environments. This is where humidification and dehumidification processes come into play, to create a more suitable and comfortable living condition depending on need.
Ranging from commercial scale to DIY and homemade remedies of humidification, there are many ways to help humidify or dehumidify a space to create a more comfortable environment.