There are many reasons why people use humidifiers in their homes. They can benefit human health, aid in the preservation of certain furniture, and help to keep tropical plants happy and thriving. But they also affect the indoor air quality, including ambient temperature.
The temperature is affected because of how the humidifiers work to introduce moisture into the air.
Impeller, ultrasonic, and wick system humidifiers don’t heat water before releasing it into a room. Steam humidifiers (most common) do heat water to release as steam. But, air temperature is only increased by a few degrees. Humidifying air can make a room feel moderately to much warmer than it actually is.
Types of Humidifiers
There are actually different types of humidifiers. They differ in how they release moisture into the air, and this plays a role in how humidifiers affect the temperature of a room and the extent to which they do this.
Impeller humidifiers have a system that creates water droplets by trickling water onto a rotating metal disc. As the droplets fly off of the disc, they pass through a diffuser and are broken into smaller droplets. These are then released into the air.
Ultrasonic humidifiers create water droplets using vibrations. These are then released into the room.
Some humidifiers utilize a wick system. Water is drawn up from a reservoir using a wick (made of paper, cloth, or another absorbent material). A fan blows onto the wick, which causes evaporation (similar to evaporative cooling). The moisture-holding air is then blown out of the humidifier into the room.
The most common type of humidifier is the steam humidifier. Similar to a coffee maker or tea kettle, the water in a steam humidifier is boiled by a hot plate or similar device that heats up through electrical power.
The heated water vaporizes and is released out of the machine and into the air using steam’s natural tendency to rise.
Does a Humidifier Cool a Room?
Impeller, Ultrasonic, and Wick System Humidifiers
Most people would call impeller, ultrasonic, and wick system humidifiers cool mist humidifiers.
This can make you think of those nice misting machines that they put around outside eating areas at certain restaurants. Those are always quite refreshing, so you’d think a cool mist humidifier would have a similar effect.
To a certain extent, this is true. If you were to stand next to the humidifier or within the path of the mist, you would benefit from the cooling effects of the water droplets.
However, this is the result of water droplets landing on your skin and evaporating into the air, taking some of your body heat with them. This is just what happens when you sweat.
The actual room temperature will not be reduced. But at least no heat is added to the room, which is the case with a steam humidifier.
Steam Humidifiers
Steam humidifiers introduce water vapor into the air and to vaporize this amount of water, an input of heat is required.
As the steam rises into the room, it mixes with the air, increasing the amount of thermal energy in the room, and, thereby, increasing the temperature of the room.
It is important to note that the water in the water reservoir of a steam humidifier must be replaced every so often as per the manufacturer’s recommendations. If it is not, the heating element will burn out.
But how much does the temperature increase?
The truth is that it’ll only increase the actual overall air temperature in a room by a few degrees and only if you are increasing the humidity levels significantly (adding more steam).
While water vaporizes at a high temperature—212 °F (100 °C)—the ratio of steam to air volume is such that the heat carried by the vapor is dispersed to the point at which overall room temperature is affected very little.
The air around the machine will be warmer than the rest of the room and the steam coming out will be scalding (so, take care!), but overall, we’re looking at 1-3 °F difference when increasing the humidity levels by 30% or more.
However, before you leave thinking that humidifiers will not change how hot or cold a room feels, we need to distinguish between actual air temperature and perceived air temperature.
Moist Air Adds to How Warm a Room Feels
While humidifiers—cold-mist and steam models—don’t have a significant impact on actual air temperature, they do have a noticeable impact on perceived air temperature.
Perceived air temperature is how hot or cold it feels to us and it is arguably more important in this case.
As humidity increases, the perceived temperature increases as well.
You can have a room reflecting 85 °F on the thermostat, but if you are running a humidifier and the relative humidity is 50%, the room will feel more like it is 88 °F.
The higher the actual room temperature, the greater the impact of humidity on perceived temperature.
While the perceived temperature of a room at 85 °F increased by 3 °F at 50% relative humidity, room at 100 °F will have a perceived temperature of 120 °F at the same humidity level. That a difference of 20 °F, which is more than six times the difference in the first example.
Why This Happens
The reason why increased moisture in the air increases how hot the air feels to us is because it slows evaporative cooling.
When we get hot (and it doesn’t have to be sweltering, just a little too warm to support our ideal body temperature), our bodies produce sweat as part of a natural cooling mechanism.
Sweat evaporates from the skin, using thermal energy (heat) to “power” the conversion of liquid to vapor, thus, we are cooled down.
The faster evaporative cooling occurs, the more heat is removed from your body.
However, evaporative cooling is affected by the humidity of the air around the skin. Air can only hold so much moisture at a certain temperature.
With high enough humidity in a room, sweat evaporates at a slower rate, releasing heat from your body at a slower rate as well.
This can make the room feel warmer since your body is losing less heat than it would in a drier room.
When it comes to higher temperatures feeling even more hot in the presence of humidity, this has to do with what we perceive as feeling cool.
When the temperatures are so high, our bodies need to cool down a lot more to be comfortable. Because they cannot achieve this due to the moisture levels in the air, we feel a lot hotter than we would if the air was dryer and our bodies’ cooling systems were able to function properly.
Need a Humidifier but Don’t Want the Heat?
With the increased perceived temperature from the reduction in heat loss from the body, a humidifier can certainly make a room feel warmer.
This is ideal for the winter and can save you some money on energy bills since less added heat would be needed to make you feel comfortably warm.
If a ceiling fan is used with a humidifier, this process can become even more efficient since the fan could better distribute the heat from both the HVAC system and the steams from the humidifier to warm and humidify your room. The ideal direction for this would be clockwise.
However, if you still need to use a humidifier in the summer for health reasons, this perception of increased heat can be a nuisance.
An energy-efficient way to combat the heat of a humidifier is to use a ceiling fan in summer mode (counterclockwise direction).
A ceiling fan in summer mode is creating a downward flow of air. The fact that the air is being pushed down in this mode introduces wind chill.
Wind chill does not actually cool the air. Instead, it cools any person in the path of that airflow by helping to increase the loss of body heat by blowing away the layer of heat that naturally forms against our skin.
The wind chill effect is limited in more humid rooms.
Looking for a Way to Cool the House (No AC)?
Although some websites may recommend using a humidifier to cool down your home, this simply doesn’t work.
Although humidifiers cannot help cool down your home, there are many different ways to cool down your home or make occupying your home more comfortable during warmer months.
- Use fans (ceiling, table, tower, etc.)
- Block sunlight with curtains
- Utilize cold night air (the range hood can help with this)
- Make DIY AC with a bowl of ice and a fan (limited benefit)
- Drink cold water
- Use cotton sheets (breathable, won’t get as warm)
- Take a cold shower
- Limit strenuous activities
- Limit usage of heat-generating appliances (oven, electronics, etc.)
- Insulate your home’s walls and attic
- Weatherstrip your doors and windows
- Use heat-generating appliances at night so the cool temperatures can offset the heat generated
- Replace incandescent light bulbs
- Use a dehumidifier
Dehumidifiers Will Cool a Room Better
Although dehumidifiers are not ideal for bathroom ventilation, dehumidifiers can definitely help cool a room.
This is because a dehumidifier does the opposite of a humidifier; it removes water vapor from a room’s air rather than adds it.
Because cooler air carries less water with it, a dehumidifier would cool air rather than introduce steam to it.
The cooled air’s moisture is left behind as it converts from vapor to liquid and this liquid collects in the dehumidifier.
A dehumidifier’s output would be cool, dry air, somewhat similar to air conditioned air but at a much smaller scale.
Along with the cooler temperature of the air cycled through the device, a dehumidifier also increases the rates of evaporative cooling.
This is because water evaporates much faster in dry air than in humid air.
If a dehumidifier is used with a ceiling fan, evaporative cooling rates would be greatly accelerated, enhancing both of their cooling effects.
Sources
https://blog.homedics.com/air/how-does-a-humidifier-work/
https://storeys.com/keep-house-cool-without-air-conditioning/
https://www.readersdigest.ca/home-garden/home-improvement/how-to-cool-your-house-without-ac/
https://home.howstuffworks.com/humidifier.htm
https://www.armstronginternational.com/files/products/humidifiers/pdf/HB5_1417.pdf