Does humidity make lower temperatures seem warmer?

[Cath]

I read on a "Frugality" board on a non hearth forum that humidity makes lower temperatures seem warmer. The person posting this bit of wisdom suggested that running a humidifier or vaporizer would make 60 degrees "feel" as much as 5 degrees warmer.

It’s pretty well known that humidity at high temps can make you more uncomfortable, which seems to translate into feeling hotter but I don’t know how this principle would operate at lower temps.

This probably can’t be quantified but perhaps someone here can speak from observation. If I could remember where I put my vaporizer I could put this theory to the test myself.

Any responses here may inspire me to dig it out. You would think the fact that we all have the flu right now would be inspiration enough.

~Cath

 

[RedRanger]

I just bought a humidifier last week for the rec-room where the insert is located. Wheras we used to get temps of 80 down there, we are now averaging 75. Humidity used to be 35%, now I keep it at 45% and it feels more comfortable.

The humidifier actually seems to keep the room cooler. We don`t sweat as much and feel more comfortable.

This really does seem like a contradiction,because out here on the West Coast during the summer when the temp hits 80 degres outside ya sweat like crazy cause of the high humidity. Yet it seems to have the opposite effect with wood heat. Would be nice if someone could explain why this is?

 

[eba1225]

Cath,

Yes I do find that when the humidifier I have running runs out of water the usual warm air doesn't feel as warm.

But there is a point where the opposite occurs, like down in the 40's to 30's where higher humidity makes the air feel more colder, at least to me.

 

[Cath]

sonnyinbc,
I have no idea how a humidifier could change the actual temperature unless it is somehow producing a lot of cold air.

However, I did a little digging and now have a better understanding of how humidity might affect the perceived temperature. If the information I found is accurate then increased humidity in a well ventilated area, but with low air flow, will increase the perceived temperature.

THE IMPLICATIONS OF THERMAL COMFORT IN NEW ZEALAND HOUSE DESIGN by Peng Chen http://www.meanradianttemperature.com/chen1.htm “The percentage of humidity necessary for thermal comfort depends upon all other parameters. If the relative humidity is very high, the heat loss by evaporation will be much greater, so raising the temperature is one practical way to compensate for the extra loss by evaporation. When temperatures are within the comfort range (19-23 °C) the RH has little effect on comfort provided that it is within the range 40-70%. Influence of humidity is not great for a person with very light or sedentary activities as well. Higher humidity will make a person feel warmer particularly in a ventilated area where the air speed is low. … Generally people are much more sensitive to extremes of temperature than extremes of humidity. (Monash University)”

Heat Index
http://www.wusa9.com/news/news_article.aspx?storyid=6904

~Cath

 

[RedRanger]

Cath: Thanks for the info.

Guess I should have stated that we have a cool air humidifier. So it does produce cool air into the room. That is why (all things being equal) we get the drop of 5 degrees. Seventy five degrees is still nice and comfy. More importantly it keeps that "dry skin syndrome at bay"..

 

[mayhem]

More humid warm air will seem warmer to a person living in it...conversely though, cold humid air will seem cooler than it is to that same person. Water is more effective heat transfer agent than air...when you add water to the air it makes it more effective at either heating or cooling your skin.

I remember I bought a mist-type humidifier awhile back...unfortunately it made the house so darn cold the heat kept coming on...though it helped in the summer. The cool mist type humidifiers seem to do this universally and I could very easily see how they could cause a temperature drop in a room...they are effectively mini swamp coolers.

 

[Jags]

If you were to take a room temp of say 70 deg with a humidity level of 35% you would have a given amount of water molecules transferring heat to your skin. If you keep the same 70 deg and increase the humidity to 45% - you would have considerably more water molecules contacting your skin and therefore transferring more of the 70 deg air temp to your skin. Water will transfer heat to skin far better than air will. Your just adding water to the air. (water will also transfer more cold to your skin, thats why there becomes a temp point that humidity can work against you)

 

[guy01]

Which is why it always feels warmer when you are fresh out of the shower in winter

 

[pdboilermaker]

Increasing the humidty to a point is a good thing in the winter. It does make you feel warmer, it helps the air hold the temp longer, keeps your skin from drying out, helps with those winter nose bleeds etc. They sell humidifiers that bolt to your furnace and have for years in Indiana and other cold states I assume.

Too much humidity can be bad, especially in a very tight house, watch for molds especially in those cool spots where the excess moister will tend to collect.

 

[DiscoInferno]

Heat generally travels from high to low temperature, and outer skin temperature averages 91 degrees (according to google); I don't think 75 degree air is going to transfer much if any heat to the skin in most cases. It simply carries less of our excess heat away than say 40 degree air. Hot humid air feels warmer than dry air at the same temp because it reduces sweat evaporation, and so perhaps it's the same effect here just at more modest temps and humidity.

 

[wallis54806]

Discoinferno, you nailed it. Your body is a heat generater and needs to loose some to maintain a constant temperature. If radiation and convection are not enough to do that then your body sweats and the evaporation of that water cools your body. More humidity will slow the evaporation process, but if you are in a cold enough environment that your body does not need to sweat, then more humidity will take more heat away from your body.

 

[ctlovell]

DiscoInferno got it right. High humidity reduces evaporation, therefore reduces heat loss causing you to feel hotter than you would feel at a lower humidity at the same temperature. Watch the Weather Channel, this is what they are talking about when they refer to the "heat index".

 

[Jags]

:down: That'll teach me to regurgitate something I read with out proper research. DiscoInferno's explanation seems to make more sense than trying to transfer 70 degree "heat" to an already 91 degree heated surface (skin). Thanks for clearing that up guys.

 

[muhca]

There is some additional info relating the heat index or humidex as they call it at
http://www.msc-smc.ec.gc.ca/cd/brochures/humidity_e.cfm

...and some other humidity definitions and calculations at
http://www.humidity-calculator.com/

Cheers

 

[billb3]

I don't know about that cold air feeling warmer after a shower.
I don't have much insulation on these bones and the cold air on the other side of that shower curtain is the last thing I want to step out into.

 

[begreen]

LOL :lol: I hear ya brother! :lol:

 

[wdc1160]

sonnyinbc,
I have no idea how a humidifier could change the actual temperature unless it is somehow producing a lot of cold air.

However, I did a little digging and now have a better understanding of how humidity might affect the perceived temperature. If the information I found is accurate then increased humidity in a well ventilated area, but with low air flow, will increase the perceived temperature.

Cath and IBC,
Your both onto something that I think is key for winter comfort.
Actual vs Perceived temperature.

Cath hit on perceived temp. Let me say IBC. You require more BTU's (heat) to keep a humid room warm.
They make many different type of humidifiers, but most that don't "cook" the water to turn it to gas, they steal heat from the air to create a phase change I.E. they change water from liquid to gas. The same phase change that cools us when we sweat.

You can actually calculate how much heat is taken from the air to humidify your house.

I won't get to geeky, but there are many charts that indicated the best humidities for given temperatures. I try to follow those. They balance out several factors: problems w/ high humidity/dryness and perceived comfort.


Cheers

 

[Roadkill]

In the winter your furnace produces dry heat. Since we are a hearth forum burning a wood stove also produces dry heat. The dry heat makes your throat scratchy, dries out your skin and creates static electricity when you touch something. Putting a steamer humidifier on a wood stove puts moisture into the air. The extra moisture helps to raise the humidity in the air and it does make you feel warmer.

http://www.inandoutlifestyles.com/steamers.html

 

[Redox]

Guys; I don't want to thinka bout humidity right now...

 

[begreen]

In the winter your furnace produces dry heat. Since we are a hearth forum burning a wood stove also produces dry heat. The dry heat makes your throat scratchy, dries out your skin and creates static electricity when you touch something. Putting a steamer humidifier on a wood stove puts moisture into the air. The extra moisture helps to raise the humidity in the air and it does make you feel warmer.

http://www.inandoutlifestyles.com/steamers.html

Agree, though not just the furnace. Any heat source is going to raise the interior temp way above the dew point. That is what determines the relative humidity inside the house. Often, on a crisp clear winter day, the dew point can be very low. Inside the house on those days can have a relative humidity in the teens or lower. Same as desert conditions.