[CaptainPanic]

In another thread, we discuss the condensation of water from a humidifier. I think my question is too much off topic, so I created a new thread.
The main question is: What's the point of a humidifier?

michel123456, on 7 December 2011 - 05:06 PM, said:

[...]ah, and it is not a good thing to deshumidify, you'll get sick. When a room has radiators, we use to put humidifiers.
Of course when you have too much humidity, you'll get sick too. You must maintain a balance.

I never understood the problem with humidity actually. After all, people live from the deserts to the rain forests, and it's not like there are certain areas in the world where everybody is sick. It's perfectly normal to live in a country with 75-100% humidity most of the time (e.g. the Netherlands), or in countries where it is quite dry. Here's a map of the world showing relative humidity.

Because I live in the Netherlands, which is naturally wet, I have never seen a humidifier like this (wiki) in my life. I don't think they are very popular in Europe actually, not even in the Mediterranean countries where it can be quite dry in summer.

In houses with radiators, I have seen a simple humidifier, which is just a water container hanging against the radiator, but I don't understand why people use those either. It seems like a waste of energy to evaporate water in a naturally wet country.
But the electric appliances that I see in Google seem able to put a lot more moisture into the air. Why?

Can anyone explain what happens if you live in a house without humidifier? What's the point of having one?

[HuMoDz]

Well, then air conditioners are pointless too, there are a lot of people that live well in places much hotter than that badly-ventilated office.


The humanity as a whole can survive on a wide range of humidity levels, but the specific individuals can't, or at least don't like it.

The same way an Egyptian would say Chile is too cold for him, even on summer.

[insane_alien]

having extremely low humidity can be uncomfortable.

In my work we have some low humidity environments (10-20% humidity) and being in them for a time can lead to dry skin and chapped lips.

nothing major, and you do acclimatise to it but it can be a bit uncomfortable to some people.

that said, i'm in scotland so i'm used to wet air.

[CaptainPanic]

insane_alien, on 28 December 2011 - 10:35 AM, said:

having extremely low humidity can be uncomfortable.

In my work we have some low humidity environments (10-20% humidity) and being in them for a time can lead to dry skin and chapped lips.

nothing major, and you do acclimatise to it but it can be a bit uncomfortable to some people.

that said, i'm in scotland so i'm used to wet air.

I agree that it can be uncomfortable, but the post of michel123456 that I partially quoted said you can get sick. Is that an exaggeration then?

In hot climates, humidifiers don't need to use much energy. They need to spray water into the air, and evaporation will take care of the rest. But my experience is that the dry lips occur mostly in winter, when the outside relative humidity is high, but indoors that translates as dry air. In such cold weather, your house will provide the heat to evaporate all that water one way or the other (either from the humidifier itself, or your central heating system). Evaporating 1 liter of water requires 2.26 MJ of heat (you must burn about 50 liters of natural gas, or use about 0.6 kWh of electricity). And 1 liter is not much to humidify a house. Google shows humidifiers with a 4 gallon (about 15 liter) reservoir.

I'm a bit skeptical to such waste of energy if it is really just about dry lips and skin, which is why I opened this thread. Maybe someone else cares to comment?

[michel123456]

It is a health issue.
http://www.ncbi.nlm....les/PMC1474709/
http://ezinearticles...alth?&id=297092

Air humidifiers are needed in over-insulated places. The actual trend is to save energy by insulating buildings like a vacuum flask. But it is not that simple, you have to live in that vacuum flask.
In older houses, one of the main issue was ventilation. I remember houses designed with ventilation pipes in each closet, and even different pipes for the wardrobe and for the shoes, pipes for in and pipes for out, making some inner walls looks like an organ. Ventilation of the basement, ventilation beneath the roof, ventilation beneath or behind the fire place, high ceilings for circulating the air, etc.
The new advices (and regulations) forget everything we have learned about the healthy way to live inside. That's why some people prefer live in old houses, even if they don't understand the exact reason for a better "feeling".

This post has been edited by michel123456: 28 December 2011 - 02:42 PM

[slavenenco]

I agree that low humidity can feel uncomfortable, but i lived in subtropical climate and i got to admit that high humidity is lot more uncomfortable

[John Cuthber]

Places like the UK are generally pretty wet. But when the weather is cold the water in the air condenses out. The absolute humidity is then quite low. If you take that air and bring it indoors and warm it up but don't add water it's fairly easy to end up with a relative humidity less than 20% which is- I assure you- rather uncomfortable.

It's usually less of a problem in domestic premises because cooking, washing etc add water to the ari but in buildings it's a real issue. I know because they forgot to provide humidifiers for the place where I work. It has led to people becoming ill: it's a real problem.

[timo]

CaptainPanic, on 28 December 2011 - 12:00 PM, said:

I'm a bit skeptical to such waste of energy if it is really just about dry lips and skin, which is why I opened this thread. Maybe someone else cares to comment?

I tend to get headaches and a strange (dry) feeling in my throat in my flat in winter time due to the air being too dry. The rather obvious solution is to put a small bowl of water on the heater (anywhere in the room should actually do the trick, too). I don't really consider this a waste of energy. And even though it's not a very scientific statement, my gut feeling tells me that the bowl of water can well compete with expensive electricity-driven devices.

[swansont]

From a technical aspect, electrical equipment doesn't like dry air. Components are more likely to arc when the air is dry; the breakdown voltage for a given gap depends on humidity.

[D H]

CaptainPanic, on 8 December 2011 - 08:44 AM, said:

The main question is: What's the point of a humidifier?

Because I live in the Netherlands, which is naturally wet, I have never seen a humidifier like this (wiki) in my life. I don't think they are very popular in Europe actually, not even in the Mediterranean countries where it can be quite dry in summer.

You live in the Netherlands, so you probably don't know. That you picked summertime rather than wintertime is a big clue that (a) you don't know why people do need humidifiers, and (b) you don't need one yourself.

Here's a simple test: Shuffle your feet as you walk across a carpeted room toward the door. Reach for the doorknob. Describe the spark that results.

• It was several centimeters / several inches long! And it hurt!
  You need a humidifier, big time.
  
  
• It was tiny, but it was there.
  You might or might not need a humidifier.
  
  
• What spark? What are you talking about?
  You need a humidifier about as much as do I.

The problem of low humidity is most acute in wintertime. If it is very, very cold outside it doesn't matter if the outdoor relative humidity is 100% or 0%. The absolute humidity is very, very low in either case. The air in your house will have a very low relativity humidity because there is essentially no moisture in the air. In a dry climate, it doesn't have to get all that cold to have a low relative humidity problem indoors.

As to why it's a health problem, the incidence of the common cold and influenza peak sometime in December or January -- precisely when absolute humidity reaches its minimum. http://www.pnas.org/...106/9/3243.long.

[CaptainPanic]

D H, on 2 March 2012 - 07:55 PM, said:

You live in the Netherlands, so you probably don't know. That you picked summertime rather than wintertime is a big clue that (a) you don't know why people do need humidifiers, and (b) you don't need one yourself.

But in wintertime, you have to provide energy to evaporate water (the heat from outside cannot be used, like in summer).

At 20 deg C (room temperature), at 100% humidity, you have about 15 g of water per m3 of air (approximation, not an exact calculation).

So, if your house is merely 100 m3 (which is a small house!), you need 1.5 kg of water in the air, which costs 3.4 MJ (which is approximately a kWh).

Basically, on an annual base, you spend a hundred $ or euro just to get some humidity, assuming quite minimal ventilation. Is it really that bad to get a spark that it's worth 100 $ to avoid it? (And do people know how much energy a humidifier costs?).

[D H]

Nobody raises the humidity to 100%. Where humidifiers are needed, they are used to raise the paltry ambient 5% humidity to a more comfortable / healthy 40% or so. Using a more reasonably sized 500 cubic meter house, but mitigated by this more reasonable humidity level, makes the energy required 8 MJ, or about 2.2 kilowatt-hour. This amounts to 0.22 euro (a US quarter) at €100 per megawatt-hour. The key is how often one needs to expend this amount of energy / spend this amount of money. If you have a leaky house you might have to expend this much energy every day to keep the humidity level comfortable and healthy. It's much less if you have a reasonably well-sealed house. Assuming the humidifier is needed 25 weeks of the year, the cost will be somewhere between 5 to 50 euro per year.

Even that upper value is pretty tiny. It's the cost of a dinner for two at a nice restaurant. Per year.

Compare that to the cost of not using a humidifier. If the ambient humidity is 5% in your heated house and if you have a piano, you just killed it. Low humidity destroys wood furniture. It is also unhealthy. Skin problems are rampant in low humidity environs. The common cold and the flu peak in December and January precisely because that is when absolute humidity reaches its low point. Raising the humidity to 35% to 45% reduces the chance catching a cold or the flu, reduces these low humidity skin diseases, and reduces the chance your wife will throw you out with the busted piano.

It appears that most of western Europe doesn't have any of the kinds of climates where a humidifier is needed. Perhaps central Spain, parts of Scandinavia, and the Alps.

This post has been edited by D H: 8 March 2012 - 12:58 PM

[CaptainPanic]

D H,

Good post. So far, it's the best answer to my initial question. Thanks.
I hadn't realized that furniture (esp. expensive things like a piano) are also affected.

Still, I think the costs of the required energy to evaporate the water shouldn't be ignored. But since you also addressed that point, I think I must admit that this is more subjective. I think that 50 euro in energy costs is not negligible. Again, that's an opinion rather than a fact.

[edit] p.s. also the link to the article regarding the influenza in december/january was informative. Thanks for that too.

This post has been edited by CaptainPanic: 8 March 2012 - 01:13 PM

[Anders Hoveland]

Obviously you have never lived in a cold dry climate.
Let me explain this. Cold air holds much less humidity than warm air. When the cold air becomes heated, it suddenly can take up much more moisture. If you live in a climate with less humidity, things can become very uncomfortable inside a building that has a heating system, but no humidifier.

Ones skin becomes very dry, and it feels uncomfortable, almost painful. I have been in a situation where I almost just wanted to stay outside in the cold, because it was so uncomfortable inside.
I have travelled to arid deserts and never had nearly so much of a problem with this. The lowest humidity in the world, for example, is found in Antarctica. If one somehow took that cold dry air and warmed it, it would have a drying action more potent than the hot dry air in most deserts.

This same effect is used in freeze drying foods. The food is warmed and then cold dry air is passed over it.

[John Cuthber]

Anders Hoveland, on 16 April 2012 - 03:43 AM, said:

This same effect is used in freeze drying foods. The food is warmed and then cold dry air is passed over it.

In a very real sense, but in a rather more real sense the food is frozen at a low temperature before being dried (often under vacuum)- hence the name.

http://en.wikipedia....i/Freeze-drying