Comment by contravariant | Hacker News Reader

Comment by contravariant | Hacker News Reader

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Convincing water to just evaporate on its own was always going to be a bit tricky. The energy needs to come from somewhere so your best bet is to just get it into contact with enough dry air and hope for the best.

Besides if you're trying to restore humidity lost by heating your room then pure energy wise there's not that much difference in evaporating the required amount of water using ambient heat or evaporating the required amount of water using a different energy source. The only thing you'll achieve by using ambient heat is that your room will cool by the amount of heat required to evaporate the water (a good thing in the summer, somewhat pointless if your aim was to make a room both warm and comfortably humid).

Fundamental thermodynamics will probably mean the 'wait and see' approach is more efficient in the end, but it makes no promises on efficacy. The difference in efficiency probably lies in the fact that you can heat a room with an efficiency >100% if done right, if you haven't managed that yet it probably doesn't really matter which way you humidify the room.

Even without a system that has >100% efficiency (i.e. a heat pump), home heating systems often use a source of heat that is significantly less expensive per watt than electricity. (For example, natural gas.)

Well that depends on what you're optimizing for, but yes.

Gas-fired humidifiers exist, though I'm not sure if you can get small ones easily.

So, there are some unpowered options, none of which are as efficient individually as a powered humidifier, but may work in tandom:

1) Plants - they release the water you put into them into the air, as part of how they pull water up from the ground to the leaves.

2) Open Water - Aquariums, fountains, etc.

3) Humidifying balls - basically rough ceramic balls which sucks water up into them, and the water naturally evaporates. Slow, though, and if your water has any impurities they will accumulate on the surface.

4) Humans - we breathe out a lot of water, and if your house is well enough sealed, you'll actually have to de-humidify, even if the air outside is dry. Costly, though.

In places with hot dry summers, the evaporative approach is vastly more efficient than boiling water.

As a resident of a place with hot dry summer, I can confirm that the last thing I want to do is to add to the heat with boiling water.

The evaporative approach will actually manage to do something that's generally impossible as it will actually cool down the air. Obviously this is the superior method to deal with hot dry air.

The use-case described in the article however:

>The east coast’s dry winter air, parched further by the radiators that can barely keep up with the chill, causes great discomfort to me and millions

suggests they're trying to heat the space they're in. At which point you'll need to recover any heat lost by evaporation anyway.

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