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Comment by DoreenMichele | Hacker News Reader

Why would it be humid? Heat doesn't cause humidity. Deserts can be hot and dry.

(Edited are to can be for the pedantic people.)

I think standard household activity would generate a lot of humidity. Usually dwellings vent outside, but here the outside is in a larger "inside".

I'm guessing the greenhouse has its own air regulation set up.

Yes, this is possibly true, depending on the details of their lifestyle.

On the other hand, the article talks about their use of composting toilets, recycling water, etc. So they may well not be engaging in the same high levels of water consumption as typical modern families in developed countries.

So I remain unconvinced that a warmer environment automatically and without exception translates to high humidity and mold. (I will confess to being born and raised in the state of Georgia. So my idea of hot and humid is perhaps more extreme than average.)

Edit: If you've never lived in dramatically different living arrangements, you may not realize how much lifestyle choices impact details like heat and humidity.

While getting divorced, my sons and I spent a year sharing a single bedroom at a relative's home. We eventually found that removing all cardboard from all food products not only dropped the temperature by 5 degrees Fahrenheit, it put a stop to roaches being attracted to our room.

Prior to that discovery, our room was frequently too hot and humid. Afterwards, it was vastly more comfortable.

We were shocked by the difference. We initially wondered if we were imagining things, but the room had a thermometer in the window. It consistently made a 5 degree difference.

I think you've been here long enough to know that a phrase like "automatically and without exception" is likely a poor interpretation of what the parent poster meant with "standard household activity".

I was born and raised in Florida. In Miami I lived in a 1950s house designed w/o A/C and with effectively no insulation. In Tallahassee I lived in a 1970s house designed for A/C. But we didn't have money, so we didn't run the A/C unless it was nasty hot.

The differences were remarkable. For the same temperature and humidity, the Miami house was much more comfortable. The vernacular architecture of high ceilings, open crawlspace, and massive amounts of windows meant there was still cooling with any sort of breeze.

With the Tallahassee home, the building was designed to insulate, to keep the A/C power bills low. The windows were small, there wasn't much cross-breeze even with all the windows open.

A/C systems include dehumidifiers, and the building has a vapor barrier to prevent the high outside humidity from coming in.

But w/o the A/C's dehumidifier, standard household activity like breathing, cooking, and showering raise the inside humidity more than the outside, with a slow rate of equilibriation.

We finally kicked on the A/C when, among other things, yes, mold started to form.

Of course 'lifestyle choices impact details like heat and humidity'. So does architecture, as I just pointed out. But btbuildem said 'standard' and 'usually'.

I'm damned if I do, damned if I don't. It doesn't matter how I phrase it, people will have a problem with my real point and will have a problem with me giving first-hand testimony from my life.

So I tried to avoid that. It didn't help.

I slept in a tent for nearly six years. I'm back in housing, but I still don't live conventionally. I'm in a hundred year old building with no AC. But I have no upholstered furniture, no mattress, a minimum of bedding.

When other residents are desperately trying to create a cross breeze to cool off their too hot room in summer, I'm usually fine. With no cardboard and no upholstered furniture, my room is not too hot.

So I tried to use specifics from the article itself, like the composting toilet. Toilets are one of the ways modern families go through a lot of water each and every day.

I know my lifestyle generates less heat and humidity in my home compared to other people in the same building as me. I also know most people act like my first-hand experience doesn't count.

I'm routinely downvoted for making such observations, no matter how I try to phrase it. I'm routinely told I'm making stuff up, that's anecdotal, it doesn't count, I need a study or something.

I've seen men here on the leader board give similar personal anecdotes and get treated like they're brilliant. Tokenadult used to tell stories of opening the shades on his windows when he was a young man living in China to use solar power to heat his room and giggling about management accusing him hiding a forbidden heater.

But my first-hand observations are not similarly respected and oohed and aahed over for their insight. Instead, I'm routinely attacked and dismissed.

After a decade, I'm pretty damn sure it isn't my phrasing. It's my gender and general lack of credibility for reasons wholly unrelated to my intelligence, veracity, etc.

It's open contempt for me as a person. And I'm quite fed up with it and even more fed up with being told it's somehow my fault that I'm subjected to this double standard.

Had no idea who you were, hadn't even considered what gender you may be, and I can say that it is your writing style and phrasing that rubs the wrong way. (IMHO) reading your posts came across as if I was being lectured to/talked down to by someone with feelings of superiority.

I observed that the statement "I remain unconvinced that a warmer environment automatically and without exception translates to high humidity and mold" - while absolutely a personal observation - was a non-sequitur as no one was making that claim.

Was it a non-sequitur?

I then made a personal observation that architecture was also important, using a similar anecdotal construction that you did. So clearly I don't have a problem with anecdotal evidence. I present a similar anecdotal observation at https://news.ycombinator.com/item?id=14876398#14878461 .

I then ended up with the comment that I don't disagree with your comment, because it's clearly true, just like how other factors are also involved.

If you look through my history you'll see I have a long history of making similar observations for other posters. I see four such on the first page of my comments history.

I'm a male with a literally randomly-selected username and have stopped posting here because of just the kind of thing you cite. It feels too much like school...it's this project to figure out what to say that people will like; fail to please the mob and out come the vultures. Life's too short and full of more wonderful adventures than that. And the payoff from getting it right just isn't there to justify the downside.

In my part of Northern Europe, in the winter the issue is keeping the inside humid enough. During winter when the air temperature is -10c or less there is basically no water in the air.

We have a MHRV system, but it doesn't account for humidity, so will happily replace all the air inside with dry air from outside (I'm trying to automate it with HASS). Our bathroom fan has a humidity sensor, so doesn't run so much in the winter, but even so the humidity often gets down to 25% rh inside.

Soviet Moscow flats are notorious for constant ~15% humidity in winter. Somehow they manage this even when there is a thaw outside and humidity is quite high.

Yeah, same here. When it's -10 C or less in the winter, relative humidity can drop to 15%. Because we have a standard heat-exchanger HRV. The rotating-filter ones do manage humidity, but they also tend to freeze up if indoor humidity goes too high.

So we end up using an aerosol humidifier in the winter, and AC plus a dehumidifier in the summer.

The greenhouse isn't 100% sealed and the top would regularly open during the warm months to regulate the heat inside. On top of that the regular vents could easily be extended slightly to just reach the outside of the greenhouse.

Plants/watering cause humidity and the glass traps it.

And although I guess they probably could, people aren't generally maintaining desert ecosystems in their greenhouses.

This is not a problem in the winter -- outside air (if brought up to room temperature) is extremely dry. So just a bit of air exchange would dry out any jungle if humidity is not supplemented.

Deserts aren’t necessarily hot, they just have very little water.

https://en.wikipedia.org/wiki/Polar_desert

They have little precipitation. There's plenty of ice in the Antarctic.

Are you sure about that? A river delta could be completely lush without any precipitation, but I don’t think that’d be a desert.

From the link someone else already provided:

Most polar deserts are covered in ice sheets, ice fields, or ice caps.

(I'm getting a chuckle out of the multiple layers of pedantry here.)

Nile delta is in a desert (4-8" rain/yr), so yes.

But greenhouses are humid. Deserts aren't covered in a dome and the dome blocks water from evaporating like in the deserts.

Not much grows in a dry desert though, to grow stuff you need water. Even if you weren't growing stuff then you'd still have the soil as an access point for moisture and get excess evaporation because of the greenhouse heat.

Depends on the desert. Here are pics of Saguaro National Park:

https://www.bing.com/images/search?q=saguaro+national+park&q...

Desert plants are adapted to low rainfall. That doesn't mean all deserts are just barren rock and sand.

saguaro national park has really grown on me. It’s a surprisingly and eerily beautiful place.

Yes, and when the rain comes they burst forth with vibrant life .. hence the specifiers "dry" & "not much".

I guess if they plan to eat agave and saguaro they'll have less humidity issues?

>Why would it be humid?

The hotter air is, the higher its capacity to hold water vapor.

https://en.wikipedia.org/wiki/Psychrometrics

https://en.wikipedia.org/wiki/File:PsychrometricChart.SeaLev...

Which actually drop relative humidity, because water does not magically appear.

Yes, but the absolute humidity is the amount of water in air, and particularly n cold climates, this water load can cause considerable trouble in structures. The correct way to design airflows and location of dew point inside the walls etc can be considerable trouble; ad hoc design tends to lead to mildew problems.

Dry cold air gets in during the winter, it expands and the RH goes down, warm humid air escapes, more dry cold air gets in, creating an extremely dry environment. Still you can get mold because of condensation when warm air meets cold rooftop.

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