(Edited are to can be for the pedantic people.)
I'm guessing the greenhouse has its own air regulation set up.
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.
So we end up using an aerosol humidifier in the winter, and AC plus a dehumidifier in the summer.
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 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.
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.
And although I guess they probably could, people aren't generally maintaining desert ecosystems in their greenhouses.
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.)
Desert plants are adapted to low rainfall. That doesn't mean all deserts are just barren rock and sand.
I guess if they plan to eat agave and saguaro they'll have less humidity issues?
The hotter air is, the higher its capacity to hold water vapor.
Part of this is a misunderstanding of building techniques that block airflow, ive seen numerous houses with all the roof vents plugged up to "save heat", walls with plastic sheeting on the inside wall creating air/moisture traps, or people replacing air-permeable house wrap with solid sheet plastic, foam and glue on every board and seam with a sealed up and moist crawl space underneath, ect. It is fairly easy to get mold in a humid place with a sealed home and no forced air, and nearly impossible to kill it all without tearing out all the drywall in the house. If everything was done right, shouldn't be a problem, but people are far more likely to pay for size and speed over quality materials or careful quality labor.
I’ve seen this turn into a problem with big renovation of old residential structures twice. My personal takeaway was make sure your envelope and HVAC are of roughly equivalent quality and era.
It's sometimes hard to imagine how hard and unprecitable lives of past generations were. For most of history people's indoor firepits didn't have chimneys, for example, and the health effects were less of a concern than wars, infectious diseases, getting hurt in physical labour, or famine.
Also, most old houses were well ventilated and built of mildew resistant materials (= poor insulation and wood).
In the 80s people started insulating them in the wrong way (on the inside), creating a condensation point between the insulation and concrete => mold.
These days we have learned that cellars must be insulated on the outside (by digging up the garden) or somehow make sure humid indoor air dont make contact with concrete behind insulation.
If you basically don't have plastic and insulation then mold is less of a problem, but you also need to spend a ton of energy keeping the house warm...
Controlling humidity and air freshness is done through vents, usually combined with a heat exchange to not let out all the warm air you just heated up.
Condensation accumulating larger drops might be a bigger issue with glass though, but only if it's already humid on the inside.
So as long as the inside and outside of the house has the same temperature, condensation in random spots should not happen?..
Condensation will be on the glass panels, where mould cannot grow.
Still a cool house though, I like their water treatment