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[Starver]

What's so terrible about venting into the hallway? Do you have a grudge against transom windows or something? Yeah, you could dig (or drill) a separate access path for ventilation alone, but that seems like a lot of extra work. What's wrong with air flowing along the same paths as traffic?

Without some assistance (where the fans/etc would be useful), there's no reason why significant amounts of air could be persuaded to divert in through one hole in a wall/door and back out of another hole in a door/wall a few tiles down a straight corridor, in preference to just going straight down that corridor.

The best way of doing this is to have angled vanes against a strong corridor draught to 'catch' some of it, push it into the room, and a similar arrangement vaned at the opposite angle (and/or rely upon Venturi/Berrnoulli effects) to draw the air out again at the second position. And then you'd be at risk of stale-air pockets sitting at the back of a bedroom (well away from the noticeable forced draught you're having to produce) thus to succumb the unwary. Especially if they are sleeping.

And if you're relying upon traffic driving your flow around, are you going to make antiparallel one-way corridors to consistently drive this mix around rather than just buffet the air up and down as users of the corridor pass each other in opposite directions?


If you're determined to have airflow, I would suggest a separate set of corridors (minimalist, and maybe with pipe-ducting if that becomes a buildable thing) leading from a safe/securable outside zone and down behind every dead-end room or other open area (and maybe also into other strategic locations), designed with constrictions and even additional mechanically-powered fans to emit a small positive pressure into the rear of a room (ideally at more than one point to generate self-interfering oscillating turbulence patterns to avoid 'dead corners') providing the freshest air in the places where the air-breathers would be more vulnerable. Let that air flow out through the rest of the fortress, passively (but stirred up by activity), with the possible exception of if you can engineer an additional, slightly negative pressured, 'extractor' route specifically out from any butchery room and other potentially miasma-prone locations.

(Details to be worked out according to the building bricks provided in any such 'ventilation update', but I'm assuming we're going for a reasonably-equipped portfolio of parts to sustain a properly usable system rather than some handwavium fudge of an attempt to implement it.)

The 'back corridors' could even be potentially usefully purposed as "servants' stairways" or special military accesses out to sally ports and in (through normally locked-but-venting rear doors) to any space that an intruder or berserkingly mad resident has been sealed into. And also used as civilian escape-routes away from all the usual horrors a fortress may experience. (Civ Alert => All non-military go to a nearby 'end room'. Hopefully you have the means and opportunity to get a lever-puller to open the emergency evacuation doors and another lever at the right time seals off the entryways in a strategically useful way. Civies then depart out through the ventilation system (previously inaccessible/unusable to any threat that might now be battling the militia or unluckier non-military) and rush off map to regroup and return when all is quiet, or start up a new home if necessary.) Or they could be your weakness. But if you're good at Turtling at the moment you surely can find a way to Turtle (against anything but a floatily fluidic/gassy enemy) with a suitably designed ventilation infrastructure in place.

Either way, 'draught-passable' settings upon doorways (independent of (un)locked and pet-(im)passible flags) would be the way I'd llike to do it. And if it's an anywhere half-decent system behind the required ventilation I'd probably do the eztra work, regardless, because it just oughtn't to work right with mere sequential fanlights letting a breeze in and then back out without a ceiling fan (or several, on both sides!) driving that flow.

[Ninjabread]

Firstly I'd like to mention, I did some re-enactment blacksmithing a while back, and at the forge we had a large (about as big as the forge itself) set of double bellows. These things had constant outward airflow into the forge if you kept them moving, as while one airbag was filling, the other was blowing, the whole thing was operated by a single wooden pole between the two sets of bellows, and I managed to heat up the forge enough to turn an iron bar into a sparkler. Anyway, point is, double bellows have constant outward airflow and can be operated by a single person, or mechanisms I imagine since it's literally just an up/down motion with enough wiggle-room to actually do more of a circular motion, and we do already have the pump operator skill. Hopefully that contributes something to the bellows discussion.

I did a little research, and they're actually called double-acting piston bellows and have existed in China since the 5th century BCE, independently invented in Greece in 240BCE for pumping water upwards, and not used in European smithing/smelting until the 16th century CE. Does that count as in-period since we aren't planning on using it for smithing/smelting?

Second thing, I found a thread in general discussions on the subject of oxygen in the caverns which is an interesting read.
http://www.bay12forums.com/smf/index.php?topic=171080.0
Probably even more interesting if you actually know how to chemistry.

[GoblinCookie]

Tolkien's dwarves were clearly able to make doors that fit absolutely perfectly, but that doesn't mean that all doors have to be airtight. If the masons knew that self-sealing bedroom doors would almost certainly kill their users, then naturally they'd want to leave small but sufficient gaps. Besides, it's a lot easier to open & close doors quietly if they don't make full contact with the sill and doorjamb. If I were a dwarf, I don't imagine I'd get much sleep in a hallway that's constantly filled with the noise of stone scraping on stone from all the comings & goings.

Where airtight doors made sense, conversely, would be rooms where you want to discourage life, such as food stockpiles. Maybe you could carry 2 torches when you enter, but leave one still burning behind you when you go, so it leaves less oxygen for the vermin? At the very least, sealed doors would keep new vermin from getting in.

I don't think Tolkien ever though about how the dwarves needed to breathe  .  I hadn't though of the potential for dwarves to basically can things by filling up a room with something and then installing an airtight door. 

Very small cracks likely won't do the job because the amount of air that gets through from the doorway might not be enough to keep the dwarf in it from suffocating, especially when there likely isn't much air in the hallway outside.  The interesting question here is how  fast does the oxygen homogenise against how much air are the dwarves using (plus fires and things). 

That leads me to think, could that not be made into an ini setting?

I don't mind bellows being sub-optimal: One of the key factors of the Innovations plan is that the player does NOT choose what gets discovered/invented, so in one game you might embark with a civilization that happened to develop Fans, while in your next game you have nothing better than the Great Bellows (but with a chance to develop Fans afterward). I'm not saying Bellows need to be a thing, I'm just saying that multiple games will be more interesting if different forts know different technologies, and half-measures like Bellows would be useful in that regard.

Neccesity is however the mother of invention.  Dwarves will likely invent a lot of technology that humans at an equivilant general level of scientific knowledge did not.  Oxygen is to a dwarf very much a real resource in a way that it is not to a human peasant living on the surface, that means dwarves are naturally going to invest a lot more resources than medieval humans would in anything related to the circulation of air.

[Bumber]

Continuous airflow from the bellows isn't the issue. It wouldn't matter if it wasn't constant. The issue is being able to push the air far enough. Bellows work great for forges because they're right next to it. They work for old diving suits because it just has to supply one person through a small hose. They wouldn't really work for large, branching corridors. You'd need a bunch of them all over the fort to keep the air going. In all likelihood, an oversized bellows is going to rupture frequently from wear and tear, especially if you can't obtain a creature with a large enough hide and have to sew a bunch of them together.

Doors could have built-in vents that are able to be set to open/close from the 'q' menu. With open vents you'd risk water and poisonous gas flowing through. With them closed, you'd need an alternate means of providing oxygen to the room.

Or, dwarves could assume that if there's enough !!FUN!! to fill the corridors with water or toxic gas, then they're pretty much screwed anyway. To me, it seems analogous to building a fallout shelter in your basement: Yeah, it might come in useful someday, but if your city does get nuked, chances are you're fuckin' dead, fallout shelter or not.

Yeah, why bother packing a parachute?

That aside, you don't necessarily want the door's vent open on the butcher's shop. Or for the pump room. Or that noble's room with the fancy lever.

[SixOfSpades]

What's so terrible about venting into the hallway? Do you have a grudge against transom windows or something? Yeah, you could dig (or drill) a separate access path for ventilation alone, but that seems like a lot of extra work. What's wrong with air flowing along the same paths as traffic?

Without some assistance (where the fans/etc would be useful), there's no reason why significant amounts of air could be persuaded to divert in through one hole in a wall/door and back out of another hole in a door/wall a few tiles down a straight corridor, in preference to just going straight down that corridor.

Ah, but (AFAIK), the airflow doesn't need to actually divert into the room, merely flowing past it should be enough, and diffusion will do the rest. I say this because I am still alive: Although I freely admit that I do not live in an underground fortress or cavern, I do keep my bedroom windows and heater vent closed pretty much ALL the time, meaning that the only openings for oxygen to diffuse into the room are the cracks around my door. And yet I keep waking up every morning. The house itself is kept sealed up pretty tightly as well, especially during the colder half of the year. So when I keep believing that a small vent in stationary air should be adequate, I'm speaking from experience, not stubbornness.

Does that [double-acting piston bellows] count as in-period since we aren't planning on using it for smithing/smelting?

I say yes. Anything before 1400AD is fair game, plus I think it should go a little beyond that if the technology has to do with stone, metal, or anything underground. Which leads into . . .

Neccesity is however the mother of invention.  Dwarves will likely invent a lot of technology that humans at an equivilant general level of scientific knowledge did not.  Oxygen is to a dwarf very much a real resource in a way that it is not to a human peasant living on the surface, that means dwarves are naturally going to invest a lot more resources than medieval humans would in anything related to the circulation of air.

Very true, but then again this is one of those needs that can be subjective. If the need for oxygen can be met simply by building your fort close to, and with good ventilation to, the surface world or a lush cavern, then your dwarves will most likely never feel the need for fans, bellows, or even chimneys. But if the fort has to be dug deep (say, the upper layers are all sand, clearly unsuited for structural purposes), then eventually some creative soul will get sick of being short of breath all the time, & try to do something about it.

To me, it seems analogous to building a fallout shelter in your basement: Yeah, it might come in useful someday, but if your city does get nuked, chances are you're fuckin' dead, fallout shelter or not.

Yeah, why bother packing a parachute?

Are you equating the combined odds of mechanical failure / pilot error in a small plane with the odds of a nuclear strike? I guess I shouldn't mark you down as an optimist, then.    Although you do have a point in the "safety belt" factor of draught-passable doors, I have no argument for why it shouldn't be an option.

[Starver]

Ah, but (AFAIK), the airflow doesn't need to actually divert into the room, merely flowing past it should be enough, and diffusion will do the rest. I say this because I am still alive: Although I freely admit that I do not live in an underground fortress or cavern, I do keep my bedroom windows and heater vent closed pretty much ALL the time, meaning that the only openings for oxygen to diffuse into the room are the cracks around my door. And yet I keep waking up every morning. The house itself is kept sealed up pretty tightly as well, especially during the colder half of the year. So when I keep believing that a small vent in stationary air should be adequate, I'm speaking from experience, not stubbornness.

Sealed enough to currently guarantee against flooding? Or ‼Flooding‼?

Apart from relative intentions and abilities to create aboveground structures imperveous to all fluid flow, we know it's something that needs to be worked against in extensive belowground excavations in realworld applications.

Flowing past a singular aperture isn't going to work well with just diffusion. Several apertures (like insect spiracles) don't work well at room-size scales (assuming we can leave the breathing in the room to the inhabitants, if we can ensure the air is refreshed enough). You either need lung-like drawing in and out (movable partitions at the opposite wall, or maybe between two different rooms for double action, themselves impermeable diaphrams) or gill-like flow (fed through, although not strictly like gills, where you send oxygen-enriched/low-CO₂ air in opposition to the CO₂-enriched/oxygen-depleted bloodstream, which is clever but not easily applicable here).

Seriously, get small amounts of nice fresh air pumped into the rear of rooms, because the alternatives are going to be much more mechanically involved and/or breezy to implement effectively to aerate those same backs of rooms, and it'd be like living in a wind-tunnel elsewhere, even if it's possible to do.


(I keep my house sealed up too. Modern double-glazing, and no forced AirCon because it's Britain. But I don't live in a sealed tank by any means. There's at least a noticeable flow of air through my roofing (at times like these opening the loft hatch reveals significant cool air flowing down from under the rafters, if I'm below, and warm air flowing up from the living areas, if I'm above), which combines with the route allowed for by chimney-breast etc setting up circulation systems sufficient to cycle air around.)

You'd also probably die (as a typical human) of excess CO₂ before you would of insufficient O₂. Assuming that's the only pair of gases you have to worry about.

[Bumber]

Although I freely admit that I do not live in an underground fortress or cavern, I do keep my bedroom windows and heater vent closed pretty much ALL the time, meaning that the only openings for oxygen to diffuse into the room are the cracks around my door. And yet I keep waking up every morning. The house itself is kept sealed up pretty tightly as well, especially during the colder half of the year. So when I keep believing that a small vent in stationary air should be adequate, I'm speaking from experience, not stubbornness.

But how many people do you live with? Back in the early days of New York, there were huge problems ventilating apartment buildings. (To be clear: They had open windows to an "outside" area, but they're encircled by the O-shaped building so air can only get in from above.) There might've been oxygen, but the air quality was terrible. Unfortunately, dwarves deeper in the fort don't even have that luxury. Take that nasty air and send it down to even more people. You really must have sufficient air flow proportional to the number of residents.

To me, it seems analogous to building a fallout shelter in your basement: Yeah, it might come in useful someday, but if your city does get nuked, chances are you're fuckin' dead, fallout shelter or not.

Yeah, why bother packing a parachute?

Are you equating the combined odds of mechanical failure / pilot error in a small plane with the odds of a nuclear strike? I guess I shouldn't mark you down as an optimist, then.    Although you do have a point in the "safety belt" factor of draught-passable doors, I have no argument for why it shouldn't be an option.

That depends. Are you equating the odds of flooding / deadly vapors inside a dwarf fortress with the odds of a nuclear strike? I notice that part of your quote is conveniently absent in your reply.

[SixOfSpades]

Sealed enough to currently guarantee against flooding? Or ?Flooding??

Well, let's examine the situation, with 3 variations. (I'm ignoring factors like being trapped long enough to die of thirst.)
1) The room has the fanciest of doors (watertight and magma-safe, with a draught vent that can be opened & closed), as well as ventilation provided through a secure backchannel isolated from the flooding. If the vent is closed, this will indisputably save the dwarf's life. If it's open, some magma might spill over the vent while the dwarf is asleep--quite possibly killing him with fire or smoke--but if it's only water, it'll just get him wet & wake him up, at which point he can just close the vent & wait for rescue, unless he'd prefer to open the door & swim towards an exit.
2) The room has the same fancy door, with no other ventilation. It has the same risks of magma / water spilling through the vent as before, except now there is no such thing as long-term safety, giving him the choice of A: Open the door and swim for it, or B: Shut the vent, wait until the air still in the room has been depleted of oxygen, and then swim for it. (Option A is likely better, as right now there's still a little air in the hallway--later, there might not be.)
3) The room has a door that is not watertight or magma-safe, and the room has no other ventilation. If the hall is flooding with magma, the dwarf is flat-out dead, no question. If it's water, the rising water level in the room will wake the dwarf up, giving him no choice but to open the door & swim for dear life.

So, Variation 1 is the only one that can (not necessarily will) save the dwarf from magma, and also the only one that allows the "sit and wait" option. Variations 2 & 3 are virtually identical, whether the flooding is of water or magma. So, all in all, it boils down to which is easier, and/or safer, to set up?
A) An entirely separate ventilation system connecting all occupied rooms in the fort with the outside, or
B) A water or magma project that doesn't overflow into the dormitory areas.
Personally, I'd go with B. But if you prefer A, that's fine too.

Back in the early days of New York, there were huge problems ventilating apartment buildings.

That link is more about residents complaining about garbage than an actual lack of adequate ventilation. Better research material can be had at the links off of this wiki page, as well as others, I'm sure.

Unfortunately, dwarves deeper in the fort don't even have that luxury. Take that nasty air and send it down to even more people. You really must have sufficient air flow proportional to the number of residents.

Oh yes, I'm in agreement there. A few dwarves a short distance from fresh air can usually get along on diffusion alone; but anything more than that (for any length of time, at least) should require some form of directed air flow.
(Oh. Great. Another thing I have to worry about in the first year. Yaaaaay.)

Are you equating the odds of flooding / deadly vapors inside a dwarf fortress with the odds of a nuclear strike?

In one of MY forts? Yes, I am. In a fort in general . . . ah, no, unfortunately.

[Starver]

I don't even think you're discussing what I'm discussing, any more.

It is a current fact that dwarven construction is impermeable where not by design (or jamming open) explicitly non-blocking. You can decide to have 'vents' , right now, by fortification carving/construction and grate-placement (or, for doors, get something dropped in it but that's even more 'venty' than a vent). If you want fanlights, airholes or extractor fans or self-sealing stembolts conduits between voids that shut in the event of liquid flooding then fair enough. Get someone to code it (probably someone whose name is an anagram of Oatydone) to add to your need for realism.

But then realise that it's not enough to just have "open to ventilation" pathing all the way to the surface to establish if a place has enough fresh air. It'd be easier computationally (just put extra burden on the current pathing check... if a dorf can establish a path through to <random surface/outside tile> through flyable+vent_passing squares, then it resets the asphyxiation counter back to nil, otherwise up the distress value and reassess for 'injury' from that value) but it would mock the apparent realism being added.

A better alternative might be to use fluid-level calculations (freed from purely horizontal flowing) where the 'sploshing' algorithm shaves and moves higher levels of breathability and/or unbreathability and/or explodability/etc onto adjacent (including vertically adjacent) tiles, perhaps adding local slosh-cycles to sporadically follow movements of beings if you want traffic to stir things up, with each dorf occasionally 'drinking' a level of breathable/'filling' a level of unbreathable (with vice-versa for plants suited to the conditions?), and any other gas-fluidic effects also applied as far as seeps being concerned. But it'd need to be tuned to be playable (not virtually insta-death once seven 'breaths' were taken) while still a challenge (realism demands that diffusion is not enough for the kind of fort I currently dig). Computationally expensive (imagine a whole-fort flood constantly going on, even if you 'tick' it only every hundred or so base tick-cycles, for both sloshing and breathing) and a one-entrance dorm (even with multiple vents onto the same group of several adjacent tiles) could easily suck the oxygen out of the air and thus the life out of the sleepers if it has an affect anywhere.



So, back to 'realism', whether done by sloshing or pressure-related movements(/dependencies) of air, also borrowed from the liquid algorithms, to simulate air-flow tracks (trace up-stream to see what has done what to the air-quality, each time you test), I contend that encouraging flow in the back of a room and out of the front (or vice-versa, but with other problems in that case) is the hypothetical better solution than the hypothetical diffusion-venting method for the hypothetically new ventilation system that is hypothetically more realistic.


And, while we're at it lets ensure that our habitual belowground plants are radiotrophic (or something similar) and allow them to act as dark-enabled 'photo'synthesisers to freshen up air. Maybe all that is needed is sufficient built-pots of collected sand/clay(/soil) growing a stand of dimple-cups in the corner of a vulnerable room, howevermuch ventilated or not. Perhaps requiring some ground granite (or, for extra oomph, pitchblende) to work properly.

This would explain some of the belowground respiratory bioligies possible, I imagine. Both figuratively and once gas-content became an actual calcuable issue.

[GoblinCookie]

Very true, but then again this is one of those needs that can be subjective. If the need for oxygen can be met simply by building your fort close to, and with good ventilation to, the surface world or a lush cavern, then your dwarves will most likely never feel the need for fans, bellows, or even chimneys. But if the fort has to be dug deep (say, the upper layers are all sand, clearly unsuited for structural purposes), then eventually some creative soul will get sick of being short of breath all the time, & try to do something about it.

Is that not really a distinction between hillocks and fortresses?