Natural Ventilation...

Natural Ventilation...a subject not often discussed or considered and in light of the current trends by the building industry on insisting that buildings need to be "air tight" and not just "draft proof" which in turn demands more technology to ventilate them and make the systems of architecture work, we as natural builders need to understand the importance of these real world aspect of architecture.

EcoMENA is just one of the many up and coming facilitators of natural building design that understands the value of relying on "natural systems" for ventilation instead of mechanical.

Hi Jay,

Me again with a wagon full of questions ...

The field of ventilation is huge and i think one of the most misunderstood if hardly known.
I am curently living in an all concrete graveyard of flats devoid of anything alive.
That is except mold and this is because of high humidity (>90%), problematic especially during winter.
The humidity gathers in the coldest spot because of terrible design ... nothing i can change.
The only solution that worked was a mechanical ventilation system.
So i built a homemade one made from whatever materials i could find.
I also added a heat recovery unit, also homemade.

The effect was dramatic, no more humidity, no more mold, and above all, clean air.

But it has it's limitations and you know them better than me.

I do not plan to live here the rest of my life ...
I want to live in a dwelling built by myself.
And ventilation is key. Not having it won't do it.

So, reading and searching, besides opening doors/windows on the opposite sides, building persian windcatchers and things like that, what source of more detailed documentation is to be found?
I am also in a more precarious position because of 2 key elements :
1. Wife can't stand even the slightest drafts ...
2. After getting myself used to clean air, i am having troubles with even cooking smells ...
These two are somewhat antagonistic and i don't have a solution for them.

Please share whatever knowledge and experience you have in this field.

PS
Friends and family think i'm nuts. They don't understand why i'm so obsessed with fresh air inside. If i want it i should go where it's plenty of it, outside ...

Hi Ionel,

GREAT...I love folks that think and ask questions...

You are most correct, we don't think enough about this topic of ventilation, and like inferences on another post, we have gotten use to living in aquariums or more like terrariums. We have built these "modern habitats" that aren't even as functional as most I would design for pythons or hummingbirds in a zoo. These modern "air tight" buildings only work in "concept" and not in the realities of the the "real world" ...or...if they do, they don't for long without major intervention and reliance on all types of $$ technologies. I too have a beautiful wife that is not a "permie" and can feel the draft of a "moth wing" and does not have a terribly good grasp on what it takes to achieve the "living environment" she thinks she "needs," which is actually a "want" not a need.

I am so sorry to read about your current living arrangement...You just named another issue with modern OPC concretes...they are just a "dead material" and anything that does grow or live on or within them, is usually not healthy for humans. I find them to be very much like old discarded kitchen sponges. They suck up water, old it and basically become culture dishes for rot and mold... OPC cement architecture is currently a dominating forces in the world of "modern architecture,"...and...one of the most unhealthy materials I have ever had the displeasure of working with for most applications...

Building your own ventilation system (aka "iron lung") is really the only recourse for a structure like you have described having to live in....I am sorry you had to do that, but glad you did...Does it have good filters and do you change them regularly?

I would also suggest, if you are going to be there more than a year more, to look into building a "living wall" and perhaps have this sit in a vivarium base to the assembly above. I like to see about 1 square meter for every 10 square meters of living space minimum. These may add humidity, but it is the correct kind of humidity, plus they "scrub" the air and energies of a living space.

So, reading and searching, besides opening doors/windows on the opposite sides, building Persian wind-catchers and things like that, what source of more detailed documentation is to be found?

I am afraid the documentation is ether limited, tech industry laden opinions (not good information) or resources we must glean and extrapolate for ourselves from topics like the living walls and other sources. Even some of this is more "new age snake oil" info rather than good tangible data. I will say that there is a great deal (most of what we need?) to be gained by simply living in a house and going in and out of doors, opening windows with the correct seasons, good roof overhangs and porches...I can't encourage folks enough to design and have portico, veranda, porches, engwa and the related eave extensions on there homes... These extensions of the roof's drip line are extremely valuable in so many ways...including good ventilation enhancers...

1. Wife can't stand even the slightest drafts....2. After getting myself used to clean air, i am having troubles with even cooking smells...These two are somewhat antagonistic and i don't have a solution for them.

Well Brother...I am afraid they are for many of us......and...I am not sure even when we do "fix the issue" it ever really does get fixed the way our "other halves" would like us to... ...

Seriously though, these are sometimes a real issue for some folks and I would never build a "drafty house." Actually, that is my entire point in architecture..."draft proof" not "air tight." However, with that said, if someone wants "fresh air" it will require some movement of that air. I like doing that with the "living wall" concepts and adding features like the vivarium with small water falls, pools, and section of the "living walls" to have moving water (aka dribble falls) on sections of them or behind them. This adds the correct type of humidity and the correct types of "air movement" not a draft per se. If simple solar operated and powered fans that come on and off according to temperature and/or times are of great value...In the past, even 5000 years ago there where hydro powered small "wave fans" to be found in more "up scale" architecture during the hotter seasons.

As for kitchen smells (I like them personally, but I dry herbs in the house and burn sage so like these organic scents)...I like two of them...one for summer (aka the "Summer Kitchen") that is outside and the other that is by a cooking hearth and wood oven inside...Neither are as extravagant as many think they are...

Friends and family think i'm nuts. They don't understand why i'm so obsessed with fresh air inside. If i want it i should go where it's plenty of it, outside ...

Well part of that is true, being "outside" (or bringing the outside in) is a better solution to many of these challenges. I have gotten use to folks thinking I am a "bit nuts" a long, long time ago...

Ionel Catanescu wrote:Hi Jay,

Me again with a wagon full of questions ...

The field of ventilation is huge and i think one of the most misunderstood if hardly known.
I am curently living in an all concrete graveyard of flats devoid of anything alive.
That is except mold and this is because of high humidity (>90%), problematic especially during winter.
The humidity gathers in the coldest spot because of terrible design ... nothing i can change.
The only solution that worked was a mechanical ventilation system.
So i built a homemade one made from whatever materials i could find.
I also added a heat recovery unit, also homemade.

The effect was dramatic, no more humidity, no more mold, and above all, clean air.

But it has it's limitations and you know them better than me.

I do not plan to live here the rest of my life ...
I want to live in a dwelling built by myself.
And ventilation is key. Not having it won't do it.

So, reading and searching, besides opening doors/windows on the opposite sides, building persian windcatchers and things like that, what source of more detailed documentation is to be found?
I am also in a more precarious position because of 2 key elements :
1. Wife can't stand even the slightest drafts ...
2. After getting myself used to clean air, i am having troubles with even cooking smells ...
These two are somewhat antagonistic and i don't have a solution for them.

Please share whatever knowledge and experience you have in this field.

PS
Friends and family think i'm nuts. They don't understand why i'm so obsessed with fresh air inside. If i want it i should go where it's plenty of it, outside ...

Ionel, according to the MODs we're not suppose to use the word "you" in our post so forgive me if my question is lacking a personal touch or feeling.

The heat ex-changer material used is? A PIC available? Is there pyschrometer data available before and after the HRV install? Actually, if it is regulating moisture-RE Humidity it is a ERV.

ASHRAE 62.2 and BSC-01 are in the industry standards for ventilation rates as flawed as they are. There we huge debates between ASHREA and Joe L. Pick your poison! They are a poor attempt at trying to make sense out of sealing toxins into building's at levels as low as .6 ACH (Air Changes Per Hour) a standard designed in Germany for Germans called "Passive House Planning Package" PHPP . America tries to make sense out or recently with a new up and coming PHIUS "Passive House Institute US" since PHPP did not work in USA, wow! Both fail to link toxins or IAQ to a standard flow rate in CFM and the ACH measure is flawed (long story), or have any correction factors for toxins occupants bring in the home after the build. America's Energy Star "Indoor Air Plus" IAQPLUS and certification program is flawed the same way.

The efforts are a result of very limited hot box testing that for one BSC and five big fish manufactures conducted that quantified r-value knock down factors for fiberglass insulation in the USA and word from Germany that got the ball rolling and took it too far imo. BCS study "Does Air Trump R-Value" Yes, nothing most did not know but the test quantified it for 8 different wall assemblies. Good info on how sensitve US walls are. In parts of Germany and China we can find an abundance of natural building materials off the shelf unlike the USA so, following their protocol makes no sense. If you look at PHPP you don't find the majority of materials listed in the database from HD and Lowes or used in US mainstream construction. That really becomes a problem not only for ventilation rates but also for using much of the HVAC software Germany uses in US applications.

What the US did not think about is there are ways to design envelops that don't degrade in r-value, degrade structurally, create fungi, from moist convective loops in wall cavities, or, there are envelopes that are hygroscopic and manage air and moisture well that don't require . 6 air changes or walls with barriers that do not allowing drying when the outdoor or indoor humidity levels are high. Air alone does a poor job at drying mass, worse at removing fungi or preventing it, we need a heat exchanger as in an inert wall the radiates enough heat or breathes and exchanges enough air to dry the wall out once the material has reached it's max moisture content. The property also drops our cooling loads, especially if it is in the ceiling. That depends on alot of factors (density, thickness, specific heat, conduction, other mass, etc) it gets complicated, too complicated for an excel spread sheet or PHPP, PHIUS.....for highly insulated envelopes that can more readily make sense to most people, those design tool can work fairly well at determining ventilation rates or whole house air changes, but for hygroscopic thermal mass designs you need better software that is not available in this industry to most, other than highly trained Engineers.

Anyway, yes America put the cart before the horse air sealing homes down to German standards before the had the materials to support it. We don't want big holes at large penetrations and heating or cooling the outdoors, granted, at the same time we don't want to suffocate ourselves in sick homes.

Terry, thank you.

Ionel, according to the MODs we're not suppose to use the word "you" in our post so forgive me if my question is lacking a personal touch or feeling.

No problem. I'm not native english speaker and have different understanding.

What you say is oh so true about the US.
But i don't live there and there are no residential ventilation codes around here.
People don't know what is ventilation (only in large commercial/industrial buildings).
Anyway, the majority of city buildings (the new-ish ones) were built in an era of intense Industry = King = our new God.
Thru Industry and whatnot we will overcome our problems ... a bunch of baloney ...
Purpose was to denude traditional villages and create huge cities with these people to fuel the industries.
Huge concrete graveyards. Not much can be done about it, period.

My solution was the only one that works. I also bought a dehumidifier but even 2 liters of condensed water / 24 hrs did not do enough.
The way the building is designed and constructed makes impossible any form of "betterment".
You ask about the heat exchanger, measurements, images ?
I don't think they matter since it was mentioned as part of mitigating the madness ... but i will give some details on it.
It is very similar with this one.
The heat exchanging material is Aluminum cooking foil, the 60micron type, $2 in total.
It is sandwiched between wood frames made of 10mm wood battens.
It functions in a counterflow fashion.
It has 2 centrifugal fans, 1 exhaust and 1 intake, balanced for pressure.

I've designed the whole thing to draw "used" air from kitchen and bath and put fresh air into the room with outside view (basically a balcony).
That is the coldest place and due to the way the apartment is designed, pretty much all humidity will go to this balcony, where it's coldest.
So, the moist air is drawn out of the room thru the bathroom and kitchen and expelled outside.
At the same time, outside air is brought to this coldest humid spot.
BUT, when outside is -15 centigrade, this air is also Very Dry.
It is heated in the exchanger.
So if the outside is -15, inside is 22, the incoming air after the exchanger is 17 but with much less humidity.

I've build the ventilation system to get rid of the winter humidity which can not be controlled otherwise.
Bonus points for the HRV is that i have fresh air and don't lose much heat.

Conclusion,
America put the cart before the horses, we followed suit but in our own very national way. Pick you poison indeed.

Jay, where do i begin ...

Does it have good filters and do you change them regularly?

That made me laugh. Seriously.
The neighborhood i live in makes them obsolete after 2 weeks.
I have given up on them.
My place is 100m from the road that is practically heavy traffic ring "around" the city, but it's actually inside the city.
The amount of dust makes any filter obsolete almost immediately.
There are also tire and detergent manufacturing around the corner ...
So if i breathe this air outside i can't help it on the inside, there is no point.

People get accustomed to the "bad" and call it "normal".
But i want out. VERY out.
This is why i research so hard.

The living wall is an option for the future build only, far away.
As it is now, the building is thought out (if it is thought at all) and made in such a way that any betterment is impossible.
Small, crammed spaces, all concrete, stupid local regulations forbidding anything "natural".
And, these places have neighbour cohabitants.
They are not much into this "nature" stuff.
Remember the part where "if you want nature, go outside" ?

The good (somewhat part) is that once the weather warms we have all windows open pretty much 24/7.
Cooking outside will get you fast a TV spot and a hefty FINE.
Winter is worse but i have the mechanical ventilation.

Ok, enough of this moaning.

I will list some things regarding natural ventilation i have found.
If there is something to add, please do.
I will also add some unanswered questions at the end.
So, natural ventilation can happen when:
1. There is a pressure difference between 2 spots of the house
2. When there is a large temperature differential between 2 spots of the house

Practical solutions belonging to the first would be:
1. have some openings on parts (usually opposing) of the building that have different pressures - upstream or downstream from wind
2. have some windcatcher tower like the persians/egyptians had
3. somethinng like this ?
4.

Practical solutions belonging to the second could be:
1. Put a chimney high, painted dark, drawing air from the house, possibly doubling as a windcatcher. Of course an intake must be provided too in one form or another.
2.

These are things that can work.
But how would one materialize them ?
I mean, the air flow should not be disturbing to the inhabitants in any situation.
And it has to flow thru the entire building/separate rooms.
And it has to work in all seasons and all weather (with or without sun or wind).

I think a combination between all the above and maybe more could achieve the desired goal.

Ionel, Jay, I'm short on time like last night sorry about all the typos I'm not as good as Jay. The ERV must be placed in a sweet spot since AL is not hygroscopic (able to hold condensation long enough to dry high levels of humidity, or something else is going on that is why I asked for a pic. I'd never use it as a vapor or heat sink in a wall assemble, it makes a good solar short wave or radiant heat reflector. Natural Hygro-thermal mass would be clay due to it's large pore structure and moisture holding capacity that can hold high levels of condensation and dry fast, lime, MGO, others. There are plenty of all concrete homes that do not suffer high humidity levels nor fungi issues, that depends on the mix, binder, aggregates, climate zone, variables. The word 'concrete' can mean alot of things. It has saved lives from tornados and hurricanes, I prefer in these zones over 2x4 construction for that reason. I'm not a fan of OPC either but it does have high mechanical properties despite what it does to the atmosphere, MGO is better especially light burnt at 800-100 F with much higher mechanical and thermal properties per density which is one of the reason OPC does not allowing drying fast (high density to get the high mechanical properties) but, expensive. MGO in the mix does wonders to OPC, and MGO board over OPC concrete floors does too since the perlite core is hygroscopic and MGO does not conduct heat or cold, it you can stand 1/8-1/4 inch added floor height, and on the ceiling. Another board is low density fiber like Durisol or Faswall (made of clay, wood, MGO). That is a retrofit solutions if there is no sweet spot like Ionel. We get very high humidity levels here all year round. and so does alot of our country especially the south.

In new construction the best way to mitigate indoor humidity to the 45-50% RH for healthy eyes and skin, lower cooling loads, etc....is the envelope I described above. I'm using a mineral wool core and MGO skins moist (3 layers, no barriers tyvek, etc) convective loops do not degrade since my assy is a vapor and heat/cold-dew management system. MGO will also absorb CO2, for CO I won't have a source, Radon mitigation as reqd. From there I'll exhaust cooking areas/high RH outdoors that will help somewhat but my envelope is the main controller, with the proper CFM. It is all about CFM, not ACH.

Vapor drive is high RH to low, pressure (PSIG) the same, and they can be opposite including winter. Forced air is not a good means for changing vapor drive, one has to lower the humidity to where you want it to flow or equalize just as pressure deltas. Cold condensation can accumulate as dew, removing it to a lower RH point outside is another challenge, and if you remove too much it can cause skin and eye issues, especially in a forced air HVAC building. A physcrometric meter is needed to design, then a humidstat with RH sensors (dry vs wet bulb) that sees the RH levels to properly control it, again by natural air friction over surfaces that cause slight heat rises and drying depending on the material properties. If that does not work the design is bad (saturated usually by barriers) and envelope. A properly designed envelope can do this naturally without air or drafts. If my clients don't mind vacuum drafts and depressurizing (PSIA) the building I'll install a cooling tower or season extender or Atriums, along with Vastu principles. Now the lower indoor pressure can be a problem if too cold outside or atmospheric pressures are high. More effective than clerstory windows due to symmetry if installed in a proper location that understand pressure differentials.

Sending vapor or dew to place where it can dry is not different than we do with fluid systems like fuel/hydraulics on auto, we push vapor out to the engine or a heat xchanger. In the case of a building that is the passive envelope, active/mechanical as reqd. Ironically, the active systems in America are getting larger as are the flow rates to offset bad passive designs.

I'm right in the middle of a new aircraft design program and my time is limited. I finally got a day off today just to work on my spec home design. I see I made alot of spelling and grammer errors and may have got confusing above. Sorry about that I am not a great writer or speller. I usually have pro's do my tech writing for me.

So I'll attempt to break down what I was trying to say above to laymen terms. It does get complex especially in light of all the mechanical (HRV/ERV) blower door test, exhaust, intake, natural air flushing, etc... but I'll try my best since this is an important subject. Feel free to do parallel research, add to or correct any statements.

I mentioned why we have come to air sealing envelopes and why it is important, more important for some types or loose fill insulation like fiberglass as opposed to dense pack cellulose, mineral wool, lime cretes, mass, etc...that being the convective loops that Building Science Corp (BSC) and a 5 other major insulation manufactures quantified by hot box testing for 8 different wall assemblies. A hot box test is a lab test in a controlled environment. The test gave r-value reductions or I call "knock down factors" when moist air enters a cavity or loops around bringing hot and/or cold air transfer, by air to the indoor or outdoor layers (drywall, sheathing) etc.....It is also referred to an "Air Barrier" ..As we know air is one method of heat transfer, conduction and radiation are the others. This gave birth along with Germany's Passivhaus methods (PHPP) to blower door testing and air sealing, and recently (last year if I remember correctly (IIRC) new American Standard PHIUS. The test measures the amount of air that escapes a pressured home our a door in "Air Changes per Hour" flow rates or ACH. When the home is pressurized to 50 pascal pros use infrared, or PSIG (gages) to try and find where CFM is moving to large holes. CFM is Cubic Feet per Min and is a flow rate too. ACH is a whole building air exchange rate. IE: .6 ACH @ 50 Pascals qualifies a home to be Passivhaus certified and it takes alot of air sealing stud bays and large penetrations, and money in retro-fits or "deep energy retrofits", or new construction. That gave birth to ACH standards ASHRAE 62.2 and BSC-01, based on alot of factors except what is really needed.

I mention the envelope since we'll see how it functions just like a ERV (Energy Recovery Ventilation) or should to avoid these moist air sensitive r-value knock down factors and IAQ issues. In new construction that is where natural ventilation starts (more later). Then we can discuss the need or not for mechanicals that in some cases can better the IAQ (Indoor Air Quality) or make it worse, depending on materials and climates. We'll also look at the difference between a HRV (Heat Recovery Ventilation ) a much simpler unit, and how to DIY either if needed or purchase out of natural materials.

To get started we need to understand some terms and establish some design criteria.

1. The first to understand is gases and partial pressures. They dissolve, diffuse, and react according to their partial pressures, not according to their concentrations in gas mixtures or liquids. Also true for the chemical reactions in biology. The necessary amount of oxygen for human respiration, and the amount that is toxic, is set by the partial pressure alone. This is true across a very wide range of oxygen present in the various inhaled breathing gasses or dissolved in the blood. ASHREA 62.2, BSC-01, PHPP, PHIUS, Energystar IAQPLUS, fails to correlate to IAQ.

I know this is contradicts alot of peoples views that there are other physical properties like temperature, air velocity, etc that dominates. I'm not a medical professional so lets stop here and if someone has more to add please do so we can establish this is a design criteria, that being partial pressures and oxygen levels in the air are of utmost concern when we are discussing air born toxins, the amount of pressure not concentrations that causes penetration to our bloodstream. There are IAQ meters that measure part per million (PPMs) which is concentration levels, not partial pressure. So how do we measure partial pressure, is it sensible, can we control it in the home? What can we do to mitigate the risk I'll discuss later.

Chew on that a while and I'll be back when time permits to define some more terms like ERV, HRV, and how the envelope of a home should function like a ERV. In very cold or hot climates air flushing does not work, or for people with allergy problems, or areas that have highly polluted or industrialized outdoor air. The good news is there are ways to design envelops and IAQ like nature to reduce the toxic PPMs and gaseous partial pressures.

Wow, Thanks Terry for such a MASS of understanding.

It did take me a lot of re-reading to get a grasp.
I will chew on it more and can't wait for the next parts.

Regarding my Alu foil, it's part of the exchanger core, not in the walls.
The exchanger is 3ft long , cross section is a square of 1ft.
It is tilted to one side lengthwise so that the condensation on the Alu foil can gravitationally flow to the lowest part where there is a small hole, draining to the outside.

The current apartment (studio) is small and humidity created by breathing, cooking, washing, etc travels extremely fast everywhere but issues happen only in the coldest part.
I can't retrofit anything anymore.
That's why i did the HRV/ERV system.
It's the least worse solution (for winter).

I am looking forward to all your posts to get a better mental picture on what (and how) a building should do to IAQ.

Ionel, now that makes sense I must of missed where the draining off condensation part when I was in a hurry. There are more effective ways to use it but that takes a phase change. That is where it gets complex so lets take it slow.

Ionel, I know you are interested in this subject and waiting for my post. Along with this thread, I've taken an integration approach to the related questions seen on different threads. In my profession of back in the day of throwing designs over the fence for the manufacturing people to figure out, times have changed. Now designs have many disciplines looking at them, Integration experts making sure all systems are relating, can be built, and not some pipe dream. The CAD model software has come along way too, making disciplines talk to one another such as "Interface Control Models" "Relationship Design Models" ....so that is why I took a holistic air flow relationship design approach. Out of respect I discussed it with Jay and I think he is ok with it.

Thread is here if interested: https://permies.com/t/48019/natural-building/Indoor-Air-Quality-Healthy-Building

Here is a research paper on the topic
Wind towers