11 ms·

How to better ventilate your home

101 points by arunbahl 6y ago

shalmanese 6y ago
The reason why paperweights exist was because, prior to air conditioning, offices were built to have a constant flow of air through them to cool down workers.
- motorbreath 6y ago
  I was going to mention something similar to this! We've all experienced first-hand how irritating it can be when your papers start flying all over the place because the windows are open. There is a lot of interesting history behind paperweights and I would love to find some of the originals in a museum. https://www.paperweight.org/museums/ https://www.paperweight.org/museums/
ThePadawan 6y ago
Surprised to read nothing about the German fascination with Stosslüften (opening as many windows as possible as wide as possible for 5 minutes, twice daily. Literally "shock airing" or "surge airing"). Every apartment I moved into (in Switzerland) had me sign a waiver that I read the instructions how to do this to avoid mold growth.
- subpixel 6y ago
  As an exchange student in Germany I never got accustomed to the urgency with which my host mother would rush into my bedroom and throw open the window exclaiming "Frische Luft! Frische Luft!"
  - ThePadawan 6y ago
    I personally got into the habit from school, where opening the windows after a double lesson (90min) before the next class came in was just the polite thing to do. Nothing worse than walking into a room with air that's been depleted of oxygen (then reading Theodor Fontane).
- 0x1F8B 6y ago
  Do people do this in the winter as well?
  - ThePadawan 6y ago
    Yes! You'd be surprised how little it changes room temperature. A lot of the thermal mass is conserved in the walls, furniture and people in the building.
    - heffer 6y ago
      This is true in Germany, where most in-home heating systems use radiant heat. I have since moved to Canada and my house uses forced air and a gas furnace. I can still feel cold at 21.5°C in my forced air heated house which I never did in Germany. Radiant heat does a much better job of heating the things in your house than forced air will. Heating things, and not just the air, is what has them store that warmth across Stoßlüften-Sessions. So technically, Stoßlüften works well with radiant heated homes, less so with forced air heated homes.
      - ThePadawan 6y ago
        That's true! I was also thinking about how German houses also tend to have relatively thick and non-wooden walls (since compared to the US, there's no significant earthquake risk). That adds a lot of thermal mass as well.
      - CyberDildonics 6y ago
        Is it much more likely that there is a difference in how your thermostat is placed or there was better insulation (so that heat ends up more even).
        war1025 6y ago
        Over the past few years I've been working on improving the thermal efficiency of our house, which has mainly been strategic air sealing / adding insulation. One thing I've definitely noticed is that as I improve the insulation in one area of the house, other areas will get colder. The reasoning is that the worst insulated spots in my house were near to the thermostat. Now they they can maintain heat decently, the further way areas are allowed to cool more before the heat kicks on. The first tool someone should buy when investigating the thermal efficiency of their house is one of the cheap ($30- $50 if I remember right) infrared thermometers. The temperature of your house is likely 5-10F off from what your thermostat claims, particularly the further you get from the thermostat.
- csunbird 6y ago
  It is also a tradition in Turkey too. I have been taught to open windows first thing in the morning to clean up the air.
- rsync 6y ago
  We do this in my home. We get to cheat a bit since we live in California so it doesn't really mean anything to open the windows for 20-30 minutes in the winter. Regardless, I cannot abide stuffy/dead air and I will ventilate any house or apartment we are staying in regardless of outside temperature. I believe this to be a very underrated disease prevention tool.
  - deleted 6y ago
    [deleted]
- shostack 6y ago
  Is there any research to back up the practice?
  - BitwiseFool 6y ago
    And, does it circulate enough air when there isn't a breeze?
    - olau 6y ago
      No, although if it's cold outside, you might get a sea breeze effect. But most of the time (say > 80% IIRC) in Northern Europe there is at least some wind, and having a large cross sectional area is just incredibly efficient. You can try the experiment yourself. The main problem is that it is a manual process requiring discipline, and if you don't do it, your brain suffers due to elevated CO2 levels.
      - ThePadawan 6y ago
        Also worth mentioning that the most common kind of window over here is hinged, not double-hung. Meaning you can actually open them to create a gap of 100% of their area, not <= 50%.
- post_break 6y ago
  In Houston you would be bringing the mold inside due to the humidity.
- marton78 6y ago
  We do this in Hungary, too. I'd venture to guess this is probably the same at least in all of ex-Habsburg Central Europe. I don't know how people in other parts of the world can stand the stench of used up air. You won't notice when you're inside the room, but coming from the outside you feel like suffocating. Or maybe where this isn't common, people have active ventilation systems?
- syntaxing 6y ago
  How do you adjust for this during the winter? Do you turn off your heat or just keep the heat on and open the windows?
  - ThePadawan 6y ago
    I would do nothing. For 5 minutes, turning off the heat wouldn't do much at all - the big heaters are generally very laggy anyway.
doctorhandshake 6y ago
I’m surprised there’s no mention here of heat recovery ventilators (HRV) or energy recovery ventilators (ERV) here. New buildings are increasingly designed to provide regular air exchange (fresh air replacing indoor air) while retaining thermal energy with these devices, and, in the case of ERV, retaining humidity.
- jonstewart 6y ago
  Yeah, ERVs are amazing. I want to install one in my house just to provide fresh air all the time.
- compumike 6y ago
  Agree. HRV / ERV is a powerful concept because it allows you to design better insulated buildings, both with fewer air gaps and thicker wall insulation, while still reducing indoor CO2 and humidity levels by bringing in fresh air. On the downside, like much in the HVAC world, it requires new construction or a fairly major retrofit to take advantage of it. My guess is that it's only going to make sense for new higher-end construction where other attention is being paid to energy efficiency. (Though I'd love to see a window box HRV for renters, just like window box air conditioners.) If you haven't heard of HRV / ERV yet, this video shows how they work in an impressive but simple demo with the 4 temperature sensors in the last few minutes: https://www.youtube.com/watch?v=QOSelUK6dpQ https://www.youtube.com/watch?v=QOSelUK6dpQ (Also compares aluminum core heat exchanger vs. desiccant enthalpy wheel) For the DIYers, here's a forum full of people building their own HRVs: https://ecorenovator.org/forum/showthread.php?t=891 https://ecorenovator.org/forum/showthread.php?t=891
  - amluto 6y ago
    They don’t necessarily need a major retrofit. Lunos makes clever paired half-HRVs that require two wall penetrations but no ducts. Zehnder makes single-room through-wall HRVs.
- mherdeg 6y ago
  Yup. Now that I'm measuring how much CO2 I have indoors and can watch what happens when I open a window and it equilibrates, it's really hard to resist 2021+ plans to retool the HVAC to put in a fresh air ventilator. There were also a few days this summer where it was 50°F and low-humidity outside, but 78°F inside, my preferred temperature was closer to 72°F, and I wished I had some better way than "open a window and stick in a Lasko box fan" to cycle in cool outdoor air.
fatnoah 6y ago
What an odd article. I'd love to know more about the author's background where he's just now considering airflow in a home. Maybe it seems strange to me since I was in my late 30's before I lived anywhere that had air conditioning, so open windows, fans, cross-drafts, and general air flow were the norm. I also want to see what happens when the author discovers the whole house fan. My very first house had one and it was amazing. Crack open a window in each room and activate the fan. Instant breeze and air circulation in every room with somewhere around 6-8 air changes per hour.
- senux 6y ago
  I believe this is related to the number of people locked at home.
- war1025 6y ago
  I have been very tempted to buy a whole house fan for a couple years now. My compromise has been to put a box fan in our attic access and leave that running, which does more than nothing, but I have to imagine a proper house fan would be much better. I've never actually been somewhere with one to know what to expect. I've heard good things though.
  - fatnoah 6y ago
    It's amazing when it works. In the summer, once the air outside was cooler than the air in the house, I'd turn it on. In about 10 minutes, the entire house would be the same temperature as outside.
  - EricE 6y ago
    Get the right one and they are quite, effective and cost efficient too! I like designs like these: https://quietcoolsystems.com https://quietcoolsystems.com It took a couple hours to install, mainly because I went back and forth where to install the intake vent. I had power readily available from a hallway outlet - added a switch above the outlet, carried it up into the attic and to the fan. If you aren't comfortable doing your own wiring that will be the hardest part of installing the fan. The rest is simple - cut a hole in the drywall of your ceiling where you want the intake, mount the insulated box with the insulated dampers that close when the fan is not in use, hang the fan with the proper 90 degree bend in the duct, wire it in and finally snap the grate on and you are done. The only "glitch" I had with my install is I had the fan pointed down a bit too much and my attic has blown in insulation (ugh). The fan ended up blowing a big "hole" in it. So I adjusted the fan, raked the insulation back into place and haven't had an issue since. My air conditioners each use about 2400 watts each (I have two!), the motor on my whole house fan is around 640 watts. We had an exceptional fall the year I put it in, and it more than paid for itself. And I got the benefits of fresh air. I live in the Mid Atlantic so spring and fall are the biggest time of year I can use it, but this year our summer wasn't too bad with humidity so I used it most of the summer too. It's amazing how much heat you can tolerate if you have a steady breeze. I highly recommend them! My only complaint is I wish mine had variable speed. There are many times at night it gets way too cold to run at normal speed, but if off the heat of everything in the house will heat the interior back up again without at least some airflow. With the size of my house I need to add a second one anyway to get enough airflow/turn over so I'm thinking about one of their units that has two fans - can run just one for a lower amount of air volume. One of my best home upgrades, that's for sure!
bluGill 6y ago
Only useful if you live in a climate where the outside air is acceptable for indoors. Since this is from Japan I believe that applies. Where I live the outside temperatures get well below freezing for months at a time so ventilation alone isn't useful
- timw4mail 6y ago
  Japan is a very temperate place, but heating is generally not central. Drafts of ventilation would still be cold, but not nearly as wasteful as in a centrally-heating building.
DoofusOfDeath 6y ago
I started taking IAQ seriously when I soundproofed my home office. The soundproofing made the room nearly airtight, so I had to think about (at the very least) CO2 buildup within the office. I've hit an interesting problem regarding CO2 monitoring: calibration and validation. Every IAQ CO2 meter I've come across allows self-calibration and/or calibration by exposure to "open air" which is assumed to be about 400 ppm CO2. But none of the meters provide any means to calibrate / validate CO2 levels other than the reference level. For example, suppose I buy two CO2 meters from Amazon. They can both tare to 400 ppm. But once the CO2 in my office builds up, one might read 1200ppm while the other reads 800ppm. According to medical literature, 800 ppm vs. 1200 ppm is a pretty significant difference for human mental performance. If the CO2 level is actually 1200 ppm, I want to crank the office ventilation system, even though it means higher background noise. At just 800 ppm, I may prefer the quiter work environment. Another downside to this difficulty in testing is that it's hard to truly evaluate a particular meter's performance. Which seriously limits side-by-side comparisons of different models, and makes it harder to hold manufacturers / retailers accountable for poor performance.
- joekrill 6y ago
  Not to derail the conversation, but I'm curious about how you soundproofed your home office. Do you have any information about how you went about that and what was involved? I've been looking into this myself recently.
  - DoofusOfDeath 6y ago
    One of the key takeaways is that the approach depends heavily on the space you're trying to soundproof, and just how much sound reduction you need at various frequencies. Feel free to DM me (see my profile) if you'd like to talk specifics.
  - turtlebits 6y ago
    Depends on what you're looking for but adding an additional layer of drywall (5/8) with acoustical sealant sandwiched is an inexpensive way reduce sound transmission.
- 6y ago
jonheller 6y ago
I always assumed running air conditioning with windows open was incredibly wasteful. Is this because Japan's summers are more temperate than where I'm used to (Northeast US)? I do find myself sometimes running the AC with windows open when it's cooler outside than indoors. For some reason it can be 65 degrees outside but 75 degrees indoors.
- fiddlerwoaroof 6y ago
  Why would it be wasteful? If the house is warmer than the outside air, opening the windows until outside and inside equalize should save a bit of energy. (Assuming that the change to the airflow patterns isn’t relevant)
  - smegcicle 6y ago
    I have no idea to what degree, but I think humid air reduces the efficiency of AC.
    - nbutyllithium 6y ago
      A bit of a complicated subject but the short answer is you're correct humidity does reduce the efficiency of air conditioning. The reason why(/long answer) is that as it cools the air the humidity in the air (i.e. water vapor) will condense into liquid water. Water requires a fair amount of energy to be removed (known as latent heat) to make this change and none of that energy removed actually changes the temperature of the air (all of it goes into changing the phase of the water). Therefore a high humidity load results in a lot of the cooling potential getting "used" up removing humidity first.
- fomine3 6y ago
  It is said by manufacturer like Daikin that stop&start A/C is inefficient than continuously running. (especially on summer, YMMV)
kyledrake 6y ago
I recently purchased a home and spent some time improving ventilation in it this year. This is a home in Minneapolis, so just "opening a window" is not an option, as it would be too cold in the winter and dramatically reduce energy efficiency. Its effectiveness also changes based on factors like the wind, and the temperature difference between inside and out. The general strategy for doing this right now with existing homes is to insulate your home as well as possible for energy efficiency, then install a continuous ventilation fan. This is essentially a bathroom fan, except that it runs all the time at a constant low speed, helping to circulate the air through and out your house by "pulling" a designed amount of air through the cracks. I didn't want to punch a new hole in the house just to do this, and already had a bathroom fan installed, so as a hack I just turned it into a whole house ventilation fan with this: https://www.aircycler.com/pages/smartexhaust https://www.aircycler.com/pages/smartexhaust Basically you calculate how much CFM you need per hour based on the square footage of your house, and then you set it on the fan control. It still acts like a bathroom fan, except every hour it also runs for a set period of time (in my case, about 12 minutes). The standard for this is ASHRAE 62.2. Use this to calculate the CFM for code: https://homes.lbl.gov/ventilate-right/step-3-whole-building-ventilation-rate https://homes.lbl.gov/ventilate-right/step-3-whole-building-... Then the formula for calculating the fan run time is on this sheet: https://cdn.shopify.com/s/files/1/0221/7316/files/AC_DOC_7_0_SmartExhaust_Cut_Sheet_rs_20ce4f30-fa23-4dc0-a879-ce2e765fc31b.pdf?v=1593031639 https://cdn.shopify.com/s/files/1/0221/7316/files/AC_DOC_7_0... And presto, you have a ventilation system without having to do a lot of work. Do _not_ try this with a crappy, rusty old bathroom fan - clean or replace the motor first, and for extra credit, use an arc fault circuit interrupter on the breaker so if the motor fails it will blow the fuse instead of potentially causing a fire. Note: This is really just to manage general air quality and VOCs. If you want to specifically make ventilation for COVID-19, that's a different problem. They focus on Air Changes per Hour (ACH), and a cubic feet calculation is used rather than square feet. There's no "recommended amount" of ACH for managing COVID-19. You're likely improving the situation by increasing it, but I wouldn't start inviting people over after you did it. ACH is very high in ICUs but staff are still getting sick there. RE Humidity - ideal range varies based on region and outside temperature, but this chart roughly shows it: https://lh3.googleusercontent.com/proxy/mPz-jGdLpnPGgvWR3EgfvrhuT5mPgkKK_AQKZNzekzAyvsOGeFvGKK6Jn0kWGPEYYGkEAFM6CE3-BXLQzDEF_7_lV-H6HAfD5bXAl5HvUGB5rAjH9X1fPLLf8Q https://lh3.googleusercontent.com/proxy/mPz-jGdLpnPGgvWR3Egf... I have an on-furnace humidifier controlled by an ecobee for the winter, it's a huge quality of life improvement if you live in cold climates, but make sure to set it to "frost control" otherwise it won't lower the humidity based on the outside air and you can get mold in your walls. For summer, a standard house A/C combined with continuous ventilation should be sufficient to bring down humidity levels. Finally, the "correct" air ventilation is a moving target with trade-offs and concerns of the moment. It was higher in 1925 (30cfm/person) to try to prevent tuberculosis and infectious diseases, then was lowered to 5cfm/person in the 70s during the energy crisis, and is currently at 15cfm/person. I imagine COVID-19 could make us re-consider the current recommendations. https://homes.lbl.gov/ventilate-right/ashrae-standard-622 https://homes.lbl.gov/ventilate-right/ashrae-standard-622
turtlebits 6y ago
Most houses are incredibly leaky/drafty (at least in the US), turning on your bathroom fan(s) a few times a day is an easy way to improve ventilation.
- ballenf 6y ago
  Consider replacing the builder grade bathroom fans first, however. The typical ones you'll find are very energy inefficient, intentionally loud, but move relatively little air. They're also probably caked in dust further reducing effectiveness. While you're at it, make sure the fan is not venting into your attic space (I don't think there's any climate where that's still acceptable, but could be wrong).
  - war1025 6y ago
    > While you're at it, make sure the fan is not venting into your attic space Why wouldn't you vent to the attic? Attics are basically "hat that sits on top of your house" They are purposefully drafty areas whose main purpose is to keep rain off your ceiling.
    - tapvt 6y ago
      If the air from within the house is pushed into the attic and that attic is cooler, moisture may condense and collect before being circulated out of the attic space. Could lead to mold issues, etc.
ChuckMcM 6y ago
Fun read, my wife sometimes accuses me of having shark DNA because I can obsess over having fresh air moving past me at all times. :-) For me though the difference is one of comfort versus a vague tension. Some folks have associated this sort of thing with claustrophobia as well. That said, we spent a few thousand dollars insulating and sealing our home so that we did not need HVAC assisted climate control. Part of that included finding ways to exchange the house air with outside air so that during the summer months we could pull in cool air at night to lower the house temperature, seal it up when the Sun came up, and then remain cool all day. Similarly with bringing in warmth during the day in winter and minimizing the temperature fall during the evening. This is not particularly great for minimizing COVID in one's home.
voisin 6y ago
I’ve been looking toward building a new house and it seems the latest and greatest concept is the Passive House which seems to be an incredibly airtight envelope combined with a fresh air system to exchange air that includes a heat recovery system. I am left dumbfounded, as you become completely reliant on this technology which may break down or (more likely) fail to perform to spec or (even more likely) be spec’d incorrectly or incompatibly relative to future uses. It seems to me it would be far better to have large thermal masses and radiant heat, and then allow for the usual air loss around windows and doors and attics. Anyone here have thoughts on this approach vs Passive House?
jkepler 6y ago
In the early 20th century, British children's educator Charlotte Mason emphasized the importance of air quality, outside air, and frequently changing one's inside air: "Unchanged Air.––Parents of pale faced town children, think of these things! The gutter children who feed on the pickings of the streets are better off (and healthier looking) in this one respect than your cherished darlings, because they have more of the first essential of life––air. There is some circulation of air even in the slums of the city, and the child who spends its days in the streets is better supplied with oxygen than he who spends most of his hours in the unchanged air of a spacious apartment. But it is not the air of the streets the children want. It is the delicious life-giving air of the country. The outlay of the children in living is enormously in excess of the outlay of the adult. The endless activity of the child, while it develops muscle, is kept up at the expense of very great waste of tissue. It is the blood which carries material for the reparation of this loss. The child must grow, every part of him, and it is the blood which brings material for the building up new tissues. Again, we know the brain is, out of all proportion to its size, the great consumer of the blood supply, but the brain of the child, what with its eager activity, what with its twofold growth, is insatiable in its demands!" (Charlotte Mason, "Home Education, p. 31. Availible online, https://www.amblesideonline.org/CM/vol1complete.html#031 https://www.amblesideonline.org/CM/vol1complete.html#031)

101 points by arunbahl 6y ago

The reason why paperweights exist was because, prior to air conditioning, offices were built to have a constant flow of air through them to cool down workers.

motorbreath 6y ago
I was going to mention something similar to this! We've all experienced first-hand how irritating it can be when your papers start flying all over the place because the windows are open. There is a lot of interesting history behind paperweights and I would love to find some of the originals in a museum. https://www.paperweight.org/museums/ https://www.paperweight.org/museums/

ThePadawan 6y ago

Surprised to read nothing about the German fascination with Stosslüften (opening as many windows as possible as wide as possible for 5 minutes, twice daily. Literally "shock airing" or "surge airing"). Every apartment I moved into (in Switzerland) had me sign a waiver that I read the instructions how to do this to avoid mold growth.

subpixel 6y ago
As an exchange student in Germany I never got accustomed to the urgency with which my host mother would rush into my bedroom and throw open the window exclaiming "Frische Luft! Frische Luft!"
- ThePadawan 6y ago
  I personally got into the habit from school, where opening the windows after a double lesson (90min) before the next class came in was just the polite thing to do. Nothing worse than walking into a room with air that's been depleted of oxygen (then reading Theodor Fontane).
0x1F8B 6y ago
Do people do this in the winter as well?
- ThePadawan 6y ago
  Yes! You'd be surprised how little it changes room temperature. A lot of the thermal mass is conserved in the walls, furniture and people in the building.
  - heffer 6y ago
    This is true in Germany, where most in-home heating systems use radiant heat. I have since moved to Canada and my house uses forced air and a gas furnace. I can still feel cold at 21.5°C in my forced air heated house which I never did in Germany. Radiant heat does a much better job of heating the things in your house than forced air will. Heating things, and not just the air, is what has them store that warmth across Stoßlüften-Sessions. So technically, Stoßlüften works well with radiant heated homes, less so with forced air heated homes.
    - ThePadawan 6y ago
      That's true! I was also thinking about how German houses also tend to have relatively thick and non-wooden walls (since compared to the US, there's no significant earthquake risk). That adds a lot of thermal mass as well.
    - CyberDildonics 6y ago
      Is it much more likely that there is a difference in how your thermostat is placed or there was better insulation (so that heat ends up more even).
      - war1025 6y ago
        Over the past few years I've been working on improving the thermal efficiency of our house, which has mainly been strategic air sealing / adding insulation. One thing I've definitely noticed is that as I improve the insulation in one area of the house, other areas will get colder. The reasoning is that the worst insulated spots in my house were near to the thermostat. Now they they can maintain heat decently, the further way areas are allowed to cool more before the heat kicks on. The first tool someone should buy when investigating the thermal efficiency of their house is one of the cheap ($30- $50 if I remember right) infrared thermometers. The temperature of your house is likely 5-10F off from what your thermostat claims, particularly the further you get from the thermostat.
csunbird 6y ago
It is also a tradition in Turkey too. I have been taught to open windows first thing in the morning to clean up the air.
rsync 6y ago
We do this in my home. We get to cheat a bit since we live in California so it doesn't really mean anything to open the windows for 20-30 minutes in the winter. Regardless, I cannot abide stuffy/dead air and I will ventilate any house or apartment we are staying in regardless of outside temperature. I believe this to be a very underrated disease prevention tool.
- deleted 6y ago
  [deleted]
shostack 6y ago
Is there any research to back up the practice?
- BitwiseFool 6y ago
  And, does it circulate enough air when there isn't a breeze?
  - olau 6y ago
    No, although if it's cold outside, you might get a sea breeze effect. But most of the time (say > 80% IIRC) in Northern Europe there is at least some wind, and having a large cross sectional area is just incredibly efficient. You can try the experiment yourself. The main problem is that it is a manual process requiring discipline, and if you don't do it, your brain suffers due to elevated CO2 levels.
    - ThePadawan 6y ago
      Also worth mentioning that the most common kind of window over here is hinged, not double-hung. Meaning you can actually open them to create a gap of 100% of their area, not <= 50%.
post_break 6y ago
In Houston you would be bringing the mold inside due to the humidity.
marton78 6y ago
We do this in Hungary, too. I'd venture to guess this is probably the same at least in all of ex-Habsburg Central Europe. I don't know how people in other parts of the world can stand the stench of used up air. You won't notice when you're inside the room, but coming from the outside you feel like suffocating. Or maybe where this isn't common, people have active ventilation systems?
syntaxing 6y ago
How do you adjust for this during the winter? Do you turn off your heat or just keep the heat on and open the windows?
- ThePadawan 6y ago
  I would do nothing. For 5 minutes, turning off the heat wouldn't do much at all - the big heaters are generally very laggy anyway.

doctorhandshake 6y ago

I’m surprised there’s no mention here of heat recovery ventilators (HRV) or energy recovery ventilators (ERV) here. New buildings are increasingly designed to provide regular air exchange (fresh air replacing indoor air) while retaining thermal energy with these devices, and, in the case of ERV, retaining humidity.

jonstewart 6y ago
Yeah, ERVs are amazing. I want to install one in my house just to provide fresh air all the time.
compumike 6y ago
Agree. HRV / ERV is a powerful concept because it allows you to design better insulated buildings, both with fewer air gaps and thicker wall insulation, while still reducing indoor CO2 and humidity levels by bringing in fresh air. On the downside, like much in the HVAC world, it requires new construction or a fairly major retrofit to take advantage of it. My guess is that it's only going to make sense for new higher-end construction where other attention is being paid to energy efficiency. (Though I'd love to see a window box HRV for renters, just like window box air conditioners.) If you haven't heard of HRV / ERV yet, this video shows how they work in an impressive but simple demo with the 4 temperature sensors in the last few minutes: https://www.youtube.com/watch?v=QOSelUK6dpQ https://www.youtube.com/watch?v=QOSelUK6dpQ (Also compares aluminum core heat exchanger vs. desiccant enthalpy wheel) For the DIYers, here's a forum full of people building their own HRVs: https://ecorenovator.org/forum/showthread.php?t=891 https://ecorenovator.org/forum/showthread.php?t=891
- amluto 6y ago
  They don’t necessarily need a major retrofit. Lunos makes clever paired half-HRVs that require two wall penetrations but no ducts. Zehnder makes single-room through-wall HRVs.
mherdeg 6y ago
Yup. Now that I'm measuring how much CO2 I have indoors and can watch what happens when I open a window and it equilibrates, it's really hard to resist 2021+ plans to retool the HVAC to put in a fresh air ventilator. There were also a few days this summer where it was 50°F and low-humidity outside, but 78°F inside, my preferred temperature was closer to 72°F, and I wished I had some better way than "open a window and stick in a Lasko box fan" to cycle in cool outdoor air.

fatnoah 6y ago

What an odd article. I'd love to know more about the author's background where he's just now considering airflow in a home. Maybe it seems strange to me since I was in my late 30's before I lived anywhere that had air conditioning, so open windows, fans, cross-drafts, and general air flow were the norm. I also want to see what happens when the author discovers the whole house fan. My very first house had one and it was amazing. Crack open a window in each room and activate the fan. Instant breeze and air circulation in every room with somewhere around 6-8 air changes per hour.

senux 6y ago
I believe this is related to the number of people locked at home.
war1025 6y ago
I have been very tempted to buy a whole house fan for a couple years now. My compromise has been to put a box fan in our attic access and leave that running, which does more than nothing, but I have to imagine a proper house fan would be much better. I've never actually been somewhere with one to know what to expect. I've heard good things though.
- fatnoah 6y ago
  It's amazing when it works. In the summer, once the air outside was cooler than the air in the house, I'd turn it on. In about 10 minutes, the entire house would be the same temperature as outside.
- EricE 6y ago
  Get the right one and they are quite, effective and cost efficient too! I like designs like these: https://quietcoolsystems.com https://quietcoolsystems.com It took a couple hours to install, mainly because I went back and forth where to install the intake vent. I had power readily available from a hallway outlet - added a switch above the outlet, carried it up into the attic and to the fan. If you aren't comfortable doing your own wiring that will be the hardest part of installing the fan. The rest is simple - cut a hole in the drywall of your ceiling where you want the intake, mount the insulated box with the insulated dampers that close when the fan is not in use, hang the fan with the proper 90 degree bend in the duct, wire it in and finally snap the grate on and you are done. The only "glitch" I had with my install is I had the fan pointed down a bit too much and my attic has blown in insulation (ugh). The fan ended up blowing a big "hole" in it. So I adjusted the fan, raked the insulation back into place and haven't had an issue since. My air conditioners each use about 2400 watts each (I have two!), the motor on my whole house fan is around 640 watts. We had an exceptional fall the year I put it in, and it more than paid for itself. And I got the benefits of fresh air. I live in the Mid Atlantic so spring and fall are the biggest time of year I can use it, but this year our summer wasn't too bad with humidity so I used it most of the summer too. It's amazing how much heat you can tolerate if you have a steady breeze. I highly recommend them! My only complaint is I wish mine had variable speed. There are many times at night it gets way too cold to run at normal speed, but if off the heat of everything in the house will heat the interior back up again without at least some airflow. With the size of my house I need to add a second one anyway to get enough airflow/turn over so I'm thinking about one of their units that has two fans - can run just one for a lower amount of air volume. One of my best home upgrades, that's for sure!

bluGill 6y ago

Only useful if you live in a climate where the outside air is acceptable for indoors. Since this is from Japan I believe that applies. Where I live the outside temperatures get well below freezing for months at a time so ventilation alone isn't useful

timw4mail 6y ago
Japan is a very temperate place, but heating is generally not central. Drafts of ventilation would still be cold, but not nearly as wasteful as in a centrally-heating building.

DoofusOfDeath 6y ago

I started taking IAQ seriously when I soundproofed my home office. The soundproofing made the room nearly airtight, so I had to think about (at the very least) CO2 buildup within the office. I've hit an interesting problem regarding CO2 monitoring: calibration and validation. Every IAQ CO2 meter I've come across allows self-calibration and/or calibration by exposure to "open air" which is assumed to be about 400 ppm CO2. But none of the meters provide any means to calibrate / validate CO2 levels other than the reference level. For example, suppose I buy two CO2 meters from Amazon. They can both tare to 400 ppm. But once the CO2 in my office builds up, one might read 1200ppm while the other reads 800ppm. According to medical literature, 800 ppm vs. 1200 ppm is a pretty significant difference for human mental performance. If the CO2 level is actually 1200 ppm, I want to crank the office ventilation system, even though it means higher background noise. At just 800 ppm, I may prefer the quiter work environment. Another downside to this difficulty in testing is that it's hard to truly evaluate a particular meter's performance. Which seriously limits side-by-side comparisons of different models, and makes it harder to hold manufacturers / retailers accountable for poor performance.

joekrill 6y ago
Not to derail the conversation, but I'm curious about how you soundproofed your home office. Do you have any information about how you went about that and what was involved? I've been looking into this myself recently.
- DoofusOfDeath 6y ago
  One of the key takeaways is that the approach depends heavily on the space you're trying to soundproof, and just how much sound reduction you need at various frequencies. Feel free to DM me (see my profile) if you'd like to talk specifics.
- turtlebits 6y ago
  Depends on what you're looking for but adding an additional layer of drywall (5/8) with acoustical sealant sandwiched is an inexpensive way reduce sound transmission.
6y ago

jonheller 6y ago

I always assumed running air conditioning with windows open was incredibly wasteful. Is this because Japan's summers are more temperate than where I'm used to (Northeast US)? I do find myself sometimes running the AC with windows open when it's cooler outside than indoors. For some reason it can be 65 degrees outside but 75 degrees indoors.

fiddlerwoaroof 6y ago
Why would it be wasteful? If the house is warmer than the outside air, opening the windows until outside and inside equalize should save a bit of energy. (Assuming that the change to the airflow patterns isn’t relevant)
- smegcicle 6y ago
  I have no idea to what degree, but I think humid air reduces the efficiency of AC.
  - nbutyllithium 6y ago
    A bit of a complicated subject but the short answer is you're correct humidity does reduce the efficiency of air conditioning. The reason why(/long answer) is that as it cools the air the humidity in the air (i.e. water vapor) will condense into liquid water. Water requires a fair amount of energy to be removed (known as latent heat) to make this change and none of that energy removed actually changes the temperature of the air (all of it goes into changing the phase of the water). Therefore a high humidity load results in a lot of the cooling potential getting "used" up removing humidity first.
fomine3 6y ago
It is said by manufacturer like Daikin that stop&start A/C is inefficient than continuously running. (especially on summer, YMMV)

kyledrake 6y ago

I recently purchased a home and spent some time improving ventilation in it this year. This is a home in Minneapolis, so just "opening a window" is not an option, as it would be too cold in the winter and dramatically reduce energy efficiency. Its effectiveness also changes based on factors like the wind, and the temperature difference between inside and out. The general strategy for doing this right now with existing homes is to insulate your home as well as possible for energy efficiency, then install a continuous ventilation fan. This is essentially a bathroom fan, except that it runs all the time at a constant low speed, helping to circulate the air through and out your house by "pulling" a designed amount of air through the cracks. I didn't want to punch a new hole in the house just to do this, and already had a bathroom fan installed, so as a hack I just turned it into a whole house ventilation fan with this: https://www.aircycler.com/pages/smartexhaust https://www.aircycler.com/pages/smartexhaust Basically you calculate how much CFM you need per hour based on the square footage of your house, and then you set it on the fan control. It still acts like a bathroom fan, except every hour it also runs for a set period of time (in my case, about 12 minutes). The standard for this is ASHRAE 62.2. Use this to calculate the CFM for code: https://homes.lbl.gov/ventilate-right/step-3-whole-building-ventilation-rate https://homes.lbl.gov/ventilate-right/step-3-whole-building-... Then the formula for calculating the fan run time is on this sheet: https://cdn.shopify.com/s/files/1/0221/7316/files/AC_DOC_7_0_SmartExhaust_Cut_Sheet_rs_20ce4f30-fa23-4dc0-a879-ce2e765fc31b.pdf?v=1593031639 https://cdn.shopify.com/s/files/1/0221/7316/files/AC_DOC_7_0... And presto, you have a ventilation system without having to do a lot of work. Do _not_ try this with a crappy, rusty old bathroom fan - clean or replace the motor first, and for extra credit, use an arc fault circuit interrupter on the breaker so if the motor fails it will blow the fuse instead of potentially causing a fire. Note: This is really just to manage general air quality and VOCs. If you want to specifically make ventilation for COVID-19, that's a different problem. They focus on Air Changes per Hour (ACH), and a cubic feet calculation is used rather than square feet. There's no "recommended amount" of ACH for managing COVID-19. You're likely improving the situation by increasing it, but I wouldn't start inviting people over after you did it. ACH is very high in ICUs but staff are still getting sick there. RE Humidity - ideal range varies based on region and outside temperature, but this chart roughly shows it: https://lh3.googleusercontent.com/proxy/mPz-jGdLpnPGgvWR3EgfvrhuT5mPgkKK_AQKZNzekzAyvsOGeFvGKK6Jn0kWGPEYYGkEAFM6CE3-BXLQzDEF_7_lV-H6HAfD5bXAl5HvUGB5rAjH9X1fPLLf8Q https://lh3.googleusercontent.com/proxy/mPz-jGdLpnPGgvWR3Egf... I have an on-furnace humidifier controlled by an ecobee for the winter, it's a huge quality of life improvement if you live in cold climates, but make sure to set it to "frost control" otherwise it won't lower the humidity based on the outside air and you can get mold in your walls. For summer, a standard house A/C combined with continuous ventilation should be sufficient to bring down humidity levels. Finally, the "correct" air ventilation is a moving target with trade-offs and concerns of the moment. It was higher in 1925 (30cfm/person) to try to prevent tuberculosis and infectious diseases, then was lowered to 5cfm/person in the 70s during the energy crisis, and is currently at 15cfm/person. I imagine COVID-19 could make us re-consider the current recommendations. https://homes.lbl.gov/ventilate-right/ashrae-standard-622 https://homes.lbl.gov/ventilate-right/ashrae-standard-622

turtlebits 6y ago

Most houses are incredibly leaky/drafty (at least in the US), turning on your bathroom fan(s) a few times a day is an easy way to improve ventilation.

ballenf 6y ago
Consider replacing the builder grade bathroom fans first, however. The typical ones you'll find are very energy inefficient, intentionally loud, but move relatively little air. They're also probably caked in dust further reducing effectiveness. While you're at it, make sure the fan is not venting into your attic space (I don't think there's any climate where that's still acceptable, but could be wrong).
- war1025 6y ago
  > While you're at it, make sure the fan is not venting into your attic space Why wouldn't you vent to the attic? Attics are basically "hat that sits on top of your house" They are purposefully drafty areas whose main purpose is to keep rain off your ceiling.
  - tapvt 6y ago
    If the air from within the house is pushed into the attic and that attic is cooler, moisture may condense and collect before being circulated out of the attic space. Could lead to mold issues, etc.

ChuckMcM 6y ago

Fun read, my wife sometimes accuses me of having shark DNA because I can obsess over having fresh air moving past me at all times. :-) For me though the difference is one of comfort versus a vague tension. Some folks have associated this sort of thing with claustrophobia as well. That said, we spent a few thousand dollars insulating and sealing our home so that we did not need HVAC assisted climate control. Part of that included finding ways to exchange the house air with outside air so that during the summer months we could pull in cool air at night to lower the house temperature, seal it up when the Sun came up, and then remain cool all day. Similarly with bringing in warmth during the day in winter and minimizing the temperature fall during the evening. This is not particularly great for minimizing COVID in one's home.

voisin 6y ago

I’ve been looking toward building a new house and it seems the latest and greatest concept is the Passive House which seems to be an incredibly airtight envelope combined with a fresh air system to exchange air that includes a heat recovery system. I am left dumbfounded, as you become completely reliant on this technology which may break down or (more likely) fail to perform to spec or (even more likely) be spec’d incorrectly or incompatibly relative to future uses. It seems to me it would be far better to have large thermal masses and radiant heat, and then allow for the usual air loss around windows and doors and attics. Anyone here have thoughts on this approach vs Passive House?

jkepler 6y ago

In the early 20th century, British children's educator Charlotte Mason emphasized the importance of air quality, outside air, and frequently changing one's inside air: "Unchanged Air.––Parents of pale faced town children, think of these things! The gutter children who feed on the pickings of the streets are better off (and healthier looking) in this one respect than your cherished darlings, because they have more of the first essential of life––air. There is some circulation of air even in the slums of the city, and the child who spends its days in the streets is better supplied with oxygen than he who spends most of his hours in the unchanged air of a spacious apartment. But it is not the air of the streets the children want. It is the delicious life-giving air of the country. The outlay of the children in living is enormously in excess of the outlay of the adult. The endless activity of the child, while it develops muscle, is kept up at the expense of very great waste of tissue. It is the blood which carries material for the reparation of this loss. The child must grow, every part of him, and it is the blood which brings material for the building up new tissues. Again, we know the brain is, out of all proportion to its size, the great consumer of the blood supply, but the brain of the child, what with its eager activity, what with its twofold growth, is insatiable in its demands!" (Charlotte Mason, "Home Education, p. 31. Availible online, https://www.amblesideonline.org/CM/vol1complete.html#031 https://www.amblesideonline.org/CM/vol1complete.html#031)