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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. Lit

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.
        CyberDildonics 6y ago
        Exactly, you can even get infrared thermometers for less now that they are being used to take people's temperatures when they enter a business.
        skoskie 6y ago
        Meanwhile, I can feel an outside gust of cold wind from the middle of my home. I don’t begin to know where to start.
        war1025 6y ago
  - LeifCarrotson 6y ago
    It changes the perceived room temperature even less than actual temperature! As you say, air has little mass and very little thermal mass, solids have a lot more thermal mass so the equalized temperature after briefly exchanging all the air for cold air is basically the same as the original. But physiologically and psychologically, human comfort levels are based not on the air temperature and convection or conduction with the air but on the mean radiant temperature, the temperature of an ideal enclosure of uniform emissivity and temperature that creates the same radiant heat transfer rates as whatever non-uniform surfaces are in the area. Sit with your face in a sunbeam in a cold house, and you'll feel like it's pleasantly warm even if the heating of the sunbeam is doing less than the motion of cold air wicking away heat. Open your garage door on a still winter day, standing in the warm air with one wall removed, exposing you to sub-freezing temperatures, and you'll feel cold even if the air is still warm. Stand in the high-temp air blast of a torpedo heater in a cold shop, with the ceiling, concrete floor, walls, and other equipment still frigid, and you'll feel cold even as the hot air melts the plastic bits on your clothes. Blast the AC in a hot car, and you might be breathing air at 40F/5C from the vents, but you'll still feel hot until the vehicle interior trim is cooled by the air.
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.

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.
      - CyberDildonics 6y ago
        Exactly, you can even get infrared thermometers for less now that they are being used to take people's temperatures when they enter a business.
      - skoskie 6y ago
        Meanwhile, I can feel an outside gust of cold wind from the middle of my home. I don’t begin to know where to start.
        war1025 6y ago
- LeifCarrotson 6y ago
  It changes the perceived room temperature even less than actual temperature! As you say, air has little mass and very little thermal mass, solids have a lot more thermal mass so the equalized temperature after briefly exchanging all the air for cold air is basically the same as the original. But physiologically and psychologically, human comfort levels are based not on the air temperature and convection or conduction with the air but on the mean radiant temperature, the temperature of an ideal enclosure of uniform emissivity and temperature that creates the same radiant heat transfer rates as whatever non-uniform surfaces are in the area. Sit with your face in a sunbeam in a cold house, and you'll feel like it's pleasantly warm even if the heating of the sunbeam is doing less than the motion of cold air wicking away heat. Open your garage door on a still winter day, standing in the warm air with one wall removed, exposing you to sub-freezing temperatures, and you'll feel cold even if the air is still warm. Stand in the high-temp air blast of a torpedo heater in a cold shop, with the ceiling, concrete floor, walls, and other equipment still frigid, and you'll feel cold even as the hot air melts the plastic bits on your clothes. Blast the AC in a hot car, and you might be breathing air at 40F/5C from the vents, but you'll still feel hot until the vehicle interior trim is cooled by the air.

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.