Stoßlüften: Shock Ventilation
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In these buildings, you can replace all air with outside air at once, and once you close the windows the thermal mass of the building will quickly heat it up again.
New buildings tend to move away from it though, instead using automatic fans for ventilation
the structure and thermal mass is similar in new buildings.
It allows heat recovery - less heating (or cooling) energy is wasted by proper ventilation.
Ventilation is constant - there is no buildup of CO2, moisture or harmful particles like VOC or viruses.
There is no need for discomfort caused by the shock ventilation when ventilation is properly dimensioned (enough for people in the room).
In that case I would disagree, it’s a magnitudes bigger waste of energy and resources and causes illness (at least for me).
Concrete masonry unit, "cinderblock" in North America. https://en.wikipedia.org/wiki/Concrete_block
Rooms are mainly heated by water radiators in Germany. These radiators are most likely under windows to compensate for the radiated cold and draft from the windows that may create discomfort. As the heat moves up then it will create (mainly) closed circulation in the room when the windows are closed.
Now when the windows are open then the heat from the radiators will instead escape from the windows. On top of this the radiators are most likely locally regulated (with thermal valves) and will heat up because of the cold air from the outside while increasing the energy loss even more.
This is the main reason why the heating must be closed during the shock ventilation and why it is less energy efficient to keep the windows slightly open for constant ventilation.
This is of course a compromise between good air quality and energy efficiency and the correct answer is to build a proper mechanical ventilation with an heat exchange.
(As a bit of trivia, the specific heat capacity of air is pretty close, +- 50%, to common building materials. Explained by the rather low density of air at normal pressure and temperature compared to those.)
The term uses the same structure "sjokklufting", which like the German means shock ventilation.
A quick search in the Norwegian National Library dates the Norwegian use of this specific term pretty firmly to ~1974 or so.
Interestingly all the uses of the term in writing in Norwegian media in 1970's seem to either be or echo the text in an ad from Jøtul, one of the largest manufacturers of cast-iron fireplaces as a negative (making it too cold), while many later mentions are positive, though also with a tinge of "we're only doing this as a fallback because our ventilation isn't good enough" in quite a few articles.
A somewhat more common Norwegian variant describing much the same is utlufting ("out-ventilation") or storutlufting ("big out-ventilation"), which is found in print at least back to the 1850's, and which tends to imply much the same, though perhaps with a less negative slant.
At some point around the 1980's, the viewpoint seems to have changed from promoting this as a good thing to describing the need for it as evidence of poor ventilation systems.
My mum would often do this, and I do it myself too, - open several windows at least a couple of times a day during winter to rapidly clear out stale air. The benefit vs. less ventilation all the time being that while you're cooling the air, it's short enough that you don't lose much heat, and neither does the building mass. It's overall much more pleasant when it's really cold outside than having a window open a crack on an ongoing basis.
I'm french and I don't think there is a specific word to describe this.
We commonly use the verb "aérer" which translates to "to ventilate". But when someone uses this term, I think it designates implicitly a short ventilation as described by this German word or your Norwegian one. At least that's what I noticed around me. I don't know of anybody keeping a window open all day long to ventilate when it's cold outside.
(My kid uses "luft" to mean both, "lufte ekkelt".)
You can do that in Norwegian too, but we tend to be a bit more shy about it than the Germans...
(Then again, having recently flown back from Norway to the UK one of the things that strikes me every winter is how floodlit Norway looks from the air at night compared to the UK despite far lower population density - Norway is still riding high on the past low energy prices...)
> Asked by the tabloid BILD-Zeitung what feelings Germany awakes in her, Angela Merkel once famously replied, 'I think of well-sealed windows! No other country can make such well-sealed and nice windows [dichte und schöne Fenster].'
https://nybooks.com/articles/2013/08/15/new-german-question/
The best way is ventilation through heat exchangers.
If you ventilate through a heat exchanger when inside and outside are different temperatures, you can have more fresh air more of the time while saving energy.
there are some potential issues if outside temp is higher and it's humid tough. these systems can cause mold.
Moreso than the shock ventilation method?
If there's worrying amounts of moisture, we could go ahead and say we'll do the same amount of air with the heat exchanger. Is that worse for mold potential than the alternative?
Because without doing the math on that, such a statement is absolute pointless.
I wouldn’t be surprised if the heat exchangers save 1000x the energy that they consume.
How much money do you spend on powering the vent in your laptop vs how much money do you spend on heating?
But the burden of proof is on the one that’s making the extraordinary claim.
It really doesn't matter how fast you replace the air. If you let in the cold air then you need to warm it up.
What you actually do is a compromise between energy conservation and properly ventilated room as for the morning the room will be filled with high concentration of CO2 and humidity (from your breathing and sweating) and you more than often end up with bad sleep and headache.
Constant proper mechanical ventilation is the key for better sleep and health when windows are goods as German windows (some other European countries make good windows too).
Ventilating quickly is preferable to ventilating slowly. Heat transfer through materials is comparatively slow. That means that exchanging the air in an instant retains the heat in the walls, furniture,… exchanging the air slowly allows heat from materials to „leak out“ as well.
There’s a nice booklet about ventilation for regular Joes called “Richtiges Lüften in Wohnungen” (Proper ventilation in apartments) published by the Fraunhofer IRB (i.e. information centre for inner spaces and construction).
This booklet explains the role of material and air humidity, how ventilation became important as buildings became more airtight, how relative humidity works, etc.
A key observation is that the main purpose of such intense ventilation is refreshing the air, i.e. removing unpleasant smells and CO2.
Landlords, experts and courts of law have nevertheless settled on the idea that 2-3x intensive ventilations per day are necessary to avoid mould.
The booklet claims that dehumidification is ideally achieved through “Spaltlüften”, which is keeping a window partly open for a longer period of time: the cool outside air enters the room in small quantities which can be quickly heated, thereby drying said air and enabling it to absorb additional humidity. Due to the longer ventilation period, materials which absorb humidity such as drapes, carpets, wallpaper or plaster can release said humidity which shall be absorbed by the dry air and ultimately exchanged with outside air. The heater must stay permanently on so that the cool air can be heated.
Some apartments have passive mechanical ventilation such as openings in the rubber seals of the windows or ventilation slots in the window frames which follow this principle.
Of course everyone who lives in Minergie homes opens the windows each morning while hanging out the duvets, and/or complains that the enormous windows are too big to open, or don't open at all.
It's like all the Minergie engineers were so busy at work they didn't notice what their wives were doing at home. (I assume the original engineering for these hear exchangers was in the 70's when that gendered statement was not controversial!)
--> Switch on captions.
This is a small segment of a weekly program that is broadcast on the french-german tv station "arte". The program is called "karambolage" and highlights interesting peculiarities in French or German culture or funny anecdotes about etymiology, history. It's quite fun. They had this piece about a french exchange student that discovered a requirement to regular "stoßlüften" in the rent-contract.
I’d say the connotation is more of a quick blowing out, ejection or (im)pulse, not a shock. Compare also “ausstoßen” and “Stoßatmung”. The main feature is the short duration.
Newer buildings probably don't need shock ventilation, as it's better by design.
A large part of the European buildings still don't have proper ventilation.
1. https://www.baubay.de/home-interface-velux-klf-200.html
2. https://community.home-assistant.io/t/velux-kfl200-ha-config...
"Lüften" is the common local term ("to air out").
I am pretty sure most modern browsers are able to display an ü so you can write "Lüften"
The only place I have trouble with mold is in the bathroom, and that's because so many homes built before the 80s were built without ventilation fans in the bathroom. The places I've lived with proper ventilation have not had mold problems.
What’s depressing is that neither rental rules do not require HRVs yo be installed nor little public places have started to upgrade.
Most of the heat is in the walls, not the air anyway.
I'm not German so I googled the word after seeing it on Twitter.
I checked a few articles and this one had the most exhaustive description imho. That's why I decided to post this link despite some cons.
thelocal.de##.article--sponsored
[0] https://web.archive.org/web/20231230110629/https://www.thelo...
When you buy a Window here, or you rent a flat it usually comes with a manual that asks you to ventilate regularly and how.
If you ventilate properly, a CO2 meter is entirely pointless. CO2 levels are very predictable and you can also usually tell when the air quality drops through your senses.
Only when you're paying attention. If I'm not paying attention, I end up in a sufficiently depressed state that I can't notice, which is extremely self-perpetuating.