[HN Gopher] Germany's inefficient love affair with open windows ...
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Germany's inefficient love affair with open windows (2021)
Author : KennyBlanken
Score : 9 points
Date : 2023-12-30 21:16 UTC (1 hours ago)
(HTM) web link (www.politico.eu)
(TXT) w3m dump (www.politico.eu)
| KolmogorovComp wrote:
| The article cites windows opening inward as a reason for
| inefficient ventilation, yet the answer is to... insulate less?
|
| > The key may be to have less insulation, because the current
| system seems to be too airtight to accomodate for residents'
| differing preferences
|
| Why not change the windows to open outward/upward?
| rad_gruchalski wrote:
| The point is: you open those windows to let the humidity out.
| Warm air holds more water than cold air. The warmer it gets
| inside, the more humidity. If you don't open your windows, the
| humidity escapes through least isolated areas, very often
| window sills. Sills get naturally colder, at below 12 degrees
| celsius you get mold in the sills. So, open your windows to
| blow the humidity out of the apartment but don't open for too
| long so the sills don't cool down too much, especially not
| below 12 degrees celsius.
| mtmail wrote:
| Related and currently on the frontpage with 80 comments:
| "Stossluften: Shock Ventilation" "This word (and concept) is
| especially found in public places and schools all around
| Germany." https://news.ycombinator.com/item?id=38813856
| hasoleju wrote:
| Based on the title I first thought there is an open source
| operating system used in Germany I was not aware of.
|
| But is really true ,,Luften" is something we do in every room
| every morning here.
|
| Luckily modern Bauhaus architecture style homes have windows down
| to the floor so that opening them is always possible because
| there is no sideboard with plants on top in front of the window.
| Slartie wrote:
| It is actually kind of common in Germany that landlords attach
| copies of news articles about the need for correct ventilation or
| similar "notes" to rental contracts when handing them over to a
| new resident. Not exactly part of the rental contract (because
| it's not legally possible to dictate the exact ventilation cycle
| desires of the landlord in a rental contract), but still a very
| clear hint at what's expected of you.
|
| I've never assumed anyone to actually do all of this excess
| ventilation, though...I've always been too lazy to "open all
| windows three times a day for five minutes each" (where the heck
| do people find the time to do that each and every day?), and the
| "solution" of just opening the window a little over a long period
| is so obviously expensive in terms of heating costs that I rather
| keep most windows closed most of the time (except bathroom after
| showers for obvious reasons).
| PreInternet01 wrote:
| OK, although "stupid Germans keep opening windows to defeat
| stupid green goals" is of course _a_ take, in reality, a modern
| energy-efficient Euro-style building will:
|
| -Indeed be 'airtight', in the sense that limited air (and noise,
| as a bonus) will enter or leave the building except via defined
| ventilation routes.
|
| -Offer primary 24/7 ventilation (mostly for CO2 management) via
| ingress/egress vents as part of a balanced ventilation system,
| which performs 'comfort' regulation of incoming air temperature
| using heat recovered from outgoing air.
|
| -Heat or cool the building via under-floor convection connected
| to a reversible heat pump. This will slowly but surely bring most
| of the building mass to a comfortable temperature regardless of
| season.
|
| - _In addition_ to basic ventilation and heating /cooling offer
| very-well-insulated yet securely operable windows for additional
| temporary ventilation. Window openings are very much defined
| ventilation routes as part of the 'airtight' plan.
|
| The important things to keep in mind here are that the balanced
| ventilation system prevents things like mold already, and that
| opening windows for brief periods of time (as in: measured in
| hours) for (perceived) comfort won't impact energy efficiency
| very much at all.
|
| The most relevant criticism here is that retrofitting existing
| buildings for the above scheme is a significant challenge, but
| that doesn't quite seem to be the point the article wants to be
| making...
| RGamma wrote:
| I highly recommend installing a decentralized ventilation system
| with enthalpy exchanger in often used rooms like the sleeping
| room.
|
| It's super efficient and improves air quality a lot when your
| building is highly insulated. The enthalpy part is important
| because winter air is pretty dry after heat exchange. Bonus
| points when you can fit good air filters (ePM1 50%+). Also, some
| systems offer a summer bypass for cooling in summer without AC as
| well as "smart functions" like orchestration of multiple devices
| or automatic control via CO2/humidity sensor.
|
| Central ventilation is unfortunately very hard to retrofit...
| amluto wrote:
| > ePM1 50%+
|
| If there's actual poor air quality (smoke, etc), this is
| inadequate. 50% is fine for a recirculating system -- fine
| particles will be reduced by half on each pass. For for a
| single pass system, if you have 50 mg/m3 outdoors (quite common
| in a lot of places, sadly) you get 25 mg/m3 coming in through
| your fancy ventilation system, which is not great.
|
| What you want is a great honking filter, 95% or better, with a
| prefilter. You'll pay several hundred dollars for that big
| filter, but you'll be running it at low velocity (maybe 150cfm
| of flow in a 24"x24" filter housing), so it will have minimal
| pressure drop and will last a _long_ time. Even an actual HEPA
| filter wouldn't be out of place here.
|
| But even the really fancy European ERV/HRV brands use those
| inadequate ePM1 50% filters. I've even measured them with a
| handheld particle counter -- they work every bit as poorly as
| one would expect from the specs. And those filters are small,
| and they gunk up quickly.
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