ᐅ Central ventilation system – is humidity recovery necessary?
Created on: 30 Dec 2019 16:17
L
ludwig88sta
Hello everyone,
for our planned single-family house with 2 floors and a basement, we have decided on a central ventilation system for all rooms with heat recovery within the thermal envelope. The brand and model are not yet determined.
I have read here on the forum a few times about an additional moisture recovery feature (MRF?), since otherwise the indoor air tends to become too dry (of course, the ventilation system also removes the moisture that naturally occurs in the room, which usually makes the air feel comfortable). I wanted to ask if anyone can confirm these issues and whether this is more common in timber frame houses or also occurs in brick houses?
Did you install additional moisture recovery in your ventilation system? How much extra cost does it involve? I assume there are also additional maintenance costs because it involves another motor and related components.
Best regards
ludwig88sta
for our planned single-family house with 2 floors and a basement, we have decided on a central ventilation system for all rooms with heat recovery within the thermal envelope. The brand and model are not yet determined.
I have read here on the forum a few times about an additional moisture recovery feature (MRF?), since otherwise the indoor air tends to become too dry (of course, the ventilation system also removes the moisture that naturally occurs in the room, which usually makes the air feel comfortable). I wanted to ask if anyone can confirm these issues and whether this is more common in timber frame houses or also occurs in brick houses?
Did you install additional moisture recovery in your ventilation system? How much extra cost does it involve? I assume there are also additional maintenance costs because it involves another motor and related components.
Best regards
ludwig88sta
This is exactly the point where the debate starts. There are numerous studies with very different results.
Most studies, however, conclude that wellbeing and concentration significantly decrease above 1500 ppm (parts per million) (including studies from Fraunhofer, Max Planck, and not just Brigitte). I don’t know where your 25,000 ppm comes from—that’s more like lying tiredly babbling in a corner...
I find air quality uncomfortable already at 1500 ppm; it quickly feels stuffy.
If you turn off the ventilation system in the bedroom, the concentration quickly shoots above 4000 ppm and keeps rising, so you end up waking up with a headache.
By the way, this is a prime example of populism. It is completely irrelevant that the percentages are small numbers...
Most studies, however, conclude that wellbeing and concentration significantly decrease above 1500 ppm (parts per million) (including studies from Fraunhofer, Max Planck, and not just Brigitte). I don’t know where your 25,000 ppm comes from—that’s more like lying tiredly babbling in a corner...
I find air quality uncomfortable already at 1500 ppm; it quickly feels stuffy.
If you turn off the ventilation system in the bedroom, the concentration quickly shoots above 4000 ppm and keeps rising, so you end up waking up with a headache.
Mottenhausen schrieb:
But even here, a lot of fuss is made unnecessarily. If the user fails to convert % to ppm and therefore has no real sense of the measured CO2 level, this all becomes pretty pointless.
By the way, this is a prime example of populism. It is completely irrelevant that the percentages are small numbers...
Lumpi_LE schrieb:
If you turn off the ventilation system in the bedroom, the CO2 concentration quickly jumps to over 4000 ppm and keeps rising, so you wake up with a headache in the morning. What is a typical value in an existing building without a ventilation system?
Of course, those buildings are less airtight, but still, how did we survive all those years?!
guckuck2 schrieb:
Of course, they are less airtight, but still, how did we manage to survive all those years?!I wonder that too.
Because of high humidity (airtight windows but an older building, so risk of mold), we have to ventilate properly 2 to 3 times a day and open all the windows wide. When I tell others this, they always look at me pityingly and say they only ventilate once in the morning and that’s it... (note, without a mechanical ventilation system)
guckuck2 schrieb:
Of course, they are less airtight, but still, how did we survive all those years?! That is probably often the deciding factor. We had wooden windows in our apartment that were so drafty that, even without manually ventilating, there was likely an air exchange rate of 0.3... although I never actually measured it back then.
“How did we survive all those years” is also a phrase I often hear from the Boomer generation in my professional environment... I’m really tired of it.
“We used to get beaten regularly – it didn’t harm us.” Really? “We used to work 95 hours a week – how did we survive that?” Yeah, yeah… blah blah blah.
@Specki is obviously very subjective; my in-laws – living in a house from the 2000s – don’t ventilate all day long when we visit because it gets cold and drafty, and the kids catch colds. After two hours, it’s nearly impossible to stay seated there, and that’s not just because of the stimulating conversations.
@Lumpi_LE Between "we've always done it this way" and today's craze for (self)optimization, there is still something else.
Limit values are often chosen arbitrarily. It is important to question their practical relevance.
I am still interested in how the CO2 level typically looks in older buildings.
Limit values are often chosen arbitrarily. It is important to question their practical relevance.
I am still interested in how the CO2 level typically looks in older buildings.
L
ludwig88sta10 Jan 2020 12:57I just took a look at CO2 monitors for private users. What I found in the last few minutes (ranging from 60 to 150) only measures from 0 to 3,000 ppm, so your morning level of 4,000 ppm can’t even be detected @Lumpi_LE
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