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
guckuck2 schrieb:
One should be allowed to question the practical relevance.
I am still interested in what the typical CO2 levels are like in older buildings. I agree with you, but just read a few studies. The values are not made up (haha, pun intended).
Regarding older buildings… no idea, maybe measure it at someone’s place.
@ludwig88sta yes, that’s probably because the recommended limit is 1500, so you don’t necessarily need to know how much higher it actually gets.
Many people also sleep with the window open because otherwise it feels too stuffy, even in older buildings. I don’t like that at all, so a controlled mechanical ventilation system is definitely a blessing in that regard.
Here is a graphic from 1988. It fits well with older buildings.
Source:
Fig. 6: Measured carbon dioxide concentration over the course of one week in the bedroom of a residential house (Mack et al., Physics Institute, University of Tübingen)
The comfort limit according to DIN is exceeded by twice, and Pettenkofer’s recommendation is exceeded by three times.
Ventilation through window airing is entirely the responsibility of the occupants. Although this method can achieve sufficient air exchange, the airing procedure is impractical in certain rooms and at certain times. Therefore, window ventilation is not considered a suitable ventilation strategy for low-energy houses.
Source:
Fig. 6: Measured carbon dioxide concentration over the course of one week in the bedroom of a residential house (Mack et al., Physics Institute, University of Tübingen)
The comfort limit according to DIN is exceeded by twice, and Pettenkofer’s recommendation is exceeded by three times.
Ventilation through window airing is entirely the responsibility of the occupants. Although this method can achieve sufficient air exchange, the airing procedure is impractical in certain rooms and at certain times. Therefore, window ventilation is not considered a suitable ventilation strategy for low-energy houses.
G
goalkeeper10 Jan 2020 17:22We discussed the installation box (IB) during yesterday’s construction meeting with the plumber and general contractor. Both agree that the IB isn’t necessarily required for the new build at this stage, as the main goal is to get the structure dried in. After 1-2 years, we will consider it further.
goalkeeper schrieb:
Yesterday during the construction meeting with the plumber and the general contractor, we discussed the ERV. Both agreed that an ERV is not necessarily needed initially in a new build, since the main goal is to get the building dry first. We will reconsider the issue after 1-2 years. Here is my practical experience:
We have now lived in the house for 25 months. It is a solid construction with flowable screed, so there was quite a bit of moisture from the build.
We installed a Zehnder Q350 with an ERV and in the first winter already struggled with overly dry air.
By now, we have a Venta LW45, and that keeps the indoor humidity fairly consistent at around 50%.
Similar topics