Hello everyone,
We are currently starting to deal with the technical aspects of our single-family home.
I haven’t found a thread discussing whether a ventilation system generally makes sense or not. So here is a general discussion thread on the topic:
At first, we looked into various timber frame construction providers, which made us quite sensitive in this area. Naturally, a ventilation system is quite important due to the tighter building envelope, which I can completely understand. However, everything is also marketed accordingly...
Since we have now decided to go with a regional solid construction company, completely different questions arise:
I currently have a detailed offer from a solid construction company:
- $10,000 additional cost for thermal insulation measures
- $13,000 additional cost for a central ventilation system or $9,000 additional cost for a decentralized ventilation system
--> So the repayment subsidy of $18,000 is of little use to me; on the contrary, I am even paying extra for this (of course, I get a “better” house in return).
Key Data:
- Single-family home city villa, 150m² (1,615 ft²) with basement
- Air-to-water heat pump
- Building material: brick
The questions I am now asking myself:
1. Is a ventilation system even necessary to achieve KfW 55 standard?
2. If yes, would it maybe make more sense to go for KfW 70 and forget about the subsidy?
3. Is a ventilation system really that great? There are many reports about noise, high maintenance, etc.
4. If yes, in our building project would a decentralized or central system be better? I have read a lot of positive things about decentralized systems, so central ones might not be an option? Is that correct or not?
5. Is it even possible to reach KfW 55 standard otherwise? Do you really have to ventilate every 2 hours? Are there any experiences?
6. Is the additional $10,000 cost for KfW 55 without a ventilation system justified? Are the prices for the ventilation systems justified?
I know this is an endless debate and there are clearly two opinions here. However, we find it really difficult to make a decision. Maybe a few discussions and information here will help us make up our minds.
We are currently starting to deal with the technical aspects of our single-family home.
I haven’t found a thread discussing whether a ventilation system generally makes sense or not. So here is a general discussion thread on the topic:
At first, we looked into various timber frame construction providers, which made us quite sensitive in this area. Naturally, a ventilation system is quite important due to the tighter building envelope, which I can completely understand. However, everything is also marketed accordingly...
Since we have now decided to go with a regional solid construction company, completely different questions arise:
I currently have a detailed offer from a solid construction company:
- $10,000 additional cost for thermal insulation measures
- $13,000 additional cost for a central ventilation system or $9,000 additional cost for a decentralized ventilation system
--> So the repayment subsidy of $18,000 is of little use to me; on the contrary, I am even paying extra for this (of course, I get a “better” house in return).
Key Data:
- Single-family home city villa, 150m² (1,615 ft²) with basement
- Air-to-water heat pump
- Building material: brick
The questions I am now asking myself:
1. Is a ventilation system even necessary to achieve KfW 55 standard?
2. If yes, would it maybe make more sense to go for KfW 70 and forget about the subsidy?
3. Is a ventilation system really that great? There are many reports about noise, high maintenance, etc.
4. If yes, in our building project would a decentralized or central system be better? I have read a lot of positive things about decentralized systems, so central ones might not be an option? Is that correct or not?
5. Is it even possible to reach KfW 55 standard otherwise? Do you really have to ventilate every 2 hours? Are there any experiences?
6. Is the additional $10,000 cost for KfW 55 without a ventilation system justified? Are the prices for the ventilation systems justified?
I know this is an endless debate and there are clearly two opinions here. However, we find it really difficult to make a decision. Maybe a few discussions and information here will help us make up our minds.
I believe I can help you a lot here. My wife is just like your fiancée—she notices every little sound. Because of that, I was also very concerned. We’ve tried all options: no ventilation, decentralized ventilation, and now centralized ventilation.
First of all: definitely go with a centralized system. The other two options are not good. Decentralized ventilation is the worst and extremely noisy, no matter how quiet these devices claim to be!
We have a Zehnder Q350, and it is very quiet. With this system, you have the option to switch to “away” mode at night—you can’t turn it off completely, and you definitely shouldn’t (otherwise the system gets dirty!). In “away” mode, it runs at only 80 m³ (2,830 ft³) per hour, and you won’t hear anything at all. The normal setting, level 1, is 160 m³ (5,650 ft³) and can only be heard by sensitive people like our wives, and only at night. But it doesn’t bother mine, because it’s very quiet. At level 2, the ventilation is noticeably louder at 230 m³ (8,120 ft³). Level 3 is unbearable, especially at night—but you really never use that setting anyway.
So overall, I can only recommend this system and assure you that you won’t have any problems if you use the timer (via the Zehnder app scheduling) to run the system in “away” mode at night. The ventilation capacity is still sufficient!
First of all: definitely go with a centralized system. The other two options are not good. Decentralized ventilation is the worst and extremely noisy, no matter how quiet these devices claim to be!
We have a Zehnder Q350, and it is very quiet. With this system, you have the option to switch to “away” mode at night—you can’t turn it off completely, and you definitely shouldn’t (otherwise the system gets dirty!). In “away” mode, it runs at only 80 m³ (2,830 ft³) per hour, and you won’t hear anything at all. The normal setting, level 1, is 160 m³ (5,650 ft³) and can only be heard by sensitive people like our wives, and only at night. But it doesn’t bother mine, because it’s very quiet. At level 2, the ventilation is noticeably louder at 230 m³ (8,120 ft³). Level 3 is unbearable, especially at night—but you really never use that setting anyway.
So overall, I can only recommend this system and assure you that you won’t have any problems if you use the timer (via the Zehnder app scheduling) to run the system in “away” mode at night. The ventilation capacity is still sufficient!
Bookstar schrieb:
I think I can help you out quite well here. My wife is just like your fiancée—she hears every little noise. I was also very concerned because of that. We've tried all the options: no ventilation, decentralized ventilation, and now central ventilation.
First of all: definitely go for the central system. The other two options are not good. Decentralized ventilation is the worst and extremely loud, no matter how quiet they claim those units to be!
We have a Zehnder Q350, and it is very quiet. With this system, you can set it to “away mode” at night, turning it off completely is not possible and should absolutely be avoided (the system will get dirty!). In away mode, it runs at only 80 m³ (about 2830 ft³) and you won’t hear anything at all. The normal setting, level 1, is 160 m³ (about 5660 ft³) and can only be heard by people with very sensitive hearing, like our wives, and only at night. But it doesn’t bother me as it’s very quiet. From level 2, it becomes noticeably louder at 230 m³ (about 8120 ft³). Level 3 is unbearable, especially at night, but you rarely need it.
So overall, I can only recommend this system and advise you that you won’t have any issues if you run the system in away mode at night using the timer (Zehnder app scheduling). The ventilation capacity will still be sufficient! Thank you very much for the quick responses!
That definitely gives me some confidence 😉
The general contractor, who is currently our favorite, uses a central ventilation system from Wolf. I will ask them if it has a timer function.
Thanks and have a nice Sunday
Or simply size the pipe network and plate valves (by number or size) so that the air velocity does not exceed about 3 m³/s (106 ft³/s) at the highest level; this will keep the system quiet. Also, consider using silencers, as the duct system tends to transmit noise throughout the house (e.g., during bedroom activities 😉 ).
Mlt1402 schrieb:
Many thanks for the quick responses!
That definitely gives hope 😉
The general contractor, who is currently our favorite, uses a central ventilation system from Wolf. I will ask there if it has a timer function.
Thanks and have a nice SundayI haven’t been following the thread here. But a Wolf!
If someone tells me they hear fleas coughing at night, then they will definitely hear the system. Of course it has a timer. And since I know that a running system should never be changed, I don’t touch the function either, because it doesn’t bother us and works well. I adjusted the heating two or three times and suddenly I stood there by the dial (what was that for again?)… and the heating didn’t work the next day.
But regarding controlled residential ventilation: You can hear airflow, you can feel airflow. If you are sensitive. I probably once said you can’t hear it. That is, of course, true for those who can easily filter out background noise. I have to mention that I am definitely in favor of controlled residential ventilation.
We have one from Wolf. The display is inconveniently positioned. It’s a general contractor house, so you can’t control everything. The controls are sufficient for the spontaneous 20-minute full ventilation or for boosting power or reducing it. At night, early morning, at 5 p.m., and in the evening at 10 p.m. it runs at full speed. You can hear the humming then. Other than that? I feel a draft on the sofa. Otherwise everything is fine 🙂 As I said before: I’m more bothered by the open utility room door with heating noises, an uneven floor, or things like that. And I’m sensitive to noise—I often turn off the radio during the day. The ventilation noise is actually quite pleasant. It doesn’t impose itself; I’m louder when I write on a sheet of paper or type. My timer for the Christmas lights is much more annoying. But I can’t say: you don’t hear anything!
KfW55 buildings are not feasible without a ventilation system. The disadvantages of a central ventilation system remain when compared to decentralized systems (hygiene costs such as energy consumption). The noise level of good systems is comparable to that of a PC or laptop fan.
parcus schrieb:
KfW55 without a ventilation system is not possible anyway.
The disadvantages of a central ventilation system remain compared to decentralized systems.
(Hygiene costs like energy consumption.) The noise level in good systems is comparable to that of a PC or laptop fan. ? Certainly, KfW55 is easily achievable without mechanical ventilation. A central system has no disadvantages compared to a decentralized system. What are you talking about? What hygiene costs? The decentralized system is more expensive to operate because it requires more filters and the heat exchanger is less efficient.
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