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.
Without a ventilation system, compliance with the Building Energy Act (Energy Saving Ordinance) is not permitted when a higher energy-saving standard is required. This also applies to KfW, which bases its requirements on the Energy Saving Ordinance or, later, the Building Energy Act.
First, you need the space, which involves costs (excluding fire protection). Then the ducts need to be maintained. The energy consumption can be up to 15 times higher due to system losses.
The efficiency of heat exchangers in all good units nowadays is well above standard values.
A disadvantage of decentralized units is that they are visible on the façade.
First, you need the space, which involves costs (excluding fire protection). Then the ducts need to be maintained. The energy consumption can be up to 15 times higher due to system losses.
The efficiency of heat exchangers in all good units nowadays is well above standard values.
A disadvantage of decentralized units is that they are visible on the façade.
parcus schrieb:
Without a ventilation system, compliance with the building energy law (Energy Saving Ordinance) is not permitted when a higher energy saving standard is required.
This also applies to KfW funding, which is based on the Energy Saving Ordinance or, later, the building energy law.
First, you need the space, which involves costs (excluding fire protection), and then the ducts must be maintained.
Energy consumption can be up to 15 times higher due to system losses.
The efficiency of heat exchangers in all good devices is now well above the standard values.
The disadvantage of decentralized systems is that they are visible on the facade. Sorry, that simply isn’t true. What system losses? The ducts are generally maintenance-free or, in some systems, can be cleaned every 10 years if desired. Decentralized systems are poor quality and are often still installed by developers in multi-family buildings. They are cheap and require no central filter management.
parcus schrieb:
First, you need to consider the space required, which is associated with costs (excluding fire protection). Then, the pipes need maintenance.
The energy consumption can be up to 15 times higher due to system losses. But you do realize we are talking about a single-family house, right? From a fire protection perspective, the entire single-family house is considered as one zone (an exception might be a masonry garage directly attached to the house, but I’m not 100% sure about that).
Maintenance of the pipes is not mandatory; it is recommended in VDI 6022 as well as in other DIN standards, but it is not a legal requirement.
If the pipes are, for example, located in an unheated roof space and are not sufficiently insulated, this can lead to increased losses. However, with proper insulation, these losses are absolutely negligible.
An exception might be a masonry garage directly attached to the house.
Nowadays, hardly anyone would do this, mainly because of the equivalent proof required for thermal bridges. Individual verification becomes far too expensive, as even a single-family house quickly involves around 50 details, with a minimum cost of €150 (euros) per detail.
Nowadays, hardly anyone would do this, mainly because of the equivalent proof required for thermal bridges. Individual verification becomes far too expensive, as even a single-family house quickly involves around 50 details, with a minimum cost of €150 (euros) per detail.
Of course, a masonry garage attached to the house is possible, even with a passive house. What thermal bridge are you referring to?
The wall between the house and the garage is insulated just like the other exterior walls.
A central ventilation system is not completely silent. I hear ours at night when everything is quiet. Adjusting the airflow downwards should make it tolerable for your fiancée as well.
In our case, each air outlet is separately ducted, so there is no noise transmission.
I wouldn’t recommend a decentralized ventilation system if you are sensitive to noise. There are frequent discussions in forums about sound issues related to decentralized systems.
I don’t feel any drafts. To notice airflow, I have to stand directly at the air outlet—without shoes on.
Whether necessary or not, I find controlled mechanical ventilation comfortable. You can ventilate when you want to, not just when you have to.
The wall between the house and the garage is insulated just like the other exterior walls.
A central ventilation system is not completely silent. I hear ours at night when everything is quiet. Adjusting the airflow downwards should make it tolerable for your fiancée as well.
In our case, each air outlet is separately ducted, so there is no noise transmission.
I wouldn’t recommend a decentralized ventilation system if you are sensitive to noise. There are frequent discussions in forums about sound issues related to decentralized systems.
I don’t feel any drafts. To notice airflow, I have to stand directly at the air outlet—without shoes on.
Whether necessary or not, I find controlled mechanical ventilation comfortable. You can ventilate when you want to, not just when you have to.
Similar topics