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.
exto1791 schrieb:
I just find it very difficult: They all probably build around 120 houses per year, all KfW 70 standard, and apparently none of them had any problems with it, or “miss” this ventilation system. They don’t have to live in those houses themselves, and they probably have trickle vents installed in the window frames. As for the residents: you don’t miss what you don’t know. I always experience this at my in-laws: house built in 2013, well sealed without any type of ventilation. When we sit there in the living room with the kids and sometimes uncle/aunt, 8 people in total, after half an hour you start feeling suffocated – then every 30 minutes all the windows and doors have to be opened wide because half the group is already about to fall asleep. Then you get a cold shock, become alert again, only to slowly doze off again once the windows are closed. The KfW standard has nothing to do with this; it’s 90% about how well and tightly the windows and doors are sealed. My wife always gets headaches after a day like that – but that may have other causes as well...
exto1791 schrieb:
So the building material is not decisive for the indoor climate, or can a certain building material not prevent mold? A building material does matter for the indoor climate, but ultimately it’s the interaction of all factors that counts. The statement “I’m building with Poroton bricks, so it can’t get moldy” is simply wrong.
exto1791 schrieb:
Is it possible for me to look for a specialist to install the ventilation system? Does this have to be installed during the main house construction, or can it (a central system) also be installed afterward, or do I need to coordinate this with my general contractor? Of course, a third-party company can also install the ventilation system. However, the scheduling must be very precise. The ducts for the ventilation system are usually installed on the unfinished subfloor, meaning they need to be placed before the underfloor heating and the subsequent screed. So the installation date has to be well planned. It is no longer possible to install this afterward.
In the past, cars had manual window cranks and phones with cords, yet no one missed these or had "problems" with them. People simply went to the phone booth on the corner.
You don’t miss what you’re not used to.
The problem with modern house building is that, due to current and intentionally tight construction methods, there is no natural airflow (unlike the houses of our parents and grandparents). In other words, nowadays you need some form of mechanical ventilation if you want "fresh air" inside the house. As Lumpi pointed out, nobody can maintain the correct ventilation intervals. Another difficulty is that hardly anyone changes their ventilation habits, and they continue to ventilate as they did when living in a rental apartment before building their own home.
This becomes obvious quickly when using a measuring device.
Of course, people always claim that they ventilate correctly and sufficiently, and general contractors say, "You just need to ventilate." Usually, they don’t know any better. As long as there is no change in mindset, houses will continue to be built the way they always have been. Why change when it has always been done that way?
The statement about dirty ducts is simply the height of ignorance. Certainly, the ducts get dirty over time, but this mainly applies to the exhaust air. Experience shows that even after 10 years, the ventilation ducts for the supply air still look like new. This is no surprise since only fresh and filtered air enters there. Dirt has no place inside—provided, of course, that you do not live near a coal mine and that filters are replaced according to the manufacturer's recommendations or when the system signals a full filter.
You don’t miss what you’re not used to.
The problem with modern house building is that, due to current and intentionally tight construction methods, there is no natural airflow (unlike the houses of our parents and grandparents). In other words, nowadays you need some form of mechanical ventilation if you want "fresh air" inside the house. As Lumpi pointed out, nobody can maintain the correct ventilation intervals. Another difficulty is that hardly anyone changes their ventilation habits, and they continue to ventilate as they did when living in a rental apartment before building their own home.
This becomes obvious quickly when using a measuring device.
Of course, people always claim that they ventilate correctly and sufficiently, and general contractors say, "You just need to ventilate." Usually, they don’t know any better. As long as there is no change in mindset, houses will continue to be built the way they always have been. Why change when it has always been done that way?
The statement about dirty ducts is simply the height of ignorance. Certainly, the ducts get dirty over time, but this mainly applies to the exhaust air. Experience shows that even after 10 years, the ventilation ducts for the supply air still look like new. This is no surprise since only fresh and filtered air enters there. Dirt has no place inside—provided, of course, that you do not live near a coal mine and that filters are replaced according to the manufacturer's recommendations or when the system signals a full filter.
I find all of this quite plausible...
I just don’t understand how this way of thinking can still prevail today...
It’s probably because most clients don’t give it any thought and just do whatever the general contractor says.
I’m going to make an appointment with a ventilation installer nearby to get his opinion. Then I can confront the general contractor with it.
The problem is that my whole perspective on the different general contractors has completely changed.
I just don’t understand how this way of thinking can still prevail today...
It’s probably because most clients don’t give it any thought and just do whatever the general contractor says.
I’m going to make an appointment with a ventilation installer nearby to get his opinion. Then I can confront the general contractor with it.
The problem is that my whole perspective on the different general contractors has completely changed.
Have you ever been inside a new building constructed according to the 2016 Energy Saving Ordinance or KfW55 standards?
General contractors usually opt for the simplest and least error-prone solutions. They don’t want to deal with complications later. Making a hole in the wall and installing a blower is super easy.
Of course, it is possible to live without ventilation in these new houses, and I haven’t seen any mold in them either. However, controlled mechanical ventilation improves things, and the air quality is noticeably better both in smell and feel.
General contractors usually opt for the simplest and least error-prone solutions. They don’t want to deal with complications later. Making a hole in the wall and installing a blower is super easy.
Of course, it is possible to live without ventilation in these new houses, and I haven’t seen any mold in them either. However, controlled mechanical ventilation improves things, and the air quality is noticeably better both in smell and feel.
exto1791 schrieb:
I just don’t understand how this way of thinking can still prevail nowadays... Because these things take decades. Most people still think heat pumps are something new and groundbreaking.
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