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.
Pinky0301 schrieb:
A mechanical ventilation system with heat recovery is not mandatory; there are other options like trickle vents in the window frame (although I don’t know what energy efficiency rating can be achieved with those). A mechanical ventilation system is very comfortable and worth every cent for me. But ultimately, that’s your decision.
I wouldn’t call it “new.” I know... There are simply so many differing opinions on this topic, which makes it incredibly difficult.
I’m of the opinion: If I do it, I do it properly! (central system).
Either: yes – Energy Efficiency Standard 55 and ventilation
Or: no – Energy Efficiency Standard 70 and no ventilation. However, I find it hard to accept because the airtightness of a Standard 70 house hardly differs from a Standard 55 house, so the mold problem doesn’t really decrease... On the other hand, there are also many builders who believe that you can easily ventilate a Standard 70 house manually.
exto1791 schrieb:
What is the lifespan of such a central system? What happens if this system fails? How quickly can you get a technician? A repair costing around 2k is certainly possible if something doesn’t work...
I just think in this area: if it’s not necessary, it doesn’t have to be, especially if it causes unnecessary costs... First of all, try not to panic so much..! If the system fails, no air will come into the house, and you won’t be able to breathe and will die. But seriously... if the system fails, things work the same way as they do for people without a ventilation system. Of course, something can break in a controlled residential ventilation system, but the technology is simple, and I can’t think of any component that would come close to costing that much... It basically consists of two fans and some electronics/sensors. You will definitely have to replace the system at some point, but we are probably talking more about 20 years than 10...
And yes, you can “easily” ventilate manually, but with controlled residential ventilation you don’t have to. Personally, I would never want to give it up again, regardless of the building type. In my opinion, there is no greater comfort gain in a single-family house than a ventilation system.
On the topic of maintenance intensity:
Photovoltaics: What maintenance?!
Heat pump: An air-to-water heat pump certainly requires less maintenance in terms of frequency and cost compared to gas (no chimney sweep, no typical wear parts, etc.). Durability with good design is at least equal to current gas condensing boilers (poor design and very frequent on/off cycling is, of course, the death of a heat pump, but this is unfortunately often wrongly done by traditional gas/oil heating people...). For ground-source heat pumps, durability is probably even longer, as the energy source is quite constant without major temperature fluctuations and there is no outdoor unit.
Yes, in a new build, a decentralized system is basically unsuitable and has mostly drawbacks (many holes in the walls, noisier operation, and as far as I know, no enthalpy heat exchangers available for those, etc.). Mechanical ventilation with heat recovery doesn’t dry the air; it brings in dry air from outside, and because of the large air exchange, when the outside air is dry, the indoor air also becomes drier accordingly.
Solution 1: Use an enthalpy heat exchanger, which recovers some humidity (this may not always be sufficient, but it increases indoor humidity by several percentage points).
Solution 2: Do as homeowners without mechanical ventilation do: switch off the system (which is not an option for me) or reduce the airflow somewhat in winter.
Solution 3: Actively humidify.
Personally, I prefer a combination. I consider an enthalpy heat exchanger an absolute must-have; it helps without any disadvantages (and you can often skip installing a pre-heater since with an enthalpy heat exchanger, frost buildup is almost entirely prevented). Additionally, I have a humidifier located in an exhaust room that adds moisture to the air, which the system then distributes through the enthalpy exchanger throughout the house. This is only necessary for a few weeks a year when it’s really cold and the outside air is extremely dry. I don’t want to reduce the ventilation rate because I really enjoy the fresh air that is constantly supplied throughout the house, for example, right after waking up in the morning.
Regarding dust: You will have less dust because significantly less enters the house! The air passes through filters, whereas with regular window opening, everything flying around outside gets indoors, including insects. This is another advantage of mechanical ventilation: in summer, there are far fewer insects inside the house since you don’t feel the need to open all the windows wide because the indoor air is uncomfortable.
Solution 1: Use an enthalpy heat exchanger, which recovers some humidity (this may not always be sufficient, but it increases indoor humidity by several percentage points).
Solution 2: Do as homeowners without mechanical ventilation do: switch off the system (which is not an option for me) or reduce the airflow somewhat in winter.
Solution 3: Actively humidify.
Personally, I prefer a combination. I consider an enthalpy heat exchanger an absolute must-have; it helps without any disadvantages (and you can often skip installing a pre-heater since with an enthalpy heat exchanger, frost buildup is almost entirely prevented). Additionally, I have a humidifier located in an exhaust room that adds moisture to the air, which the system then distributes through the enthalpy exchanger throughout the house. This is only necessary for a few weeks a year when it’s really cold and the outside air is extremely dry. I don’t want to reduce the ventilation rate because I really enjoy the fresh air that is constantly supplied throughout the house, for example, right after waking up in the morning.
Regarding dust: You will have less dust because significantly less enters the house! The air passes through filters, whereas with regular window opening, everything flying around outside gets indoors, including insects. This is another advantage of mechanical ventilation: in summer, there are far fewer insects inside the house since you don’t feel the need to open all the windows wide because the indoor air is uncomfortable.
Tego12 schrieb:
Yes, a decentralized system has no place in a new build; it actually has only disadvantages (many holes in the walls, louder operation, I haven’t heard of enthalpy heat exchangers being used there, etc.). The controlled mechanical ventilation with heat recovery does not dry the air itself but brings in dry air from outside, and due to the high air exchange rate, the indoor air becomes correspondingly drier when the outside air is dry.
Solution 1: Enthalpy heat exchanger, which recovers some moisture (not necessarily enough, but it raises the indoor humidity by several percent).
Solution 2: Do what homeowners without controlled mechanical ventilation do: turn off the system (which wouldn’t be a solution for me) or reduce the airflow somewhat in winter.
Solution 3: Actively humidify.
Personally, I prefer a combination. I consider an enthalpy heat exchanger essential, as it helps without any downsides (plus you can avoid a possible pre-heating coil since frost buildup is almost impossible with an enthalpy exchanger). Additionally, I have a humidifier placed in an exhaust room that humidifies the air, and the system distributes it through the enthalpy heat exchanger throughout the house (but this is only needed for a few weeks a year when it’s really cold and the outside air is extremely dry). I don’t want to reduce the ventilation rate because I enjoy the fresh air that is continuously supplied throughout the house, for example, right after waking up in the morning.
Regarding dust: you get less dust inside because less dust enters! The air passes through filters; with normal window opening, everything that is floating around outside—including insects—gets inside. That is another direct advantage of controlled mechanical ventilation: significantly fewer insects in the house during summer, as there is no need to open all the windows wide because the indoor air quality is good. KfW 55 surcharge + central system with enthalpy heat exchanger possible for 18k? How high were your costs?
exto1791 schrieb:
KfW 55 surcharge + central system with enthalpy heat exchanger for 18k possible? How high were your costs?To be honest, I have no idea because it was included in my fixed price from the start. I have a Zehnder Q350 myself, but the surcharge for the enthalpy heat exchanger was definitely under 1,000€
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