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.
S
Strahleman22 Jun 2020 12:24exto1791 schrieb:
Is the central ventilation system with heat pump also eligible for subsidies? Only when combined with a heat pump? What exactly does it depend on?Yes, subsidies are available when the controlled ventilation system and the heat pump are managed or controlled together. This can be done either through a shared interface (for example, as with Nibe) or even via smart home solutions (KNX, wireless). It still applies that the seasonal performance factor of the heat pump must be at least 4.5. More information can also be found on the BAFA website or in a datasheet from Zehnder.
Hello,
I was going to start a new thread, but since this one is exactly about the topic, I’ll just post here. Here’s the situation:
Our general contractor includes KfW55 energy standard as standard, regardless of whether a ventilation system is installed. Our building consultant advised against a central ventilation system because he is not convinced about the issue of germ-free air. Personally, I have no idea how to assess this topic. What definitely speaks against the central ventilation system from our point of view is the price of a hefty 19,120 EUR. Keep in mind, that is just for the ventilation system. We are building with 200 m² (2,150 sq ft) of living space.
It should be mentioned that our general contractor is positioned in the higher price range but has a very good (if not the best) reputation. Still, with that amount, you really start wondering if it’s really necessary. A decentralized ventilation system would be several thousand euros cheaper but doesn’t look very attractive. Also, we haven’t met anyone so far who says their decentralized ventilation system isn’t noisy.
One of our future neighbors, who apparently has built several times, is convinced by a different approach: no ventilation system at all, but using drying machines after completion to remove initial moisture and then simply ventilating by opening windows.
The idea we had that somehow connects these concepts: Our ground floor basically consists of one big room (from the front door straight through the ground floor into living, dining, and kitchen), then stairs up to the hall upstairs. Would it be conceivable to simply install one or two (more powerful?) decentralized ventilation units downstairs and upstairs to at least create some airflow when no one is at home? In the hallway, it wouldn’t bother anyone anyway. We could easily leave the doors to the other rooms open when no one is at home. Otherwise, we are absolute fresh air enthusiasts—our windows are almost always open. What do you think?
I was going to start a new thread, but since this one is exactly about the topic, I’ll just post here. Here’s the situation:
Our general contractor includes KfW55 energy standard as standard, regardless of whether a ventilation system is installed. Our building consultant advised against a central ventilation system because he is not convinced about the issue of germ-free air. Personally, I have no idea how to assess this topic. What definitely speaks against the central ventilation system from our point of view is the price of a hefty 19,120 EUR. Keep in mind, that is just for the ventilation system. We are building with 200 m² (2,150 sq ft) of living space.
It should be mentioned that our general contractor is positioned in the higher price range but has a very good (if not the best) reputation. Still, with that amount, you really start wondering if it’s really necessary. A decentralized ventilation system would be several thousand euros cheaper but doesn’t look very attractive. Also, we haven’t met anyone so far who says their decentralized ventilation system isn’t noisy.
One of our future neighbors, who apparently has built several times, is convinced by a different approach: no ventilation system at all, but using drying machines after completion to remove initial moisture and then simply ventilating by opening windows.
The idea we had that somehow connects these concepts: Our ground floor basically consists of one big room (from the front door straight through the ground floor into living, dining, and kitchen), then stairs up to the hall upstairs. Would it be conceivable to simply install one or two (more powerful?) decentralized ventilation units downstairs and upstairs to at least create some airflow when no one is at home? In the hallway, it wouldn’t bother anyone anyway. We could easily leave the doors to the other rooms open when no one is at home. Otherwise, we are absolute fresh air enthusiasts—our windows are almost always open. What do you think?
Abzug86 schrieb:
KfW55Abzug86 schrieb:
decentralized ventilationAbzug86 schrieb:
almost always open windowsWhy build an ultra-tight KfW55-standard house and then create openings in the building envelope with minimal heat recovery, or keep the windows open (tilted?) all day?
Abzug86 schrieb:
Topic of germ controlHow does he view germ control regarding fresh water and wastewater pipes? Stagnant water is said to be liquid death.MayrCh schrieb:
ultra-dichten Let’s not exaggerate MayrCh schrieb:
KfW55-Bau hinstellen As mentioned, because it’s the standard with our general contractor.
MayrCh schrieb:
und sich dann Löcher mit minimaler Wärmerückgewinnung in die Außenhaut hauen lassen As mentioned, because we find 19,120 EUR for a central ventilation system quite excessive.
MayrCh schrieb:
bzw. den ganzen Tag die Fenster auf (Kipp?) lassen? As mentioned, because we are fresh air enthusiasts.
S
Strahleman25 Jun 2020 22:05Are you building with a heat pump? If so, are you achieving a seasonal performance factor (SPF) of 4.5 or higher? If yes, apply for BAFA funding together with a controlled mechanical ventilation system with heat recovery (these must be managed together, for example, via wireless control). This way, you can get a 35% subsidy on the systems, which almost covers the cost of the ventilation system.
Otherwise, what does the energy consultant say about building to KfW 55 standard without controlled mechanical ventilation? Decentralized solutions always mean that you bring the noise of the fans into the room and the heat recovery efficiency will be close to zero or zero. But especially if you prefer fresh air, I would consider investing in a controlled mechanical ventilation system.
Otherwise, what does the energy consultant say about building to KfW 55 standard without controlled mechanical ventilation? Decentralized solutions always mean that you bring the noise of the fans into the room and the heat recovery efficiency will be close to zero or zero. But especially if you prefer fresh air, I would consider investing in a controlled mechanical ventilation system.
P
pagoni202025 Jun 2020 22:18@Abzug86
It will be similar for us, and I guess we’re a bit old-fashioned as well. I plan to have a controlled mechanical ventilation system shown to me somewhere, but at that price, I would probably drop the idea immediately.
Our kids have moved out, and we have an open gallery area. I think the need for air exchange is different compared to fully enclosed rooms on separate floors with 4-6 occupants.
In the back of my mind, I still have the option, similar to yours, of bringing air into or out of the house through the unfinished attic. I could retrofit this later on, almost invisibly and for little money, if some air exchange were necessary.
On the ground floor, we can open windows and ventilate almost the entire house; with floor plans featuring multiple enclosed rooms on 2-3 levels, you would really have to walk around to ventilate properly… I would find that quite inconvenient.
It will be similar for us, and I guess we’re a bit old-fashioned as well. I plan to have a controlled mechanical ventilation system shown to me somewhere, but at that price, I would probably drop the idea immediately.
Our kids have moved out, and we have an open gallery area. I think the need for air exchange is different compared to fully enclosed rooms on separate floors with 4-6 occupants.
In the back of my mind, I still have the option, similar to yours, of bringing air into or out of the house through the unfinished attic. I could retrofit this later on, almost invisibly and for little money, if some air exchange were necessary.
On the ground floor, we can open windows and ventilate almost the entire house; with floor plans featuring multiple enclosed rooms on 2-3 levels, you would really have to walk around to ventilate properly… I would find that quite inconvenient.
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